Minimize JPSS

JPSS (Joint Polar Satellite System)

JPSS is the next generation polar-orbiting operational environmental satellite system of the USA, procured by NOAA (National Oceanic and Atmospheric Administration) through NASA, with the following major objectives: 1) 2) 3) 4) 5) 6)

• Increase timeliness and accuracy of severe weather event forecasts

• Provide advanced atmospheric temperature, moisture and pressure profiles from space

• Provide advanced imaging capability to analyze fires, volcanoes, Gulf oil tracking and other adverse incidents

• Direct broadcast data to field terminals at hour scale latency

• Maintain continuity of climate observations and critical environmental data from the polar orbit.

1) JPSS consists of five satellites [Suomi-NPP, JPSS-1, JPSS-2, FF-1(Free Flyer-1), FF-2 (Free Flyer-2)], ground system and operations through 2028

- The JPSS mission is to provide global imagery and atmospheric measurements using polar-orbiting satellites

2) JPSS is a partnership between NOAA and NASA

- NOAA has final decision authority and is responsible for overall program commitment

- JPSS Program is the subset of JPSS managed by NASA

- NASA is the acquisition agent for the flight system (satellite, instruments and launch vehicle), ground system, leads program systems engineering, and program safety and mission assurance

- NOAA is responsible for operations, data exploitation and archiving, infrastructure.

3) The partnership is governed by the NOAA and NASA JPSS Management Control Plan

- The JPSS Program is executed in accordance with NPR 7120.5D (NASA Procedural Requirements) as a loosely-coupled program

4) NASA Categorization for JPSS-1 and JPSS-2

- Mission Category 1

- Risk Class B Mission

- Category 2 Expendable Launch Vehicle

5) NASA Categorization for FF-1 and FF-2

- Mission Category 2

- Risk Class C Mission

- Category 2 Expendable Launch Vehicle.

JPSS represents significant technological and scientific advances in environmental monitoring and will help advance environmental, weather, climate, and oceanographic science. JPSS's primary user, NOAA's NWS (National Weather Service), will use the JPSS data in models for medium- and long-term weather forecasting. JPSS will allow scientists and forecasters to monitor and predict weather patterns with increased speed and accuracy and is the key for continuity of long-standing climate measurements, allowing the study of long-term climate trends. JPSS will improve and extend climate measurements for 30 different EDRs (Environmental Data Records) of the atmosphere, land, ocean, climate and space environment.

The JPSS FF-1 (Free Flyer-1) spacecraft, to be launched in 2017, will accommodate the following instrument suite:

• TSIS (Total Solar Irradiance Sensor)

• A-DCS (Advanced Data Collection System)

• SARSAT (Search and Rescue) instruments.


Some background:

Since the 1960's the United States has operated two separate polar-orbiting environmental satellite programs:

- NOAA's POES (Polar-orbiting Operational Environmental Satellite) series

- USAF's DMSP (Defense Metrological Satellite Program) series.

• In 19994, the NPOESS (National Polar-orbiting Environmental Satellite System) program was created (under a Presidential Decision Directive) with the expectation that combining the civil (POES) and military (DMSP) programs would reduce duplication and result in cost savings

• A tri-agency IPO (Integrated Program Office) was formed to manage the program

- NOAA was responsible for overall program management of the converged system and satellite operations

- USAF (United States Air Force) was responsible for acquisition

- NASA responsible for technology insertion.

• Program was to launch NPP (NPOESS Preparatory Project) to reduce risk

• The first NPOESS contract awarded in 2002

- Program estimated to cost $7 billion through 2018

- Scope of program included six satellites (three orbits) each hosting up to 13 instruments, and a ground system.

• NPOESS program encountered significant challenges

- Technical challenges in VIIRS sensor development

- Program cost growth

- Schedule delays

• By 2005, the cost had increased to $10 billion and the first launch had to be delayed from 2008 to 2010

• A decision to restructure the program was made in 2006

- Driven by a Nunn-McCurdy breach

- Satellites reduced from six to four (in two orbits) – EUMETSAT would provide mid-morning orbit

- Number of instruments reduced from 13 to nine

• Even after restructure, program continued to encounter issues

- Technical issues continued with VIIRS

- Management challenges with governance structure

- Cost increases – expected to exceed $14 billion

- Further schedule delays. The major challenge of NPOESS was jointly executing the program between three agencies of different size with divergent objectives and different acquisition procedures.

• In 2009, EOP/OSTP (Executive Office of the President/Office of Science and Technology Policy) led a task force to investigate management and acquisition options that would improve NPOESS. An IRT (Independent Review Team) concluded that the current NPOESS program, in the absence of managerial and funding adjustments, has a low probability of success and data continuity is at extreme risk. The Office of Science and Technology, with the Office of Management and Budget and the National Security Council, as well as representatives from each agency, examined various options to increase the probability of success and reduce the risk to data continuity.

In February 2010, with the release of the FY2011 President's Budget, OSTP announced the restructure of the NPOESS program – specifically, NOAA and DoD would be responsible for different orbits. 7) 8) 9)

- NOAA responsible for the afternoon orbit - JPSS

- DoD responsible for the early morning orbit - DWSS (Defense Weather Satellite System)

- Partnership with EUMETSAT would continue for mid-morning orbit

- Both agencies would share a common ground system.

• Restructure codified and executed through:

- National Space Policy

- Administration's Implementation Plan for Polar-orbiting Environmental Satellites

- NPOESS Deputies Meeting Summary

- Series of DoD Acquisition Decision Memorandums: Continued support to NPP; Close out of the IPO; Transfer of sensors and ground system from DoD to NOAA/NASA; Identified sensor suite on DWSS.

The Administration decision for the restructured JPSS (Joint Polar Satellite System) will continue the development of critical Earth observing instruments required for improving weather forecasts, climate monitoring, and warning lead times of severe storms. NASA’s role in the restructured program will be modeled after the procurement structure of the successful POES (Polar Operational Environmental Satellite) and GOES (Geostationary Operational Environmental Satellite) programs, where NASA and NOAA have a long and effective partnership. The partner agencies are committed to maintaining collaborations towards the goal of continuity of Earth observations from space.

Note: Since this transition, the DWSS satellite program has been canceled and replaced with the WFO (Weather Follow On) program. As part of the restructuring of the program, some responsibilities have been shifted to accomplish the environmental and climate observing missions. For JPSS, NASA’s Goddard Space Flight Center has the responsibility for the acquisition for the afternoon orbit satellites, along with the acquisition, system engineering and integration for the Ground System (GS) for the US next-generation of weather and climate satellites. After the start of the JPSS program, the DWSS, which was to be responsible for the early morning orbit satellites, was cancelled due to lack of funding. EUMETSAT (European Organization for the Exploitation of Meteorological Satellites) will be relied on for the mid-morning orbit satellites of the MetOp series (Ref. 61).



Figure 1: JPSS implements US civil commitment inter-agency and international agreements to afford a 3-orbit global coverage (image credit: NOAA, NASA)


Figure 2: JPSS overview (image credit: NOAA, NASA, Ref. 1)

The restructured Joint Polar Satellite System is planned to provide launch readiness capability in FY 2015 and FY 2018 (with launches of JPSS-1 in 2017 and JPSS-2 in 2022, respectively) in order to minimize any potential loss of continuity of data for the afternoon orbit in the event of an on orbit or launch failure of other components in the system. Final readiness dates will not be baselined until all transition activities are completed.


Figure 3: Continuity of polar operational satellite programs as of December 2012 (image credit: NOAA, Ref. 4)


Figure 4: JPSS program projection within the overall polar weather program missions as of mid-2012 (image credit: NASA, NOAA, Ref 1)


Figure 5: Simplified schematic composition of the JPSS system (image credit: NASA, NOAA)



The JPSS spacecraft are procured at NASA/GSFC. NASA in turn awarded a contract to BATC (Ball Aerospace and Technologies Corporation) of Boulder, CO to design and develop the JPSS-1 spacecraft bus, the OMPS (Ozone Mapping and Profiler Suite) instrument, integrating all instruments, and performing satellite-level testing and launch support. 10) 11)

JPSS-1, a clone of the Suomi-NPP (also referred to as SNPP) satellite, employs the BCP-2000 (Ball Commercial Platform -2000) spacecraft bus.

• 3-axis stabilized (50 arcsec control, 21 arcsec knowledge, and 75 m position)

• Launch mass of 2540 kg

• Power: 1932 W (BOL)

• For JPSS-1, Ball is converting the NPP spacecraft design from IEEE 1394 (FireWire) to a SpaceWire databus protocol for use by the CrIS and the VIIRS instruments.

• Ka-band 300 Mbit/s downlink. In addition, a backup Ka-band SMD (Science Mission Data) downlink is added for TDRSS (Tracking and Data Relay Satellite System) transmissions (to improve future latency issues). 12)

• X-band 15 Mbit/s HRD (High Rate Data) direct broadcast to users

• Lifetime: 7 years


Figure 6: Illustration of the deployed JPSS-1 spacecraft (image credit: NASA, NOAA)


Figure 7: JPSS-1 spacecraft zenith deck layout (left) and nadir deck layout (right), image credit: BATC 13)

In December 2012, a four-day delta Critical Design Review (dCDR) of work was conducted at BATC with representatives of NASA and NOAA and the instrument providers. With this successful review, the spacecraft has now been approved to proceed into implementation. 14)


Launch: A launch of the JPSS-1 spacecraft is planned for 2017 (Ref. 3).

Orbit: Sun-synchronous orbit, altitude of 833 km (±17 km), inclination = 98.7º, period = 101 minutes, ground track: 20 km repeat accuracy at the equator with 20 day repeat cycle, LTAN = 13:30 hours ±10 minutes.



Sensor complement: (ATMS, CrIS, CERES, OMPS, VIIRS)

Contracts with instrument developers: NASA signed the final contract on June 19, 2012 with Raytheon Space and Airborne Systems of El Segundo, CA, for the VIIRS (Visible Infrared Imager Radiometer Suite) instrument. The ATMS (Advanced Technology Microwave Sounder) contract was signed with Northrop Grumman Electronic Systems of Azusa, CA, in April, 2012. NASA completed the JPSS-1 spacecraft and the OMPS (Ozone Mapping and Profiler Suite) instrument contract with Ball Aerospace in 2011. The contract to Raytheon Intelligence and Information Systems for the JPSS Ground System was also completed in 2011, as was the CrIS (Cross-track Infrared Sounder) instrument contract with ITT Exelis (Ref. 10). 15)


Figure 8: JPSS-1 flight configuration and allocation of the instrument suite, identical to the one of NPP (image credit: NASA, NOAA) 16)

Note: Due to JPSS-1 (NPP Clone) bus limitations, the JPSS FF-1 (JPSS Free Flyer-1) mission was developed, a complementary mission to the JPSS-1 satellite. It will fly the instruments, which were originally planned for the former NPOESS satellites, but could not be accommodated on the JPSS satellites.

JPSS Free Flyer-1 will accommodate the following instruments:

• TSIS (Total Solar Irradiance Sensor)

• A-DCS (Advanced Data Collection System)

• SARSAT (Search and Rescue) instruments.


ATMS (Advanced Technology Microwave Sounder)

ATMS, of Suomi-NPP heritage, provides sounding observations necessary to retrieve atmospheric temperature and moisture profiles for civilian operational weather forecasting, as well as continuity of these measurements for climate monitoring. In addition to temperature and moisture profiles, some of ATMS-derived products include integrated water vapor content, cloud liquid water content, precipitation rate, snow cover and sea ice concentration.

ATMS is the next generation cross-track microwave sounder that will combine the capabilities of current generation microwave temperature sounders AMSU-A, AMSU-B and AMSU-B/MHS, into a single instrument. The ATMS draws its heritage directly from AMSU-A/B, but with reduced volume, mass and power. The ATMS has 22 microwave channels to provide temperature and moisture sounding capabilities. Sounding data from CrIS and ATMS will be combined to construct atmospheric temperature profiles at 1 degree Kelvin accuracy for 1 km layers in the troposphere and moisture profiles accurate to 15% for 2 km layers. Higher (spatial, temporal and spectral) resolution and more accurate sounding data from CrIS and ATMS will support continuing advances in data assimilation systems and NWP models to improve short- to medium-range weather forecasts beyond three days. - The ATMS instrument was developed at Northrop Grumman Electronic Systems of Azusa, CA.


Figure 9: Photo of the ATMS instrument (image credit: MIT/LL, NASA) 17)

ATMS instrument dimensions

70 cm x 60 cm x 40 cm

Instrument mass

75 kg

Operational average power (peak)

100 W (200 W)

Data rate

30 kbit/s

Absolute calibration accuracy

0.6 K

Maximum nonlinearity

0.35 K

Frequency stability

0.5 MHz

Pointing knowledge



0.3/0.5/1.0/2.0 K

Swath width

~2600 km

Table 1: Summary of key instrument parameters 18)


Figure 10: Functional block diagram of ATMS (image credit: NASA)


frequency (GHz)

Max. bandwidth (GHz)

Center frequency stability (MHz)

Temp. sensitivity NEΔT (K)

Calibration accuracy (K)

Static beamwidth (º)

Quasi polarization

Characterization at nadir
(reference only)









Vapor 100 mm









Vapor 500 mm



























Surface air


53.596 ±0.115







4 km ~700 mb









9 km ~ 400 mb









11 km ~ 250 mb









13 km ~ 180 mb









17 km ~ 90 mb


57.290344 ±0.217







19 km ~ 50 mb


57.290344 ±0.3222 ±0.048







25 km ~ 25 mb


57.290344 ±0.3222







29 km ~ 10 mb


57.290344 ±0.3222







32 km ~ 6 mb


57.290344 ±0.3222







37 km ~ 3 mb









H2O 150 mm









H2O 18 mm









H2O 8 mm









H2O 4.5 mm









H2O 2.5 mm









H2O 1.2 mm









H2O 0.5 mm

Table 2: Channel characteristics of ATMS

Instrument calibration: The instrument includes on-board calibration sources viewed by the reflectors during each scan cycle. The calibration of the ATMS is a so-called through-the-aperture type, two-point calibration subsystem. The warm reference point is a microwave blackbody target whose temperature is monitored. In addition, cold space is viewed during each scan cycle. Both calibrations provide for the highly accurate microwave sounding measurements required by the operational and science applications of ATMS data.

There are three antenna beamwidths. The temperature sounding channels are 2.2º (Nyquist-sampling in both along-scan & down-track directions) while the humidity channels are 1.1º. Channels 1 and 2 have a larger beam width of 5.2º. This is due to the limited volume available on the spacecraft for ATMS.

The ATMS post-launch calibration/validation:

• Tasks within the phases can be categorized:

- Sensor evaluation: interference, performance evaluation, etc.

- TDR/SDR verification: geolocation, accuracy, etc.

- SDR algorithm tunable parameters: bias correction, space view sector, etc.

• Activation phase: Sensor is turned on and a sensor functional evaluation is performed; ATMS is collecting science data

• Checkout phase: Performance evaluation and RFI evaluations

• Intensive Cal/Val: Verification of SDR attributes such as geolocation, resampling, brightness temperature accuracy (simultaneous nadir overpass, double difference, radiosondes/NWP simulations, aircraft verification campaigns), and satellite maneuvers.


Figure 11: Atmospheric transmission at microwave wavelengths (image credit: MIT/LL)

ATMS provides 3 EDRs (Environmental Data Records) with CrIS:

• Atmospheric vertical moisture profile

• Atmospheric vertical temperature profile

• Pressure (surface/profile).


CrIS (Cross-track Infrared Sounder)

CrIS is the first in a series of advanced operational sounders that will provide more accurate, detailed atmospheric temperature and moisture observations for weather and climate applications. This high-spectral resolution infrared instrument will take 3-D images of atmospheric temperatures, water vapor and trace gases. It will provide over 1,000 infrared spectral channels at an improved horizontal spatial resolution and measure temperature profiles with keen vertical resolution to an accuracy approaching 1 K (the absolute temperature scale). This information will help significantly to improve climate prediction, including both short-term weather "nowcasting" and longer-term forecasting. It will also provide a vital tool for NOAA to take the pulse of the planet continuously and assist in understanding major climate shifts. The CrIS instrument is developed by ITT Exelis, Fort Wayne, Indiana.


Figure 12: Photo of the CrIS instrument (image credit: NOAA) 19)

CrIS, of HIRS/4 (POES) and AIRS (Aqua) heritage, is a high-spectral and high-spatial resolution infrared sounder for atmospheric profiling applications. The overall objective is to perform daily measurements of Earth's upwelling infrared radiation to determine the vertical atmospheric distribution (surface to the top of the atmosphere) of temperature (profiles to better than 1 K accuracy in the lower troposphere and lesser accuracy at higher altitudes), moisture (profiles to better than 20-35% accuracy depending on altitude) and pressure (profiles to better than 1.0% accuracy ) with an associated 1.0 km vertical layer resolution. The Michelson interferometer sounder has 1305 spectral channels, it covers a spectral range of 650-2550 cm-1 (or 3.9 to 15.4 µm), with a spectral resolution of 0.6525 cm-1 (LWIR), and a ground spatial resolution (IFOV) of 14.0 km (from an orbital altitude of 833 km). Each scan (with an 8-second repeat interval) includes views of the internal calibration target (warm calibration point), and a deep space view (cold calibration point). The overall instrument data rate is <1.5Mbit/s. Only photovoltaic detectors are used in the CrIS instrument. The detectors are cooled to approximately 81K using a 4-stage passive cooler with no moving parts. They have a low-risk heritage design of over 50 space units. The IFOVs are arranged in a 3 x 3 array. The swath width is 2200 km (FOV of ±50º), with 30 Earth-scene views.

The CrIS optical system was designed to provide an optimum combination of optical performance and compact packaging. Its key subsystems include a step and settle two-axis scene selection module with image motion compensation capability, a full-aperture internal calibration source, a large-aperture Michelson interferometer, a three-element all reflective telescope, a cooled aft optics module, a multiple-stage passive cooler, and an attached electronics assembly. The interferometer uses a flat-mirror Michelson configuration equipped with a dynamic alignment system to minimize misalignments within the interferometer and has a maximum optical path difference of ±0.8 cm. 20)

The “unapodized spectral resolution” requirement is defined as I/(2L), where L is the maximum optical path difference from ZOND (Zero Path Difference) to MPD (Maximum optical Path Difference). The on-axis unapodized spectral resolution for each spectral band shall be ≤to the values given in Table 3. Since L determines the unapodized spectral resolution, the nominal value for L is also given in the table. 21)

Requirement/Spectral band




Channel center wavenumber range

650-1095 cm-1
15.38-9.14 µm

1210-1750 cm-1
8.26-5.71 µm

2155-2550 cm-1
4.64-3.92 µm

No of channels




Unapodized spectral resolution, nominal L

≤ 0.625, 0.8 cm

≤ 1.25, 0.4 cm

≤ 2.5, 0.2 cm

Absolute spectral uncertainty

< 10 (5) PPM

< 10 (5) PPM

< 10 (5) PPM

Characterize self-apodized ILS for each spectral bin




ILS (Instrument Line Shape) shape uncertainty

< 1.5% FWHM

< 1.5% FWHM

< 1.5% FWHM

ILS shape stability over 30 days

< 1% FWHM

< 1% FWHM

< 1% FWHM

Table 3: Spectral requirements of the CrIS instrument

Instrument: The CrIS instrument consists of 6 modular assemblies: optical bench, scanning telescope, interferometer, PV focal plane arrays, 4-stage passive cooler, and electronics. The optical bench provides a stable structure for mounting all of the other assemblies. The scanning telescope scans the Earth views, the ICT (Internal Calibration Target), and deep space, and focuses the IR energy into the interferometer. The interferometer sequentially "breaks" the IR energy into the spectral bands, much like the "rainbow" from a DVD surface. The PV detectors sense the sequenced IR energy (from the interferometer), and provide an electrical signal corresponding to the incoming IR energy. The 4-stage cooler is used to cool the detectors, and hence reduce any spurious detector noise. The electronics assembly controls the instrument. It also conditions and formats the telescope scan and detector signals for output to the spacecraft. 22) 23)

• 8 cm clear aperture

• A collimator is used to perform the spatial and spectral characterizations

• 4-stage split-patch passive cooler (81 K for LWIR patch temperature, 98 K for MWIR/SWIR patch)

• High-performance PV (photovoltaic) detectors

• 3 x 3 arrays (14 km IFOVs)

• Three spectral bands (SWIR, MWIR, TIR), co-registered so that the FOVs of each band see the radiance from the same region of the Earth's atmosphere

• All-reflective telescope

• Proven Bomem plane-mirror Michelson interferometer with dynamic alignment

• Deep-cavity internal calibration target based on MOPITT design

• Two-axis scene selection module with image motion compensation

• A modular design (allowing for future addition of an active cooler and >3 x 3 arrays

The flight configuration for the CrIS DPM (Detector Preamplifier Module) consists of three spectrally separate (SWIR, MWIR and LWIR) FPAAs (Focal Plane Array Assemblies), three (SWIR, MWIR and LWIR) signal flex cable assemblies, a warm signal flex cable/vacuum bulk head assembly, and the DPM warm electronics CCAs (Circuit Card Assemblies). The FPAAs are cooled to cryogenic temperature (98 K SWIR, MWIR, 81 K for LWIR) by the detector cooler module. The cryogenic portions of the DPM (FPAAs, and signal flex cable assemblies) mate to the ambient temperature portions of the DPM (warm signal flex cable assembly and the ambient temperature portions of the transimpedance amplifier, mounted within the CCAs) through the vacuum bulk head assembly mounted on the detector cooler assembly housing. 24)

Spectral bands
- TIR (also known as LWIR)

Total of 1305 channels
(2155 - 2550 cm-1) or 4.64 - 3.92 µm, 159 channels
(1210 - 1750 cm-1) or 8.62 - 5.7 µm, 433 channels
(650 - 1095 cm-1) or 15.3 - 9.1 µm, 713 channels

Spectral resolution:

(<2.5 cm-1) or 5.4 nm (at 4.64 µm) to 38.4 nm (at 3.92 µm)
(<1.25 cm-1) or 92.8 nm (at 8.62 µm) to 40.6 nm (at 5.7 µm)
(<0.625 cm-1) or 146 nm (at 15.3 µm) to 51.7 nm (at 9.1 µm)

Band-to-band co-registration
IFOV motion (jitter)
Mapping accuracy

< 1.4%
< 50 µrad/axis
< 1.5 km

Number of IFOVs

3 x 3 at 14 km diameter for each band

IFOV diameter

14 km

Absolute radiometric uncertainty

<0.8% (SWIR), <0.6% (MWIR), <0.45% (TIR)

Radiometric stability

<0.65% (SWIR, <0.5% (MWIR), <0.4% (TIR)

Instrument size

71 cm x 88 cm x 94 cm

Instrument mass, average power, data rate

152 kg, 124 W, 1.5 Mbit/s (average), 1.5 Mbit/s (max)

Table 4: Key performance characteristics of CrIS

CrIS calibration: The calibration of the interferometer is accomplished with both LASER wavelength calibration, and also with a Neon bulb spectral calibration. The ICT (Internal Calibration Target) consists of a highly emissive, deep-cavity blackbody, utilizing a flight-proven, MOPITT (Measurement of Pollution in the Troposphere)-heritage design. Temperature knowledge of the ICT is better than 80mK. A passive vibration isolation system is included to allow instrument operation in a 50mG environment. The instrument optics are thermally decoupled from both the structure and the instrument electronics. The overall instrument design is modular, which allows for parallel assembly and rapid instrument integration.

The primary data product of the CrIS instrument are interferograms collected from 27 infrared detectors that cover 3 IR bands and 9 FOVs. 25)

Data of CrIS will be combined in particular with those of ATMS to construct atmospheric temperature profiles at 1 K accuracy for 1 km layers in the troposphere and moisture profiles accurate to 15% for 2 km layers. 26)


CERES (Clouds and the Earth's Radiant Energy System)

The CERES measurements seek to develop and improve weather forecast and climate models prediction. CERES will help provide measurements of the space and time distribution of the Earth's Radiation Budget (ERB) components, further developing a quantitative understanding of the links between the ERB and the properties of the atmosphere and surface that define the budget. The observations from CERES are essential to understanding the effect of clouds on the energy balance (energy coming in from the sun and radiating out from the earth), which is one of the largest sources of uncertainty in our modeling of the climate. NASA/LaRC is procuring the CERES instrumentation.

Background: The ERB measurements provided by the CERES instruments are key elements in the production of ERB Climate Data Records; these records that have been produced on a continuous basis for more than 20 years, including measurements from the ERBE (Earth Radiation Budget Experiment) prior to CERES. Maintaining the continuity of these measurements and the ERB records are part of an overarching NOAA program objective to sustain continuity and enhance Earth observation analysis, forecasting and climate monitoring capabilities from global polar-orbiting observations.

The level of measurement accuracy necessary to assess climate change and understand the interactions of natural and anthropogenic effects occurring on a decadal time scale requires that instruments making these measurements overlap on orbit for sufficient periods to achieve transfer of calibration from one instrument to the next. The CERES instruments currently operating on the EOS (Earth Observing System) Terra and Aqua missions have provided over 10 years of accurate measurements of the solar reflected and Earth emitted energy.

The CERES FM5 instrument is currently flown on the Suomi-NPP mission while the CERES FM6 instrument is planned for launch on the JPSS-1 mission. These missions should provide continuity of ERB measurements into the next decade.

CERES Flight Model (FM)




PFM (Proto-Flight Model)

TRMM (Tropical Rainfall Measuring Mission)

Nov. 27, 1997

PFM performed for 8 months, then PFM was turned off from Aug. 1998 to June 2002, when it was on to provide a comparison with CERES on Aqua

FM-1, -2

Terra (2 CERES instruments)

Dec. 19, 1999

SSO at 705 km altitude

FM-3, -4

Aqua (2 CERES instruments)

May 04, 2002

SSO at 705 km altitude



Oct. 28, 2011

SSO at 824 km altitude


JPSS (Joint Polar Satellite System)-1

Planned 2017

SSO at 833 km altitude

CBERS Follow-on

JPSS (Joint Polar Satellite System)-2

Planned 2022


Table 5: CBERS instruments on NASA missions


Figure 13: Overview of past, current and future missions with corresponding CERES instrument FM generations (image credit: NASA/LaRC) 27)

CERES instrument measures the reflected shortwave (SW) and Earth emitted radiances. The objectives are to continue a consistent database of accurately known fields of Earth’s reflected solar and Earth’s emitted thermal radiation. CERES satisfies four JPSS EDRs, in combination with other instruments. 28) 29) 30) 31) 32)

- Net solar radiation at TOA (Top of the Atmosphere)

- Downward longwave radiation at the surface

- Downward shortwave radiation at the surface

- Outgoing longwave radiation at TOA.

CERES instrument: The CERES instrument consists of three major subassemblies: 1) Cassegrain telescope, 2) baffle for stray light, and 3) detector assembly, consisting of an active and compensating element. Radiation enters the unit through the baffle, passes through the telescope and is imaged onto the IR detector. Uncooled infrared detection is employed.


Figure 14: Cross section of the CERES telescope (image credit: NASA/LaRC) 33)

A CERES instrument consists of 2 identical scanners: total mass of 114 kg , power = 100 W (average, 2 instruments), data rate = 20 kbit/s, duty cycle = 100%, thermal control by heaters and radiators, pointing knowledge = 180 arcsec. The design life is six years. CERES measures longwave (LW) and shortwave (SW) infrared radiation using thermistor bolometers to determine the Earth's radiation budget. There are three spectral channels in each radiometer:

- VNIR+SWIR: 0.3 - 5.0 µm (also referred to as SW channel); measurement of reflected sunlight to an accuracy of 1%.

- Atmospheric window: 8.0 - 12.0 µm (also referred to as LW channel); measurement of Earth-emitted radiation, this includes coverage of water vapor

- Total channel radiance in the spectral range of 0.35 - 125 µm;. reflected or emitted infrared radiation of the Earth-atmosphere system, measurement accuracy of 0.3%.

Limb-to-limb scanning with a nadir IFOV (Instantaneous Field of View) of 14 mrad, FOV = ±78º cross-track, 360º azimuth. Spatial resolution = 10-20 km at nadir. Each channel consists of a precision thermistor-bolometer detector located in a Cassegrain telescope.

Instrument calibration: CERES is a very precisely calibrated radiometer. The instrument is measuring emitted and reflected radiative energy from the surface of the Earth and the atmosphere. A variety of independent methods are used to verify calibration: 34)

• Internal calibration sources (blackbody, lamps)

• MAM (Mirror Attenuator Mosaic) solar diffuser plate. MAM is used to define in-orbit shifts or drifts in the sensor responses. The shortwave and total sensors are calibrated using the solar radiances reflected from the MAM's. Each MAM consists of baffle-solar diffuser plate systems, which guide incoming solar radiances into the instrument FOV of the shortwave and total sensor units.

• 3-channel deep convective cloud test

- Use night-time 8-12 µm window to predict longwave radiation (LW): cloud < 205 K

- Total - SW = LW vs Window predicted LW in daytime for same clouds <205 K temperatures

• 3-channel day/night tropical ocean test

• Instrument calibration:

- Rotate scan plane to align scanning instruments TRMM, Terra during orbital crossings (Haeffelin: reached 0.1% LW, window, 0.5% SW 95% configuration in 6 weeks of orbital crossings of Terra and TRMM)

- FM-1 and FM-2 instruments on Terra at nadir

Instrument heritage

Earth Radiation Budget Experiment (ERBE)

Prime contractor

Northrop Grumman Aerospace Systems

NASA center responsible

LaRC (Langley Research Center)

Three channels in each radiometer

Total radiance (0.3 to 100 µm); Shortwave (0.3 to 5 µm); Window (8 to 12 µm)


Limb to limb

Spatial resolution

20 km at nadir

Instrument mass, duty cycle

~45 kg/scanner, 100%

Instrument power

45 W (average) per scanner, 104 W (peak: biaxial mode) both scanners

Data rate

10.5 kbit/scanner (average)

Thermal control

Use of heaters and radiators

Thermal operating range

38±0.1ºC (detectors)

FOV (Field of View)

±78º cross-track, 360º azimuth


14 mrad

Instrument pointing requirements (3σ)

720 arcsec
180 arcsec
79 arcsec/6.6 sec

Instrument size

60 cm x 60 cm x 57.6 cm/unit

Table 6: CERES instrument parameters


Figure 15: Illustration of the CERES scanning radiometer (image credit: NASA/LaRC)


OMPS (Ozone Mapping and Profiler Suite)

Ozone in the atmosphere keeps the Sun's ultraviolet radiation from striking the Earth. The OMPS will measure the concentration of ozone in the atmosphere, providing information on how ozone concentration varies with altitude. Data from OMPS will continue three decades of climate measurements of this important parameter used in global climate models. The OMPS measurements also fulfill the U.S. treaty obligation to monitor global ozone concentrations with no gaps in coverage. OMPS is comprised of two sensors: (1) a nadir sensor, and (2) a limb sensor. Measurements from the nadir sensor are used to generate total column ozone measurements, while measurements from the limb sensor generate ozone profiles of the along-track limb scattered solar radiance.

OMPS is a limb- and nadir-viewing UV hyperspectral imaging spectrometer, designed and developed at BATC (Ball Aerospace & Technologies Corp.), Boulder, CO. The objective is to measure the total amount of ozone in the atmosphere and the ozone concentration variation with altitude. OMPS is of SBUV/2, TOMS and GOME heritage. Also, the OMPS limb-sounding concept/technology was already tested with ISIR (Infrared Spectral Imaging Radiometer) flown on Shuttle flight STS-85 (Aug. 7-19, 1997) and with SOLSE/LORE flown on STS-87 (Nov 19 - Dec. 5, 1997). The vertical resolution requirement demands an instrument design to include a limb-viewing sensor in addition to a heritage-based nadir-viewing sensor. 35) 36) 37)

OMPS on JPSS consists of three spectrometers:

• Nadir total column spectrometer covers a 50 km x 2800 km cross-track swath

• Nadir Profile Spectrometer provides performance over (250 km x 250 km) cell

• Limb sensor provides 1 km vertical sampling along three slits enabling ozone profile retrieval (Not provided on JPSS-1) 38)

Basic requirement

Measurement parameter


1) Global daily maps of the amount of ozone
in the vertical column of the atmosphere

Horizontal cell size
Long-term stability

50 km @ nadir
50-650 Dobson Units (DU)
15 DU or better
3 DU+0.5% total ozone or better
1% over 7 years or better

2) Provision of volumetric ozone concentration
profiles in specified segments of a vertical column
of the atmosphere with a 4-day revisit time

Vertical cell size
Horizontal cell size
Vertical coverage

Long-term stability

3 km
250 km
Tropopause height to 60 km
0.1 - 15 ppmv
Greater of (20%, 0.1 ppmv) below 15 km
Greater of (10%, 0.1 ppmv) above 15 km
3%, 15-50 km; 10% TH-15 and 50-60 km

Table 7: Overall mission requirements for OMPS ozone observations 39)

The OMPS instrument design features two coregistered spectrometers in the OMPS nadir sensor. The grating spectrometer and focal plane for total column measurements provide 0.45 nm spectral sampling across the wavelength range of 300 to 380 nm. The IFOV for the nadir cell of the total column measurement is 49.5 km cross track with an along-track reporting interval of 50 km. The total FOV cross track is 110º to provide daily global coverage.

Nadir-viewing instrument: The nadir sensor wide-field telescope feeds two separate spectrometers, a) for total column observations (mapper) and b) for nadir profiling observations. The total column spectrometer (300-380 nm spectral range, resolution of 0.45 nm) has a 2800 km cross-track swath (FOV = 110º and an along-track slit width of 0.27º) divided into 35 IFOVs of nearly equal angular extent. The CCD pixel measurements from its cross-track spatial dimension are summed into 35 bins. The summed bins subtend 3.35º (50 km) at nadir and 2.84º at ±55º. The along-track resolution is 50 km at nadir due to spacecraft motion during the 7.6 second reporting period. Measurements from this spectrometer are used to generate total column ozone data with a resolution of about 50 km x 50 km at nadir.

The nadir profile spectrometer (250-310 nm) has a 250 km cross-track swath corresponding to a single cell (cross-track FOV = 16.6º, and 0.26º along-track slit width). Co-registration with the total column spectrometer provides the total ozone, surface and cloud cover information needed for nadir profile retrievals. All of the cross-track pixels are binned spatially to form a single cell of 250 km x 250 km. Some instrument parameters are: 40)

- The telescope is a three mirror, near telecentric, off-axis design. The FOV is allowed to curve backward (concave in the anti-ram direction) by 8.5º at 55º cross-track in order to maintain straight entrance slits for the spectrometers. The mirrors are made with a glass which matches the thermal expansion of Titanium, are coated with an enhanced aluminum, and have an rms surface roughness of < 15A.

- Each of the 2 spectrometers has a CCD detector array, a split column frame transfer CCD 340 x 740 (column x row) operated in a backside illuminated configuration. The pixel pitch is 20 µm in the column (spectral) dimension and 25 µm in the row (spatial) dimension and every pixel in both the active and storage regions contains a lateral overflow antiblooming structure integrated into a 4-phase CCD architecture.

- Both spectrometers sample the spectrum at 0.42 nm, 1 nm FWHM end-to-end resolution

- Electronics: a) CCD preamplifier electronics in sensor housing, b) main electronics box performs A/D conversion and on-orbit pixel correction

- The OMPS nadir instrument has a mass of 12.5 kg and a size of 31 cm x 32 cm x 20 cm.

Polarization compensators are used to reduce polarization sensitivity for both Nadir instruments. Long-term calibration stability is monitored and corrected by periodic solar observations using a “Working” and “Reference” reflective diffuser system (similar to that successfully deployed on the TOMS sensors).


Figure 16: Photo of the OMPS instrument (image credit: BATC) 41)



Nadir Total Column (Nadir Mapper)

Nadir Profile (Nadir Profiler)

Spectral range

300-380 nm

250-310 nm

Spectral radiance range [photons/(s cm2 sr nm)]

9 el 3 (380 nm)
8 el 1 (308 nm)

2 el 3 (310 nm)
1.5 el 8 (252 nm)

Minimum SNR


35 (252 nm)
400 (310 nm)

Integration time

7.6 s

38 s

Spectral resolution

1 nm FWHM
2.4 samples/FWHM

1 nm FWHM
2.4 samples/FWHM


110º x 1.0º (cross-track x along-track)

16.6º x 0.26º

Cell size

49 km x 50 km (nadir)

250 km x 250 km (single cell at nadir)

Revisit time




2800 km

250 km

Table 8: Performance parameters of the OMPS spectrometers


VIIRS (Visible/Infrared Imager Radiometer Suite)

VIIRS will combine the radiometric accuracy of the AVHRR-3 (Advanced Very High Resolution Radiometer), which is currently flown on the NOAA polar orbiters with the high spatial resolution (0.56 km) of the OLS (Operational Linescan System) flown on DMSP. VIIRS will provide imagery of clouds under sunlit conditions in about a dozen bands, and will also provide coverage in a number of infrared bands for night and day cloud imaging applications.

VIIRS will have multi-band imaging capabilities to support the acquisition of high-resolution atmospheric imagery and generation of a variety of applied products, including visible and infrared imaging of hurricanes and detection of fires, smoke and atmospheric aerosols. VIIRS will also provide capabilities to produce higher-resolution and more accurate measurements of sea surface temperature than currently available from the heritage AVHRR-3 instrument on POES, as well as provide an operational capability for ocean-color observations and a variety of derived ocean-color products. The VIIRS instrument is developed by the Raytheon Company, El Segundo, CA. 42)

VIIRS is an advanced, modular, multi-channel imager and radiometer (of OLS, AVHRR-3, MODIS, and SeaWiFS heritage) with the objective to provide global observations (moderate spatial resolution) of land, ocean, and atmosphere parameters at high temporal resolution (daily). 43) 44) 45) 46) 47) 48) 49)

VIIRS is a multispectral (22-band) opto-mechanical radiometer, employing a cross-track rotating telescope fore-optics design (operating on the whiskbroom scanner principle), to cover a wide swath. The rotating telescope assembly (RTA of 20 cm diameter) concept of SeaWiFS heritage allows a low straylight performance. An observation scene is imaged onto three focal planes, separating the VNIR, SWIR/MWIR, and TIR energy - covering a spectral range of 0.4 - 12.5 µm. The VNIR FPA (Focal Plane Array) has nine spectral bands, the SWIR/MWIR FPA has eight spectral bands, and the TIR FPA four spectral bands. The integral DNB (Day Night Band) capability provides a very large dynamic range low-light capability in all VIIRS orbits. The detector line arrays [16 detectors in each array for the SWIR/MWIR and TIR bands, 32 detectors in the array for the VNIR and DNB (Pan) bands] of the whiskbroom scanner are oriented in the along-track direction. This arrangement provides a parallel coverage of 11.87 km along-track in one scan sweep (cross-track direction). The wide along-track coverage permits sufficient integration time for all cells in each scan sweep. One cross-track scan period of RTA is 1.786 s in length. The data quantization is 12 bits (14 bit A/C converters for lower noise).

Typical data products (types) of VIIRS include atmospheric, clouds, earth radiation budget, clear-air land/water surfaces, sea surface temperature, ocean color, and low-light visible imagery. A swath width of 3000 km is provided (corresponding to FOV=±55.84º) with a spatial resolution for imagery related products of no worse than 0.4 km to 0.8 km (nadir to edge-of-scan). The radiometric bands provide a resolution about twice in size to the imagery bands. Note: Most derived data products will be produced at somewhat coarser resolutions by aggregation of on-board data.


Figure 17: Photo of the VIIRS instrument (image credit: NASA, Raytheon, Ref. 48)

The VIIRS instrument design employs an all-reflective optics assembly taking advantage of recent optics advances: a) single 4 mirror imager, b) 2 dichroics and 1 fold, c) aluminum DPT-bolt together technology (DPT = Diamond Point Turning). A rotating off-axis and afocal TMA (Three Mirror Anastigmatic) telescope assembly is employed [Note: The telescope rotates 360º, thus scanning the Earth scene, and then internal calibration targets.]. The aperture of the imaging optics is 18.4 cm in diameter, the focal length is 114 cm (f/5.97). The VIIRS optical train consists of the fore optics (TMA), the aft optics [an all-reflective FMA (Four Mirror Anastigmat) imager], and the back-end optics, which include microlenses for the cooled focal planes.

A total of 22 spectral bands have been selected as defined in Table 9. VIIRS features band-to-band registration for all bands (optical alignment of all FPAs). A total of three focal planes and four FPAs (Focal Plane Arrays) cover the spectral range of the instrument, one FPA for DNB (Day-Night Band), one for VNIR, SWIR/MWIR, and TIR. The DNB spectral range of 0.5-0.9 µm CCD detector features four light-sensitive areas (3 with TDI, one without) and near-objective sample spacing.

The VNIR FPA employs a PIN (Positive Insulator Negative) diode array/ROIC (Readout Integrated Circuit) design collocated with the DNB monolithic CCD. All detectors in the SWIR/MWIR/TIR regions employ photovoltaic (PV) detectors with an element spacing of 12 µm. A ROIC (Readout Integrated Circuit) at each FPA provides improved noise levels and built-in offset correction. A cryogenic module (three-stage radiative cooler) provides FPA cooling.

A single-board instrument computer provides a processing capability including data aggregation, data compression [lossless (2:1 Rice compression) and lossy (JPEG) algorithms are used], and CCSDS data formatting.

Calibration is performed with three on-board calibrators: a) a solar diffuser (SD) provides full aperture solar calibration, b) a solar diffuser stability monitor, and c) a blackbody. Instrument calibration of VIIRS is based on that of the MODIS instrument: 50) 51) 52)

• VNIR: 1) View of a spectralon plate at the poles every few days; 2) Deep space view

• SWIR/MWIR/TIR: 1) View of blackbody every scan; 2) Deep space view


Figure 18: Major subsystems/components of VIIRS (functional block diagram)


Figure 19: Schematic of VIIRS rotating TMA (Three Mirror Anastigmatic) telescope assembly

The VIIRS instrument has a mass of 252 kg, power of ~ 191 W (operational average), and a size of 134 cm x 141 cm x 85 cm. The data rate is 10.5 Mbit/s (high rate mode) and 8 Mbit/s (average rate) mode with 10:1 JPEG compression). The VIIRS instrument features a SBC (Single Board Computer) for all instrument operations and control; it communicates with the S/C via an IEEE 1394a cable interface.

Some operational features of VIIRS:

• All functions are individually commandable

• Macro commands (stored sequences, all macros are reprogrammable) simplify the commanding and reduce the uplink data

• Time-tagged commands allow delayed execution (provides for 30 days autonomous operations)

• The swath widths and locations are individually programmable by band (improved resolution views of selected target near nadir)

• Diagnostic mode features improved versatility.


Center wave (µm)

Bandwidth (µm)

Comment (driving EDR observation requirements)

VNIR (Visible Near-Infrared) spectral region, use of Si detectors in FPA




Day Night Band, broad bandwidth maximizes signal (essential nighttime reflected band)




Ocean color, suspended matter, net heat flux, mass loading




Ocean color, suspended matter, net heat flux, mass loading




Ocean color EVI, surface type, aerosols suspended matter, net heat flux, mass loading




Ocean color, surface type, suspended matter, net heat flux, mass loading




Imagery, NDVI, cloud mask/cover, cloud optical properties, surface type, albedo, snow/ice, soil moisture




Ocean color, aerosols, suspended matter, net heat flux, littoral transport, mass loading




Ocean color, mass loading




Imagery NDVI (NDVI heritage band), snow/ice, surface type, albedo




Ocean color, cloud mask/cover, aerosols, soil moisture, net heat flux, mass loading

SWIR (Short-Wave Infrared) spectral region, use of PV (Photovoltaic) HgCdTe detectors




Cloud optical properties (essential over snow/ice), active fires




Cloud mask/cover (thin cirrus detection), aerosols, net heat flux




Aerosols, cloud optical properties, cloud mask/cover (cloud/snow detection), active fires, soil moisture, net heat flux




Imagery snow/ice (cloud/snow differentiation), surface type, albedo




Aerosols (optimal aerosol optical thickness over land), cloud optical properties, surface type, active fires, net heat flux

MWIR (Mid-Wave Infrared) spectral region, use of PV (Photovoltaic) HgCdTe detectors




Imagery (identification of low and dark stratus), active fires




SST (Sea Surface Temperature), cloud mask/cover, cloud EDRs, surface type, land/ice surface temperature, aerosols




SST (essential for skin SST in tropics and during daytime), land surface temperature, active fires, precipitable water

TIR (Thermal Infrared) spectral region, use of PV (Photovoltaic) HgCdTe detectors




Cloud mask/cover (pivotal for cloud phase detection at night, cloud optical properties




SST, cloud EDRs and SDRs (Science Data Records), land/ice surface temperature, surface type




Imagery (nighttime imagery band)




SST, cloud mask/cover, land/ice surface temperature, surface type

Table 9: Definition of VIIRS spectral bands

DNB (Day-Night Band) FPA




One broadband

9 bands

8 bands

4 bands, 1 with TDI

CCD detector

Si PIN diodes

PV HgCdTe detector

PV HgCdTe detector

FPIE (Focal Plane Interface Electronics)

ROIC (Readout Integrated Circuit)





Si micro-lens array

Ge micro-lens array

Tops = 253 K

Tops = ambient





Tops = 80 K

Tops = 80 K

Table 10: Overview of the FPA design of VIIRS

Some key EDRs of VIIRS: 53)

• SST (Sea Surface Temperature). VIIRS is capable to provide a nadir resolution of 750 m (by aggregating detectors 3:l in-track near nadir, 2:l in-track aggregation out to a 2,000 swath, and 1:1 out to 3,000 km) to simultaneously optimize spatial resolution and noise performance. - The SST solution combines the traditional long-wave infrared (LWIR) split window with a second split window in the mid-wave infrared (MWIR) for a globally robust SST algorithm. The MWIR split window has a higher transmissivity than the traditional LWIR split window for improved atmospheric correction. The low-noise design is operable day and night with 0.25 K precision, and 0.35 K total measurement uncertainty (rms error).

• Imagery and cloud detection/typing. The imagery solution provided on VIIRS includes six high-resolution bands and an additional 16 moderate-resolution bands. One of these, a reflective panchromatic band (DNB), is operable in low-light conditions down to a quarter moon. A swath with of 3000 km is provided.

• Soil moisture. A VIIRS/CMIS data fusion solution was derived. The approach combines the fine spatial resolution of VIIRS with traditional coarser-resolution microwave-derived soil moisture retrievals to achieve excellent results over both open and partially vegetated scenes. The estimation procedure involves two steps: 1) CMIS estimates soil moisture at coarse spatial resolution. This involves inversion of dual-polarized microwave brightness temperatures. 2) CMIS-derived low-resolution soil moisture is linked to the scene optical parameters, such as NDVI (Normalized Difference Vegetation Index), surface albedo, and LST (Land Surface Temperature). The linkage of the microwave-derived soil moisture to NDVI, surface albedo and LST is based on the “Universal Triangle” approach of relating land surface parameters. The three high-resolution optical parameters are aggregated to microwave resolution for the purpose of building the linkage model. The linkage model, in conjunction with high-resolution NDVI, surface albedo, and LST, is then used to disaggregate microwave soil moisture into high-resolution soil moisture.

VIIRS will collect radiometric and imagery data in 22 spectral bands within the visible and infrared region ranging from 0.4 to 12.5 µm. These data are calibrated and geolocated in ground processing to generate SDRs (Sensor Data Records) that are equivalent to NASA Level 1B products. The VIIRS SDRs in turn will be used to generate 22 EDRs (Environmental Data Records) including two KPPs (Key Performance Parameters): SST (Sea Surface Temperature) and Imagery. Since the quality of these EDRs depends upon the quality of the underlying SDRs, adequate SDR quality is crucial to JPSS mission success. 54) 55)

DNB (Day Night Band) overview in VIIRS:

The DNB will measure VIS radiances from the Earth and atmosphere (solar/lunar reflection and both natural and anthropogenic nighttime light emissions) during both day and night portions of the orbit. In comparison to the OLS (Operational Linescan System) of the DMSP series, some of the DNB channel improvements include 1) reduced instances of pixel saturation, 2) a smaller IFOV, leading to reduced spatial blurring, 3) superior calibration and radiometric resolution, 4) collocation with multispectral measurements on VIIRS and other NPOESS sensors, 5) and generally increased spatial resolution and elimination of cross-track pixel size variation. 56)

The DNB is implemented as a dedicated focal plane assembly (FPA) that shares the optics and scan mechanism of the other VIIRS spectral bands. This integral design approach offers lower overall system complexity, cost, mass, and volume compared to a separate DNB sensor. Unlike the OLS, the DNB will feature radiometric calibration, with accuracy comparable to the other VIIRS spectral bands.

To achieve satisfactory radiometric resolution across the large dynamic range (seven orders of magnitude) of day/night radiances encountered over a single orbit, the DNB selects its amplification gain dynamically from three simultaneously collecting stages (groups of detectors residing upon the same FPA). The stages detect low-, medium-, and high-radiance scenes with relative radiometric gains of 119,000:477:1 (high:medium:low gain). Each of the three stages covers a radiance range of more than 500:1, so that the three together cover the entire required radiance range with generous overlap. Two identical copies of the high-gain stage are provided, which improves the SNR at very low signal levels and allows for the correction of pixels impacted by high-energy subatomic particles. The scene is scanned sequentially such that each scene is imaged by all three gains virtually simultaneously.

The signals from all gain stages are always digitized, using 14 bits for the high-gain stage and 13 bits for the medium- and low-gain stages. This fine digitization assures the DNB will have a sufficiently fine radiometric resolution across the entire dynamic range. Logic in the VIIRS Electronics Module (EM) then selects, on a pixel-by-pixel basis, the most appropriate of the three stages to be transmitted to Earth. In general, the VIIRS EM logic chooses the most sensitive stage in which the pixel is not saturated. This imaging strategy produces nonsaturated calibrated radiances in bright areas, and data with a lower dynamic range in the darkest areas with less SNR and radiometric accuracy.

In summary, the VIIRS DNB feature will bring significant advances to operational and research applications at night (over OLS operations) due to the increased sensitivity of the instrument.


RSB (Reflective Solar Band) radiometric calibration: 57) 58)

VIIRS features 15 reflective solar bands (RSB) in the range of 0.4-2.25 µm. The reflective bands use sunlight reflected from a SD (Solar Diffuser) after passing through an attenuating SDS (Solar Diffuser Screen) as a reference illumination source. The RSB calibration is currently performed by offline trending of calibration scale factors derived from the SD and SV (Space View) observations. These calibration scale factors are used to periodically update LUT (Look-Up Tables) used by the ground processing to generate the calibrated earth radiance and reflectance in the Sensor Data Records (SDR).

RSB calibration data is acquired once per orbit when sunlight incident on the SD uniformly illuminates the VIIRS detectors, providing a large and calculable reference radiance level. The calibration scale factor is the ratio of the calculated SD radiance at the RTA entrance aperture to the SD radiance measured by the instrument using calibration coefficients derived from the pre-launch calibration. The calibration scale factor in effect measures the change in instrument “gain” as the instrument ages on orbit relative to the gain measured during pre-launch instrument response characterization.

TED (Thermal Emissive Band) calibration: 59)

VIIRS has 7 thermal emissive bands use an OBC-BB (On-Board Calibrator Blackbody) maintained at a constant elevated temperature as a reference illumination source. The 7 emissive bands are centered at 3.74, 11.45, 3.75, 4.05, 8.55, 10.76, and 12.01 µm. The two emissive image bands are mainly for cloud imagery and precise geolocation. The 5 moderate-resolution emissive bands are used to determine surface temperature and cloud top pressure. The only dual gain band TEB M13 is used for determining surface temperature at low radiance, and fire detection at high radiance.

The VIIRS emissive band calibration concept is a common two-point calibration by viewing onboard blackbody and cold space. However, the VIIRS emissive band calibration algorithm is more complicated than other sensors such as AVHRR and MODIS, because of the instrument response verses the scan angle. The TEBs (Thermal Emissive Bands) are calibrated using OBC-BB that has been carefully characterized in prelaunch activities. The OBC-BB emissivity is estimated to be 0.99609-0.99763 for the TEB bands based on prelaunch testing in the thermal vacuum chamber. The OBC-BB temperature is carefully controlled using heater elements and thermistors. The calibration algorithm, based on measured BB temperature and emissivity, computes radiances and compares it with counts to determine gain adjustments.

VIIRS significantly outperforms the legacy AVHRR in spatial, spectral, and radiometric accuracy. Early assessment of the VIIRS TEB calibration shows the sensor is stable and exceeds the specification. The onboard calibration accuracy for NEdT compares very favorably with pre-launch thermal vacuum tests. Consistency tests among VIIRS, MODIS, AVHRR, and CrIS further confirm the stability and accuracy of the VIIRS TEB.



JPSS Common Ground System (CGS):

In September 2010, the Raytheon Company was awarded a contract by NASA on behalf of NOAA for the development of JPSS-1 (Joint Polar Satellite System-1). The award of the JPSS Common Ground System enables uninterrupted support to meet both civilian and defense weather needs. It allows Raytheon to continue the development and evolution of the ground system into an exceptional operational program for JPSS and DMSP (Defense Meteorological Satellite Program). 60) 61) 62)

The main elements of the JPSS common ground system for NOAA and DoD – currently comprises:

• C3S (Command, Control and Communications Segment)

- Includes mission planning, enterprise management, antenna resource scheduling, satellite operations, data relay and spacecraft and instrument engineering. A key feature of the C3S is the 15 unmanned global ground stations that receive JPSS and DWSS mission data, termed the DRN (Distributed Receptor Network). The receptors, linked with high-bandwidth commercial fiber, can quickly transport the data to four U.S. data processing centers. Most data will ultimately be completely processed and delivered to the Weather Centrals in less than 30 minutes from the time of collection.

- The MMC (Mission Management Center) provides accurate, high-performance tools that precisely manage JPSS and DWSS missions. The C3S tools give crews keen insight, comprehensive operational oversight, detailed mission planning capability, full control of space and ground assets, continuous monitoring and assessment of overall system performance.

• IDPS (Interface Data Processing Segment). The IDPS features high-speed, symmetric, multi-processing computers that will rapidly convert large streams of JPSS and DWSS sensor data that are 100 times the volume of legacy data, providing numerous EDRs (Environmental Data Records) at four weather Centrals in the United States. These vital EDRs range from atmospheric to land and ocean surface products. The EDRs detail cloud coverage, temperature, humidity and ozone distribution, as well as snow cover, vegetation, sea surface temperatures, aerosols, space environment and earth radiation budget information. This wealth of information enables numerous users to monitor and predict changes in weather, climate, and ocean conditions. JPSS and DWSS products will also be available to the scientific community to expand our knowledge of the environment.

• FTS (Field Terminal Segment). The FTS, equipped with specially configured IDPS software, will permit worldwide fixed and mobile field terminals deployed aboard ships, at military bases, in theaters of operation, and at educational and scientific institutions to receive and process the continuous broadcasts of JPSS and DWSS sensed data as the satellites pass overhead.


Figure 20: JPSS operations overview (NASA, NOAA, Ref. 1)


Figure 21: JPSS high level operational concept (Ref. 61)

Satellite owner


JPSS service


Suomi-NPP (launch on October 28, 2011)
JPSS-1 (launch in 2017)
JPSS-2 (launch in 2022)

Full Service: commanding and data processing

DoD (Department of Defense)

Coriolis (launch January 6, 2003)

Data acquisition and routing

JAXA (Japan Aerospace Exploration Agency)

GCOM-W1 (launch May 17, 2012)
GCOM-C1 (launch in 2014)

Data processing

EUMETSAT (European Organization for the Exploitation of Meteorological Satellites)

MetOp-A (launch October 19, 2006)
MetOp-B (launch September 17, 2012)

Data routing

Table 11: JPSS satellite fleet (Ref. 61)


US Partnerships in JPSS program:


- EUMETSAT provides mid-morning orbit

- Both support planning and operations (e.g., Antarctic Data Acquisition)

• JAXA (Japan Aerospace Exploration Agency)

- GCOM-W1 (Global Change Observation Mission – Water) provides AMSR-2 data – continuity for NASA’s Aqua satellite

- NOAA provides ground system services in exchange for data from AMSR-2

• NSC (Norwegian Space Center), Norway

- Provision of satellite tracking and environmental data acquisition services

• Canada (DND) and France (CNES) for SARSAT Program

• France (CNES) – Argos Program

Since being deployed for NOAA's Suomi-NPP (National Polar-orbiting Partnership) in 2011, JPSS CGS, one of the few multi-mission ground solutions, is now providing unprecedented global observation capability. Leveraging a common ground system across national and international agencies is the most efficient and cost effective way to improve global environmental observational capabilities. 63)

By leveraging a flexible architecture and integrating new and legacy technologies, the JPSS CGS reduces development and sustainment costs and has proven it can be quickly adapted to a variety of mission needs spanning civil, military and scientific communities.

In addition to supporting NOAA's Suomi-NPP and the GCOM-W1 mission of JAXA, other JPSS CGS support includes the MetOp series of EUMETSAT (European Organization for the Exploitation of Meteorological Satellites) and DoD's DMSP (Defense Meteorological Satellite Program) series.


Figure 22: JPSS ground system high-level architecture as of July 2012 (image credit: NASA, NOAA, Ref. 1)

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The information compiled and edited in this article was provided by Herbert J. Kramer from his documentation of: ”Observation of the Earth and Its Environment: Survey of Missions and Sensors” (Springer Verlag) as well as many other sources after the publication of the 4th edition in 2002. - Comments and corrections to this article are always welcome for further updates.