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RA2/MWR Data Formats Products
Frequently Asked Questions
Main RA-2 Level 2 Algorithms (Non-Ocean)
Main MWR Level 1b algorithms
Main RA-2 Level 1b algorithms
MWR Instrument
RA-2 Instrument
RA-2 and MWR Instruments
MWR Instrument Characteristics and Performance
In-flight performance verification
MWR Instrument Description
RA-2 Instrument Characteristics and Performance
In-flight Performance verification
RA2/MWR Products and Algorithms
RA-2/MWR Auxiliary files
Common Auxiliary Data Sets
Level 2 processing
Level 1b processing
Specific Topics Related To The Radar Altimeter
Orbit interpolation
Measurement Reference
Time Handling And Leap Seconds
RA-2/MWR Level 2 Products And Algorithms
RA2/MWR Level 2 Products
Averaged Ku chirp band
Ocean depth/land elevation
RA-2 ionospheric correction
RA-2/MWR Level 1b Products and Algorithms
RA-2/MWR Level 1b product
MWR Level 1b algorithms
Level 0 products
MWR Level 0 products
Products Evolution History
Definitions and Conventions
Organisation of Products
Data Handling Cookbook
Characterisation And Calibration
Latency, Throughput And Data Volume.
Product size
RA2/MWR Products User Guide
Further reading
How to use RA-2/MWR data
How To Choose RA-2/MWR Data Products
Summary of Applications vs. Products
Peculiarities of MWR
Peculiarities of RA2
Geophysical Coverage
Principles Of Measurement
Scientific Background
ENVISAT RA2/MWR Product Handbook
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Frequently asked questions
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1.1 How To Choose RA-2/MWR Data Products

1.1.1 Geophysical Measurements

The RA-2 measures the transit time and radar backscatter power of individual transmitted pulses. The transit time is proportional to the satellite's altitude above the ocean, land, or ice surface. Over ocean surfaces the measured range is accurate to better than 2.5 cm. The magnitude and shape of the returned echoes also contain information about the characteristics of the reflecting surface, from which it is possible to retrieve geophysical parameters such as (when over the ocean) significant wave height, wind speed, and sea ice edge location.


The RA-2 instrument has several new features offering a significant advance upon the performance of the RA-1 flown on ERS. The RA-2 has a second radar channel (S-band, 3.2 GHz) allowing in-situ correction of the range delay due to the ionosphere. The S-band should als benefit new applications including ice type classification and rain-cell detection. The RA-2 uses a robust Model Free Tracker and surface tracking logic which switches autonomously between 3 different resolution modes to provide greater coverage in areas of difficult terrain.


The MWR is a nadir-viewing, two channel, passive microwave radiometer operating at 23.8 and 36.5 GHz. At these two frequencies, it receives and measures microwave radiation generated and reflected by the Earth. The signals received can be related to surface temperature but, most importantly, combined together they provide an estimate of the total water content in the atmosphere, which will be used to correct for the altimeter measurements path delay. The MWR has a 20 km diameter field of view.

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry