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Parameter Tables

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2.4.3 Parameter Tables

Utilising the high degree of flexibility in the instrument design can only be accomplished through parameterisation of on-board operations. For the execution of scientific and calibration & monitoring measurements this means that associated functions must be predefined and stored on-board with ground control having the capabilities to modify the instrument configuration by commanding. Changing the instrument status includes software updates via patching as well as parameter settings via commanding. Those sets of parameters which are associated with basic instrument properties, e.g. scanner, thermal and mechanism control definitions are termed engineering parameters. Parameters relating to the configuration of the spectrometer while measuring are the so-called measurement parameters. Engineering and measurement parameters are organized in a series of parameter tables defining common functional tasks.

Measurement tables in most cases relate to individual measurement states (see below) but so-called ‘common’ tables serve all states (table 2-7). Particularly, the values of the pixel exposure times and the co-adding factors ensure, in conjunction with the definition of wavelength clusters, optimised signal-to-noise ratios over the complete orbit. The product of PET and co-adding factor yields the integration time, which defines the read-out frequency. In the case where SWIR channels run into saturation, the so-called Hot Mode parameters allow decreasing the exposure times in channels 6-8 below the minimum PET of 31.25 msec. The characteristics of the ASM/ESM rotations are defined via the Scanner State, Basic Scan Profile and Relative Scan Profile parameters. The Basic Scan Profile specifies the underlying standard motion of the respective mirror whereas the Relative Scan Profile is a mirror movement superimposed onto the Basic Scan Profile, e.g. fast upward/downward scans in elevation while the ESM is basically slowly moving in elevation.


Type  Table 
State  Scanner State 
  Pixel Exposure Time 
  Hot Mode 
  State Index 
  State Duration 
  Detector Cmd Words 
  DME Enable 
Common  Basic Scan Profile 
  Relative Scan Profile 
  Cluster per Channel 
  Cluster Definition 

Table 2-7: Measurement parameter tables

2.4.4 Measurement States

The individual functions to operate SCIAMACHY in measurement modes are defined as states. A state is a sequence of activities for a particular measurement task, e.g. nadir observations with certain pixel exposure times, sun occultation with certain scan geometry, etc. SCIAMACHY’s scientific measurement objectives and requirements have led to the definition of the 70 individual states as listed in (table 2-8). 34 states implement scientific requirements, 26 are for the purpose of in-flight calibration, 4 for in-flight monitoring and the data from 6 states can be used for scientific and calibration analyses. The high number of calibration & monitoring states is the result of the thorough and complex in-flight calibration & monitoring concept.


State ID  State  Measurement Type  Remark 
1 - 7   nadir 960 km swath  science  all orbital positions 
8, 26, 46, 63, 67  dark current  calibration  pointing at 250 km 
9 - 15  nadir 120 km swath  science  all orbital positions 
16  NDF monitoring, NDF out  monitoring   
17 - 21  sun ASM diffuser  calibration  sun above atmosphere 
22  sun ASM diffuser atmosphere  monitoring  various azimuth angles 
23 - 25, 42 - 45  nadir pointing  science  all orbital positions 
27  limb mesosphere  science  scanning 150 - 80 km 
28 - 33  limb 960 km swath  science  all orbital positions 
34 - 37, 40, 41  limb no swath  science  all orbital positions 
38  nadir pointing left  monitoring   
39  dark current Hot Mode  calibration   
47  SO&C scanning/pointing  science, calibration  sun through and above atmosphere 
48  NDF monitoring, NDF in  monitoring   
49  SO&C nominal scanning, long duration  science, calibration  sun through and above atmosphere 
50  SO&C fast sweep scanning  calibration   
51  SO&C pointing  science, calibration  sun through and above atmosphere 
52  sun ESM diffuser, NDF out  calibration  sun above atmosphere 
53  sub-solar pointing  calibration   
54  moon nominal scanning  calibration  moon above atmosphere 
55  limb mesosphere_thermosphere  science  scanning 150-60 km 
56  moon pointing  science, calibration  moon through atmosphere 
57  moon pointing, long duration  science, calibration  moon through and above atmosphere 
58  sub-solar pointing/nominal scanning  calibration   
59  SLS  calibration   
60  sub-solar fast sweep scanning  calibration   
61  WLS  calibration   
62  sun ESM diffuser, NDF in  calibration  sun above atmosphere 
64  sun extra mirror pointing  calibration  sun above atmosphere 
65  ADC, scanner maintenance  calibration   
66  sun extra mirror nominal scanning  calibration  sun above atmosphere 
68  sun extra mirror fast sweep scanning  calibration  sun above atmosphere 
69  SLS ESM diffuser  calibration   
70  WLS ESM diffuser  calibration   

Table 2-8: Measurement state definition as of early 2009


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