# OSIRIS_ECMWF¶

A climatology class that provides the background atmospheric state used in Odin-OSIRIS retrievals. The atmospheric state parameters are derived from the ECMWF climatology interpolated to individual OSIRIS scan. The advantage of the class is that a much smaller file size can store the ECMWF information for one scan and it is much quicker to read in the small file than the entire ECMWF climatology.

The class only considers mjd when updating the cache and completely ignores any latitude and longitude parameters provided by the user. The class is very useful for providing the atmospheric state of OSIRIS scans but has limited value outside this purpose:

mjd = 52393.3792987115;
climate = ISKClimatology('OSIRIS_ECMWF')
climate.UpdateCache( [0,0,0,mjd])
[ok, value] = climate.GetParameter( SKCLIMATOLOGY_AIRNUMBERDENSITY_CM3(), ...
[0.0, 0.0, 25000, mjd]);
[ok, value] = climate.GetParameter( SKCLIMATOLOGY_PRESSURE_PA(),   [0.0, 0.0, 25000, mjd]);
[ok, value] = climate.GetParameter( SKCLIMATOLOGY_TEMPERATURE_K(), [0.0, 0.0, 25000, mjd]);


## Supported Species¶

• SKCLIMATOLOGY_AIRNUMBERDENSITY_CM3
• SKCLIMATOLOGY_TEMPERATURE_K
• SKCLIMATOLOGY_PRESSURE_PA

## Software Package¶

This climatology is installed as part of the OSIRIS Level 1 Services (Version 2.48 or higher) and your system has access to the OSIRIS Level 1 data products.