Development of a prototype algorithm for the operational retrieval of height-resolved products from GOME

				AUTHOR

Robert Spurr

Smithsonian Astrophysical Observatory
60 Garden Street
Cambridge
MA 02138
USA

Tel : (617) 496 7819
fax : (617) 495 7389
email : rspurr@gome.harvard.edu

				ABSTRACT

GOME (Global Ozone Monitoring Experiment) was launched on April 21st 1995 
aboard the second European Remote Sensing Satellite (ERS-2).  The GOME Data
Processor (GDP), designed and implemented by the German Remote Sensing Data 
Center (DFD), is now fully operational.  Level 1 earthshine/solar spectra
and level 2 total ozone columns are the main data products.  So far, level
1-2 processing has concentrated on total column retrieval using differential
absorption fitting.

Recently, scientific studies of test cases have demonstrated the
feasability of ozone profile retrieval from GOME spectra.  The step from
off-line case studies to routine product generation on a global basis
requires a new algorithm based in part on the scientific work.  This paper
presents a blueprint for an operational prototype algorithm that will
perform this task.

The retrieval strategy is to generate a preliminary ozone profile based on
UV data below 300 nm generated typically every 12 seconds, then to use this
result as a priori input data for selected profile retrievals from spectra
generated every 1.5 seconds in GOME channels 2 and 3.  Long readout data 
will generate only stratospheric profiles above 20 km; tropospheric ozone
information is retrieved from the short readout spectra.

Optimal estimation is the preferred fitting technique.  We discuss the
composition of the state vector of retrieved parameters, the generation
and usage of diagnostic variables, the integration of a suitable
radiative transfer forward model, and the proposed contents of the
level 2 ozone profile product.  A basic treatment of clouds in this
algorithm is also included.  


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Regards



Robert Spurr

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