A Sensitivity Study for the Wavelength Calibration of GeoTASO for KORUS-AQ Campaign

Abstract:

The cooperative field campaign for KOREA-US Air Quality (KORUS-AQ) study is under preparation. For the success of campaign, Megacity Air Pollution Studies-SEOUL (MAPS-SEOUL) as a preliminary study is now going on. The major objective of MAPS is the trial run of the laboratory and airborne measurement and the preparation for the sensor calibration. From these campaigns, it is possible to increase the accuracy of air quality model and also to assess the retrieval algorithm for Geostationary Environment Monitoring Spectrometer (GEMS). The Geostationary Trace-gas and Aerosol Sensor Optimization (GEO-TASO) instrument which will be onboard aircraft utilizes Offner spectrometer with a 4 mirror telescope. For the data processing, we plan to develop the wavelength calibration algorithm for the raw measurements from this airborne hyperspectral sensor. The important parameters considered in spectral calibration of radiance spectra are absorption of ozone and ring effect. We would adapt the similar process with the heritage programs such as OMI, GOME and OMPS and so on. However, the airborne flying environment in troposphere would be different compared to GEMS’s geostationary orbit. Therefore, the parameters which cause wavelength change could be different. For example, the variation of aircraft altitude would bring additional uncertainties in wavelength change. Here, the GEMS prototype algorithm is applied to Geo-TASO measurement to derive slit functions and check wavelength shift. And the algorithm sensitivity to each parameter will be examined. Through these tests, the characteristics of each parameter and their correlation will be used to refine the GEMS algorithm and to futher KORUS-AQ study.