HR: 0830h
AN: A21C-0978    [PDF]
TI: Improvements in the DOAS Based Total Ozone Column Algorithm for OMI
AU: De Haan, J F
EM: haandej@knmi.nl
AF: Royal Dutch Meteorological Institute, P.O.Box 301, De Bilt, 3730AE Netherlands
AU: Veefkind, J P
AF: Royal Dutch Meteorological Institute, P.O.Box 301, De Bilt, 3730AE Netherlands
AU: Valks, P
AF: Royal Dutch Meteorological Institute, P.O.Box 301, De Bilt, 3730AE Netherlands
AU: * Brinksma, E
AF: Royal Dutch Meteorological Institute, P.O.Box 301, De Bilt, 3730AE Netherlands
AU: Levelt, P F
AF: Royal Dutch Meteorological Institute, P.O.Box 301, De Bilt, 3730AE Netherlands
AB: The Ozone Monitoring Instrument is a nadir pointing imaging spectrometer with a wide swath (about 2600 km) that records reflected radiance spectra in the wavelength range 270-500 nm with a spectral resolution of about 0.5 nm. The high spatial resolution (13x24 km at nadir) makes it possible to obtain information on tropospheric ozone as problems due to (partly) cloudy pixels are reduced compared with instruments like GOME and SCIAMACHY. OMI is scheduled for launch early 2004 as part of the NASA EOS-Aura mission. To obtain accurate total ozone columns from OMI spectra an improved DOAS based algorithm is used as compared to the algorithm used in the operational processor for GOME and SCIAMACHY data. The following improvements have been implemented. First, the DOAS fit window is changed from 325-335 nm to 331.6 - 336.6 nm, making the retrieved columns less sensitive to the temperature and ozone profile. To further improve the accuracy we adopt a so-called empirical procedure to calculate air mass factors. In this procedure the DOAS method is applied to simulated spectra. These air mass factors are exact if the atmospheric model used in the calculations corresponds to the actual atmosphere. The third improvement is that the air mass factor is regarded as a function of the slant column density that results from the DOAS fit of a measured spectrum. These improvements have been implemented in the operational algorithm for OMI. We are currently investigating further improvements by handling rotational Raman scattering in a more advanced manner. In this poster presentation the improvements are discussed and some results based on GOME spectra will be presented.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0345 Pollution--urban and regional (0305)
DE: 0365 Troposphere--composition and chemistry
DE: 0368 Troposphere--constituent transport and chemistry
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting