Tropospheric Oh Primary Production from Ers-2 Data

In order to calculate the OH primary production rate from satellite measurements, one has to estimate the following quantities: profile of the photodissociation rate of ozone to O(D), tropospheric ozone profile and tropospheric water vapour profile. The estimation of tropospheric OH primary production rate from ERS-2 data is demonstrated. The tropospheric ozone profiles retrieved at the Rutherford Appleton Laboratory (RAL) from GOME narrow-swath mode (40 km by 80 km) available via the British Atmospheric Data Centre (BADC) are used. Tropospheric actinic flux profiles and photodissociation rates of ozone are calculated from GOME and ATSR-2 measurements using the TUV radiation model with the DISORT radiative transfer code. For partially cloudy GOME ground pixels the photodissociation rates are approximated as a linear combination from the clear-sky and the fully cloudy cases according to an independent pixel approximation. Total ozone, ozone profile, NO2 column, spectral albedo, solar spectrum, UTC date and time of pixel at the end of integration time, and ground pixel location co-ordinates are used in the TUV model from the GOME measurements. Thick and thin cloud fraction and cloud top height for GOME field of view (FOV) are used from the ATSR-2 measurements processed by RAL and available via BADC. The cloud optical thickness is determined from GOME albedo at 350 nm using the radiative transfer model. The simulated GOME albedo spectra are validated with the measured ones. Specific humidity profiles from ECMWF data are used to estimate the tropospheric OH primary production rates.