EOS Validation Program

Institution: Visiting Professor, Department of Physics
                    University of Toronto
                    Toronto, Ontario, Canada M5S 1A7
Phone: (416) 978-0341
FAX: (416) 978-8905
E-mail: leonid@atmosp.physics.utoronto.ca

Eugeny I. Grechko, Russian Academy of Sciences, Moscow, Russia
Boyd Tolton, University of Toronto, Canada
Anatoly V. Dzhola, Institute of Atmospheric Physics, Moscow, Russia

Final Report, January 2002

The aim of MOPITT correlative gas spectrometer is to determine vertical profiles of CO and total column CH4 abundance from space. Ground-based solar IR spectroscopy appears to be an appropriate tool for its validation from the ground. Grating spectrometers of moderate resolution (0.2 cm-1) have been being used for a long time for total column CO measurements in Russia. Routine CO and CH4 measurements are under way now at two sites in Russia (Zvenigorod and Kislovosk). Now a Russian spectrometer is moved for a comparison and intercalibration to Canada. We propose to install it side-by-side with a FTIR high-resolution spectrometer at the Egbert station near Toronto (AES of Canada) for a comparison. Later on the grating spectrometer will be used in field validation campaigns during the EOS flight in combination with surface in situ measurements and/or aircraft sampling (sites and time-table TBD). The comparison of the boundary layer CO mixing ratios with concurrent total column data allows us to get CO profiles with an accuracy comparable with that of MOPITT. The proposed intercalibration against the FTIR, which is just one of a dozen such instruments, which are run routinely at the NDSC network, would give us (I) assurance of validity of the grating spectrometer data, and (II) a possibility to use Russian spectroscopic data, obtained by the same technique, for the validation of MOPITT. All these activities will be undertaken in close collaboration with the MOPITT International Science Team. Both Canadian and Russian activities will be funded by national programs. We do not solicit funding from NASA.

Additional Information:

It is well known, that the total column amount of a gas in the entire atmosphere, measured using the spectroscopic technique, depends on an assumed profile of the gas. As a rule, spectroscopists take a likely model profile and tune it by scaling to minimize the discrepancy between the observed and calculated spectra. However, this approach does not work well for CO: its profile changes a lot with a season and geographic location.

Here we propose to combine spectroscopic measurements with surface in situ sampling. We have already implemented this approach in Alaska (http://www.atmosp.physics.utoronto.ca/MOPITT/mop_workshop/al95-int.htm). The boundary layer is well mixed for CO throughout all the Arctic (http://www.atmosp.physics.utoronto.ca/MOPITT/mop_workshop/leo.htm). Comparing CO total column with surface measurements we can determine the average rate of CO mixing ratio change with altitude. This combination would allow us to save a lot of money eliminating the need for expensive airborne sampling. The place for these measurements will be chosen separately.

The second aim of this proposal is to attract valuable CO and CH4 observations from the Russian territory for the MOPITT validation. These measurements are underway since 1971 (see the recent publication http://www.agu.org/GRL/articles/97GL50990/GL080W01.html). A spectrometer, which is identical to those, installed in Russia, is now at the University of Toronto. We plan to compare its readings with CO and CH4 measurements made by Dr. Hans Fast of Atmospheric Environment, Canada, at the Egbert station by a FTIR. This would make it possible to compare the Russian data with those obtained by a dozen FTIRs which are working routinely all over the world at the NDSC network (http://climon.wwb.noaa.gov/).