No abstract

The TIROS (Television Infrared Observation Satellite) Operational Vertical Sounder (TOVS) Pathfinder Path A dataset is currently a 9-yr dataset, 1985-93, of global fields of surface and atmospheric parameters derived from analysis of HIRS2 and MSU data on the NOAA-9, NOAA-10, NOAA-11, and NOAA-12 polar-orbiting operational meteorological satellites. The retrieved fields include land and ocean surface skin temperature, atmospheric temperature and water vapor profiles, total atmospheric 0 3 burden, cloud-top pressure and radiatively effective fractional cloud cover, outgoing longwave radiation (OLR) and longwave cloud radiative forcing, and precipitation estimate. The fields are gridded on a 1° x 1° latitude-longitude grid and stored on a 1-day mean, 5-day mean, and monthly mean basis, with data from each satellite's local A.M. and P.M. orbits stored separately. Preliminary validation studies of the interannual differences of geophysical parameters derived from the TOVS Pathfinder dataset imply sufficient accuracy for their use both to study atmospheric behavior as well as to validate the ability of general circulation models to reproduce this behavior. The TOVS dataset is particularly suitable for climate studies because surface, atmospheric, cloud, and radiative parameters are all produced simultaneously in an internally consistent manner. Hence, statistical relationships between them will not be impaired by the heterogeneity inherent in data from different sources. In addition, the close agreement of OLR computed from the products with that observed by the Earth Radiation Budget Experiment enables explanation of interannual variability of OLR in terms of the variability of its component parts. The dataset is available for all users through the Goddard Space

The Measurements of Pollution in the Troposphere (MOPITT) instrument, which was launched aboard the Earth Observing System (EOS) Terra spacecraft on 18 December 1999, is designed to measure tropospheric CO and CH(4) by use of a nadir-viewing geometry. The measurements are taken at 4.7 mum in the thermal emission and absorption for the CO mixing ratio profile retrieval and at 2.3 and 2.2 mum in the reflected solar region for the total CO column amount and CH(4) column amount retrieval, respectively. To achieve the required measurement accuracy, it is critical to identify and remove cloud contamination in the radiometric signals. We describe an algorithm to detect cloudy pixels, to reconstruct clear column radiance for pixels with partial cloud covers, and to estimate equivalent cloud top height for overcast conditions to allow CO profile retrievals above clouds. The MOPITT channel radiances, as well as the first-guess calculations, are simulated with a fast forward model with input atmospheric profiles from ancillary data sets. The precision of the retrieved CO profiles and total column amounts in cloudy atmospheres is within the expected ?10% range. Validations of the cloud-detecting thresholds with the moderate-resolution imaging spectroradiometer airborne simulator data and MOPITT airborne test radiometer measurements were performed. The validation results showed that the MOPITT cloud detection thresholds work well for scenes covered with more than 5-10% cloud cover if the uncertainties in the model input profiles are less than 2 K for temperature, 10% for water vapor, and 5% for CO and CH(4).

No abstract