Improved stratospheric and mesospheric sounder validation: General approach and in-flight radiometric calibration
Journal of Geophysical Research Atmospheres 101:D6 (1996) 9775-9793
Abstract:
This paper introduces a series of papers describing the validation of data products from the improved stratospheric and mesospheric sounder (ISAMS) on the Upper Atmosphere Research Satellite. ISAMS is a limb-sounding infrared gas-correlation radiometer, measuring thermal emission from a range of constituents. The constituents measured are ozone, water vapor, methane, nitrous oxide, nitric oxide, nitrogen dioxide, nitrogen pentoxide, nitric acid, carbon monoxide, and aerosol. Atmospheric temperature and composition data were obtained for approximately 180 days between September 26, 1991, and July 29, 1992, with near-global coverage. The instrument and the retrieval process are briefly described, together with aspects of the validation process relevant to all data products, including the radiometric calibration and the analysis of the calibrated radiances to produce data on a standard time-altitude grid. Copyright 1996 by the American Geophysical Union.Reference Model for Methane and Nitrous Oxide
Advances in Space Research 18:9-10 (1996) 91-124
Abstract:
Data from the Stratospheric and Mesospheric Sounder (SAMS) on Nimbus 7 have been used as the basis for a model of the abundances of nitrous oxide and methane in the stratosphere. The model is presented in tabular form on seventeen pressure surfaces from 20 to 0.1-mb, in 10° latitude bins from 50°S to 70°N, and for each month of the year. Some details of the acquisition of the data which went into the model, its limitations, and the general behaviour of methane and nitrous oxide in the middle atmosphere are given. Formal errors in the data and other uncertainties, interannual variability, and systematic trends are discussed. As expected, no trends which exceed the estimated error in the data are found in either methane or nitrous oxide over the five-year period of SAMS observations.The H2 so4 component of stratospheric aerosols derived from satellite infrared extinction measurements: Application to stratospheric transport studies
Geophysical Research Letters 23:17 (1996) 2219-2222
Abstract:
The ambient water vapour and temperature conditions of stratospheric sulphate aerosol particles govern their composition and thereby influence their infrared extinction properties. This causes problems in the use of the infrared aerosol extinction as a tracer because variations in the aerosol composition modify the changes in extinction that may arise from the transport of aerosols. An improved tracer which can be derived from measurements of the infrared aerosol extinction, temperature and water vapour abundance, is the H2SO4 component of aerosols. The application of this tracer to studies of stratospheric transport is demonstrated using data from instruments on the Upper Atmosphere Research Satellite and the results are compared to a contour advection calculation. Copyright 1996 by the American Geophysical Union.Validation of temperature measurements from the improved stratospheric and mesospheric sounder
Journal of Geophysical Research Atmospheres 101:D6 (1996) 9795-9809
Abstract:
Atmospheric temperature measurements from the improved stratospheric and mesospheric sounder (ISAMS) are evaluated. Flown on the Upper Atmosphere Research Satellite (UARS), ISAMS obtained 180 days of science data between September 26, 1991 and July 29, 1992. Typically, over 2600 temperature profiles/day were retrieved, spaced every 200 km along the limb-viewing track and nominally extending from 100 to 0.01 mbar (15-80 km). The latitude coverage ranged from 80°S to 80°N, depending on the particular ISAMS/UARS viewing geometry on any day. UARS is in a near-Sun-synchronous orbit, so that while the 15 orbits/d are spaced approximately every 24° longitude around the equator, the sampled local solar time actually changes by 20 min/d. The ISAMS temperature retrieval process is outlined and the various products are described. A detailed error budget for the retrieval is presented and comparisons are made with temperature measurements from other sources. Finally, a table is provided summarizing the best estimates of ISAMS temperature bias and precision. The results suggest a general cold bias of around 1 K in the stratospheric temperatures, with a superimposed 2-3 K warm bias associated with the densest part of the Pinatubo aerosol cloud. The precision of individual profiles is ±2 K throughout the stratosphere but falls off in the mesosphere to about ±10 K at 80 km. The error bars produced by the retrieval appear to be reasonable (although slightly pessimistic) estimates of the precision. Copyright 1996 by the American Geophysical Union.Dinitrogen pentoxide measurements from the improved stratospheric and mesospheric sounder: Validation of preliminary results
JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 101:D6 (1996) 9897-9906