|Instrument: ISAMS : Improved Stratospheric And Mesospheric Sounder|
Earth Remote Sensing Instruments
Instrument Class: Passive Remote Sensing
Instrument Type: Profilers/Sounders
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The Space Shuttle Discovery carrying UARS was launched on September
12, 1991 from Kennedy Space Flight Center. UARS was released to orbit
on September 15, 1991, and the Improved Stratospheric and Mesospheric
Sounder (ISAMS) began scientific observations of the earth's upper
atmosphere September 26, 1991.
ISAMS is a limb-sounding radiometer which uses a combination of
pressure-modulated and wide-band infrared channels to measure Carbon
Monoxide, Water Vapour, Nitrogen Dioxide, Nitric Acid, Ozone, Nitric
Oxide, Nitrous Oxide, Methane, Dinitrogen Pentoxide, Aerosol, and
Temperature in the middle atmosphere. Typically, ISAMS produces
vertical profiles of constituents and temperature every 200 km along
the tangent track, with an instantaneous field of view of about 2.4 km
vertically. ISAMS made measurements, with several significant gaps,
between 80 S and 80 N from 26 September 1991 to 29 July 1992. UARS is
in a near sun-synchronous orbit so that while the 15 orbits/day are
spaced approximately every 24 degrees of longitude around the equator,
the sampled local solar time actually changes by 20 minutes/day.
The ISAMS Primary Science Objectives:
(1) To determine the thermal structure of the middle atmosphere and
its fluctuations in space and time,
(2) To investigate the photochemistry of nitrogen-containing species,
(3) To study the water vapour budget,
(4) To investigate the role of volcanic and polar stratospheric
aerosol in stratospheric chemistry.
Typically, over 2600 temperature profiles/day were retrieved, spaced
every 200 km along the limb-viewing track and nominally extending from
100-0.01 mb (15-80 km).
ISAMS Principal Investigator: Fred W. Taylor
Taylor, F. W., Scaddan, R. J. and Callard, L. Improved Stratospheric
and Mesospheric Sounder. Optical Engineering, 810, pp. 81-90, 1988.
Taylor, F. W., C. D. Rodgers, J. G. Whitney, S. T. Werrett, J. J.
Barnett, G. D. Peskett, P. Venters, J. Ballard, C. W. P. Palmer,
R. J. Knight, P. Morris, T. Nightingale, A. Dudhia, Remote Sensing of
Atmospheric Structure and Composition by Pressure Modulator Radiometry
from Space: The ISAMS Experiment on UARS, J. Geophys. Res., 98, p10,
Taylor F. W., J. Ballard, A. Dudhia, M. Goss-Custard, B. J. Kerridge,
A. Lambert, M. Lopez-Valverde, C. D. Rodgers and J. J. Remedios,
Stratospheric and Mesospheric observations with ISAMS, Adv. in Space
Res., 14, pp. (9)41-(9)52, 1994.
Taylor F. W., A. Lambert, R. G. Grainger, C. D. Rodgers and J. J.
Remedios, Properties of Northern Hemisohere Polar Stratospheric Clouds
and Volcanic Aerosol in 1991/2 from UARS/ISAMS Satellite Measurements,
J. Atmos. Sci., 51, pp3019-3026, 1994.
Instrument Owner: NASA