Polar Ozone and Aerosol Measurement III (POAM III)

The Polar Ozone and Aerosol Measurement III (POAM III) instrument is similar to POAM II, and is designed to extend the POAM II data in time. POAM III is carried by the SPOT-4 spacecraft sponsored by the Centre National d'Etudes Spatiales (CNES), the French Space Agency. SPOT-4 is the most recent in the SPOT series of remote sensing spacecraft: the acronym "SPOT" stands for "Satellite Pour l'Observation de la Terre". SPOT-4 was launched on an Ariane-4 rocket in March 1998, from CNES' facility in Kourou, French Guayana. The orbit is essentially identical to that of POAM II [Latitude figure]. POAM III includes several improvements relative to POAM II. It is more sensitive, and will therefore be able to measure deeper into the atmosphere. It has two Sun-sensor quadrant detectors instead of one: a 10 degree Wide Field Sun Sensor as well as the 1 degree Narrow Field Sun Sensor used in POAM II. The Wide Field Sun Sensor will simplify initial acquistion of the Sun at the beginning of sunrise and sunset events. The interference filters used by the science channels in POAM III were manufactured via a newer, better technology than that for the POAM II filters. And finally, the wavelenths and bandwidths of the science channels differ slightly from those in POAM II. The science channels for POAM III are given in the table below (with all wavelengths in nanometers):

Update: The POAM III instrument failed on Dec 5, 2005

POAM III Science Channels

Channel	Center Wavelength (nm)	Width (nm)	Primary Purpose
1	353.4	9.71	Rayleigh Extinction
2	439.6	2.1	NO2 (on peak)
3	442.2	2.1	NO2 (off peak)
4	603	17.7	Ozone
5	761.3	2.3	Oxygen (on peak)
6	779	10.2	Oxygen (off peak), Aerosol
7	922.4	2.6	H2O (off peak)
8	935.9	2.9	H2O (on peak)
9	1018	11.6	Aerosol Extinction

POAM III, like POAM II, was fabricated by ThermoTrex Corporation in San Diego, California.

For further information on POAM II contact the principal investigator

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