PCW/PHEMOS-WCA: Quasi-geostationary viewing of the Arctic of the Arctic and environs for Weather, Climate and Air quality
Résumé
The PCW (Polar Communications and Weather) mission is a dual satellite mission with each satellite in a highly eccentric orbit with apogee ~ 42,000 km and a period (to be decided) in the 12-24 hour range to deliver continuous communications and meteorological data over the Arctic and environs. At and near apogee the viewing is quasi-geostationary due to the slow satellite motion. The operational meteorological instrument is a 21-channel spectral imager with UV, visible, NIR and MIR channels similar to MODIS and ABI. The PHEMOS WCA (Weather, Climate and Air quality) mission is an atmospheric science complement to the operational PCW mission. The PHEMOS WCA instrument package consists of FTS and UVS imaging sounders with viewing range of ~4.5 degrees or a Field of Regard (FoR) ~ 3400x3400 km2 from near apogee. The spatial resolution at apogee of each imaging sounder is targeted to be 10Ã--10 km2 or better and the image repeat time is targeted at ~ 2 hours or better. The FTS has 4 bands that span the MIR and NIR. The MIR bands cover 700-1500 cm-1 and 1800-2700 cm-1 with a spectral resolution of 0.25 cm-1 i,e, a similar spectral resolution to IASI. They should provide vertical tropospheric profiles of temperature and water vapour in addition to partial columns of other gases of interest for air quality such as O3, CO, HCN, CH3OH, etc and also CO2 and CH4. The two NIR bands cover 5990-6010 cm-1 (0.25 cm-1) and 13060-13168 cm-1 (0.5 cm-1) and target columns of CO2 and CH4 and the O2-A band for surface pressure, aerosol OD and albedo. The UVS is an imaging spectrometer that covers the spectral range of 280 â€" 650 nm with 0.9 nm resolution and targets the tropospheric column densities of O3 and NO2. It is also planned to obtain the tropospheric columns of BrO, SO2, HCHO and (HCO)2 and the aerosol index (AI) as well as stratospheric columns of O3, NO2 and BrO. The quasi-stationary viewing will provide the ability to measure the diurnal behavior of atmospheric properties under the satellites and the ability to provide data for weather forecasting and also chemical data assimilation. Important goals for PHEMOS-WCA include measurement of meteorological and air quality data and the measurement of changes in CO2 and CH4 throughout the day-lit hours in the NIR near apogee (see FTS poster). In addition, the imaging design is to be sufficiently flexible so that it can be directed at special events possibly with the FoR reduced to have more rapid spatial coverage. In this paper we will outline the scientific objectives, status of retrieval algorithms and also the viewing geometry necessary with 2 satellites. PHEMOS WCA Phase A study was completed in March 2012. It was funded by the Canadian Space Agency (CSA).