The spectral parameters of the water vapor absorption cross section (line positions and widths) are temperature and pressure dependent. For this reason, DA10 incorporates WXT534 that measures surface temperature, pressure, and humidity. The temperature and pressure measurements are vertically extrapolated assuming the International Organization for Standardization ISO 2533:1975 standard atmospheric model. The extrapolated profiles are then used to estimate the depths and widths of the water vapor absorption lines from the high-resolution transmission molecular absorption database (HITRAN) to model the observed signal in the water vapor retrieval algorithm.
The surface humidity measurements are used to establish the water vapor mixing ratio at the ground level and below the lowest DA10 altitude level.
In the current release, the surface pressure is reported in units of bar and the surface temperature in units of Kelvin. In later releases, the reporting units will be hPa and Celsius. |