Determination of water vapor continuum coefficients in the far-infrared from the RHUBC-II Campaign

 

Authors

Eli Jay Mlawer — Atmospheric and Environmental Research, Inc.
David D. Turner — NOAA- Global Systems Laboratory
Karen E. Cady-Pereira — Atmospheric and Environmental Research, Inc.
Gombos Dan — AER
Rick Pernak — Atmospheric and Environmental Research, Inc.
Luca Palchetti — Istituto Nazionale di Ottica, INO-CNR

Category

Radiation

Description

The ARM Program conducted RHUBC-II in Aug-Oct 2009 to improve knowledge of emission and absorption of water vapor in the mid-to-upper troposphere, most notably water vapor transitions in the far-infrared. This campaign was situated at a high-aititude site in the Atacama Desert of Chile, where precipitable water vapor (PWV) values as low as 0.2 mm were observed during clear period. Very low PWV values are a necessary condition for observing spectral features in the normally opaque far-IR. The methods used to retrieve accurate water vapor and temperature profiles from RHUBC-sondes, observations from a colocated 183 GHz (water vapor absorption line) microwave radiometer, and AERI measurements in carbon dioxide bands will be presented. These retrieved fields are used as input to LBLRTM, and the calculated radiances are compared to far-IR measurements from the Radiation Explorer in the Far Infrared (REFIR) instrument, as well as AERI measurements in the (mid-IR) water vapor fundamental absorption band. The implications of these radiative closures analyses for the water vapor continuum in the far-IR (and mid-IR) will be shown.