The RHUBC-II Campaign: Analysis of Water Vapor Profiles

Eli Mlawer Atmospheric & Environmental Research, Inc.
Jennifer Delamere Tech-X Corporation
Vivienne Payne Jet Propulsion Laboratory/California Institute of Technology
David Turner National Oceanic and Atmospheric Administration
Maria Cadeddu Argonne National Laboratory

Category: Field Campaigns

Working Group: Cloud Life Cycle

Radiative heating and cooling are important drivers of Earth’s climate. In the mid-to-upper troposphere, the dominant radiative processes in both the solar and thermal regimes are due to water vapor. These processes are imperceptible from the ground in typical conditions due to absorption by water vapor in the intervening lower atmosphere. A set of field experiments, the Radiative Heating in Underexplored Bands Campaigns (RHUBC), has been conducted as part of the Atmospheric Radiation Measurement (ARM) Climate Research Facility in order to provide a robust and complete data set that would allow radiative transfer models to be evaluated in spectral regions where water vapor absorbs strongly. RHUBC-II was held from August–October 2009 near the summit of Cerro Toco in the Atacama Desert in Chile—during this period of austral late winter/early spring, clear conditions were pervasive and the water vapor loading was as low as 0.2 mm. Measurements of spectrally resolved radiances throughout the infrared and sub-millimeter regions were obtained from a number of different instruments; the analysis of these measurements critically depends on accurate water vapor profiles. Vaisala RS-92 radiosondes were regularly launched during operational periods of RHUBC-II, but these sondes have well-known accuracy issues in conditions of low humidity and during daytime. This study will analyze candidate RHUBC-II water vapor profiles: the raw radiosondes, radiosonde profiles that have been modified using the method of Miloshevich et al., sonde profiles that have been uniformly scaled using coincident microwave measurements by the G-band Vapor Radiometer Profiler (GVRP), and profiles that have been obtained from a multi-parameter retrieval from GVRP measurements. The poster will present direct comparisons of the water vapor profiles from these different methods. Also, the impact of their use on comparisons with measured radiances in other spectral regions will be shown.

This poster will be displayed at ASR Science Team Meeting.

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