Validation of TES Temperature and Water Vapor Retrievals with ARM Observations
| Cady-Pereira, Karen | Atmospheric and Environmental Research, Inc. |
| Shephard, Mark | Atmospheric and Environmental Research, Inc. |
| Clough, Shepard | Atmospheric and Environmental Research |
| Mlawer, Eli | Atmospheric & Environmental Research, Inc. |
| Turner, David | University of Wisconsin-Madison |
Category: Atmospheric State and Surface
The primary objective of the TES (Tropospheric Emission Spectrometer) instrument on the Aura spacecraft is the retrieval of trace gases, especially water vapor and ozone. The TES retrievals extremely useful for global monitoring of the atmospheric state, but they must be validated. The ARM sites are well instrumented and provide continuous measurements, which are very valuable for the validation of satellite retrievals. Species retrievals require accurate temperature profiles. We are currently comparing ARM radiosonde profiles of temperature and water vapor with TES retrieved profiles. Our initial temperature profile comparisons show a systematic difference between TES retrievals and TWP radiosonde profiles in the upper troposphere/lower stratosphere. Validation of water vapor retrievals against radiosonde profiles is more problematic. Water vapor is generally much more variable than temperature in the atmosphere,; thus the validation of satellite observations requires closely collocated and cotemporal in situ water vapor measurements. Furthermore, radiosondes exhibit significant sonde-to-sonde variability and day/night bias (e.g., Turner et al, 2003; Miloshevic et al 2005). The ARM sites have the advantage of coincident PWV (precipitable water vapor) measurement provided by the MWR (Microwave Radiometer), which can be used to scale the radiosonde water vapor profiles. The LBLRTM/AERI validations have demonstrated that the residuals between the line-by-line calculation and the AERI observations are greatly improved when using the MWR scaled radiosonde water vapor profiles. Since the scaling of the radiosondes by the MWR total PWV is critical in improving the accuracy of the radiosonde profiles, we are investigating in detail the MWR and sonde PWV measurements from the ARM SGP site over a long period (2003-2005). We have observed that the MWR/Sonde PWV ratio has a strong seasonal component and an overall decreasing trend with time: over the 2003-2005 period, the daytime dry bias decreased significantly, while a nighttime moist bias developed and increased.
This poster will be displayed at the ARM Science Team Meeting.
