An Evaluation ofGOES-8Retrievals

Abstract

The Geostationary Operational Environmental Satellite (GOES-8) temperature-moisture retrievals were compared with collocated National Weather Service radiosonde observations (RAOBs) to assess retrieval performance. Retrieved values of temperature and dewpoint were evaluated at individual levels. Precipitable water and thickness also were evaluated, and the GOES-8 retrievals were compared with the first-guess data used in the algorithm. The dataset consisted of 1113 RAOB-retrieval pairs (collocated to within 50 km) over the United States at 1200 UTC during August-November 1995.GOES-8 temperature retrievals were found to agree better with their RAOB-derived counterparts than did the dewpoints. However, both temperatures and dewpoints were found to be highly dependent on their first-guess data from the Nested Grid Model. Retrievals generally were closer to the RAOBs than was the first guess. However, this was never guaranteed, even for large first-guess discrepancies. In fact, some retrievals did not agree as well with the RAOBs as did the first guess.GOES-8 and RAOB-derived precipitable water (PW) and thickness showed closer agreement than the levelspecific data. Both integrated parameters were dependent on their first guess. However, GOES-8 and RAOB PW agreed more often in layers above the surface where the guess was less accurate.Comparison with a previous evaluation of retrievals from the Visible and Infrared Spin Scan Radiometer Atmospheric Sounder (VAS) indicated that GOES-8 retrievals agreed better with RAOBs than did the VAS versions. This improvement is likely due to GOES-8's increased number of channels and better signal-to-noise values, along with the assumed increase in quality of the first-guess data being used.

Evaluation of the GOES-R ABI LAP Retrieval Algorithm Using the GOES-13 Sounder

“…The SGP site was selected as the first ARM field measurement site because of its high variability of weather conditions, large seasonal variability of temperature, moisture and precipitation, spatially homogeneous terrain, and easy accessibility. Raob temperature/water vapor profiles have been widely used to evaluate remotely sensed profiles (Fuelberg and Olson 1991;Rao and Fuelberg 1998;Jin et al 2008). Recently, the ARM CART site has been selected as a site in the Global Climate Observing System (GCOS) Reference Upper-Air Network (GRUAN) to provide long-term, highly accurate measurements of the atmospheric profiles.…”

Regionalization of the GOES-10 retrieval algorithm for tropical South America

“…Improvement over the first guess (IFG) Olson 1991, Rao andFuelberg 1998) was also calculated, which determines whether there is improvement in the GOES-10 profile compared with the first guess provided by the Global Model. IFG can be written as…”

“…The collocated points of the radiosonde and GOES-10 retrievals were determined using a maximum distance of 50 km, following the methodology proposed by Fuelberg and Olson (1991) and Rao and Fuelberg (1998). It is important to clarify that the validations were performed at the second sweep sector of GOES-10, as shown in figure 1(b).…”

“…change insignificantly when the original (dashed lines) and the new covariance matrices (solid lines) are used. In general, biases are between -0.5 and 0.5 K, agreeing with the results obtained by Rao and Fuelberg (1998) using GOES-8 for the USA. The highest bias is found at 780 hPa, which seems to be associated with the first guess from the Global Model used in the retrieval scheme.…”

“…Rao and Fuelberg (1998) found correlation below 90% for GOES-8. The RMSE found in this study (around 4 mm) was higher than that found by Schmit et al (2002) and Li et al (2008) (around 2.5 mm) for GOES-10 validation.…”