Impact of Infrared, Microwave, and Radio Occultation Satellite Observations on Operational Numerical Weather Prediction

Abstract

A comparison of the impact of infrared (IR), microwave (MW), and radio occultation (RO) observations on NCEP's operational global forecast model over the month of March 2013 is presented. Analyses and forecasts with only IR, MW, and RO observations are compared with analyses and forecasts with no satellite data and with each other. Overall, the patterns of the impact of the different satellite systems are similar, with the MW observations producing the largest impact on the analyses and RO producing the smallest. Without RO observations, satellite radiances are over-or under-bias corrected and RO acts as an anchor observation, reducing the forecast biases globally. Positive correlation coefficients of temperature impacts are generally found between the different satellite observation analyses, indicating that the three satellite systems are affecting the global temperatures in a similar way. However, the correlation in the lower troposphere among all three systems is surprisingly small. Correlations for the moisture field tend to be small in the lower troposphere between the different satellite analyses. The impact of the satellite observations on the 500-hPa geopotential height forecasts is much different in the Northern and Southern Hemispheres. In the Northern Hemisphere, all the satellite observations together make a small positive impact compared to the base (no satellite) forecasts. The IR and MW, but not the RO, make a small positive impact when assimilated alone. The situation is considerably different in the Southern Hemisphere, where all the satellite observations together make a much larger positive impact, and all three observation types (IR, MW, and RO) make similar and significant impacts.

Assimilation of GPSRO Bending Angle Profiles into the Brazilian Global Atmospheric Model

“…Using sensitivity techniques from the adjoint method, the authors pointed out that GPSRO provides 10% of the 24-h forecast error reduction together with the Infrared Atmospheric Sounding Interferometer (IASI) and Atmospheric Infrared Sounder (AIRS). Cucurull and Anthes [10] confirmed the role of GPSRO data as an anchor observation, reducing the global forecast bias. A more effective use of satellite radiances was produced and a greater number of these observations passed through quality control procedures by assimilating GPSRO data.…”

A Case Study of the Effect of the Observation Time in 3D-Var on Near-Surface Wind Forecasts in a Limited Region

“…The selection of wind observations is very important in the prediction of near-surface winds because such winds are strongly affected by terrain features, land surface processes, turbulence and the stability of the PBL. Although the assimilation of satellite observations can lead to better predictions of atmospheric profiles, many studies have shown that the assimilation of conventional observations alone can be more effective in the prediction of near-surface winds (Stauffer and Seaman 1991;Zapotocny et al 2008;Cucurull and Anthes 2014;Zhang and Wang 2014;Zhang et al 2015). The selection and configuration of data assimilation schemes will have a large impact on the prediction of near-surface winds.…”

A Two-Season Impact Study of Radiative Forced Tropospheric Response to Stratospheric Initial Conditions Inferred From Satellite Radiance Assimilation

“…Utilization of infrared and microwave measurements generally have different and distinct impacts on tropospheric weather prediction models [25]. As noted by Zou et al (2013) [26], more valuable information within and below clouds can be obtained when using microwave radiance technologies.…”

“…Microwave radiation can penetrate non-precipitation clouds as well as carrying atmospheric humidity information within the cloud, as compared to infrared humidity sensors which do not give this information. In NWP systems, Cucuruul and Anthes (2014) [25] evaluated satellite microwave measurements of the stratosphere. Authors found that they can lead to larger impacts than infrared measurements when assimilated separately in the global operational forecast model in NCEP.…”