CrIS data coverage (green dots) overlapped on GOES-15 Imager infrared window band brightness temperature image (black/white). Comparing the total number of assimilated CrIS radiances, there are 12.71 % more observations that are assimilated with CrIS cloud-cleared radiances than CrIS clear observations only. Credit: Wang et al., 2017, Figure 5b
Source: Journal of Geophysical Research: Atmospheres

In numerical weather prediction (NWP), the radiance measurements from high spectral resolution infrared (IR) sounders on-board weather satellites have provided positive impact on weather forecasts. However, so far only radiances in clear skies and limited radiances in cloudy skies from those advanced IR sounders are assimilated in the current NWP systems. Wang et al. [2017] propose a new approach to make use of ample partially cloudy scenes to take advantage of the thermodynamic information from cloudy skies through the assimilation of cloud-cleared IR radiances. By assimilating more information from cloudy regions, the authors demonstrate significant improvement in the NWP forecasting for Hurricane Joaquin (2015) and Hurricane Matthew (2016). Comparing temperature, specific humidity, and U/V winds with radiosondes indicates that the data impacts are growing larger with longer time forecasts (beyond 72-hour forecast). The improvement on reducing the track forecast error is also achieved with the assimilation of cloud-cleared radiances.

Citation: Wang, P., Li, J., Li, Z., Lim, A. H. N., Li, J., Schmit, T. J., & Goldberg, M. D. [2017]. The impact of Cross-track Infrared Sounder (CrIS) cloud-cleared radiances on Hurricane Joaquin (2015) and Matthew (2016) forecasts. Journal of Geophysical Research: Atmospheres, 122.

—Zhanqing Li, Editor, JGR: Atmospheres

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