Impact Analysis of LEO Hyperspectral Sensor IFOV Size on the Next-Generation High-Resolution NWP Model Forecast Performance

Reduced errors in the initial conditions and improved forecast models have led to steady improvements of forecast skill in the past three decades. Some of the reductions in initial condition errors come from increases in the quality and quantity of satellite observations. The spatial resolution of satellite observations must increase to maintain its positive influence on forecast skill as Numerical Weather Prediction (NWP) Centers move to higher resolution forecast models. Increasing the spatial resolution of satellite observations and decreasing spatial inhomogeneity in satellite observations is crucial for satellite radiance assimilation.

Some NWP Centers have begun assimilating cloudy radiance observations, but challenges remain before substantial forecast impact from cloudy radiances could be achieved. Infrared radiance observations are very sensitive to clouds and cloud detection plays an important role in the use of hypersepctral infrared sounders. A smaller field-of-view (FOV) will have a higher probability of being cloud free, increasing the percentage of infrared radiance observations to be assimilated and thus potentially making a larger contribution to the quality of the forecast initialization.

To support the National Oceanic and Atmospheric Administration’s Joint Polar Satellite System (NOAA/JPSS) Program in planning for the next generation hyperspectral sounder, the impact of FOV size of the hypersepctral infrared sounder such as Cross-track Infrared Sounder CrIS instrument on NWP will be assessed. The NOAA National Centers for Environmental Prediction’s (NCEP) Global Data Assimilation system/Global Forecast System (GDAS/GFS) will be used, in the presence of the existing observing network, to assess the impact of the CrIS sensor with a smaller FOV. Impact assessment will be performed in a simulated environment, also known as an Observing System Simulation Experiment (OSSE). Observations from current observing network; CrIS observations at both the current and increased resolution are simulated from a known state of the atmosphere or the Nature Run. Prior to carrying out the CrIS experiments, the OSSE system needs to be calibrated against the real system to verify that the simulated data impact is comparable to the real data impact. Preliminary results on the impact of increased spatial resolution of CrIS observations will be presented.

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