New Observation Operators for Cloud Liquid/Ice Water Path From ABI and Their Impact on Assimilation and Hurricane Forecasts

Abstract

AbstractThe cloud liquid/ice water path (LWP/IWP) can provide valuable information about the cloud and precipitation. For the first time, the Gridpoint Statistical Interpolation (GSI) system is applied to examine the impact of the high spatial and temporal resolution LWP and IWP products derived from the Advanced Baseline Imager (ABI) on the new generation geostationary environmental satellites (GOES‐R series) in numerical weather prediction (NWP). To extend the GSI's capability to assimilate LWP and IWP products, a pair of new observation operators of LWP and IWP is developed to avoid the requirement for hydrometeor control variables. The new observation operators enable the direct use of hydrometeor background information from the NWP model and allow the vertical propagation of the water vapor increment according to the Jacobian distributions for the new LWP and IWP operators. The new LWP and IWP observation operators are evaluated by the single observation tests and the cycling assimilation and forecast experiments of Hurricane Irma (2017) and Hurricane Maria (2017). The results from single observation tests show that the assimilations of pseudo‐LWP and pseudo‐IWP can achieve positive water vapor increments, which also spread vertically according to the Jacobian distributions. The impact studies on two hurricanes demonstrate that the ABI LWP and IWP measurements can be successfully assimilated into the NWP model by the new observation operators, which enhances the water vapor analysis and further improves other atmospheric state variables in the forecast fields. The improved environmental fields lead to the overall forecast improvement for the two hurricanes, with the most notable track improvement.