Assimilation of water vapor extracted from radar refractivity observations into a cloud-scale numerical model

Radar refractivity measures changes in water vapor, pressure, and temperature. During the warm season, refractivity is most strongly influenced by changes in water vapor. During IHOP, the refractivity measurements are obtained from the S-Pol radar in the Oklahoma panhandle. In this study, we explore the impact of the extracted water vapor from the refractivity measurements on initialization of a cloud-scale model. A case of an isolated storm observed during IHOP is used to examine the feasibility of assimilating the derived water vapor field into the cloud-scale model by a 4DVar technique. The impact of the water vapor assimilation on storm initiation is also investigated. The results indicate that the assimilation of the water vapor field makes a significant difference in the initiation of the storm.