An Observing System Simulation Experiment (OSSE) to Assess the Impact of Doppler Wind Lidar (DWL) Measurements on the Numerical Simulation of a Tropical Cyclone

The importance of wind observations has been recognized for many years. However, wind observations—especially three-dimensional global wind measurements—are very limited. A satellite-based Doppler Wind Lidar (DWL) is proposed to measure three-dimensional wind profiles using remote sensing techniques. Assimilating these observations into a mesoscale model is expected to improve the performance of the numerical weather prediction (NWP) models. In order to examine the potential impact of the DWL three-dimensional wind profile observations on the numerical simulation and prediction of tropical cyclones, a set of observing simulation system experiments (OSSEs) is performed using the advanced research version of the Weather Research and Forecasting (WRF) model and its three-dimensional variational (3DVAR) data assimilation system. Results indicate that assimilating the DWL wind observations into the mesoscale numerical model has significant potential for improving tropical cyclone track and intensity forecasts. 1. Introduction Although numerical weather prediction (NWP) models have been improved significantly over the past two decades, the forecast accuracy of high-impact weather events, such as tropical cyclones, is still a challenging problem in practical applications. Since most tropical cyclones occur over tropical oceans, where conventional observations are sparse, large uncertainties are presented in the numerical simulations and predictions due to inaccurate initial conditions. Remote sensing techniques provide an opportunity to observe the atmosphere, especially the atmospheric temperature, moisture, and ozone over the oceans either directly or indirectly. However, among all the variables used to represent the state of the atmosphere, wind measurements are the most limited, although the importance of wind observations for meteorological analysis has been recognized for many years [1–3]. Previous studies indicate that wind information plays an important role in improving the tropical and extratropical cyclone forecasts [4–14]. However, the current global observing system does not provide a uniform distribution of tropospheric wind measurements, especially in the tropics, southern hemisphere, and northern hemispheric oceans, where conventional observations are very sparse. During the past two decades there have been several satellites measuring wind over the oceans, such as the Geosat altimeter, the National Aeronautics and Space Administration (NASA) Scatterometer (NSCAT), Quick Scatterometer (QuikSCAT), the Special Sensor Microwave Imager (SSM/I), and