461 Understanding How CYGNSS Will Depict Convective Variability by Ingesting a High Temporal Resolution WRF Simulation in NASA's End-to-End Simulator

Monday, 11 January 2016
Tyler Castillo, University of Alabama, Huntsville, AL; and J. Mecikalski, T. J. Lang, T. Chronis, and X. Li

In conjunction with the Cyclone Global Navigation Satellite System (CYGNSS), work has been conducted to produce a high-resolution wind dataset over the Indian Ocean using the Dynamics of the Madden Julian Oscillation (DYNAMO) field campaign. DYNAMO took place from October 2011 through March 2012 across the equatorial central Indian Ocean region. The primary goal of DYNAMO was to enhance our understanding of key processes that pertain to MJO initiation, specifically the convective-evaporative feedback processes. The goal of this study is to determine the accuracy of CYGNSS system's expected configuration and wind retrieval methods, with an emphasis on helping understand how enhanced wind data relates and pertains to convective variability. With respect to the MJO, the hypothesis is that increased wind information (as available from DYNAMO), and especially when collected by CYGNSS in regions of precipitation (which other satellites are unable to do with high skill), will help in the prediction of the upscale growth of precipitation regions that in turn drive MJO dynamics through broad latent heat release.

Assimilation of a wide array of DYNAMO observations into the Weather Research and Forecasting (WRF) model, using the 3DVAR data assimilation methodology, produces the enhanced, high-resolution wind field for this project. The assimilated data includes the upper-air sounding network, vector winds from the Advanced Scatterometer (ASCAT) and Oceansat-2 Scatterometer (OSCAT), radial velocities from the TOGA and S-Polka radars, and a buoy network.

To reach the project's goals, WRF simulations using a 30 minutes output were ran for 26 October 2011, and was analyzed to determine a time period when a potential outflow boundary was present and potentially connected to a westerly wind burst (WWB). The MJO event of ~15-30 October was associated with much deeper convection than the first half of the month, which was dominated by isolated convective cells. It was determined through careful analysis that a period of more rapid convective system development occurred centered around 26 October, thus making it a key analysis time for our experiment. Once the outflow was found, a higher-resolution WRF simulation (3-minute output) was then developed. These 3-minute WRF data were then ingested into the CYGNSS End-to-End Simulator (E2ES), in order to test the ability of CYGNSS to provide insight on the relationships between surface winds and oceanic precipitation on a smaller, convective scale. Results will be shown displaying CYGNSS specular points overlaid on the ingested WRF winds for a direct comparison. Overall, this research will improve our understanding of the utility of CYGNSS, especially for identifying key processes of the MJO, which will lead to better understanding the life cycle of tropical storms.

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