Plans for Data Assimilation and Forecast Experiment with Dropsondes during T-PARCII

The first aircraft mission was conducted with two newly-developed GPS dropsonde systems for tropical cyclone (TC) Lan on 21 and 22 October 2017 as part of the Tropical Cyclones-Pacific Asian Research Campaign for the Improvement of Intensity Estimations/Forecasts (T-PARCII). One of the main objectives of this research project is to improve the quality of TC intensity estimation and forecast so as to contribute reducing TC-related disasters.

During the first flight with several eye soundings in 0500-0700 UTC on the first day, this typhoon was at its maximum intensity with a central pressure of 925 hPa. The flight route was originally designed to go outside of the eyewall with the diameter of 200-km radius, but was modified to go into the eye. This decision was made during flight using information of an aircraft nose radar. The Gulfstream-II jet flew at 43,000 feet (~13 km) of altitude, and totally 8 and 10 of the Meisei iMDS-17 dropsondes were deployed in the eye and around the eyewall, respectively. On the second day, 5 dropsondes were deployed in the eye and surrounding areas.

In this presentation, a plan for data assimilation and forecast experiment with dropsondes during T-PARCII will be discussed in order to improve the quality of analysis and forecast. Another potential research topic is to check if a targeting observation strategy for TC intensity is effective or not. Currently, we are working on conducting a sensitivity analysis in terms of TC intensity signals and introducing these observations into “non-hydrostatic model”-based data assimilation systems. If possible, we will discuss further potential improvements made by adding dropsondes obtained from an aircraft mission, which was conducted almost simultaneously for TC Lan, as part of a dropsonde observations for typhoon surveillance near Taiwan Region (DOTSTAR) project.