A utilization of new observation data in KLAPS (Korean Local Analysis and Prediction System) and the impacts on a very short-range precipitation forecast

The Korea Meteorological Administration (KMA) has been operated a very short-range forecast system, named Korean Local Analysis and Prediction System (KLAPS), which runs every 10 minutes at 5 km horizontal resolution since 2019. To reflect rapidly changing atmosphere state in real-time, numerous data sources such as surface observations, upper-air measurement, radar data, satellite, aircraft reports, wind profiler data are ingested into the three-dimensional analysis. To date, 13 different types of observation data have been utilized, and for recent two years, two more observation data are tried to utilize newly to improve the forecast performances. The first one is a freezing level (0^oC) data interpreted by a bright band due to the enhanced radar reflectivity. Another one is the commercial aircraft-based meteorological information from Automatic Dependent Surveillance Broadcast (ADSB) Mode-Selective (Mode-S). In this study, we present the method to utilize these data and the result of the very short-range precipitation forecast.  
To ingest the freezing level data to KLAPS system, firstly each polar-form data at 10 radar station over the domain is converted into a cartesian coordinate system. And then the individual freezing level data are merged to three-dimension grid on KLAPS, and finally utilized for the temperature analysis with a climatological quality control procedure. Meanwhile, the ADSB Mode-S data are simply applied to KLAPS analysis system by referring to the Aircraft Meteorological Data and Relay (AMDAR) data package. But the Mode-S observation are required a data thinning process to reduce observation redundancy and correlated biases due to its high dense resolution in both space and time (Met Office, 2019). In this study, a median value of the Mode-S data within each 5km horizontal grid, 22-vertical level, and 10-minute time window, is newly considered as a thinning method. During the conference, the improved performances of KLAPS are going to be presented in details.