Jong-Chul Ha

Parameter Estimation Using the Genetic Algorithm in Terms of Quantitative Precipitation Forecast

In this study, the optimal parameter estimation is performed for both physical and computational parameters in a mesoscale meteorological model, and its impact on the quantitative precipitation forecasting (QPF) is assessed for a heavy rainfall case occurred at the Korean peninsula in June 2005. Experiments are carried out using the PSU/NCAR MM5 model and the genetic algorithm (GA) for two parameters: the reduction rate of the convective available potential energy in the Kain-Fritsch (KF) scheme for cumulus parameterization, and the Asselin filter parameter for numerical stability. The fitness function is defined based on a QPF skill score. It turns out that each optimized parameter significantly improves the QPF skill. Such improvement is maximized when two optimized parameters are used simultaneously. Our results indicate that optimizations of computational parameters as well as physical parameters and their adequate applications are essential in improving model performance.

The Analysis of Meterological Environment over Jeju Moseulpo Region for HALE UAV

In this study, the characteristics of main wind direction, vertical temperature and wind speed profile near the Moseulpo airfield for HALE UAV(High Altitude Long Endurance Unmaned Aerial Vehicle) is investigated. The results are summarized as follows, main wind direction is governed by air mass according to season and local wind such as land-sea breeze. The directions of landing and take-off of HALE UAV will be selected as the south-east direction in June ~ August, north-west direction in October ~ March, and south-east direction at daytime in April ~ May, September. Annual variation of temperature at 100 hPa showed that temperature in summer season is lower than winter season. On the other hands, wind speed at 250 hPa in winter season is higher than summer season. The threshold values of temperature and wind speed for HALE UAV flight are and , which were determined by 5 % frequency value(), respectively.

Development of Compact High Altitude Imager and Sounding Radiometer (CHAISR) microwave radiometers for meteorological observation from HALE UAV

A set of compact microwave radiometers are under development for tropospheric sounding and imaging, as a part of the Compact High Altitude Imager and Sounding Radiometer (CHAISR) that operates in lower stratosphere. It aims to observe vertical temperature profiles and column-averaged water vapour for entire troposphere where most weather system takes place. Given total weight (4 kg) and power (50 W) constraints for the CHAISR are not the only challenges. The CHAISR requires nominal operation in thermal range between -75 and +43 °C up to 50 hPa. Along with optical cameras and in situ sensors in the CHASIR, microwave radiometers are to fit in 130 mm diameter and 290 mm length with total weight less than 1.5 kg for conical scan unit. Maximum power consumption of less than 15 W does not allow conventional internal blackbody calibration facility onboard, and alternative methods has been developed. Frequency ranges of three radiometer bands are ~20, ~40, and ~55 GHz, with 16 total channels. This MMIC based compact radiometers use quasi-correlation design for continuous observation for both reference and scene. Numerical simulation of the radiometer design shows less than 1 °K of RMSE is expected. Manufacture of the CHAISR is expect to be first quarter of 2017 and test flight is planned in summer of the same year.