Abstract
Ensemble verification of low-level wind shear (LLWS) is an important issue in airplane landing operations and management. In this study, we conducted an accuracy and reliability analysis using a rank histogram, Brier score, and reliability diagram to verify LLWS ensemble member forecasts based on grid points over the Jeju area of the Republic of Korea. Thirteen LLWS ensemble member forecasts derived from a limited area ensemble prediction system (LENS) were obtained between 1 July 2016 and 30 May 2018, and 3-h LLWS forecasts for lead times up to 72 h (three days) were issued twice a day at 0000 UTC (9 am local time) and 1200 UTC (9 pm local time). We found that LLWS ensemble forecasts have a weak negative bias in summer and autumn and a positive bias in the spring and winter; the forecasts also have under-dispersion for all seasons, which implies that the ensemble spread of an ensemble is smaller than that of the corresponding observations. Additionally, the reliability curve in the associated reliability diagram indicates an over-forecasting of LLWS events bias. The selection of a forecast probability threshold from the LLWS ensemble forecast was confirmed to be one of the most important factors for issuing a severe LLWS warning. A simple method to select a forecast probability threshold without economic factors was conducted. The results showed that the selection of threshold is more useful for issuing a severe LLWS warning than none being selected.
Highlights
Wind shear events are usually associated with atmospheric instabilities caused by convective activity, gust fronts and microbursts (National Research Council 1983)
Damage related to high-impact weather, including wind shear, is continuously reported and resulted in 3010 flight delays and cancellations in Korea in Prediction of the low-level wind shear (LLWS) over the airports has been mostly focused on detection and early warning systems based on measurements from the low level windshear alert system (LLWAS) and terminal doppler weather radar (TDWR) [3,4]
A lot of data should be provided, or as mentioned by Zhou et al [16], the economic factors that have an impact on the probability threshold selection rule should be considered
Summary
Wind shear events are usually associated with atmospheric instabilities caused by convective activity, gust fronts and microbursts (National Research Council 1983). Atmosphere 2020, 11, 198 reliable and useful warnings about wind hazards [5,6] Forecasting such wind disturbances is still an ongoing area of development in the field of NWP systems. It is more appropriate, to utilize numerical forecasting to provide information on the relative likelihood of possible weather events. Ensemble-based weather forecasting has been applied to aviation meteorology to predict the weather hazards affecting aircraft operation and has been presented as a better tool for describing wind disturbances and their likely positions [13,14].
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