Application of AIRS Soundings to Afternoon Convection Forecasting and Nowcasting at Airports

Nan-Ching Yeh,Hsin-Shuo Peng,Chih-Ying Chen,Yao-Chung Chuang

doi:10.3390/atmos13010061

Abstract

In Taiwan, the frequency of afternoon convection increases in summer (July and August), and the peak hour of afternoon convection occurs at 1500–1600 local solar time (LST). Afternoon convection events are forecasted based on the atmospheric stability index, as computed from the 0800 LST radiosonde data. However, the temporal and spatial resolution and forecast precision are not satisfactory. This study used the observation data of Aqua satellite overpass near Taiwan around 1–3 h before the occurrence of afternoon convection. Its advantages are that it improves the prediction accuracy and increases the data coverage area, which means that more airports can use results of this research, especially those without radiosondes. In order to determine the availability of Atmospheric Infrared Sounder (AIRS) in Taiwan, 2010–2016 AIRS and radiosonde-sounding data were used to determine the accuracy of AIRS. This study also used 2017–2018 AIRS data to establish K index (KI) and total precipitable water (TPW) thresholds for the occurrence of afternoon convection of four airports in Taiwan. Finally, the KI and TPW were calculated using the independent AIRS atmospheric sounding (2019–2020) to forecast the occurrence of afternoon convection at each airport. The average predictive accuracy rate of the four airports is 84%. Case studies at Hualien Airport show the average predictive accuracy rate of this study is 81.8%, which is 9.1% higher than that of the traditional sounding forecast (72.7%) during the same period. Research results show that using AIRS data to predict afternoon convection in this study could not only increase data coverage area but also improve the accuracy of the prediction effectively.

Highlights

IntroductionHeavy convection storms are relevant to flight safety during takeoff and landing
Introduction published maps and institutional affilHeavy convection storms are relevant to flight safety during takeoff and landing.The World Meteorological Organization (WMO) defined nowcasting as forecasting with local detail, by any method, over a period from the present to six hours ahead, including a detailed description of the present weather
The pre- and post-conditions were similar to those for temperature, and the root-mean-square error (RMSE) and Standard deviation (SD) of each level were reduced. These results indicate that this study’s modified equations effectively reduced errors for the Atmospheric Infrared Sounder (AIRS) measurements of temperature and humidity in Taiwan, making the AIRS measurements closer to their sounding-observation counterparts

Summary

Introduction

Heavy convection storms are relevant to flight safety during takeoff and landing. The World Meteorological Organization (WMO) defined nowcasting as forecasting with local detail, by any method, over a period from the present to six hours ahead, including a detailed description of the present weather. It is of great concern to aeronautical meteorological forecasting and nowcasting. When deep convection occurs in Taiwan, the temperature and humidity of each vertical layer of the atmospheric environment increase [1,2]. Even if the rainfall pattern has great variability, it is very important to estimate the rainfall characteristics of different scales, seasons, and environments [5,6,7,8]

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Conclusion