雲中閃電資料應用於雷暴即時預警之研究

全閃電（total lightning）次數的增加，代表對流系統正逐漸活躍中，因此全閃電次數的躍升，即全閃電次數時間變率的突增（jump），可做為雷暴所伴隨劇烈天氣現象的預警參考指標。本文使用台電公司觀測之雲中（intra-cloud, IC）閃電資料，並採用較簡單的雲中閃電次數躍升（IC jump）定義方法，分析臺灣三種不同型態的雷暴系統，以檢視國內閃電資料應用於雷暴即時預警的適用性。結果顯示，在午後雷暴個案裡，IC jump出現於數個對流胞合併成對流系統的過程中，並於IC jump達門檻後40分鐘出現最強的單站及區域10分鐘瞬時降雨；在移動性雹暴系統個案裡，當IC次數大量增加約15分鐘後，出現冰雹的目擊報告；在颱風雨帶環境下的移動性雷暴系統個案裡，當IC jump達到門檻後40分鐘，地面觀測到10分鐘強瞬時降雨。顯然，分析IC jump出現的時間，有助於極短時預警伴隨雷暴之劇烈天氣現象，甚至對雷暴於成熟階段的強瞬時降雨亦可適用。

關鍵字

即時預警；劇烈天氣現象；強瞬時降雨

並列摘要

Since the increase of total lightning activity represents that the convective system is active, the total lightning jump, which defined as the rapid growth of the time rate of total flash in a specific time, is indicative of the following severe weather associated with the thunderstorm. In this study, the intra-cloud (IC) lightning data observed by Taiwan Power Company were used to assess the utility of the IC jump for thunderstorm nowcasting. With a relatively simple IC jump definition, three thunderstorms occurred at Taiwan were investigated. In an afternoon thunderstorm case, IC jump appeared when several cells merged into one larger convective system. Forty minutes later, not only single-station but also regional heavy 10-min accumulated precipitations were observed. In a moving hail storm case, surface hail was observed unofficially about 15 minutes later than the IC flashes increased abruptly. In typhoon Matmo's rainband-embedded moving thunderstorm case, heavy 10-min rainfall was observed 40 minutes after the IC jump. This study suggests that the severe weather/heavy short-term rainfall associated with thunderstorm can potentially be diagnosed by analyzing IC jump.

並列關鍵字

Thunderstorm nowcasting ； IC Jump ； Severe weather ； Heavy 10-min accumulated precipitations

國際替代計量

雲中閃電資料應用於雷暴即時預警之研究

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