上海及周邊地區地閃活動特征及海陸差異
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中國氣象科學研究院基本科研業務費專項資金(2010Z004)、國家自然科學基金(41005006)、國家科技支撐計劃(2008BAC36B04)和氣象關鍵技術集成與應用項目(CAMGJ2012M78) 資助


Characteristics of Cloud to Ground Lightning in Shanghai and Its Circumjacent Regions and Land Sea Difference
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    摘要:

    利用LS8000閃電定位系統2009—2011年的地閃觀測資料對上海及周邊地區(120~1225°E,30~32°N)的地閃活動特征進行了研究。結果表明:分析區域內正地閃的比例約占85%,大電流地閃(電流絕對值大于50 kA)的比例約為56%。地閃活動主要集中在6—9月,峰值出現在8月;日變化上,12:00—19:00閃電活動最為活躍,峰值出現在14:00,凌晨閃電活動最弱。從日變化上來說,正地閃和大電流地閃比例在地閃活動較強時段低于地閃活動較弱時段;在月分布上,在地閃活動最強的夏季,正地閃比例普遍在10%以下,在地閃活動較弱的春、秋、冬季,正地閃比例普遍在10%以上。以北緯31°為界,分析區域北部地閃密度基本在6~12次〖DK〗·km-2〖DK〗·a-1以上,南部基本在24~48次〖DK〗·km-2〖DK〗·a-1。同時陸地上的地閃密度要顯著高于湖泊和海洋上的地閃密度,而海洋上的正地閃比例和大電流地閃比例要顯著高于陸地。閃電空間分布的時間變化說明,下午地閃活動主要出現在陸地,而凌晨地閃主要出現在水體附近,其它時段則表現出過渡特征,這與下墊面的加熱作用緊密相關。

    Abstract:

    In terms of the observations from the LS8000 lightning location system, Cloud to Ground (CG) lightning activities in Shanghai and its circumjacent regions are studied. The percentage of positive CG lightning in total CG lightning is about 85% and that of large current CG lightning (with the absolute value of current larger than 50 kA) is 56%. CG lightning activities highly centralized in the period from June to September, and peaked in August; for the temporal distribution of CG lightning, 13:00 to 21:00BT is an active periods, with peaks at 14:00BT and valleys in the morning. The monthly and hourly distributions of the percentage of the PCG (positive cloud to ground) lightning in total CG lightning present negative relationship to CG lightning. Setting 31°N as the boundary, the CG lightning density is generally 6 to 12 flushes/(km2〖DK〗·a) in the northern part of the analysis area and 24 to 48 flushes/(km2〖DK〗·a) in the southern part. At the same time, the CG lightning density on land is higher than those in lake and oceanic areas, while the percentage of PCG lightning and the large current CG lightning in the oceanic area is significantly higher than those on land. The time changes of spatial distribution of CG lightning show that CG lightning activities mainly appear on the land in afternoon and near the water in the morning, while in other periods presents the characters of transition, which is closely related to the heating effect of the underlying surface.

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宋曉爽,鄭棟,張義軍,姚雯,戴建華,王強.上海及周邊地區地閃活動特征及海陸差異[J].氣象科技,2014,42(1):164~172

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  • 收稿日期:2012-10-24
  • 定稿日期:2013-04-10
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  • 在線發布日期: 2014-02-28
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