Statistics of convection initiation by use of Meteosat rapid scan data during the Convective and Orographically-induced Precipitation Study (COPS)
Statistics of convection initiation by use of Meteosat rapid scan data during the Convective and Orographically-induced Precipitation Study (COPS)
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DOI：
10.1127/0941-2948/2008/0337
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发表时间：
2008-12
影响因子：
1.2
通讯作者：
F. Aoshima;A. Behrendt;H. Bauer;V. Wulfmeyer
中科院分区：
文献类型：
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作者：
F. Aoshima;A. Behrendt;H. Bauer;V. Wulfmeyer
在对流和地形诱导降水研究（COPS）期间，Meteosat8（也称为Meteosat第二代1，MSG1）上的旋转增强型可见光和红外成像仪（SEVIRI）的快速扫描（RS）服务提供了2007年6月1日至8月31日从大约15至69◦N的纬度带的5分钟扫描。利用这些高时间分辨率的数据，我们研究了cop区域的对流起始（CI），该区域覆盖了法国东部/德国西南部孚日山脉和黑森林的低山区，以及介于两者之间的莱茵河流域。在所有可获得Meteosat-8数据的cop密集观察期（IOPs）内，即在16 IOPs内的30天内，总共确定了94个CI事件。该算法以2007年7月15日的孤立CI事件（COPS IOP 8b）为例进行了说明，10.8 μm的RS亮度温度数据显示云顶温度的最小变化率为-4.0 K/min。研究发现，CI站点分布在整个cop区域；然而，孚日山脉和黑森林山区的CI密度（本研究调查的30天内约30个风暴/（10000公里））比莱茵河流域高约3倍。CI分布呈日循环，在1300 ~ 1400 UTC之间，即1130 UTC当地中午后2小时，CI最大值明显。仅在这1小时内，18%的CI事件发生（如果忽略与天气面锋相关的CI事件，则为25%）。与此相反，我们发现只有4%的CI事件发生在2100到0400 UTC之间的晚上。
Rapid Scan (RS) service from the Spinning Enhanced Visible and Infrared Imager (SEVIRI) on Meteosat8 (also called Meteosat Second Generation 1, MSG1) during the Convective and Orographically-induced Precipitation Study (COPS) provided five-minute scans of the latitude belt from approximately 15 to 69 ◦N from 1 June to 31 August 2007. With these high-temporal resolution data, we investigate convection initiation (CI) in the COPS domain, an area covering the low-mountain regions of the Vosges and Black Forest with the Rhine Valley in between in eastern France/south-western Germany. In total, 94 CI events are identified during all COPS Intensive Observation Periods (IOPs) for which Meteosat-8 data are available, i.e., on 30 days within 16 IOPs. The algorithm to find CI sites is illustrated by the isolated CI event of 15 July 2007 (COPS IOP 8b) for which the RS brightness temperature data at 10.8 μm reveal a minimum temperature change rate at the cloud top of –4.0 K/min. We find that the CI sites are distributed over the whole COPS region; however, the CI density is about 3 times higher in the mountainous regions of the Vosges and the Black Forest (∼30 storms/(10000 km) on the 30 days investigated in this study) than in the Rhine Valley. The CI distribution shows a diurnal cycle with a pronounced CI maximum between 1300 and 1400 UTC, i.e., 2 hours after the local noon of 1130 UTC. In this 1-hour period alone, 18 % of all CI events take place (25 % if we neglect those CI events which are related to a synoptic surface front). In contrast to this, we find only 4 % of all CI events at night between 2100 and 0400 UTC.