The Characteristics of Tropical and Midlatitude Mesoscale Convective Systems as Revealed by Radar Wind Profilers
The Characteristics of Tropical and Midlatitude Mesoscale Convective Systems as Revealed by Radar Wind Profilers
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雷达风廓线仪揭示的热带和中纬度中尺度对流系统特征
DOI：
10.1029/2018jd030087
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
R. Houze
中科院分区：
文献类型：
--
作者：
Dié Wang;S. Giangrande;K. Schiro;M. Jensen;R. Houze
这项研究对比了美国能源部大气辐射测量计划扩展的地面雷达风廓线仪（RWP）部署所观察到的成熟飑线中尺度对流系统（MCS）的特征。本分析将美国俄克拉荷马州（中纬度）RWP 站点上与 MCS 事件相关的动力结构、降水和冷池特性与 GoAmazon2014/5 活动期间（热带）巴西马瑙斯的 RWP 部署 2 年期间观察到的结果进行了比较。 MCS 显示相似的对流线降雨率和总降雨量。然而，中纬度事件表明层状对总降水量的贡献更大。对于这两个区域，对流管线冷池与管线通过时间附近的表面等效位温 (θe) 急剧下降（约 10 K）相关。这两个地区的地表 θe 特性表明降雨率与观测到可测量地表降雨的概率之间存在适度的关系。研究发现，在热带和中纬度 MCS 事件中观测到对流上升气流的概率与低层雷达反射率的函数相似。然而，中纬度 MCS 与更强烈的对流上升气流有关，向上的空气运动（平均、最大）在更高的高度达到峰值。最明显的对比是中纬度 MCS 倾向于出现更深、更强烈的下降气流。使用简单的混合假设进行基于观察到的下吸特性的分析。对于这些事件，亚马逊河和俄克拉荷马州之间对流层低层的 θe 垂直梯度相对一致，表明源自 3 km (0.1 km−1) 以下的下降气流的混合率相似。然而，如果下沉气流起源于接近 SGP 的最小 θe 水平，则混合可能会以相当于 0.3 km−1 的速率发生。
This study contrasts characteristics of mature squall‐line mesoscale convective systems (MCSs) observed by extended ground‐based radar wind profiler (RWP) deployments from the U.S. Department of Energy Atmospheric Radiation Measurement program. This analysis compares the dynamical structure, precipitation, and cold pool properties associated with MCS events over RWP sites in Oklahoma, USA, (midlatitude) to those observed during a 2‐year RWP deployment to Manaus, Brazil, during GoAmazon2014/5 campaign (tropical). The MCSs indicate similar convective line rainfall rates and total rainfall accumulations. However, midlatitude events suggest a larger fractional stratiform contribution to total precipitation. For both regions, convective line cold pools are associated with sharp decreases (approximately 10 K) in the surface equivalent potential temperature (θe) near the time of line passage. Surface θe properties for both regions suggest a modest relationship between rainfall rate and the probability of observing measurable surface rainfall. The probability of observing convective updrafts in both tropical and midlatitude MCS events is found to be similar as a function of low‐level radar reflectivity. However, midlatitude MCSs are associated with more intense convective updrafts, with upward air motions (mean, maximum) peaking at higher altitude. The most pronounced contrast is the propensity for deeper and more intense downdrafts in midlatitude MCSs. An analysis based on observed downdraft properties is performed using simple mixing assumptions. For these events, the vertical gradient of θe in the lower troposphere is relatively consistent between the Amazon and Oklahoma, suggesting similar mixing rates for downdrafts originating below 3 km (0.1 km−1). However, if downdrafts originate nearer to the level of minimum θe at SGP, mixing may be occurring at rates comparable to 0.3 km−1.
大气辐射测量程序 915 MHz 风廓线仪的信号后处理和反射率校准
影响因子：
2.2
作者：
Battaglia A
通讯作者：
Battaglia A