Exploring the Land–Ocean Contrast in Convective Vigor Using Islands
Exploring the Land–Ocean Contrast in Convective Vigor Using Islands
复制标题
利用岛屿探索对流强度的陆地与海洋对比
DOI：
10.1175/2010jas3558.1
复制
发表时间：
2011
影响因子：
3.1
通讯作者：
D. Kirshbaum
中科院分区：
文献类型：
--
作者：
F. Robinson;S. Sherwood;D. Gerstle;Chuntao Liu;D. Kirshbaum
众所周知，湿对流一般在大陆地区比在海洋地区更强烈，上升气流速度更大，并且产生了和闪电。这项研究探讨了从海洋对流到大陆对流的过渡，通过比较热带降雨测量使命（TRMM）雷达和微波（37和85千兆赫）观测岛屿的大小不断增加的趋势，由cloudresolving模型模拟。所观察到的风暴基本上是海洋超过100平方公里的岛屿和大陆超过10 000平方公里的岛屿，与之间的逐渐过渡。等效雷达和微波量模拟云解析运行的天气研究和预报模式通过离线辐射代码。模式配置wasalizated，与岛屿代表的地区，均匀的表面热通量没有地形，使用一系列的初始探测条件，没有强烈的水平风或气溶胶。正如预期的那样，模拟的风暴强度随初始探测而变化，但也以与观测相似的方式随岛屿大小急剧增加。较强的模拟风暴与较高浓度的大水凝物有关。虽然偏差随不同的冰微物理方案而变化，但测试的所有三个方案的趋势相似，并且在2D和3D模型配置中也可以看到。这种理想化强迫的趋势的成功再现支持了先前的建议，即地面加热的中尺度变化，而不是湿度，气溶胶或大气状态的其他方面的任何差异，是大陆和大岛上对流比海洋上更强烈的主要原因。一些动力风暴方面，特别是最大降雨量和最小地面气压低，更敏感的地面强迫比大气探空或冰计划。大水凝物浓度和模拟的微波和雷达信号，但是，至少作为敏感的初始湿度水平的表面强迫和更敏感的冰计划。讨论了TRMM模拟器在2D模拟上运行的问题，但它们似乎不如对模型微观物理的敏感性严重，这在2D和3D中是相似的。这支持进一步使用2D模拟来经济地探索建模的不确定性。
Moist convection is well known to be generally more intense over continental than maritime regions, with larger updraft velocities, graupel, and lightning production. This study explores the transition from maritime to continental convection by comparing the trends in Tropical Rainfall Measuring Mission (TRMM) radar and microwave (37 and 85 GHz) observations over islands of increasing size to those simulated by a cloudresolving model. The observed storms were essentially maritime over islands of ,100 km 2 and continental over islands .10 000 km 2 , with a gradual transition in between. Equivalent radar and microwave quantities were simulated from cloud-resolving runs of the Weather Research andForecasting model viaofflineradiation codes. The model configuration wasidealized,with islands represented by regions of uniform surface heat flux without orography, using a range of initial sounding conditions without strong horizontal winds or aerosols. Simulated storm strength varied with initial sounding, as expected, but also increased sharply with island size in a manner similar to observations. Stronger simulated storms were associated with higher concentrations of large hydrometeors. Although biases varied with different ice microphysical schemes, the trend was similar for all three schemes tested and was also seen in 2D and 3D model configurations. The successful reproduction of the trend with such idealized forcing supports previous suggestions that mesoscale variation in surface heating—rather than any difference in humidity, aerosol, or other aspects of the atmospheric state—is the main reason that convection is more intense over continents and large islands than over oceans. Some dynamical storm aspects, notably the peak rainfall and minimum surface pressure low, were more sensitive to surface forcing than to the atmospheric sounding or ice scheme. Large hydrometeor concentrations and simulated microwave and radar signatures, however, were at least as sensitive to initial humidity levels as to surface forcing and were more sensitive to the ice scheme. IssueswithrunningtheTRMMsimulatoron2Dsimulationsarediscussed,buttheyappeartobelessserious than sensitivities to model microphysics, which were similar in 2D and 3D. This supportsthe furtheruse of 2D simulations to economically explore modeling uncertainties.