Growth of Mesoscale Convective Systems in Observations and a Seasonal Convection-Permitting Simulation over Argentina
Growth of Mesoscale Convective Systems in Observations and a Seasonal Convection-Permitting Simulation over Argentina
复制标题
DOI：
10.1175/mwr-d-20-0411.1
复制
发表时间：
2021-08
影响因子：
3.2
通讯作者：
Zhixiao Zhang;A. Varble;Zhe Feng;J. Hardin;E. Zipser
中科院分区：
文献类型：
--
作者：
Zhixiao Zhang;A. Varble;Zhe Feng;J. Hardin;E. Zipser
在阿根廷进行了为期6.5个月、允许对流的模拟，覆盖了RELAMPAGO-CACTI野外活动，并与观测结果进行了比较，以评估中尺度对流系统（MCS）的增长预测。观测到的和模拟的mcs被一致地识别、跟踪，并根据大气顶红外亮度、温度和地面降雨量将其分为生长、成熟和衰变阶段。模拟的MCS数量、寿命、季节和昼夜周期以及各种云屏蔽特性（包括增长率）与观测结果相似。然而，模拟产生较小的降雨区域，较大比例的强降雨和更快的系统传播。长寿命MCSs的降雨面积明显被低估，而短寿命MCSs的降雨面积则被高估。这些差异是由模型和卫星反演偏差的结合造成的，其中模拟的MCS降雨率从轻转向重，而卫星反演的降雨相对于雨量计的估计过于频繁。然而，模拟很好地再现了卫星检索的MCS云屏蔽演变，支持其用于检查MCS增长的环境控制。MCS的起始位置与对流抑制的去除有关，而不是与最大的低层水汽辐合或不稳定有关。快速增长与较强的高空急流（ULJ）和较深的西北阿根廷低压有关，后者导致较强的偏北低空急流（LLJ），增加热量和水分通量，低空垂直风切变，斜压性和不稳定性。持续增长与类似的LLJ、斜压性和不稳定条件相对应，但对ULJ、大规模垂直运动或低层切变不太敏感。生长养分比生长速率更能控制MCS的最大程度。
A 6.5-month, convection-permitting simulation is conducted over Argentina covering the RELAMPAGO-CACTI field campaign and compared to observations to evaluate mesoscale convective system (MCS) growth prediction. Observed and simulated MCSs are consistently identified, tracked, and separated into growth, mature, and decay stages using top-of-atmosphere infrared brightness temperature and surface rainfall. Simulated MCS number, lifetime, seasonal and diurnal cycles, and various cloud shield characteristics including growth rate are similar to those observed. However, the simulation produces smaller rainfall areas, greater proportions of heavy rainfall, and faster system propagations. Rainfall area is significantly underestimated for long-lived MCSs, but not shorter-lived MCSs, while rain rates are always overestimated. These differences result from a combination of model and satellite retrieval biases, in which simulated MCS rain rates are shifted from light to heavy, while satellite-retrieved rainfall is too frequent relative to rain gauges estimates. However, the simulation reproduces satellite-retrieved MCS cloud shield evolution well, supporting its usage to examine environmental controls on MCS growth. MCS initiation locations are associated with removal of convective inhibition more than maximized low-level moisture convergence or instability. Rapid growth is associated with a stronger upper-level jet (ULJ) and a deeper Northwestern Argentinean Low that causes a stronger northerly low-level jet (LLJ), increasing heat and moisture fluxes, low-level vertical wind shear, baroclinicity, and instability. Sustained growth corresponds with similar LLJ, baroclinicity, and instability conditions, but is less sensitive to the ULJ, large-scale vertical motion, or low-level shear. Growth sustenance controls MCS maximum extent more than growth rate.