A comparison of roll and nonroll convection and the subsequent deepening moist convection: An LEM case study based on SCMS data
A comparison of roll and nonroll convection and the subsequent deepening moist convection: An LEM case study based on SCMS data
复制标题
DOI：
10.1175/2008mwr2450.1
复制
发表时间：
2009
影响因子：
3.2
通讯作者：
Qian Huang;J. Marsham;D. Parker;Wenshou Tian;T. Weckwerth
中科院分区：
文献类型：
--
作者：
Qian Huang;J. Marsham;D. Parker;Wenshou Tian;T. Weckwerth
摘要利用大涡模式（LEM）模拟了小积云微物理研究（SCMS）野外活动期间观测到的卷。模拟的边界层特性与探空剖面和飞机观测结果吻合良好，模型再现了观测到的边界层滚转。当-Zi/L超过一个阈值时，滚动开始衰减，其值在5到45之间。这里Zi和L分别指对流边界层顶部的高度和Monin-Obukhov长度。这个值被发现依赖于低层风切变，CBL的高度，和涡流速度尺度的无量纲组合。较大的表面浮力通量和较小的剪切阈值较高。对于模拟的情况，滚转持续的表面浮力通量小于110 W m−2，并形成边界层风切变大于5 × 10−3 s−1，这与以前的研究是一致的。将模拟的滚转对流与非滚转对流进行了比较。
Abstract Rolls observed during the Small Cumulus Microphysical Study (SCMS) field campaign are simulated using a large eddy model (LEM). The simulated boundary layer properties were in a good agreement with sounding profiles and aircraft observations, and the observed boundary layer rolls were reproduced by the model. Rolls started to decay when −Zi/L exceeded a threshold, with a value between 5 and 45. Here Zi and L refer to the height of the top of convective boundary layer and the Monin–Obukhov length, respectively. This value was found to depend on a nondimensional combination of the low-level wind shear, the height of the CBL, and the eddy velocity scale. Larger surface buoyancy fluxes and smaller shears gave higher thresholds. For the case modeled, rolls persisted for surface buoyancy fluxes less than 110 W m−2, and formed for boundary layer wind shears greater than 5 × 10−3 s−1, which is consistent with previous studies. The simulated roll convection was compared with a nonroll simulation, which wa...