The impact of overshooting deep convection on local transport and mixing in the tropical upper troposphere/lower stratosphere (UTLS)
The impact of overshooting deep convection on local transport and mixing in the tropical upper troposphere/lower stratosphere (UTLS)
复制标题
DOI：
10.5194/acp-15-6467-2015
复制
发表时间：
2015-01-01
影响因子：
6.3
通讯作者：
Lane, T. P.
中科院分区：
文献类型：
--
作者：
Frey, W.;Schofield, R.;Lane, T. P.
在这项研究中，我们研究了模拟的向下运输和混合平流层空气进入热带对流层上层的研究飞行过程中观察到的SCUT-O3运动与深对流系统。我们使用先进的研究天气和研究预报（WRF-ARW）模式，水平分辨率为333米，检查这种向下的运输。与雷达和飞机观测结果相比，模拟再现了深对流系统，其时间和超调高度相当好。被动示踪剂初始化风暴前的时间表明，空气从平流层到对流层上层的向下运输，以及从边界层向上运输到云砧和过冲顶部。例如，被动臭氧示踪剂（即不经过化学处理的示踪剂）显示，在对流层上部，云中局部的增强高达约30 ppbv，而现场测量显示增加了50 ppbv。然而，被动的一氧化碳示踪剂表现出增加，而观测结果显示减少约10 ppbv，表明在热带对流层顶层中的传输过程的一个错误的模型表示。此外，它可能指出模型中的卷吸和脱吸不足。模拟结果表明，平流层下部的空气普遍增湿，但也表现出局部脱水的特征。在这里，我们使用该模型来解释导致传输的过程，并揭示模型和观测之间的不一致之处。
In this study we examine the simulated downward transport and mixing of stratospheric air into the upper tropical troposphere as observed on a research flight during the SCOUT-O3 campaign in connection with a deep convective system. We use the Advanced Research Weather and Research Forecasting (WRF-ARW) model with a horizontal resolution of 333m to examine this downward transport. The simulation reproduces the deep convective system, its timing and overshooting altitudes reasonably well compared to radar and aircraft observations. Passive tracers initialised at pre-storm times indicate the downward transport of air from the stratosphere to the upper troposphere as well as upward transport from the boundary layer into the cloud anvils and overshooting tops. For example, a passive ozone tracer (i.e. a tracer not undergoing chemical processing) shows an enhancement in the upper troposphere of up to about 30 ppbv locally in the cloud, while the in situ measurements show an increase of 50 ppbv. However, the passive carbon monoxide tracer exhibits an increase, while the observations show a decrease of about 10 ppbv, indicative of an erroneous model representation of the transport processes in the tropical tropopause layer. Furthermore, it could point to insufficient entrainment and detrainment in the model. The simulation shows a general moistening of air in the lower stratosphere, but it also exhibits local dehydration features. Here we use the model to explain the processes causing the transport and also expose areas of inconsistencies between the model and observations.