Methodology to determine the coupling of continental clouds with surface and boundary layer height under cloudy conditions from lidar and meteorological data
Methodology to determine the coupling of continental clouds with surface and boundary layer height under cloudy conditions from lidar and meteorological data
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DOI：
10.5194/acp-22-1453-2022
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发表时间：
2022-01
影响因子：
6.3
通讯作者：
T. Su;Youtong Zheng;Zhanqing Li
中科院分区：
文献类型：
--
作者：
T. Su;Youtong Zheng;Zhanqing Li
抽象的。海洋层积云与地面或边界层之间的耦合状态的研究比大陆低云要广泛得多，部分原因是陆地上空的热力学结构更为复杂。一个表现是缺乏强有力的遥感方法来识别陆地上空的耦合云和分离云。根据确定海洋上空云耦合的想法，我们根据位温廓线将耦合和解耦的概念推广到陆地上空的低云。此外，通过使用1998年至2019年美国能源部大气辐射测量计划南部大平原站点的激光雷达和一套地面气象仪器的大量测量，我们开发了一种方法，可以同时检索行星边界层（PBL）高度（PBLH）和白天多云条件下的耦合状态。新的激光雷达为基础的方法依赖于PBLH，解除凝结水平，和云基地诊断云耦合。用这种方法得到的耦合态与用无线电探空仪得到的耦合态具有很好的一致性。本研究解决了激光雷达遥感中的一个长期难题--多云条件下的PBLH反演问题。我们的方法可以导致高质量的反演的PBLH在多云条件下和云耦合状态的确定。新的方法，我们发现，耦合云是敏感的变化，在边界层具有较强的日周期，而去耦云和边界层弱相关。由于耦合云和解耦云具有不同的特征，因此我们的新方法提供了一种先进的工具来分别研究它们在气候系统中的作用。
Abstract. The states of coupling between clouds and surface or boundary layer have been investigated much more extensively for marine stratocumulus clouds than for continental low clouds, partly due to more complex thermodynamic structures over land. A manifestation is a lack of robust remote sensing methods to identify coupled and decoupled clouds over land. Following the idea for determining cloud coupling over the ocean, we have generalized the concept of coupling and decoupling to low clouds over land, based on potential temperature profiles. Furthermore, by using ample measurements from lidar and a suite of surface meteorological instruments at the U.S. Department of Energy's Atmospheric Radiation Measurement Program's Southern Great Plains site from 1998 to 2019, we have developed a method to simultaneously retrieve the planetary boundary layer (PBL) height (PBLH) and coupled states under cloudy conditions during the daytime. The new lidar-based method relies on the PBLH, the lifted condensation level, and the cloud base to diagnose the cloud coupling. The coupled states derived from this method are highly consistent with those derived from radiosondes. Retrieving the PBLH under cloudy conditions, which has been a persistent problem in lidar remote sensing, is resolved in this study. Our method can lead to high-quality retrievals of the PBLH under cloudy conditions and the determination of cloud coupling states. With the new method, we find that coupled clouds are sensitive to changes in the PBL with a strong diurnal cycle, whereas decoupled clouds and the PBL are weakly related. Since coupled and decoupled clouds have distinct features, our new method offers an advanced tool to separately investigate them in climate systems.