Mesoscale convective systems in the third pole region: Characteristics, mechanisms and impact on precipitation

Abstract

The climate system of the Third Pole region, including the (TP) and its surroundings, is highly sensitive to global warming. Mesoscale convective systems (MCSs) are understood to be a vital component of this climate system. Driven by the monsoon circulation, surface heating, and large-scale and local moisture supply, they frequently occur during summer and mostly over the central and eastern TP as well as in the downstream regions. Further, MCSs have been highlighted as important contributors to total precipitation as they are efficient rain producers affecting water availability (seasonal precipitation) and potential flood risk (extreme precipitation) in the densely populated downstream regions. The availability of multi-decadal satellite observations and high-resolution climate model datasets has made it possible to study the role of MCSs in the under-observed TP water balance. However, the usage of different methods for MCS identification and the different focuses on specific subregions currently hamper a systematic and consistent assessment of the role played by MCSs and their impact on precipitation over the TP headwaters and its downstream regions. Here, we review observational and model studies of MCSs in the TP region within a common framework to elucidate their main characteristics, underlying mechanisms, and impact on seasonal and extreme precipitation. We also identify major knowledge gaps and provide suggestions on how these can be addressed using recently published high-resolution model datasets. Three important identified knowledge gaps are 1) the feedback of MCSs to other components of the TP climate system, 2) the impact of the changing climate on future MCS characteristics, and 3) the basin-scale assessment of flood and drought risks associated with changes in MCS frequency and intensity. A particularly promising tool to address these knowledge gaps are convection-permitting climate simulations. Therefore, the systematic evaluation of existing historical convection-permitting climate simulations over the TP is an urgent requirement for reliable future climate change assessments.

Intensification of Mesoscale Convective Systems in the East Asian Rainband Over the Past Two Decades

“…The GPM IMERG V06B precipitation product is an integrated retrieval data set from a network of GPM constellation satellite partners (Huffman et al., 2019), with a temporal resolution of 30 min and a spatial resolution of ∼10 km. Previous evaluation studies over the U.S. and China suggested that the MCS tracking results by using GPM IMERG precipitation product provides consistent results with those derived from ground‐based radar data (Feng et al., 2021; Kukulies et al., 2021, 2023; Wu et al., 2023). It should be noted the hourly precipitation intensity could be changed due to the changes in the satellite constellation contributing to GPM IMERG, therefore, the efforts have been taken to ensure a seamless transition from TRMM to GPM (Huffman et al., 2019; Tan et al., 2019), and Tang et al.…”

Intensification of mesoscale convective systems in the East Asian rainband over the past two decades

“…The GPM IMERG V06B precipitation product is an integrated retrieval data set from a network of GPM constellation satellite partners (Huffman et al, 2019), with a temporal resolution of 30 min and a spatial resolution of ∼10 km. Previous evaluation studies over the U.S. and China suggested that the MCS tracking results by using GPM IMERG precipitation product provides consistent results with those derived from ground-based radar data (Feng et al, 2021;Kukulies et al, 2021Kukulies et al, , 2023Wu et al, 2023). It should be noted the hourly precipitation intensity could be changed due to the changes in the satellite constellation contributing to GPM IMERG, therefore, the efforts have been taken to ensure a seamless transition from TRMM to GPM (Huffman et al, 2019;Tan et al, 2019), andTang et al (2020) documented that there is little difference between the TRMM era (2013) and GPM era (2014)(2015), which indicates that GPM IMERG is quite robust in the transition between the two eras.…”

Km‐Scale Simulations of Mesoscale Convective Systems Over South America—A Feature Tracker Intercomparison

“…Several definitions using various cloud system parameters and thresholds have been used in the literature to provide an objective classification of MCS, preventing actual quantitative comparisons (e.g., recent reviews by Kukulies et al. (2023)). Houze (2004) broadly defined MCSs as “…a cumulonimbus cloud system that produces a contiguous precipitation area ∼100 km or more in at least one direction.” We translate this definition into objective rules, which can be used in tracking algorithms, and can be applied to satellite‐based observations.…”