Quantitative Analysis of Water Vapor Transport during Mei-Yu Front Rainstorm Period over the Tibetan Plateau and Yangtze-Huai River Basin

Abstract

There are continuous precipitation systems moving eastward from the Tibetan Plateau to the middle and lower reaches of the Yangtze-Huai River during the Mei-yu period. We selected 20 typical Mei-yu front precipitation cases from 2010 to 2015 based on observational and reanalysis data and studied the characteristics of their environmental fields. We quantitatively analyzed the transport and sources of water vapor in the rainstorms using the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT_4.9) model. All 20 Mei-yu front precipitation cases occurred in a wide region from the Tibetan Plateau to the Yangtze-Huai River. The South Asian high and upper level jet stream both had strong intensities during the Mei-yu front rainstorm periods. Heavy rainfall mainly occurred in the divergence zone to the right of the high-level jet and in the convergence zone of the low-level jet, where strong vertical upward flows provided the dynamic conditions required for heavy rainfall. The water vapor mainly originated from the Indian Ocean, Bay of Bengal, and South China Sea. 52% of the air masses over the western Tibetan Plateau originated from Central Asia, which were rich in water vapor. The water vapor contribution at the initial position was only 41.5% due to the dry, cold air mass over Eurasia, but increased to 47.6% at the final position. Over the eastern Tibetan Plateau to the Sichuan Basin region, 40% of the air parcels came from the Indian Ocean, which was the main channel for water vapor transport. For the middle and lower reaches of the Yangtze River, 37% of the air parcels originated from the warm and humid Indian Ocean. The water vapor contribution at the initial position was 38.6%, but increased to 40.2% after long-distance transportation.

Spatiotemporal Variation in Precipitation and Water Vapor Transport Over Central Asia in Winter and Summer Under Global Warming

“…Most previous studies, although important in revealing the relationship between precipitation and the regional water vapor balance, were limited by their use of a Eulerian approach, which is unable to assess the origin of moisture from remote source regions (James et al, 2004;Xu et al, 2008b;Chen et al, 2010;Jiang et al, 2019). Trajectory analysis methods based on a Lagrangian framework have been developed to provide a good technical approach to study the transport of water vapor and sourcesink analysis (Stohl and James, 2004;Jiang et al, 2013;Huang and Cui, 2015;Stein et al, 2015;Yang et al, 2019). Several models, such as the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) (Draxler and Hess, 1998) or FLEXible PARTicle (Stohl et al, 2005) models allow the calculation of back-trajectories.…”

An Evaluation and Improvement of Microphysical Parameterization for a Heavy Rainfall Process during the Meiyu Season

“…Many studies analyzed the dynamical and thermodynamical processes [14][15][16][17][18] and water vapor transport [19] favorable for heavy Meiyu rainfall. With the advancements in observation ability, the microphysical observations on Meiyu frontal heavy rainfall have also received increasing attention.…”

ConvLSTM Network-Based Rainfall Nowcasting Method with Combined Reflectance and Radar-Retrieved Wind Field as Inputs

“…Lavers [12] points out that the poor rainfall forecast effect is related to the uncertainty of the location of horizontal mass convergence. For different types of extreme rainstorms, water vapor transport is also very different [13], and the intensity of rainfall is consistent with the variation of boundary water vapor input and regional water vapor convergence [14]. It has been proven to be an effective and feasible method to predict mid-range extreme weather by using water vapor flux, which can characterize the process of water vapor transport [15].…”