A179-0007
East Asia Atmospheric River Catalog based on a Updated AR Algorithm (PanLu2.0): Annual Cycle, Climatic Regulation, and Precipitation
East Asia Atmospheric River Catalog based on a Updated AR Algorithm (PanLu2.0): Annual Cycle, Climatic Regulation, and Precipitation
Tuesday, 15 December 2020
Poster
Abstract:
The identification, climatic modulation and hydrological impact of Atmospheric Rivers (ARs) is an emergent scientific topic. In this study, we update our AR algorithm (Pan & Lu, 2019) to version 2.0 (PanLu2.0), which is adoptable for global AR detection. In order to probe into the AR structure, a segmentation algorithm is employed to divide AR into segments, and a novel AR metric (
) is proposed to capture the localized IVT coherence. Different “flavors” of AR segments corresponding to diverse weather systems (e.g., TC-like features, ECs) are flagged in this catalog. Based on PanLu2.0, a comprehensive AR catalog is established for East Asia (EA) for the first time. An eight-stage annual cycle in the climatological AR frequency is revealed, features in Stage 1 (12 Mar-15 May): the formation of Western North Pacific Subtropical Height (WNPSH) near the SCS steers and confines AR in its northwest flank over SEC; Stages 2-5 (16 May-15 Aug): the spatial variation of the AR main route echoes the northward displacement of WNPSH, coincides with the prevailing monsoonal wind onset and stepwise propagation of rain belt; Stages 6-7 (16 Aug- 11 Mar): AR enters the weakest stage in a year, and mainly locates over the North Pacific; Stage 8 (25 Nov – 11 Mar): The warm moisture-laden air of the wintertime ARs confronts the dry and cold air over SEC, contributing to the winter precipitation. Explored by the Pearson’s correlation analysis, we find potential predictability of precipitation day or heavy precipitation day by the occurrence of ARs over the mid-latitude (
) during the late-spring to early-summer, and over SEC and south Japan from late-winter to early-spring, which counterintuitively suggests that the regions/seasons with lower ARs frequency are deserved to be further studied.
) is proposed to capture the localized IVT coherence. Different “flavors” of AR segments corresponding to diverse weather systems (e.g., TC-like features, ECs) are flagged in this catalog. Based on PanLu2.0, a comprehensive AR catalog is established for East Asia (EA) for the first time. An eight-stage annual cycle in the climatological AR frequency is revealed, features in Stage 1 (12 Mar-15 May): the formation of Western North Pacific Subtropical Height (WNPSH) near the SCS steers and confines AR in its northwest flank over SEC; Stages 2-5 (16 May-15 Aug): the spatial variation of the AR main route echoes the northward displacement of WNPSH, coincides with the prevailing monsoonal wind onset and stepwise propagation of rain belt; Stages 6-7 (16 Aug- 11 Mar): AR enters the weakest stage in a year, and mainly locates over the North Pacific; Stage 8 (25 Nov – 11 Mar): The warm moisture-laden air of the wintertime ARs confronts the dry and cold air over SEC, contributing to the winter precipitation. Explored by the Pearson’s correlation analysis, we find potential predictability of precipitation day or heavy precipitation day by the occurrence of ARs over the mid-latitude () during the late-spring to early-summer, and over SEC and south Japan from late-winter to early-spring, which counterintuitively suggests that the regions/seasons with lower ARs frequency are deserved to be further studied.
References:
, & Lu, . (2020). East Asia Atmospheric River Catalog: Annual Cycle, Transition Mechanism and Precipitation. Geophysical Research Letters, 47, e2020GL089477. https://doi.org/10.1029/2020GL089477
, & (2019). A novel atmospheric river identification algorithm. Water Resources Research, 55, 6069– 6087. https://doi.org/10.1029/2018WR024407