Water Vapor Transport Related to the Interdecadal Shift of Summer Precipitation over Northern East Asia in the Late 1990s

This study reveals an obvious interdecadal change in the summer water vapour budget over Northeast Asia around the late-1990s accompanied with the abrupt rainfall decrease. After the late-1990s, water vapour transported into Northeast Asia is apparently reduced under control of a local anomalous anticyclone. The water vapour transport is further explored by decomposing the water vapour flux into stationary and transient components, which are associated with the mean flow and transient eddy, respectively. The results indicate that the stationary component accounts for nearly 84% of the total water vapour budget change, much larger than the contribution from the transient component (16%). The correlation coefficient between the interdecadal variation of net and stationary (transient) water vapour budget is 0.95 (0.14). Hence, the stationary term plays a dominant role in contributing to interdecadal change in the total water vapour transport. In addition, change in the water vapour budget over Northeast Asia around the late-1990s is primarily attributed to the wind field change at the lower troposphere. A further comparison of the water vapour budgets in four boundaries of Northeast Asia shows that the water vapour budgets via the southern and northern boundaries display remarkable changes around the late-1990s, exerting significant influences on the total moisture budget change. The anomalous atmospheric water vapour transport circulations in association with the southern and northern boundaries both present a wave-like teleconnection pattern over the Eurasia, whose formation may be partly due to the combined impacts from the Pacific Decadal Oscillation and Atlantic Multidecadal Oscillation. K E Y W O R D S atmospheric circulation, interdecadal change, Northeast Asia, sea surface temperature, water vapour budgets, water vapour transport 1 | INTRODUCTION Northeast Asia occupies a vast area spanning from middle to high latitudes, including Northeast China, part of Mongolia, Korean peninsula, Japan and the Russian Far East. Most parts of it receive annual rainfall amount less than 400 mm, mainly covering arid and semi-arid climate zones (

“…In particular, the region analysed in Hu et al . (2018) extends more eastward than that used in this study. In addition, Hu et al .…”

Section: Resultsmentioning

confidence: 61%

“…In addition, Hu et al . (2018) defined summer season by averaging June, July and August, which is different from this study (i.e., July–August‐average).…”

Section: Resultsmentioning

confidence: 78%

Section: Resultsmentioning

confidence: 89%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Water vapour transport changes associated with the interdecadal decrease in the summer rainfall over Northeast Asia around the late‐1990s

Piao

Chen

2020

Roles of oceanic moisture exports in modulating summer rainfall over the middle‐lower Yangtze River Basin: Inter‐annual variability and decadal transition

Chen

Zhang

2019

Precipitation over the mid‐lower reaches of the Yangtze River Basin (YRB), which is a typical East Asian monsoon region in China, is strongly impacted by oceanic moisture exports (OMEs) and features variability at multiple spatial‐temporal scales, resulting in frequent floods and droughts. We focus on two key issues of OME and its relevance to the summer rainfall variability over the YRB: determination of the individual contributions of OME from three specific oceanic sub‐regions: the Arabian Sea (ARS), Bay of Bengal (BOB), and South China Sea (SCS), and their roles in the inter‐annual variability and decadal changes in YRB summer rainfall. Using a Lagrangian forward trajectories tracing approach, we create a catalogue of OME‐based diagnosed precipitation fields for three sub‐regions spanning the summer seasons (May to August) of 1980–2013 with 6‐hourly resolution using ERA‐Interim data. The results show that the pattern of the diagnosed OME‐based precipitation resembles the observed pattern over the YRB in terms of climatology and temporal variation. Climatologically, the SCS region accounts for the largest relative contribution (60.7%), followed by the ARS (30.8%), whereas the contributions of the BOB (8.5%) are almost negligible. On the inter‐annual scale, the variation in OME‐based rainfall originated from the ARS, and the BOB is out of phase with that of the SCS. In contrast to climatology, the inter‐annual changes in rainfall over the YRB are primarily modulated by the variation in the OME from the ARS. However, for the decadal changes, particularly in 1992/1993 over the YRB, the SCS and ARS are equivalent contributors to the summer precipitation over the YRB. These findings thus provide new insights into our understanding of the multi‐scale variability of summer precipitation over the YRB region.

Long‐term trend and variability of surface humidity from 1973 to 2018 in South Korea

Shin

Kim

et al. 2021

Water vapour is among the most critical variables that shape the Earth's energy balance and hydrologic cycle. Surface relative humidity (RH) and specific humidity (SH) are the main measures of atmospheric moisture. Long-term changes in these variables in South Korea vary regionally as well as locally, but have not been explored using long-term observation data. This study analyzes the annual trends of the means and SD of RH, surface air temperature, and SH in South Korea at 55 stations for the period 1973-2018. Three trend detection tests based on the Mann-Kendall test have been performed to detect trends at the 5% significance level for the annual and monthly statistics (means and SD) of these variables. Significant decreasing and increasing trends have been detected in the annual means of RH and air temperature, while the annual mean of SH has remained nearly constant. Overall, the surface air in South Korea has become drier over the study period, particularly in winter. The trend in RH and SH varies widely according to months to result in the increase in the SD over the annual cycle. The monthly SD of RH, SH, and surface air temperature show especially large positive trends for March and September, when the transition from winter to spring and summer to fall, respectively, occurs. K E Y W O R D S climate change, global warming, relative humidity, specific humidity, trend analysis 1 | INTRODUCTION Water vapour is one of the most critical greenhouse gases which often contribute to the greenhouse effect more than CO 2 (Trenberth and Josey, 2007). It is also an important component of the water cycle because water vapour is the main source of water for precipitation in all weather systems. Several meteorological variables, namely surface relative humidity (RH), surface specific humidity (SH), and surface vapour pressure, can be used to express the near-surface water vapour content. RH and SH are the main measures of