Water Vapor Changes Affect Cross-Seasonal Strong Drought Events in the Eastern Region of Northwest China

Drought in eastern Northwest China (ENC) is severely affected by water vapor conditions. An in-depth study of the primary sources of water vapor and its characteristics, at intraseasonal and interannual timescales, was conducted. This information is crucial for further study of the causes and mechanisms of extreme droughts and floods in the ENC. This study evaluated the spatial distribution and transport characteristics of water vapor over ENC during the 1981–2019 period based on the fifth generation of the European Center for Medium-Range Weather Forecasts atmospheric reanalyzes data of the global climate (ERA5). We studied the water vapor transport routes, water vapor convergence, water vapor budgets as well as the changes in water vapor fluxes and budgets over time in four areas surrounding ENC. The Mediterranean Sea, Black Sea, Caspian Sea, Indian Ocean, Bay of Bengal, and the South China Sea were the main sources of water vapor in ENC, supplemented by mid to high-latitude continental sources. The monthly change in water vapor flux in ENC exhibited the peak on July. The transport of water vapor in ENC was mainly toward the east and north. For most cross-seasonal drought events, the water vapor output is the main way in the south boundary and the west boundary. However, for the longest duration of cross-seasonal strong drought events, it is characterized by that the water vapor output is the main way in the south boundary, while the water vapor input in the north boundary is obviously weak. Water vapor paths in cross-seasonal strong drought events are analyzed, by which the Hybrid Single-Particle Lagrangian Integrated Trajectory model (HYSPLIT). The intensity of the subtropical high in the western Pacific is weak and the position is south, which corresponds to the occurrence of cross-seasonal strong drought in the ENC.

Download Full-text

Meteorological Characteristics and Overland Precipitation Impacts of Atmospheric Rivers Affecting the West Coast of North America Based on Eight Years of SSM/I Satellite Observations

Journal of Hydrometeorology ◽

10.1175/2007jhm855.1 ◽

2008 ◽

Vol 9 (1) ◽

pp. 22-47 ◽

Cited By ~ 375

Author(s):

Paul J. Neiman ◽

F. Martin Ralph ◽

Gary A. Wick ◽

Jessica D. Lundquist ◽

Michael D. Dettinger

Keyword(s):

Water Vapor ◽

Vapor Transport ◽

South Coast ◽

Water Vapor Transport ◽

North Coast ◽

The South ◽

Cool Season ◽

Atmospheric Rivers ◽

Vapor Flux ◽

The North

Abstract The pre-cold-frontal low-level jet within oceanic extratropical cyclones represents the lower-tropospheric component of a deeper corridor of concentrated water vapor transport in the cyclone warm sector. These corridors are referred to as atmospheric rivers (ARs) because they are narrow relative to their length scale and are responsible for most of the poleward water vapor transport at midlatitudes. This paper investigates landfalling ARs along adjacent north- and south-coast regions of western North America. Special Sensor Microwave Imager (SSM/I) satellite observations of long, narrow plumes of enhanced integrated water vapor (IWV) were used to detect ARs just offshore over the eastern Pacific from 1997 to 2005. The north coast experienced 301 AR days, while the south coast had only 115. Most ARs occurred during the warm season in the north and cool season in the south, despite the fact that the cool season is climatologically wettest for both regions. Composite SSM/I IWV analyses showed landfalling wintertime ARs extending northeastward from the tropical eastern Pacific, whereas the summertime composites were zonally oriented and, thus, did not originate from this region of the tropics. Companion SSM/I composites of daily rainfall showed significant orographic enhancement during the landfall of winter (but not summer) ARs. The NCEP–NCAR global reanalysis dataset and regional precipitation networks were used to assess composite synoptic characteristics and overland impacts of landfalling ARs. The ARs possess strong vertically integrated horizontal water vapor fluxes that, on average, impinge on the West Coast in the pre-cold-frontal environment in winter and post-cold-frontal environment in summer. Even though the IWV in the ARs is greater in summer, the vapor flux is stronger in winter due to much stronger flows associated with more intense storms. The landfall of ARs in winter and north-coast summer coincides with anomalous warmth, a trough offshore, and ridging over the Intermountain West, whereas the south-coast summer ARs coincide with relatively cold conditions and a near-coast trough. ARs have a much more profound impact on near-coast precipitation in winter than summer, because the terrain-normal vapor flux is stronger and the air more nearly saturated in winter. During winter, ARs produce roughly twice as much precipitation as all storms. In addition, wintertime ARs with the largest SSM/I IWV are tied to more intense storms with stronger flows and vapor fluxes, and more precipitation. ARs generally increase snow water equivalent (SWE) in autumn/winter and decrease SWE in spring. On average, wintertime SWE exhibits normal gains during north-coast AR storms and above-normal gains during the south-coast AR storms. The north-coast sites are mostly lower in altitude, where warmer-than-normal conditions more frequently yield rain. During those events when heavy rain from a warm AR storm falls on a preexisting snowpack, flooding is more likely to occur.

Download Full-text

Estimation of the precipitable water and water vapor flux using MAX-DOAS in two typical cities of China

10.5194/egusphere-egu21-10653 ◽

2021 ◽

Author(s):

Hongmei Ren ◽

Ang Li ◽

Pinhua Xie ◽

Zhaokun Hu ◽

Jin Xu ◽

...

Keyword(s):

Water Vapor ◽

Precipitable Water ◽

Reanalysis Data ◽

Vapor Transport ◽

Water Vapor Transport ◽

Optical Absorption Spectroscopy ◽

Water Vapor Flux ◽

Vapor Flux ◽

The North ◽

Two Cities

<p>&#160; &#160; &#160; Water vapor transport affects regional precipitation and climate change. The measurement of precipitable water and water vapor flux is of great significance to the study of precipitation and water vapor transport. In the study, a new method of computing the precipitable water and estimating the water vapor transport flux using multi-axis differential optical absorption spectroscopy (MAX-DOAS) were presented. The calculated precipitable water and water vapor flux were compared to the European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis data and the correlation coefficient of the precipitable water, the zonal and meridional water vapor flux and ECMWF are r&#8805;0.92, r=0.77 and r&#8805;0.89, respectively. The seasonal and diurnal climatologies of precipitable water and water vapor flux in the coastal (Qingdao) and inland (Xi&#8217;an) cities of China using this method were analyzed from June 1, 2019 to May 31, 2020. The results indicated that the seasonal and diurnal variation characteristics of the precipitable water in the two cities were similar. The zonal fluxes of the two cities were mainly transported from west to east, Qingdao's meridional flux was mainly transported to the south, and Xi'an was mainly transported to the north. The results also indicated that the water vapor flux transmitting belts appear near 2km and 1.4km above the surface in Qingdao and appeared around 2.8km, 1.6km and 1.0km in Xi'an.&#160;</p>

Download Full-text

Meteorological Drought Changes and Related Circulation Characteristics in Yulin City of the Northern Shaanxi from 1961 to 2015

Atmosphere ◽

10.3390/atmos11111196 ◽

2020 ◽

Vol 11 (11) ◽

pp. 1196

Author(s):

Yixing Yin ◽

Lijuan Zhang ◽

Xiaojun Wang ◽

Wucheng Xu ◽

Wenjun Yu ◽

...

Keyword(s):

Water Vapor ◽

Standardized Precipitation Index ◽

Meteorological Drought ◽

Precipitation Process ◽

Observation Data ◽

The South ◽

Vapor Flux ◽

The North ◽

Northern Shaanxi ◽

Yulin City

This study explored the spatio-temporal patterns of meteorological drought change and the mechanisms of drought occurrence in Yulin City of the northern Shaanxi by using Standardized Precipitation Index (SPI), Empirical Orthogonal Function (EOF) analysis and composite analysis based on the meteorological observation data and NCEP/NCAR reanalysis data from 1961 to 2015. The main findings of the research are as follows: (1) In the annual and seasonal drought series, there is a non-significant trend toward drought in summer, while there are non-significant trends toward wetness for the other series. Overall, the frequency of drought is low in the southeast and high in the west and the north of the study area. (2) EOF1 is characterized by a uniform pattern in the whole region, i.e., there is a feature of consistent drought or flood in Yulin City. EOF2, EOF3 and EOF4 mainly indicate opposite characteristics of the changes of floods and droughts in the eastern/western parts and the southeast/other parts in the study area. (3) In the summer of the typical drought (flood) years, the study area is controlled by the northwest airflow behind the trough (zonal airflow at the bottom of low-pressure trough), and the meridional circulation (zonal circulation) is distributed in the mid-latitudes, which is conducive to the intrusion of cold air into the south (north) of China. The cold and warm air intersection area is to the south (to the north). The water vapor flux is weak (strong) and the water vapor divergence (convergence) prohibits (enhances) the precipitation process in the study area.

Download Full-text

Precipitation and Water Vapor Transport in the Southern Hemisphere with Emphasis on the South American Region

Journal of Applied Meteorology and Climatology ◽

10.1175/2009jamc2030.1 ◽

2009 ◽

Vol 48 (9) ◽

pp. 1902-1912 ◽

Cited By ~ 34

Author(s):

Josefina Moraes Arraut ◽

Prakki Satyamurty

Keyword(s):

Water Vapor ◽

South America ◽

North Atlantic ◽

Vapor Transport ◽

Water Vapor Transport ◽

The South ◽

Meridional Transport ◽

Moisture Flow ◽

The North ◽

The North Atlantic

Abstract December–March climatologies of precipitation and vertically integrated water vapor transport were analyzed and compared to find the main paths by which moisture is fed to high-rainfall regions in the Southern Hemisphere in this season. The southern tropics (20°S–0°) exhibit high rainfall and receive ample moisture from the northern trades, except in the eastern Pacific and the Atlantic Oceans. This interhemispheric flow is particularly important for Amazonian rainfall, establishing the North Atlantic as the main source of moisture for the forest during its main rainy season. In the subtropics the rainfall distribution is very heterogeneous. The meridional average of precipitation between 35° and 25°S is well modulated by the meridional water vapor transport through the 25°S latitude circle, being greater where this transport is from the north and smaller where it is from the south. In South America, to the east of the Andes, the moisture that fuels precipitation between 20° and 30°S comes from both the tropical South and North Atlantic Oceans whereas between 30° and 40°S it comes mostly from the North Atlantic after passing over the Amazonian rain forest. The meridional transport (across 25°S) curve exhibits a double peak over South America and the adjacent Atlantic, which is closely reproduced in the mean rainfall curve. This corresponds to two local maxima in the two-dimensional field of meridional transport: the moisture corridor from Amazonia into the continental subtropics and the moisture flow coming from the southern tropical Atlantic into the subtropical portion of the South Atlantic convergence zone. These two narrow pathways of intense moisture flow could be suitably called “aerial rivers.” Their longitudinal positions are well defined. The yearly deviations from climatology for moisture flow and rainfall correlate well (0.75) for the continental peak but not for the oceanic peak (0.23). The structure of two maxima is produced by the effect of transients in the time scale of days.

Download Full-text

Analyzing Variations in the Association of Eurasian Winter–Spring Snow Water Equivalent and Autumn Arctic Sea Ice

Remote Sensing ◽

10.3390/rs14020243 ◽

2022 ◽

Vol 14 (2) ◽

pp. 243

Author(s):

Jiajun Feng ◽

Yuanzhi Zhang ◽

Jin Yeu Tsou ◽

Kapo Wong

Keyword(s):

Water Vapor ◽

Sea Ice ◽

Snow Water Equivalent ◽

Arctic Sea Ice ◽

Water Vapor Transport ◽

Northern Eurasia ◽

Distribution Characteristics ◽

Vapor Flux ◽

The North ◽

Snow Water

Because Eurasian snow water equivalent (SWE) is a key factor affecting the climate in the Northern Hemisphere, understanding the distribution characteristics of Eurasian SWE is important. Through empirical orthogonal function (EOF) analysis, we found that the first and second modes of Eurasian winter SWE present the distribution characteristics of an east–west dipole and north–south dipole, respectively. Moreover, the distribution of the second mode is caused by autumn Arctic sea ice, with the distribution of the north–south dipole continuing into spring. As the sea ice of the Barents–Kara Sea (BKS) decreases, a negative-phase Arctic oscillation (AO) is triggered over the Northern Hemisphere in winter, with warm and humid water vapor transported via zonal water vapor flux over the North Atlantic to southwest Eurasia, encouraging the accumulation of SWE in the southwest. With decreases in BKS sea ice, zonal water vapor transport in northern Eurasia is weakened, with meridional water vapor flux in northern Eurasia obstructing water vapor transport from the North Atlantic, discouraging the accumulation of SWE in northern Eurasia in winter while helping preserve the cold climate of the north. The distribution characteristics of Eurasian spring SWE are determined primarily by the memory effect of winter SWE. Whether analyzed through linear regression or support vector machine (SVM) methods, BKS sea ice is a good predictor of Eurasian winter SWE.

Download Full-text

Abundant Precipitation in Qilian Mountains Generated from the Recycled Moisture over the Adjacent Arid Hexi Corridor, Northwest China

Water ◽

10.3390/w13233354 ◽

2021 ◽

Vol 13 (23) ◽

pp. 3354

Author(s):

Zhihua Zhang ◽

Qiudong Zhao ◽

Shiqiang Zhang

Keyword(s):

Water Vapor ◽

Water Cycle ◽

Precipitable Water ◽

Northwest China ◽

Hexi Corridor ◽

Qilian Mountains ◽

Mountain Areas ◽

Reanalysis Dataset ◽

Weather Forecasts ◽

Endorheic Basin

The observed precipitation was suggestive of abundant precipitation in upstream Qilian mountains and low precipitation in the downstream oasis and desert in an endorheic basin. However, precipitation in mountains generated from the recycled moisture over oasis and desert areas has rarely been studied. The climatological patterns of water vapor from 1980 to 2017 in the Qilian Mountain Region (QMR) and Hexi Corridor Region (HCR) were investigated by the European Centre for Medium-Range Weather Forecasts Interim reanalysis dataset and the Modern-Era Retrospective Analysis for Research and Application, Version 2 reanalysis dataset. The results suggest that the precipitable water content decreases from the adjacent to the mountain areas. There are two channels that transport water vapor from the HCR to the QMR in the low troposphere (surface—600 hPa), suggesting that parts of recycled moisture generated from evapotranspiration over the oasis and desert of the HCR is transported to the QMR, contributing to the abundant precipitation in the QMR. This indicates that the transport mechanism is probably because of the “cold and wet island effect” of the cryosphere in QMR. This is likely one of the essential mechanisms of the water cycle in endorheic river basins, which has rarely been reported.

Download Full-text

Changes in Winter Atmospheric Rivers along the North American West Coast in CMIP5 Climate Models

Journal of Hydrometeorology ◽

10.1175/jhm-d-14-0080.1 ◽

2015 ◽

Vol 16 (1) ◽

pp. 118-128 ◽

Cited By ~ 105

Author(s):

Michael D. Warner ◽

Clifford F. Mass ◽

Eric P. Salathé

Keyword(s):

Water Vapor ◽

North American ◽

West Coast ◽

American West ◽

Climate Models ◽

Water Vapor Transport ◽

The West ◽

North American West ◽

The North ◽

Extreme Precipitation Events

Abstract Most extreme precipitation events that occur along the North American west coast are associated with winter atmospheric river (AR) events. Global climate models have sufficient resolution to simulate synoptic features associated with AR events, such as high values of vertically integrated water vapor transport (IVT) approaching the coast. From phase 5 of the Coupled Model Intercomparison Project (CMIP5), 10 simulations are used to identify changes in ARs impacting the west coast of North America between historical (1970–99) and end-of-century (2070–99) runs, using representative concentration pathway (RCP) 8.5. The most extreme ARs are identified in both time periods by the 99th percentile of IVT days along a north–south transect offshore of the coast. Integrated water vapor (IWV) and IVT are predicted to increase, while lower-tropospheric winds change little. Winter mean precipitation along the west coast increases by 11%–18% [from 4% to 6% (°C)−1], while precipitation on extreme IVT days increases by 15%–39% [from 5% to 19% (°C)−1]. The frequency of IVT days above the historical 99th percentile threshold increases as much as 290% by the end of this century.

Download Full-text

Ocean Salinity as a Precursor of Summer Rainfall over the East Asian Monsoon Region

Journal of Climate ◽

10.1175/jcli-d-18-0756.1 ◽

2019 ◽

Vol 32 (17) ◽

pp. 5659-5676 ◽

Cited By ~ 6

Author(s):

Biao Chen ◽

Huiling Qin ◽

Guixing Chen ◽

Huijie Xue

Keyword(s):

Water Vapor ◽

Asian Monsoon ◽

East Asian Monsoon ◽

Summer Rainfall ◽

Vapor Transport ◽

Water Vapor Transport ◽

Asian Monsoon Region ◽

Water Vapor Flux ◽

Vapor Flux ◽

Land Water

Abstract The sea surface salinity (SSS) varies largely as a result of the evaporation–precipitation difference, indicating the source or sink of regional/global water vapor. This study identifies a relationship between the spring SSS in the tropical northwest Pacific (TNWP) and the summer rainfall of the East Asian monsoon region (EAMR) during 1980–2017. Analysis suggests that the SSS–rainfall link involves the coupled ocean–atmosphere–land processes with a multifacet evolution. In spring, evaporation and water vapor flux divergence were enhanced in some years over the TNWP where an anomalous atmospheric anticyclone was established and a high SSS was well observed. As a result, the convergence of water vapor flux and soil moisture over the EAMR was strengthened. This ocean-to-land water vapor transport pattern was sustained from spring to summer and played a leading role in the EAMR rainfall. Moreover, the change in local spring soil moisture helped to amplify the summer rainfall by modifying surface thermal conditions and precipitation systems over the EAMR. As the multifacet evolution is closely related to the large-scale ocean-to-land water vapor transport, it can be well represented by the spring SSS in the TNWP. A random forest regression algorithm was used to further evaluate the relative importance of spring SSS in predicting summer rainfall compared to other climate indices. As the SSS is now monitored routinely by satellite and the global Argo float array, it can serve as a good metric for measuring the water cycle and as a precursor for predicting the EAMR rainfall.

Download Full-text

Seasonal variability and anomalies of the currents of the cyclonic gyre in the northeastern sector of Caspian sea

Водные ресурсы ◽

10.31857/s0321-0596465485-495 ◽

2019 ◽

Vol 46 (5) ◽

pp. 485-495

Author(s):

A. K. Ambrosimov

Keyword(s):

Experimental Data ◽

Caspian Sea ◽

Cold Water ◽

Eastern Region ◽

Cyclonic Gyre ◽

Southern Slope ◽

The South ◽

Near Surface ◽

The North ◽

North Eastern

The experimental data presented in the article show that in the North-Eastern sector of the Middle Caspian sea in the area of Peschanomyssky uplift there is a disturbance of currents caused by the interaction of the cyclonic cycle with the southern slope of the uplift. As a result of this interaction, the waters of the cyclonic cycle are divided into branches – the lower and upper. The lower bottom branch is thrown by the uplift in the South-Western direction, where at the Cape of the uplift it collides with the waters flowing down the bottom of the South-Buzachinsky deflection in the South-Eastern direction, and the upper branch, consisting of near-surface and intermediate cold waters, is pushed up and passes through the uplift. As a result of the rise of cold water in the surface layer formed upwelling, which extends to the entire North-Eastern region of the sea.

Download Full-text