scholarly journals Water Vapor Transport Paths and Accumulation during Widespread Snowfall Events in Northeastern China

2013 ◽  
Vol 26 (13) ◽  
pp. 4550-4566 ◽  
Author(s):  
Bo Sun ◽  
Huijun Wang
Keyword(s):  
Water Vapor ◽  
Eastern China ◽  
Northeastern China ◽  
Vapor Transport ◽  
Specific Humidity ◽  
Water Vapor Transport ◽  
The Sea Of Japan ◽  
Atmospheric Flow ◽  
Precipitation Gauge ◽  
Humidity Field

Abstract This study aims to identify the distinct characteristics of water vapor transport (WVT) and its role in supplying moisture for widespread snowfall (WS) events in northeastern China (NEC). Fifty WS events in NEC were selected based on cumulative precipitation gauge data taken at 12-h intervals from 1980 to 2009 and a qualified set of criteria. The evolution of WVT during WS events in NEC was analyzed using 6-h ECMWF Interim Re-Analysis (ERA-Interim) data and discussed in regard to WVT paths and water vapor budgets over NEC. The results of this analysis indicate that southerly WVT, which carries moisture over eastern China, its adjacent seas, and the Sea of Japan, has played a key role in supplying water vapor for WS, which is quite different from the climatology of winter WVT. Moreover, the results indicate that there tends to be an 18-h lag between the WVT budget and precipitation, resulting in a great amount of water vapor accumulating over NEC before WS. The amount of preaccumulated water vapor could account for about 47% of the total precipitation, whereas synchronous WVT could only supply a limited amount of moisture that could hardly sustain WS. In addition, the original atmospheric moisture over NEC has likely made a considerable contribution to WS. The lag between the WVT budget and precipitation appears to be an outcome of the cooperation between the atmospheric flow field and the specific humidity field.

scholarly journals Water Vapor Transport and Moisture Budget over Eastern China: Remote Forcing from the Two Types of El Niño

2014 ◽  
Vol 27 (23) ◽  
pp. 8778-8792 ◽  
Author(s):  
Xiuzhen Li ◽  
Wen Zhou ◽  
Deliang Chen ◽  
Chongyin Li ◽  
Jie Song
Keyword(s):  
Water Vapor ◽  
El Niño ◽  
El Nino ◽  
Eastern China ◽  
Vapor Transport ◽  
Water Vapor Transport ◽  
Moisture Budget ◽  
Southern Boundary ◽  
Middle Troposphere ◽  
Moisture Deficit

Abstract The water vapor transport and moisture budget over eastern China remotely forced by the cold-tongue (CT) and warm-pool (WP) El Niño show striking differences throughout their lifetime. The water vapor transport response is weak in the developing summer but strong in the remaining phases of CT El Niño, whereas the opposite occurs during WP El Niño. WP El Niño causes a moisture deficit over the Yangtze River valley (YZ) in the developing summer and over southeastern China (SE) in the developing fall, whereas CT El Niño induces a moisture surplus first over SE during the developing fall with the influential area expanding in the decaying spring and shifting northward in the decaying summer. It is the divergence of meridional water vapor transport that dominates the total water vapor divergence anomaly, with the divergence of zonal transport showing an opposite pattern with smaller magnitude. Investigation of the vertical profile of moisture budget shows a great baroclinicity, with the strongest abnormal moisture budget occurring in different levels. The moisture transport via the southern boundary plays a crucial role in the regional moisture budget anomalies and is located near the surface over SE, in the lower troposphere over the YZ, and at the lower-middle troposphere over the eastern part of northern China. The enhanced moisture surplus near the surface forced by WP El Niño over SE in the mature winter and decaying spring is offset by a moisture deficit within the lower-middle troposphere due to a diverse response circulation at different vertical levels.

scholarly journals Subseasonal Variations of Wintertime North Pacific Evaporation, Cold Air Surges, and Water Vapor Transport

2017 ◽  
Vol 30 (23) ◽  
pp. 9475-9491 ◽  
Author(s):  
Xuejuan Ren ◽  
Xiu-Qun Yang ◽  
Haibo Hu
Keyword(s):  
Water Vapor ◽  
North Pacific ◽  
Wave Train ◽  
Vapor Transport ◽  
Specific Humidity ◽  
Water Vapor Transport ◽  
Vapor Source ◽  
Air Mass ◽  
Cold Air ◽  
The North

This study addresses subseasonal variations of oceanic evaporation E over the North Pacific during winter and the connection with the cold air surges (CASs) and atmospheric water vapor transport using the OAFlux and ERA-Interim daily data. By performing an empirical orthogonal function (EOF) analysis, two dominant modes of subseasonal evaporation anomaly E′ are identified: a zonal wave train–like pattern (EOF1) and an east negative–west positive dipolar pattern (EOF2) in the midlatitude basin. Further analyses yield the following conclusions. 1) The Siberian high (SH)-related CAS has a crucial role in generation of the EOF1 mode of E′. When the dry and cold air mass passes the region of the warm Kuroshio and its extension [Kuroshio–Oyashio Extension (KOE)], the increased air–sea temperature and moisture differences and intensified wind speed lead to the above-normal oceanic E, and vice versa. 2) The Aleutian low (AL)-related CAS contributes to the EOF2 mode of E′. The intensified AL transports a dramatically colder and drier air mass toward the KOE region and a slightly warmer and wetter one toward the west coast of North America, leading to the east negative–west positive structure of E′ in the midlatitude basin. 3) A quasi-linear relationship exists between E′ and divergent water vapor transport anomalies over the KOE region. Positive (negative) E′ is generally accompanied by anomalous vapor source (sink). 4) The divergent water vapor transport anomalies associated with the two EOFs are preliminarily decided by their individual lower-level wind field anomalies and second by the meridional inhomogeneity of subseasonal specific humidity anomalies. Hydroclimate effects on precipitation over the pan–North Pacific region are also discussed.

scholarly journals Different Roles of Water Vapor Transport and Cold Advection in the Intensive Snowfall Events over North China and the Yangtze River Valley

Atmosphere ◽  
2019 ◽  
Vol 10 (7) ◽  
pp. 368 ◽  
Author(s):  
Zhixing Xie ◽  
Bo Sun
Keyword(s):  
Water Vapor ◽  
Yangtze River ◽  
North China ◽  
Dominant Role ◽  
Eastern China ◽  
Yangtze River Valley ◽  
River Valley ◽  
Vapor Transport ◽  
Water Vapor Transport

Intensive snowfall events (ISEs) have a profound impact on the society and economy in China during winter. Considering that the interaction between northerly cold advection and southerly water vapor transport (WVT) is generally an essential condition for the occurrence of ISEs in eastern China, this study investigates the different roles of anomalous southerly WVT and northerly cold advection during the ISEs in the North China (NC) and Yangtze River valley (YRV) regions based on a composite analysis of seventy ISE cases in NC and forty ISE cases in the YRV region from 1961 to 2014. The results indicate that the ISEs in NC are mainly associated with a significant pre-conditioning of water vapor over NC induced by southerly WVT anomalies over eastern China, whereas the ISEs in the YRV region are mainly associated with a strengthened Siberian High (SH) and strong northerly cold advection invading the YRV region. These results suggest a dominant role of anomalous southerly WVT in triggering the ISEs in NC and a dominant role of northerly cold advection in triggering the ISEs in the YRV region. The different roles of anomalous southerly WVT and northerly cold advection in the ISEs over the NC and YRV regions are largely attributed to the different winter climate in the NC and YRV regions—during winter, the NC (YRV) region is dominated by cold and dry (relatively warm and moist) air flow and hence southerly WVT (northerly cold advection) is the key factor for triggering the ISEs in NC (the YRV region).

Precursors and Formation Mechanisms of Event-based Extreme Precipitation during Springtime in Central-Eastern China

2021 ◽  
pp. 1-42
Author(s):  
Wei Shang ◽  
Xuejuan Ren ◽  
Shuangshuang Li ◽  
Keqin Duan
Keyword(s):  
Water Vapor ◽  
Extreme Precipitation ◽  
Eastern China ◽  
Specific Humidity ◽  
Horizontal Wind ◽  
Formation Mechanisms ◽  
The Sea Of Japan ◽  
Budget Analysis ◽  
Central Eastern ◽  
Event Based

AbstractThis study investigates the precursors and formation mechanisms of spring (April-May) event-based extreme precipitation (EEP) during 1961-2014 in central-eastern China. The EEP events during springtime are primarily characterized by extreme precipitation that occurs at the first half of an event. During early stages of spring EEP events, a Rossby wave grows over Western Europe and the North Atlantic Ocean. The wave propagates eastward toward East Asia, exhibiting a circumglobal teleconnection (CGT) pattern. A strong anticyclone related to the CGT pattern is formed over Japan Islands in the upper troposphere, enhancing the divergence anomalies and bringing more water vapor anomalies from the Sea of Japan into central-eastern China. Meanwhile, the westerly jet jump northward and anomalous southwesterly water vapor flux is significantly prevalent, which is associated with the onset of the Bay of Bengal summer monsoon (BOBSM). Combined the anomalous southwesterly and northeasterly moisture flux into central-eastern China, strong convergence is formed and provided abundant water vapor for the extreme precipitation. The moisture budget analysis further suggests that the dynamic processes associated with horizontal wind anomalies play a crucial role in the moisture convergence for the spring EEP events. The advection of zonal and meridional moisture is strongly related with the anomalous winds of the CGT waves and BOBSM, respectively. While the horizontal thermodynamic processes related to specific humidity and vertical advection contribute much less. The results indicate the preceding signals in the midlatitude and subtropics for the spring EEP events, favoring for extreme precipitation forecasting and hydrological prediction.

scholarly journals Tropospheric Water Vapor Transport as Determined from Airborne Lidar Measurements

2010 ◽  
Vol 27 (12) ◽  
pp. 2017-2030 ◽  
Author(s):  
Andreas Schäfler ◽  
Andreas Dörnbrack ◽  
Christoph Kiemle ◽  
Stephan Rahm ◽  
Martin Wirth
Keyword(s):  
Water Vapor ◽  
Wind Speed ◽  
Moisture Transport ◽  
Lower Troposphere ◽  
Airborne Lidar ◽  
Vapor Transport ◽  
Specific Humidity ◽  
Water Vapor Transport ◽  
Horizontal Wind ◽  
Warm Sector

Abstract The first collocated measurements during THORPEX (The Observing System Research and Predictability Experiment) regional campaign in Europe in 2007 were performed by a novel four-wavelength differential absorption lidar and a scanning 2-μm Doppler wind lidar on board the research aircraft Falcon of the Deutsches Zentrum für Luft- und Raumfahrt (DLR). One mission that was characterized by exceptionally high data coverage (47% for the specific humidity q and 63% for the horizontal wind speed υh) was selected to calculate the advective transport of atmospheric moisture qυh along a 1600-km section in the warm sector of an extratropical cyclone. The observations are compared with special 1-hourly model data calculated by the ECMWF integrated forecast system. Along the cross section, the model underestimates the wind speed on average by −2.8% (−0.6 m s−1) and overestimates the moisture at dry layers and in the boundary layer, which results in a wet bias of 17.1% (0.2 g kg−1). Nevertheless, the ECMWF model reproduces quantitatively the horizontally averaged moisture transport in the warm sector. There, the superposition of high low-level humidity and the increasing wind velocities with height resulted in a deep tropospheric layer of enhanced water vapor transport qυh. The observed moisture transport is variable and possesses a maximum of qυh = 130 g kg−1 m s−1 in the lower troposphere. The pathways of the moisture transport from southwest via several branches of different geographical origin are identified by Lagrangian trajectories and by high values of the vertically averaged tropospheric moisture transport.

scholarly journals Extreme Floods in the Eastern Part of Europe: Large-Scale Drivers and Associated Impacts

Water ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1122
Author(s):  
Monica Ionita ◽  
Viorica Nagavciuc
Keyword(s):  
Water Vapor ◽  
Heavy Rainfall ◽  
Large Scale ◽  
Vapor Transport ◽  
Water Vapor Transport ◽  
Flood Events ◽  
Rainfall Events ◽  
Catchment Areas ◽  
Large Scale Atmospheric Circulation ◽  
Heavy Rainfall Events

The role of the large-scale atmospheric circulation in producing heavy rainfall events and floods in the eastern part of Europe, with a special focus on the Siret and Prut catchment areas (Romania), is analyzed in this study. Moreover, a detailed analysis of the socio-economic impacts of the most extreme flood events (e.g., July 2008, June–July 2010, and June 2020) is given. Analysis of the largest flood events indicates that the flood peaks have been preceded up to 6 days in advance by intrusions of high Potential Vorticity (PV) anomalies toward the southeastern part of Europe, persistent cut-off lows over the analyzed region, and increased water vapor transport over the catchment areas of Siret and Prut Rivers. The vertically integrated water vapor transport prior to the flood peak exceeds 300 kg m−1 s−1, leading to heavy rainfall events. We also show that the implementation of the Flood Management Plan in Romania had positive results during the 2020 flood event compared with the other flood events, when the authorities took several precaution measurements that mitigated in a better way the socio-economic impact and risks of the flood event. The results presented in this study offer new insights regarding the importance of large-scale atmospheric circulation and water vapor transport as drivers of extreme flooding in the eastern part of Europe and could lead to a better flood forecast and flood risk management.

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