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 Influence of Boreal Winter Intraseasonal Variation of Aleutian Low on Water Vapor Transport and Atmospheric Rivers

Atmosphere ◽  
2019 ◽  
Vol 10 (2) ◽  
pp. 49 ◽  
Author(s):  
Yating Xiong ◽  
Qiuyu Chen ◽  
Xuejuan Ren
Keyword(s):  
Water Vapor ◽  
North Pacific ◽  
Vapor Transport ◽  
Water Vapor Transport ◽  
Aleutian Low ◽  
Intraseasonal Variation ◽  
Atmospheric Rivers ◽  
The North ◽  
North Pacific Region ◽  
The North Pacific

The Aleutian Low (AL) operates multiple time scales. The intraseasonal variation of AL is responsible for the subseasonal variability over the pan-North Pacific region. Atmospheric water vapor transport and atmospheric rivers (ARs) changes associated with the intraseasonal variation of AL are investigated over the North Pacific region for the winters of 1979–2014 in this study. The AL’s intraseasonal variation with a peak period of 40 days is identified. A total of 43 events that demonstrate the AL’s feature of strengthening and then weakening is picked and used for composition analysis. During the AL’s strengthening stage, eastward water vapor transport is dominant to the west of 150° W over the mid-basin. Meanwhile, poleward transport is dominant between 150–125° W. During the AL’s weakening stage, the eastward transport is weakened, and the poleward transport is concentrated over the center basin. Accompanied by the AL’s intraseasonal intensity oscillation, the frequency of ARs firstly increases, and then decreases over the ARs’ climatological mean body region over the North Pacific. The moisture source over the western North Pacific is hoarded during non-AR days, while the moisture sinks over the northeastern North Pacific during the AL’s strengthening stage, and the moisture sources over the center basin during the AL’s weakening stage converge during AR days. Hydroclimate effects on anomalies in precipitation over the west coast of North America are also analyzed.

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

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>      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≥0.92, r=0.77 and r≥0.89, respectively. The seasonal and diurnal climatologies of precipitable water and water vapor flux in the coastal (Qingdao) and inland (Xi’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. </p>

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

2009 ◽  
Vol 48 (9) ◽  
pp. 1902-1912 ◽  
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.

scholarly journals Estimation of the Precipitable Water and Water Vapor Fluxes in the Coastal and Inland Cities of China Using MAX-DOAS

2021 ◽  
Vol 13 (9) ◽  
pp. 1675
Author(s):  
Hongmei Ren ◽  
Ang Li ◽  
Pinhua Xie ◽  
Zhaokun Hu ◽  
Jin Xu ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Water Vapor ◽  
Precipitable Water ◽  
Vapor Transport ◽  
Water Vapor Transport ◽  
Continuous Precipitation ◽  
Air Mass ◽  
Torrential Rain ◽  
Two Cities ◽  
High Level

Water vapor transport affects regional precipitation and climate change. The measurement of precipitable water (PW) and water vapor flux (WVF) is of great importance for the study of precipitation and water vapor transport. This study presented a new method of computing PW and estimating WVF using the water vapor vertical column density (VCD) and profile retrieved from multi-axis differential optical absorption spectroscopy (MAX-DOAS), combined with the European Centre for Medium-Range Weather Forecasts (ECMWF) ERA5 wind profiles. We applied our method to MAX-DOAS observations in the coastal (Qingdao) and inland (Xi’an) cities of China from June 2019 to May 2020 and compared the results to the ERA5 reanalysis datasets. Good agreement with ERA5 datasets was found; the correlation coefficient (r) of the PW and the zonal and meridional WVFs were r ≥ 0.92, r = 0.77, and r ≥ 0.89, respectively. The comparison results showed the feasibility and reliability of estimating PW and WVF using MAX-DOAS. Then, we analyzed the seasonal and diurnal climatology of the PW and WVFs in Qingdao and Xi’an. The results indicated that the seasonal and diurnal variations of the PW in the two cities were similar. The zonal water vapor transport of the two cities mainly involved eastward transport, Qingdao’s meridional water vapor mainly involved southward transport, and that of Xi’an mainly involved northward transport. The WVFs of the two cities were higher in the afternoon than in the morning, which may be related to wind speed. The results also indicated that the WVF transmitting belts appeared at around 2 and 1.4 km above the surface in Qingdao and around 2.8, 2.6, 1.6, and 1.0 km above the surface in Xi’an. Before precipitation, the WVF transmitting belt moved from near the ground to a high level, reaching its maximum at about 2 km, and the PW and meridional vertically integrated WVF increased. Finally, the sources and transports of water vapor during continuous precipitation and torrential rain were analyzed according to a 24 h backward trajectory. The air mass from the southeast accounted for more than 84% during continuous precipitation in Xi’an, while the air mass from the ocean accounted for more than 75% during torrential rain in Qingdao and was accompanied by a high-level ocean jet stream. As an optical remote sensing instrument, MAX-DOAS has the advantages of high spatiotemporal resolution, low cost, and easy maintenance. The application of MAX-DOAS to meteorological remote sensing provides a better method for evaluating the PW and WVF.

scholarly journals Dropsonde Observations of Total Integrated Water Vapor Transport within North Pacific Atmospheric Rivers

2017 ◽  
Vol 18 (9) ◽  
pp. 2577-2596 ◽  
Author(s):  
F. M. Ralph ◽  
S. F. Iacobellis ◽  
P. J. Neiman ◽  
J. M. Cordeira ◽  
J. R. Spackman ◽  
...  
Keyword(s):  
Water Vapor ◽  
Liquid Water ◽  
North Pacific ◽  
Vapor Transport ◽  
Water Vapor Transport ◽  
Amazon River ◽  
Vertical Profiles ◽  
Total Water ◽  
Atmospheric Rivers ◽  
The Mean

Abstract Aircraft dropsonde observations provide the most comprehensive measurements to date of horizontal water vapor transport in atmospheric rivers (ARs). The CalWater experiment recently more than tripled the number of ARs probed with the required measurements. This study uses vertical profiles of water vapor, wind, and pressure obtained from 304 dropsondes across 21 ARs. On average, total water vapor transport (TIVT) in an AR was 4.7 × 108 ± 2 × 108 kg s−1. This magnitude is 2.6 times larger than the average discharge of liquid water from the Amazon River. The mean AR width was 890 ± 270 km. Subtropical ARs contained larger integrated water vapor (IWV) but weaker winds than midlatitude ARs, although average TIVTs were nearly the same. Mean TIVTs calculated by defining the lateral “edges” of ARs using an IVT threshold versus an IWV threshold produced results that differed by less than 10% across all cases, but did vary between the midlatitudes and subtropical regions.

scholarly journals Lidar Observations Versus Forecast of Water Vapor Transport

2020 ◽  
Vol 237 ◽  
pp. 06008
Author(s):  
Brian Carroll ◽  
Belay Demoz ◽  
Ruben Delgado
Keyword(s):  
Water Vapor ◽  
Great Plains ◽  
Temporal Evolution ◽  
Forecast Model ◽  
Vapor Transport ◽  
Water Vapor Transport ◽  
Forecast System ◽  
Convective Systems ◽  
The North ◽  
Lidar Observations

Water vapor advection is an important diagnostic parameter for initiation and sustenance of convective systems. This variable has traditionally been explored with balloon soundings or models, but lidar provides a unique opportunity to continuously resolve spatial and temporal evolution of water vapor transport with relatively high resolution. In this study we utilize co-located Doppler wind lidars and water vapor lidars (DIAL and Raman) at multiple sites to investigate water vapor advection. A case of nocturnal convection in the Great Plains is analyzed with these observations and compared to the North American Mesoscale Forecast System (NAM) operational forecast model.

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.

A study on the water vapor transport trend and water vapor source of the Tibetan Plateau

2020 ◽  
Vol 140 (3-4) ◽  
pp. 1031-1042 ◽  
Author(s):  
Kepiao Xu ◽  
Lei Zhong ◽  
Yaoming Ma ◽  
Mijun Zou ◽  
Ziyu Huang
Keyword(s):  
Water Vapor ◽  
Tibetan Plateau ◽  
Vapor Transport ◽  
Water Vapor Transport ◽  
The Tibetan Plateau ◽  
Vapor Source ◽  
Water Vapor Source

scholarly journals Why the Increasing Trend of Summer Rainfall over North China Has Halted since the Mid-1990s

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Haiwen Liu ◽  
Jiarui Miao ◽  
Kaijun Wu ◽  
Mengxing Du ◽  
Yuxiang Zhu ◽  
...  
Keyword(s):  
Water Vapor ◽  
North China ◽  
Asian Summer Monsoon ◽  
Summer Rainfall ◽  
Vapor Transport ◽  
Water Vapor Transport ◽  
Precipitation Trend ◽  
The North ◽  
Asian Summer ◽  
Upper Level

Previous studies indicate that the summer (July-August) rainfall over North China has decreased since the mid-1970s due to the weakening of East Asian summer monsoon (EASM). However, this study firstly discovers the new evidences that the summer rainfall over North China had a significant increasing tendency during 1979–1996; since 1997, this increasing tendency has halted while more summer droughts occurred over North China. One important cause for the halted increasing tendency over North China is the interdecadal decrease of the westerly water vapor transport during 1997–2016 in addition to the weakened EASM. The decrease of the westerly water vapor transport during 1997–2016 was due to the interdecadal warming over Lake Baikal. The interdecadal warming in the upper troposphere at 200 hPa forced the weakening of the upper-level zonal winds since 1997, which resulted in the anomalous descending flow over the north side of North China and the halted precipitation trend in North China.

Decadal Changes in Multiscale Water Vapor Transport and Atmospheric River Associated with the Pacific Decadal Oscillation and the North Pacific Gyre Oscillation

2015 ◽  
Vol 17 (1) ◽  
pp. 273-285 ◽  
Author(s):  
Xu Liu ◽  
Xuejuan Ren ◽  
Xiu-Qun Yang
Keyword(s):  
North Pacific ◽  
Moisture Transport ◽  
Vapor Transport ◽  
Water Vapor Transport ◽  
Height Anomaly ◽  
The North ◽  
The Pacific ◽  
North Pacific Gyre Oscillation ◽  
North Pacific Gyre ◽  
The North Pacific

Abstract This study investigates the features of atmospheric circulation and moisture transport associated with two modes of decadal variability in the North Pacific: the Pacific decadal oscillation (PDO) and the North Pacific Gyre Oscillation (NPGO), with emphasis on the multiscale water vapor transport and atmospheric river (AR) over the North Pacific region. During the positive phase of PDO, the geopotential height anomaly at 500-hPa exhibits a Pacific–North American-like pattern. During the positive phase of NPGO, the geopotential height anomaly at 500 hPa features a dipole pattern with a negative anomaly north of 40°N and a positive anomaly south of 40°N over the North Pacific. Associated with the positive PDO phase, the ocean-to-land moisture transport is enhanced between 25° and 35°N and reduced over the northeastern Pacific (25°–62°N, 180°–110°W) for the time-mean integrated vapor transport (IVT). The synoptic poleward transport is suppressed north of 40°N and enhanced south of 40°N. In the positive NPGO phase, the zonal moisture transport is intensified south of 20°N and between 40° and 50°N for the time-mean IVT and weakened over the west coast of North America for the low-frequency (10–100 days) IVT. The synoptic poleward transport is suppressed south of 30°N. The eastern part of the North Pacific AR belt moves southward during positive PDO as the entire North Pacific AR belt shifts slightly northward during positive NPGO. An investigation of AR anomalies during a period over which the PDO and NPGO coexist demonstrates that the AR frequency over the North American western coastal regions is significantly influenced by the conjunction of the PDO and NPGO modes.

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