scholarly journals The Impact of the Sierra Nevada on Low-Level Winds and Water Vapor Transport

2007 ◽  
Vol 8 (4) ◽  
pp. 790-804 ◽  
Author(s):  
Jinwon Kim ◽  
Hyun-Suk Kang
Keyword(s):  
Water Vapor ◽  
Sierra Nevada ◽  
Climate Model ◽  
Northern Region ◽  
Vapor Transport ◽  
Water Vapor Transport ◽  
Western Slope ◽  
Mountain Range ◽  
Low Level ◽  
The Impact

Abstract To understand the influence of the Sierra Nevada on the water cycle in California the authors have analyzed low-level winds and water vapor fluxes upstream of the mountain range in regional climate model simulations. In a low Froude number (Fr) regime, the upstream low-level wind disturbances are characterized by the rapid weakening of the crosswinds and the appearance of a stagnation point over the southwestern foothills. The weakening of the low-level inflow is accompanied by the development of along-ridge winds that take the form of a barrier jet over the western slope of the mountain range. Such upstream wind disturbances are either weak or nonexistent in a high-Fr case. A critical Fr (Frc) of 0.35 inferred in this study is within the range of those suggested in previous observational and numerical studies. The depth of the blocked layer estimated from the along-ridge wind profile upstream of the northern Sierra Nevada corresponds to Frc between 0.3 and 0.45 as well. Associated with these low-level wind disturbances are significant low-level southerly moisture fluxes over the western slope and foothills of the Sierra Nevada in the low-Fr case, which result in significant exports of moisture from the southern Sierra Nevada to the northern region. This along-ridge low-level water vapor transport by blocking-induced barrier jets in a low-Fr condition may result in a strong north–south precipitation gradient over the Sierra Nevada.

scholarly journals The Impact of Diffusive Water Vapor Transport on Snow Profiles in Deep and Shallow Snow Covers and on Sea Ice

2020 ◽  
Vol 8 ◽  
Author(s):  
Mahdi Jafari ◽  
Isabelle Gouttevin ◽  
Margaux Couttet ◽  
Nander Wever ◽  
Adrien Michel ◽  
...  
Keyword(s):  
Water Vapor ◽  
Sea Ice ◽  
Vapor Transport ◽  
Water Vapor Transport ◽  
The Impact

Role of Tibetan Plateau in Northern Drought induced by Changes in Subtropical Westerly Jet

2021 ◽  
pp. 1-40
Author(s):  
Qingzhe Zhu ◽  
Yuzhi Liu ◽  
Tianbin Shao ◽  
Run Luo ◽  
Ziyuan Tan
Keyword(s):  
Water Vapor ◽  
Tibetan Plateau ◽  
North China ◽  
Lower Troposphere ◽  
Vapor Transport ◽  
Water Vapor Transport ◽  
The Tibetan Plateau ◽  
Westerly Jet ◽  
The Impact ◽  
Subtropical Westerly Jet

AbstractThe Tibetan Plateau (TP), the “Water Tower of Asia”, plays an important role in the water cycle. However, few studies have linked the TP’s water vapor supply with the climate over North China. In this study, we found that changes in the subtropical westerly jet (SWJ) dynamically induce drought in North China, and the TP plays an important role in this relationship. During July-August for the period of 1981-2019, the SWJ center between 75°E and 105°E obviously shifted northward at a rate of 0.04° per year. Correspondingly, the zonal winds in the southern subtropics were incredibly weakened, causing the outflow of water vapor from the TP to decrease dramatically. Combined with numerical simulations, we discovered that a reduction in water vapor transport from the TP can obviously decrease the precipitation over North China. Sensitivity experiments demonstrated that if the water vapor outflow from the eastern border of the TP decreases by 52.74%, the precipitation in North China will decrease by 12.69% due to a decrease in the local cloud fraction caused by a diminished water vapor content in the atmosphere. Therefore, although less water vapor transport occurs in the upper troposphere than in the lower troposphere, the impact of transport from the TP in the former on the downstream precipitation cannot be ignored.

scholarly journals The Impact of the NAO on the Delayed Break-Up Date of Lake Ice over the Southern Tibetan Plateau

2018 ◽  
Vol 31 (22) ◽  
pp. 9073-9086 ◽  
Author(s):  
Yong Liu ◽  
Huopo Chen ◽  
Huijun Wang ◽  
Yubao Qiu
Keyword(s):  
Water Vapor ◽  
Tibetan Plateau ◽  
North Atlantic ◽  
Vapor Transport ◽  
Water Vapor Transport ◽  
Freezing Process ◽  
Lake Ice ◽  
Break Up ◽  
The Impact ◽  
Ice Phenology

The changing characteristics of lake ice phenology over the Tibetan Plateau (TP) are investigated using historical satellite retrieved datasets during 2002–15 in this study. The results indicate that the freezing process mainly starts in December, and the ice melting process generally occurs in April for most lakes. However, the changes in lake ice phenology have varied depending on the location in recent years, with delayed break-up dates and prolonged ice durations in the southern TP, but no consistent changes have occurred in the lakes in the northern TP. Further analysis presents a close connection between the variation in the lake ice break-up date/ice duration over the southern TP and the winter North Atlantic Oscillation (NAO). The positive NAO generally excites an anomalous wave activity that propagates southward from the North Atlantic to North Africa and, in turn, strengthens the African–Asian jet stream at its entrance. Because of the blocking effect of the TP, the enhanced westerly jet can be divided into two branches and the south branch flow can deepen the India–Myanmar trough, which further strengthens the anomalous cyclonic circulation and water vapor transport. Therefore, the increased water vapor transport from the northern Indian Ocean to the southern region of the TP can increase the snowfall over this region. The increased snow cover over the lake acts as an insulating layer and lowers the lake surface temperature in the following spring by means of snow–ice feedback activity, resulting in a delayed ice break-up date and the increased ice duration of the lakes over the southern TP in recent years.

Meridional distribution of moisture transport associated to Tropical Cyclones

2020 ◽  
Author(s):  
Daniele Peano ◽  
Enrico Scoccimarro ◽  
Alessio Bellucci ◽  
Malcolm Roberts ◽  
Annalisa Cherchi ◽  
...  
Keyword(s):  
Water Vapor ◽  
High Resolution ◽  
Tropical Cyclones ◽  
Moisture Transport ◽  
Climate Models ◽  
Climate Model ◽  
Water Vapor Transport ◽  
The North ◽  
Good Ability ◽  
The Impact

<p>Tropical cyclones (TCs) transport energy and moisture along their pathways interacting with the climate system and TCs activities are expected to extend further poleward during the 21<sup>st</sup> century.</p><p>For this reason, it is important to assess the ability of state-of-the-art climate models in reproducing an accurate meridional distribution of TCs as well as a reasonable meridional portrait of moisture transport associated with TCs.</p><p>Since high resolutions are required to reconstruct observed TCs activity, the present work is based on the simulations performed as part of HighResMIP in the framework of the community CMIP6 effort. To inspect this feature, two horizontal resolutions for each climate model are considered. Besides, the impact of boundary conditions, i.e. observed ocean surface state, is examined by considering both coupled and atmosphere-only configurations.</p><p>In the present work, the north Atlantic region is analyzed as a sample region, while the same approach is applied on a multi-basin basis. In the sample area, climate models present a good ability in reproducing the TCs distribution, with a general underestimation at lower latitudes and a slight overestimation at high-latitudes compared to observed TCs tracks (e.g. IBTRACK).</p><p>The meridional distribution of moisture transport associated with TCs is evaluated by considering the radial average of the integrated water vapor transport along the TC tracks. When compared to observation (IBTRACS and JRA-55 reanalysis), the simulated moisture transport associated with TCs displays reasonably good performance in atmosphere-only high-resolution models configuration. The interannual variability of water vapor associated with TCs, instead, is poorly represented in climate models.</p><p>Climate models in high-resolution configuration can then be used in estimating future TCs meridional distribution and changes in meridional moisture transport associated with TCs.</p><p>This effort is part of HighResMIP and it is developed in the framework of the EU-funded PRIMAVERA project.   </p>

scholarly journals The impact of thermal conductivity and diffusion rates on water vapor transport through gas diffusion layers

2009 ◽  
Vol 190 (2) ◽  
pp. 485-492 ◽  
Author(s):  
Sergei F. Burlatsky ◽  
Vadim V. Atrazhev ◽  
Mallika Gummalla ◽  
Dave A. Condit ◽  
Fuqiang Liu
Keyword(s):  
Thermal Conductivity ◽  
Water Vapor ◽  
Gas Diffusion ◽  
Vapor Transport ◽  
Water Vapor Transport ◽  
Gas Diffusion Layers ◽  
Diffusion Layers ◽  
Diffusion Rates ◽  
The Impact ◽  
And Diffusion

scholarly journals Changes in extreme Integrated water Vapor Transport on the U.S. west coast in NA-CORDEX, and relationship to mountain and inland precipitation

2021 ◽  
Author(s):  
Mimi Hughes ◽  
Dustin Swales ◽  
James D. Scott ◽  
Michael Alexander ◽  
Kelly Mahoney ◽  
...  
Keyword(s):  
Water Vapor ◽  
Sierra Nevada ◽  
Great Basin ◽  
Climate Models ◽  
High Elevation ◽  
Vapor Transport ◽  
Water Vapor Transport ◽  
Total Precipitation ◽  
Cool Season ◽  
The U.S

Abstract Western U.S. (WUS) rainfall and snowpack vary greatly on interannual and decadal timescales. This combined with their importance to water resources makes future projections of these variables highly societally relevant. Previous studies have shown that precipitation events in the WUS are influenced by the timing, positioning, and duration of extreme integrated water vapor transport (IVT) events (e.g., atmospheric rivers) along the coast. We investigate end-of-21st-century projections of WUS precipitation and IVT in a collection of regional climate models (RCMs) from the North American Coordinated Regional Downscaling Experiment (NA-CORDEX). Several of the NA-CORDEX RCMs project a decrease in cool season precipitation at high elevation (e.g., across the Sierra Nevada) with a corresponding increase in the Great Basin of the U.S. We explore the causes of this terrain-related precipitation change in a subset of the NA-CORDEX RCMs through an examination of IVT-events. Projected changes in frequency and duration of IVT-events depend on the event's extremity: By the end of the century extreme IVT-events increase in frequency whereas moderate IVT-events decrease in frequency. Furthermore, in the future, total precipitation across the WUS generally increases during extreme IVT-events, whereas total precipitation from moderate IVT-events decreases across higher elevations. Thus, we argue that the mean cool season precipitation decreases at high elevations and increases in the Great Basin are largely determined by changes in moderate IVT-events which are projected to be less frequent and bring less high-elevation precipitation.

The Impact of Moisture on Mountain Waves during T-REX

2009 ◽  
Vol 137 (11) ◽  
pp. 3888-3906 ◽  
Author(s):  
Qingfang Jiang ◽  
James D. Doyle
Keyword(s):  
Sierra Nevada ◽  
Mesoscale Model ◽  
Buoyancy Frequency ◽  
Mountain Range ◽  
Linear Wave ◽  
Owens Valley ◽  
Mountain Waves ◽  
Low Level ◽  
The Impact ◽  
Moist Layer

Abstract The impact of moist processes on mountain waves over Sierra Nevada Mountain Range is investigated in this study. Aircraft measurements over Owens Valley obtained during the Terrain-induced Rotor Experiment (T-REX) indicate that mountain waves were generally weaker when the relative humidity maximum near the mountaintop level was above 70%. Four moist cases with a RH maximum near the mountaintop level greater than 90% have been further examined using a mesoscale model and a linear wave model. Two competing mechanisms governing the influence of moisture on mountain waves have been identified. The first mechanism involves low-level moisture that enhances flow–terrain interaction by reducing windward flow blocking. In the second mechanism, the moist airflow tends to damp mountain waves through destratifying the airflow and reducing the buoyancy frequency. The second mechanism dominates in the presence of a deep moist layer in the lower to middle troposphere, and the wave amplitude is significantly reduced associated with a smaller moist buoyancy frequency. With a shallow moist layer and strong low-level flow, the two mechanisms can become comparable in magnitude and largely offset each other.

scholarly journals Role and Mechanisms of Black Carbon Affecting Water Vapor Transport to Tibet

2020 ◽  
Vol 12 (2) ◽  
pp. 231 ◽  
Author(s):  
Min Luo ◽  
Yuzhi Liu ◽  
Qingzhe Zhu ◽  
Yuhan Tang ◽  
Khan Alam
Keyword(s):  
Water Vapor ◽  
Black Carbon ◽  
Summer Monsoon ◽  
Asian Summer Monsoon ◽  
Vapor Transport ◽  
Water Vapor Transport ◽  
The South ◽  
Asian Summer ◽  
Cooling Effects ◽  
The Impact

Although some studies reported the impact of black carbon (BC) on the climate over the Tibetan Plateau (TP), the contribution and mechanisms of BC affecting the water vapor transport to Tibet are not fully understood yet. Here, utilizing the satellite observations and reanalysis data, the effects of BC on the climate over the TP and water vapor transport to the Tibet were investigated by the Community Earth System Model (CESM 2.1.0). Due to the addition of BC, a positive net heat forcing (average is 0.39 W/m2) is exerted at the surface, which induces a pronounced warming effect over the TP and consequently intensifies the East Asian Summer monsoon (EASM). However, significant cooling effects in northern India, Pakistan, Afghanistan and Iran are induced due to the BC and related feedbacks, which reduces significantly the meridional land–sea thermal contrast and finally weakens the South Asian summer monsoon (SASM). Consequently, the water vapor transport to the south border is decreased due to addition of BC. Moreover, through affecting the atmospheric circulation, the BC could induce an increase in the imported water vapor from the west and east borders of the TP, and an increase outflowing away from the north border of the TP. Overall, due to the BC, the annual mean net importing water vapor over TP is around 271 Gt, which could enhance the precipitation over the TP. The results show that the mean increase in the precipitation over TP is about 0.56 mm/day.

scholarly journals Dropsonde Observations in Low-Level Jets over the Northeastern Pacific Ocean from CALJET-1998 and PACJET-2001: Mean Vertical-Profile and Atmospheric-River Characteristics

2005 ◽  
Vol 133 (4) ◽  
pp. 889-910 ◽  
Author(s):  
F. Martin Ralph ◽  
Paul J. Neiman ◽  
Richard Rotunno
Keyword(s):  
Water Vapor ◽  
Pacific Ocean ◽  
Static Stability ◽  
Vapor Transport ◽  
Vertical Shear ◽  
Water Vapor Transport ◽  
Low Level ◽  
Stable Conditions ◽  
Thermodynamic Conditions ◽  
The Mean

Dropsonde observations are used to document the mean vertical profiles of kinematic and thermodynamic conditions in the pre-cold-frontal low-level-jet (LLJ) region of extratropical cyclones over the eastern Pacific Ocean. This is the region within storms that is responsible not only for the majority of heavy rainfall induced by orography when such storms strike the coast, but also for almost all meridional water vapor transport at midlatitudes. The data were collected from NOAA’s P-3 aircraft in 10 storms during the California Land-falling Jets Experiment (CALJET) of 1998 and in 7 storms during the Pacific Land-falling Jets Experiment (PACJET) of 2001. The mean position of the dropsondes was 500 km offshore, well upstream of orographic influences. The availability of data from two winters that were characterized by very different synoptic regimes and by differing phases of ENSO—that is, El Niño in 1998 and La Niña in 2001—allowed examination of interannual variability. The composite pre-cold-frontal profiles reveal a well-defined LLJ at 1.0-km altitude with a wind speed of 23.4 m s−1 and a wind direction of 216.7°, as well as vertical shear characteristic of warm advection. The composite thermodynamic conditions were also documented, with special attention given to moist static stability due to the nearly saturated conditions that were prevalent. Although the dry static stability indicated very stable conditions (4.5 K km−1), the moist static stability was approximately zero up to 2.8-km altitude. Although the composite winds, temperatures, and water vapor mixing ratios in 2001 differed markedly from 1998, the moist static stability remained near zero from the surface up to 2.8–3.0-km altitude for both seasons. Hence, orographic precipitation enhancement is favored in this sector of the storm, regardless of the phase of ENSO. The dropsonde data were also used to characterize the depth and strength of atmospheric rivers, which are responsible for most of the meridional water vapor transport at midlatitudes. The vertically integrated along-river water vapor fluxes averaged 525 × 105 kg s−1 (assuming a 100-km-wide swath), while the meridional and zonal components were 387 × 105 kg s−1 and 302 × 105 kg s−1, respectively. Although the composite meridional transport in 2001 was less than half that in 1998 (230 × 105 kg s−1 versus 497 × 105 kg s−1), the characteristic scale height of the meridional water vapor transport remained constant; that is, 75% of the transport occurred below 2.25-km altitude.

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