Seasonal transition features of large-scale moisture transport in the Asian-Australian monsoon region

2007 ◽  
Vol 24 (1) ◽  
pp. 1-14 ◽  
Author(s):  
Jinhai He ◽  
Chenghu Sun ◽  
Yunyun Liu ◽  
Jun Matsumoto ◽  
Weijing Li
Keyword(s):  
Moisture Transport ◽  
Large Scale ◽  
Monsoon Region ◽  
Seasonal Transition ◽  
Australian Monsoon

scholarly journals Evaluating vector winds in the Asian-Australian monsoon region simulated by 37 CMIP5 models

2018 ◽  
Vol 53 (1-2) ◽  
pp. 491-507 ◽  
Author(s):  
Fang Huang ◽  
Zhongfeng Xu ◽  
Weidong Guo
Keyword(s):  
Cmip5 Models ◽  
Monsoon Region ◽  
Australian Monsoon

scholarly journals Asian monsoon projection with a new large-scale monsoon definition

2021 ◽  
Author(s):  
Xingang Dai ◽  
Yang Yang ◽  
Ping Wang
Keyword(s):  
South Asia ◽  
Summer Monsoon ◽  
Moisture Transport ◽  
Large Scale ◽  
Asian Monsoon ◽  
Monsoon Season ◽  
Northwest China ◽  
Winter Monsoon ◽  
Climate Simulation ◽  
Northwestern Part

Abstract This paper focuses on Asian monsoon projection with CMIP5 multi-model outputs. A large-scale monsoon herewith is defined as a vector field of vertically integrated moisture flux from the surface to 500 hPa. Results demonstrate that the model ensemble mean underestimated the summer monsoon and overestimated slightly the winter monsoon over South Asia in both CMIP5 historical climate simulation and the monsoon projection for 2006–2015. The major of the bias is the model climate drift (MCD), which is removed in the monsoon projection for 2016–2045 under scenarios RCP4.5 for reducing the uncertainty. The projection shows that two increased moisture flows northward appeared across the Equator of Indian Ocean, the first is nearby Somalia coast toward northwestern part of South Asia, leading to excess rainfall in where the wet jet could reach, and the second starts from the equatorial Sect. (80°E–100°E) toward northeastern Bay of Bengal, leading to more rainfall spreading over the northwestern coast of Indochina Peninsula. In addition, a westward monsoon flow is intensified over the Peninsula leading to local climate moisture transport belt shifted onto South China Sea, which would reduce moisture transport toward Southwest China on one hand, and transport more moisture onto the southeast coast of the China mainland. The anomalous monsoon would result in a dry climate in Northwest China and wet climate in the coast belt during summer monsoon season for the period. Besides, the Asian winter monsoon would be seemingly intensified slightly over South Asia, which would bring a dry winter climate to Indian subcontinent, Northwest China, but would be more rainfall in southeast part of Arabian Peninsula with global climate warming.

scholarly journals Precipitable water characteristics during the 2013 Colorado flood using ground-based GPS measurements

2017 ◽  
Vol 10 (11) ◽  
pp. 4055-4066 ◽  
Author(s):  
Hannah K. Huelsing ◽  
Junhong Wang ◽  
Carl Mears ◽  
John J. Braun
Keyword(s):  
United States ◽  
Moisture Transport ◽  
Large Scale ◽  
Precipitable Water ◽  
Tropical Eastern Pacific ◽  
Public And Private ◽  
Maximum Rainfall ◽  
Water Characteristics ◽  
Synoptic Features ◽  
Saturated Atmosphere

Abstract. During 9–16 September 2013, the Front Range region of Colorado experienced heavy rainfall that resulted in severe flooding. Precipitation totals for the event exceeded 450 mm, damages to public and private properties were estimated to be over USD 2 billion, and nine lives were lost. This study analyzes the characteristics of precipitable water (PW) surrounding the event using 10 years of high-resolution GPS PW data in Boulder, Colorado, which was located within the region of maximum rainfall. PW in Boulder is dominated by seasonal variability with an average summertime maximum of 36 mm. In 2013, the seasonal PW maximum extended into early September and the September monthly mean PW exceeded the 99th percentile of climatology with a value 25 % higher than the 40-year climatology. Prior to the flood, around 18:00 UTC on 8 September, PW rapidly increased from 22 to 32 mm and remained around 30 mm for the entire event as a result of the nearly saturated atmosphere. The frequency distribution of September PW for Boulder is typically normal, but in 2013 the distribution was bimodal due to a combination of above-average PW values from 1 to 15 September and much drier conditions from 16 to 30 September. The above-normal, near-saturation PW values during the flood were the result of large-scale moisture transport into Colorado from the Tropical Eastern Pacific and the Gulf of Mexico. This moisture transport was the product of a stagnating cutoff low over the southwestern United States working in conjunction with an anticyclone located over the southeastern United States. A blocking ridge located over the Canadian Rocky Mountains kept both of the synoptic features in place over the course of several days, which helped to provide continuous moisture to the storm, thus enhancing the accumulated precipitation totals.

scholarly journals Synoptic and Mesoscale atmospheric features associated with an extreme Snowstorm over the Central Andes in August 2013

2019 ◽  
Author(s):  
Marcelo Zamuriano ◽  
Paul Froidevaux ◽  
Isabel Moreno ◽  
Mathias Vuille ◽  
Stefan Brönnimann
Keyword(s):  
Spatial Distribution ◽  
Snow Cover ◽  
Rossby Wave ◽  
Moisture Transport ◽  
Large Scale ◽  
Amazon Basin ◽  
Cold Front ◽  
Wave Train ◽  
Pressure System ◽  
The Andes

Abstract. We study the synoptic and mesoscale characteristics of a snowfall event over the Bolivian Altiplano in August 2013 that caused severe damage to people, infrastructure and livestock. This event was associated with a cold front episode following the eastern slope of the Andes-Amazon interface and a cut-off low pressure system (COL) over the Pacific Ocean. Large scale analyses suggest a two-stage mechanism: The first phase consisted of a strong cold surge to the east of the Andes inducing low level blocking of southward moisture transport over the SW Amazon basin due to post-frontal high-pressure up to 500 hPa synchronized to a Rossby wave train. The second stage was initiated by the displacement of 500 hPa anticyclone over the Andes due to a Rossby wave passage and a subsequent increase in north-easterly moisture transport, while another cold front along the eastern Andes provided additional lifting. We analyse an analog event (July 2010) to confirm the influence of these large-scale features on snow formation. We conduct a mesoscale analysis using the Weather Research and Forecasting (WRF-ARW) model. For this purpose, we perform a series of high-resolution numerical experiments that include sensitivity studies where we apply orographic and lake Titicaca temperature modifications. We compare our findings to MODIS snow cover estimates and in-situ measurements. The control simulation is able to capture the snow cover spatial distribution and sheds light over several aspects of the snowfall dynamics. In our WRF simulations, daytime snowfall mainly occurs around complex orography whereas nocturnal snowfall is concentrated over the plateau due to a combination of nocturnal winds and complex orography inside the plateau. The sensitivity experiments indicate the importance of the lake and mountain for thermal wind circulation affecting the spatial distribution of snowfall by shifting the position of the convergence zones. The influence of the lake's thermal effect is not evident around the regions surrounding the lake.

Using a long-term climate simulation to address future changes in Western Europe precipitation regimes due to global warming

2020 ◽  
Author(s):  
Pedro M. Sousa ◽  
Alexandre M. Ramos ◽  
Ricardo M. Trigo ◽  
Christoph C. Raible ◽  
Martina Messmer ◽  
...  
Keyword(s):  
Global Warming ◽  
Moisture Transport ◽  
Large Scale ◽  
Western Europe ◽  
Warming Trend ◽  
Water Vapor Transport ◽  
Climate Simulation ◽  
Wet Season ◽  
Precipitation Regimes

<p>Moisture transport and Atmospheric Rivers (ARs) over the Northeastern Atlantic are a very relevant process for the inter-annual variability of precipitation over Western Europe. Based on a long-term transient simulation (850-2100CE) from the CESM model, we have showed that moisture transport towards Western Europe (using the vertically integrated horizontal water vapor transport, IVT) has been increasing significantly since pre-industrial period, in a clear association with the global warming trend. Both current and projected changes (using RCP 8.5) significantly exceed the range given by inter-annual to inter-decadal internal/external variability observed during the last millennium.</p><p>We have checked the emergence of the temperature, IVT and precipitation signals in Iberia and the UK, showing that while the first two have now clearly emerged from the pre-warming state, precipitation series are still slightly below that threshold. Nevertheless, projections clearly show an increase in rainfall at higher latitudes (i in phase with a warmer and moister atmosphere); and a decrease at lower latitudes decoupled from the overall increase in moisture availability. Additionally we have explored the role played by large-scale circulation and atmospheric dynamics for these contrasting projections. Overall, results show that a poleward migration of moisture corridors and ARs explain a significant fraction of these projected trends. Based on the Clausius–Clapeyron relation we have separated the thermodynamical from dynamical changes. We also show how that a significant increase in subtropical anticyclonic activity over Iberia is responsible for: i) dynamical circulation changes; ii) a shortening of the wet season; iii) to less efficient precipitation regimes in the region. These results highlight the urge to adapt to a drying trend in Mediterranean-type climates, as a consequence of Global Warming.</p><p> </p><p>The financial support for this work was possible through the following FCT project: HOLMODRIVE - North Atlantic Atmospheric Patterns influence on Western Iberia Climate: From the Lateglacial to the Present [PTDC/CTA-GEO/29029/2017]</p>

scholarly journals Mesoscale Moisture Transport by the Low-Level Jet during the IHOP Field Experiment

2008 ◽  
Vol 136 (10) ◽  
pp. 3781-3795 ◽  
Author(s):  
Edward I. Tollerud ◽  
Fernando Caracena ◽  
Steven E. Koch ◽  
Brian D. Jamison ◽  
R. Michael Hardesty ◽  
...  
Keyword(s):  
Great Plains ◽  
Cross Sections ◽  
Moisture Transport ◽  
Large Scale ◽  
Wrf Model ◽  
The United States ◽  
Small Scale ◽  
Low Level ◽  
Convective Scale ◽  
Low Level Jet

Previous studies of the low-level jet (LLJ) over the central Great Plains of the United States have been unable to determine the role that mesoscale and smaller circulations play in the transport of moisture. To address this issue, two aircraft missions during the International H2O Project (IHOP_2002) were designed to observe closely a well-developed LLJ over the Great Plains (primarily Oklahoma and Kansas) with multiple observation platforms. In addition to standard operational platforms (most important, radiosondes and profilers) to provide the large-scale setting, dropsondes released from the aircraft at 55-km intervals and a pair of onboard lidar instruments—High Resolution Doppler Lidar (HRDL) for wind and differential absorption lidar (DIAL) for moisture—observed the moisture transport in the LLJ at greater resolution. Using these observations, the authors describe the multiscalar structure of the LLJ and then focus attention on the bulk properties and effects of scales of motion by computing moisture fluxes through cross sections that bracket the LLJ. From these computations, the Reynolds averages within the cross sections can be computed. This allow an estimate to be made of the bulk effect of integrated estimates of the contribution of small-scale (mesoscale to convective scale) circulations to the overall transport. The performance of the Weather Research and Forecasting (WRF) Model in forecasting the intensity and evolution of the LLJ for this case is briefly examined.

scholarly journals An Explanation for the Sensitivity of the Mean State of the Community Atmosphere Model to Horizontal Resolution on Aquaplanets

2017 ◽  
Vol 30 (13) ◽  
pp. 4781-4797 ◽  
Author(s):  
Adam R. Herrington ◽  
Kevin A. Reed
Keyword(s):  
Moisture Transport ◽  
General Circulation ◽  
Large Scale ◽  
General Circulation Models ◽  
Horizontal Resolution ◽  
Hadley Cell ◽  
Community Atmosphere Model ◽  
The Mean ◽  
Atmosphere Model ◽  
Mean State

The sensitivity of the mean state of the Community Atmosphere Model to horizontal resolutions typical of present-day general circulation models is investigated in an aquaplanet configuration. Nonconvergence of the mean state is characterized by a progressive drying of the atmosphere and large reductions in cloud coverage with increasing resolution. Analyses of energy and moisture budgets indicate that these trends are balanced by variations in moisture transport by the resolved circulation, and a reduction in activity of the convection scheme. In contrast, the large-scale precipitation rate increases with resolution, which is approximately balanced by greater advection of dry static energy associated with more active resolved vertical motion in the ascent region of the Hadley cell. An explanation for the sensitivity of the mean state to horizontal resolution is proposed, based on linear Boussinesq theory. The authors hypothesize that an increase in horizontal resolution in the model leads to a reduction in horizontal scale of the diabatic forcing arising from the column physics, facilitating finescale flow and faster resolved convective updrafts within the dynamical core, and steering the coupled system toward a new mean state. This hypothesis attempts to explain the underlying mechanism driving the variations in moisture transport observed in the simulations.

scholarly journals A Mathematical Framework for Analysis of Water Tracers. Part II: Understanding Large-Scale Perturbations in the Hydrological Cycle due to CO2 Doubling

2016 ◽  
Vol 29 (18) ◽  
pp. 6765-6782 ◽  
Author(s):  
Hansi K. A. Singh ◽  
Cecilia M. Bitz ◽  
Aaron Donohoe ◽  
Jesse Nusbaumer ◽  
David C. Noone
Keyword(s):  
Moisture Transport ◽  
Large Scale ◽  
Climate Model ◽  
Hydrological Cycle ◽  
Global Climate ◽  
Global Climate Model ◽  
Mathematical Framework ◽  
Surface Evaporation ◽  
And Shifts

Abstract The aerial hydrological cycle response to CO2 doubling from a Lagrangian, rather than Eulerian, perspective is evaluated using information from numerical water tracers implemented in a global climate model. While increased surface evaporation (both local and remote) increases precipitation globally, changes in transport are necessary to create a spatial pattern where precipitation decreases in the subtropics and increases substantially at the equator. Overall, changes in the convergence of remotely evaporated moisture are more important to the overall precipitation change than changes in the amount of locally evaporated moisture that precipitates in situ. It is found that CO2 doubling increases the fraction of locally evaporated moisture that is exported, enhances moisture exchange between ocean basins, and shifts moisture convergence within a given basin toward greater distances between moisture source (evaporation) and sink (precipitation) regions. These changes can be understood in terms of the increased residence time of water in the atmosphere with CO2 doubling, which corresponds to an increase in the advective length scale of moisture transport. As a result, the distance between where moisture evaporates and where it precipitates increases. Analyses of several heuristic models further support this finding.

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