Influence of the South Asian high‐intensity variability on the persistent heavy rainfall and heat waves in Asian monsoon regions

2019 ◽  
Vol 40 (4) ◽  
pp. 2153-2172
Author(s):  
Wei Shang ◽  
Xuejuan Ren ◽  
Keqin Duan ◽  
Chengwu Zhao
Keyword(s):  
South Asian ◽  
High Intensity ◽  
Heavy Rainfall ◽  
Asian Monsoon ◽  
Heat Waves ◽  
South Asian High ◽  
The South ◽  
Persistent Heavy Rainfall

scholarly journals Insensitivity of the Summer South Asian High Intensity to a Warming Tibetan Plateau in Modern Reanalysis Datasets

2017 ◽  
Vol 30 (8) ◽  
pp. 3009-3024 ◽  
Author(s):  
Liguang Wu ◽  
Xiaofang Feng ◽  
Mei Liang
Keyword(s):  
Tibetan Plateau ◽  
South Asian ◽  
High Intensity ◽  
Thermal Condition ◽  
Sensible Heat Flux ◽  
South Asian High ◽  
The Tibetan Plateau ◽  
The South ◽  
Condition Change ◽  
Surface Sensible Heat Flux

The South Asia high (SAH) is a prominent circulation system of the Asian summer monsoon, exerting profound influences on the weather and climate in China and surrounding regions. Its formation and maintenance is closely associated with strong summertime continental heating in the form of surface sensible heat flux and the latent heat release in connection with the Asian monsoon. In this study, the possible response of the South Asian high intensity to the thermal condition change in the Tibetan Plateau is examined with four modern reanalysis datasets, including the Modern-Era Retrospective Analysis for Research and Applications (MERRA), MERRA version 2 (MERRA-2), the European Centre for Medium-Range Weather Forecasts (ECMWF) interim reanalysis (ERA-Interim), and the Japanese 55-year Reanalysis (JRA-55). Despite the surface air warming in the four modern reanalysis datasets, reduced surface wind speed in three of the reanalysis datasets, and decreased surface sensible heat flux in the MERRA-2 dataset, there is no statistically significant trend in the SAH intensity over the period 1979–2015. One of the possible reasons is that the response of the upper-level circulation to the thermal condition change of the Tibetan Plateau occurs mainly in the 200-hPa subtropical westerly jet stream, which is located far away from the center of the South Asian high. Thus the South Asian high intensity is not particularly sensitive to the thermal condition change of the Tibetan Plateau, while the center of the South Asian high intensity over the plateau exhibits a northward trend over the period.

scholarly journals Synoptic Preconditions for Extreme Flooding during the Summer Asian Monsoon in the Mumbai Area

2014 ◽  
Vol 15 (1) ◽  
pp. 229-242 ◽  
Author(s):  
Marco Lomazzi ◽  
Dara Entekhabi ◽  
Joaquim G. Pinto ◽  
Giorgio Roth ◽  
Roberto Rudari
Keyword(s):  
Time Series ◽  
South Asian ◽  
Asian Monsoon ◽  
Indian Subcontinent ◽  
Monsoon Season ◽  
Value Added ◽  
South Asian Monsoon ◽  
Flood Events ◽  
The South ◽  
Synoptic Conditions

Abstract The summer monsoon season is an important hydrometeorological feature of the Indian subcontinent and it has significant socioeconomic impacts. This study is aimed at understanding the processes associated with the occurrence of catastrophic flood events. The study has two novel features that add to the existing body of knowledge about the South Asian monsoon: 1) it combines traditional hydrometeorological observations (rain gauge measurements) with unconventional data (media and state historical records of reported flooding) to produce value-added century-long time series of potential flood events and 2) it identifies the larger regional synoptic conditions leading to days with flood potential in the time series. The promise of mining unconventional data to extend hydrometeorological records is demonstrated in this study. The synoptic evolution of flooding events in the western-central coast of India and the densely populated Mumbai area are shown to correspond to active monsoon periods with embedded low pressure centers and have far-upstream influences from the western edge of the Indian Ocean basin. The coastal processes along the Arabian Peninsula where the currents interact with the continental shelf are found to be key features of extremes during the South Asian monsoon.

scholarly journals Connection between Anomalous Zonal Activities of the South Asian High and Eurasian Summer Climate Anomalies

2016 ◽  
Vol 29 (22) ◽  
pp. 8249-8267 ◽  
Author(s):  
Jian Shi ◽  
Weihong Qian
Keyword(s):  
South Asian ◽  
Surface Air Temperature ◽  
Northern China ◽  
Boreal Summer ◽  
South Asian High ◽  
The South ◽  
Climate Anomalies ◽  
Precipitation Anomalies ◽  
Air Column ◽  
Air Temperature Anomalies

Abstract Using the daily mean anomalies of atmospheric variables from the NCEP Reanalysis-1 (NCEP R1), this study reveals the connection between anomalous zonal activities of the South Asian high (SAH) and Eurasian climate anomalies in boreal summer. An analysis of variance identifies two major domains with larger geopotential height variability located in the eastern and western flanks of the SAH at around 100 and 150 hPa, respectively. For both eastern and western domains, extreme events are selected during 1981–2014 when normalized height anomalies are greater than 1.0 (less than −1.0) standard deviation for at least 10 consecutive days. Based on these events, four SAH modes that include strong and weak Tibetan modes (STM and WTM, respectively) and strong and weak Iranian modes (SIM and WIM, respectively) are defined to depict the zonal SAH features. The positive composite in the eastern (western) domain indicates the STM (SIM) manifests a robust wavelike pattern with an anomalous low at 150 hPa, and surface cold and wet anomalies over Mongolia and northern China (Kazakhstan and western Siberia) are surrounded by three anomalous highs at 150 hPa and surface warm and dry anomalies over Eurasia. Opposite distributions are also evident in the negative composites of the two domains (WTM and WIM). The surface air temperature anomalies are the downward extension of an anomalous air column aloft while the precipitation anomalies are directly associated with the height anomalies above the air column.

scholarly journals The remote response of the South Asian Monsoon to reduced dust emissions and Sahara greening during the middle Holocene

2021 ◽  
Vol 17 (3) ◽  
pp. 1243-1271
Author(s):  
Francesco S. R. Pausata ◽  
Gabriele Messori ◽  
Jayoung Yun ◽  
Chetankumar A. Jalihal ◽  
Massimo A. Bollasina ◽  
...  
Keyword(s):  
South Asian ◽  
Asian Monsoon ◽  
Monsoon Season ◽  
Dust Emission ◽  
Northern Africa ◽  
South Asian Monsoon ◽  
The South ◽  
Airborne Dust ◽  
Orbital Parameters ◽  
Humid Period

Abstract. Previous studies based on multiple paleoclimate archives suggested a prominent intensification of the South Asian Monsoon (SAM) during the mid-Holocene (MH, ∼6000 years before present). The main forcing that contributed to this intensification is related to changes in the Earth's orbital parameters. Nonetheless, other key factors likely played important roles, including remote changes in vegetation cover and airborne dust emission. In particular, northern Africa also experienced much wetter conditions and a more mesic landscape than today during the MH (the so-called African Humid Period), leading to a large decrease in airborne dust globally. However, most modeling studies investigating the SAM changes during the Holocene overlooked the potential impacts of the vegetation and dust emission changes that took place over northern Africa. Here, we use a set of simulations for the MH climate, in which vegetation over the Sahara and reduced dust concentrations are considered. Our results show that SAM rainfall is strongly affected by Saharan vegetation and dust concentrations, with a large increase in particular over northwestern India and a lengthening of the monsoon season. We propose that this remote influence is mediated by anomalies in Indian Ocean sea surface temperatures and may have shaped the evolution of the SAM during the termination of the African Humid Period.

Characteristics of Precipitating Convective Systems in the South Asian Monsoon

2011 ◽  
Vol 12 (1) ◽  
pp. 3-26 ◽  
Author(s):  
Ulrike Romatschke ◽  
Robert A. Houze
Keyword(s):  
South Asian ◽  
Diurnal Cycle ◽  
Bay Of Bengal ◽  
Arabian Sea ◽  
Asian Monsoon ◽  
South Asian Monsoon ◽  
Western Himalayas ◽  
The South ◽  
Convective Systems ◽  
Large Systems

Abstract Eight years of Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) data show how convective systems of different types contribute to precipitation of the South Asian monsoon. The main factor determining the amount of precipitation coming from a specific system is its horizontal size. Convective intensity and/or number of embedded convective cells further enhance its precipitation production. The precipitation of the monsoon is concentrated in three mountainous regions: the Himalayas and coastal ranges of western India and Myanmar. Along the western Himalayas, precipitation falls mainly from small, but highly convective systems. Farther east along the foothills, systems are more stratiform. These small and medium systems form during the day, as the monsoon flow is forced upslope. Nighttime cooling leads to downslope flow and triggers medium-sized systems at lower elevations. At the mountainous western coasts of India and Myanmar, small and medium systems are present throughout the day, as an orographic response to the southwesterly flow, with a slight superimposed diurnal cycle. Medium systems are favored over the eastern parts of the Arabian Sea and large systems are favored over the Bay of Bengal when an enhanced midlevel cyclonic circulation occurs over the northern parts of these regions. The systems forming upstream of coastal mountains over the Bay of Bengal are larger than those over the Arabian Sea, probably because of the moister conditions over the bay. The large systems over the bay exhibit a pronounced diurnal cycle, with systems forming near midnight and maximizing in midday.

Climate response of the south Asian monsoon system to West Asia, Tibetan Plateau and local dust emissions

2019 ◽  
Vol 53 (9-10) ◽  
pp. 6245-6264 ◽  
Author(s):  
Charu Singh ◽  
Dilip Ganguly ◽  
Puneet Sharma ◽  
Shiwansha Mishra
Keyword(s):  
Tibetan Plateau ◽  
South Asian ◽  
Asian Monsoon ◽  
South Asian Monsoon ◽  
Climate Response ◽  
The South ◽  
Dust Emissions ◽  
Monsoon System ◽  
Local Dust
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