scholarly journals Land-sea Thermal Contrast in Relation With Summer Monsoon Onset Over the Chao Phraya River Basin

2022 ◽  
Author(s):  
Tomohito J. Yamada ◽  
Sourabh Shrivastava ◽  
Ryosuke Kato
Keyword(s):  
Surface Temperature ◽  
River Basin ◽  
Summer Monsoon ◽  
Asian Summer Monsoon ◽  
Thermal Conditions ◽  
Total Heat ◽  
Western Hemisphere ◽  
Summer Monsoon Onset ◽  
Chao Phraya River ◽  
Early Late

Abstract An earlier onset of the Southeast Asian summer monsoon (SAM) was observed over the Chao Phraya River basin in Thailand using Thai Meteorological Department (TMD)-derived high-resolution merged rainfall from 1981 to 2016. As the SAM is precipitous, its variability depends on many local and global factors, such as thermal conditions over the Bay of Bengal (BoB) and Tibetan Plateau (TbT). Despite tremendous studies in the past, the role of thermal heat contrast over SAM is still not fully understood. Using the observation and reanalysis datasets, it was found that the absolute value of total heat over the BoB was higher. However, the interannual variability in total heat is higher over the TbT. Significant changes in surface temperature (±1.5°C), air thickness (±20 meters) and geopotential height found over the TbT were associated with early (late) SAM onset. The results also suggested that the significant changes in air thickness were influenced by the surface temperature difference over the TbT, and the changes in the integrated apparent heat source and integrated apparent moisture sink were up to ± 100 Wm−2, which resulted in stronger (weaker) convective activities over the BoB and mainland of the Indochina Peninsula during early (late) SAM onset. At the intraseasonal timescale, the instance MJO found over the Indian Ocean and Western Hemisphere at 4 to 10 days span during early SAM onset. An opposite scenario is found for a late SAM onset years with MJO location over Western Pacific and Maritime continent.

scholarly journals Relative impact of insolation and Warm Pool surface temperature on the East Asia Summer Monsoon during the MIS-13 interglacial

2014 ◽  
Vol 10 (2) ◽  
pp. 1025-1051 ◽  
Author(s):  
Q. Z. Yin ◽  
U. K. Singh ◽  
A. Berger ◽  
Z. T. Guo ◽  
M. Crucifix
Keyword(s):  
Surface Temperature ◽  
Summer Monsoon ◽  
Climate Modeling ◽  
Southern China ◽  
Asian Summer Monsoon ◽  
Summer Precipitation ◽  
Northern China ◽  
Warm Pool ◽  
Pool Surface ◽  
The Impact

Abstract. During Marine Isotope Stage (MIS) 13, an interglacial about 500 000 years ago, the East Asian summer monsoon (EASM) was suggested exceptionally strong by different proxies in China. However, MIS-13 is a weak interglacial in marine oxygen isotope records and has relatively low CO2 and CH4 concentrations compared to other interglacials of the last 800 000 years. In the mean time, the sea surface temperature (SST) reconstructions show that the Western Pacific Warm Pool was relatively warm during MIS-13. Based on climate modeling experiments, this study aims at investigating whether this Warm Pool warming could explain the exceptionally strong EASM occurring during the relatively cool interglacial MIS-13. The individual contributions of insolation and of the Warm Pool SST as well as their synergism are quantified through experiments with the Hadley Centre atmosphere model, HadAM3 and using the factor separation technique. The SST over the Warm Pool region has been increased based on geological reconstructions. Our results show that the pure impact of a strong summer insolation contributes to strengthen significantly the summer precipitation in northern China but only little in southern China. The pure impact of enhanced Warm Pool SST reduces, slightly, the summer precipitation in both northern and southern China. However, the synergism between insolation and enhanced Warm Pool SST contributes to a large increase of summer precipitation in southern China but to a decrease in northern China. Therefore, the ultimate role of enhanced Warm Pool SST reinforces the impact of insolation in southern China but reduces its impact in northern China. We conclude that enhanced SST over the Warm Pool region does help to explain the strong MIS-13 EASM precipitation in southern China as recorded in proxy data, but other explanation is needed for explaining the exceptionally strong EASM in northern China.

A Moist Entropy Budget View of the South Asian Summer Monsoon Onset

2019 ◽  
Vol 46 (8) ◽  
pp. 4476-4484
Author(s):  
Ding Ma ◽  
Adam H. Sobel ◽  
Zhiming Kuang ◽  
Martin S. Singh ◽  
Ji Nie
Keyword(s):  
South Asian ◽  
Summer Monsoon ◽  
Asian Summer Monsoon ◽  
Monsoon Onset ◽  
South Asian Summer Monsoon ◽  
The South ◽  
Summer Monsoon Onset ◽  
Asian Summer ◽  
Entropy Budget

Relationship between sea surface temperature anomalies over tropical Atlantic in late spring and East Asian summer monsoon

2020 ◽  
Author(s):  
Joong-Bae Ahn ◽  
Yeon-Woo Choi
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Summer Monsoon ◽  
East Asian Summer Monsoon ◽  
Asian Summer Monsoon ◽  
East Asian ◽  
Late Spring ◽  
Sea Surface ◽  
Tropical Atlantic ◽  
Asian Summer

<p>This study investigates the relationship between the preceding late spring Sea Surface Temperature (SST) over the tropical Atlantic and the East Asian Summer Monsoon (EASM) based on the observational data and Coupled Model Intercomparison Project Phase 5 (CMIP5) historical simulations. The results show that warm (cold) tropical Atlantic SST (TASST) during May tends to be followed by a strong (weak) EASM with positive (negative) precipitation anomalies over the subtropical frontal area. Evidence is also provided that the atmospheric teleconnections propagating in both east and west directions are the key mechanisms linking the EASM with the preceding May TASST. That is, the warm TASST anomaly during late spring can persist through the subsequent summer, which, in turn, induces the Gill-type Rossby wave response in the eastern Pacific, exciting the westward relay of the Atlantic signal, as well as the eastward propagation of the Rossby wave along the jet stream. Furthermore, the westward (eastward) propagating teleconnection signal may induce the anomalous anticyclone in the lower troposphere over the Philippine Sea (anomalous tropospheric anticyclone with barotropic structure over the Okhotsk Sea). The anomalous anticyclonic circulation over the Philippine Sea (Okhotsk Sea) brings warm and humid (cold) air to higher latitudes (lower latitudes). These two different types of air mass merge over the Baiu-Meiyu–Changma region, causing the enhanced subtropical frontal rainfall. To support the observational findings, CMIP5 historical simulations are also utilized. Most state-of-the-art CMIP5 models can simulate this relationship between May TASST and the EASM.</p><p>Reference: Choi, Y., Ahn, J. Possible mechanisms for the coupling between late spring sea surface temperature anomalies over tropical Atlantic and East Asian summer monsoon. Clim Dyn <strong>53, </strong>6995–7009 (2019) doi:10.1007/s00382-019-04970-3</p><p>Acknowledgment: This work was funded by the Korea Meteorological Administration Research and Development Program under Grant KMI2018-01213.</p><p> </p>

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