A study on the role of land-atmosphere coupling on the south Asian monsoon climate variability using a regional climate model

2015 ◽  
Vol 127 (3-4) ◽  
pp. 949-964 ◽  
Author(s):  
C. K. Unnikrishnan ◽  
M. Rajeevan ◽  
S. Vijaya Bhaskara Rao
Keyword(s):  
Climate Variability ◽  
Regional Climate Model ◽  
South Asian ◽  
Asian Monsoon ◽  
Climate Model ◽  
Regional Climate ◽  
South Asian Monsoon ◽  
Monsoon Climate ◽  
The South

scholarly journals Regional climate model experiments to investigate the Asian monsoon in the Late Miocene

2011 ◽  
Vol 7 (3) ◽  
pp. 847-868 ◽  
Author(s):  
H. Tang ◽  
A. Micheels ◽  
J. Eronen ◽  
M. Fortelius
Keyword(s):  
Tibetan Plateau ◽  
Regional Climate Model ◽  
Late Miocene ◽  
Asian Monsoon ◽  
Climate Model ◽  
Regional Climate ◽  
Northern China ◽  
Regional Model ◽  
Monsoon Climate ◽  
Northern Tibetan Plateau

Abstract. The Late Miocene (11.6–5.3 Ma) is a crucial period in the history of the Asian monsoon. Significant changes in the Asian climate regime have been documented for this period, which saw the formation of the modern Asian monsoon system. However, the spatiotemporal structure of these changes is still ambiguous, and the associated mechanisms are debated. Here, we present a simulation of the average state of the Asian monsoon climate for the Tortonian (11–7 Ma) using the regional climate model CCLM3.2. We employ relatively high spatial resolution (1° × 1°) and adapt the physical boundary conditions such as topography, land-sea distribution and vegetation in the regional model to represent the Late Miocene. As climatological forcing, the output of a Tortonian run with a fully-coupled atmosphere-ocean general circulation model is used. Our regional Tortonian run shows a stronger-than-present East Asian winter monsoon wind as a result of the enhanced mid-latitude westerly wind of our global forcing and the lowered present-day northern Tibetan Plateau in the regional model. The summer monsoon circulation is generally weakened in our regional Tortonian run compared to today. However, the changes of summer monsoon precipitation exhibit major regional differences. Precipitation decreases in northern China and northern India, but increases in southern China, the western coast and the southern tip of India. This can be attributed to the changes in both the regional topography (e.g. the lower northern Tibetan Plateau) and the global climate conditions (e.g. the higher sea surface temperature). The spread of dry summer conditions over northern China and northern Pakistan in our Tortonian run further implies that the monsoonal climate may not have been fully established in these regions in the Tortonian. Compared with the global model, the high resolution regional model highlights the spatial differences of the Asian monsoon climate in the Tortonian, and better characterizes the convective activity and its response to regional topographical changes. It therefore provides a useful and compared to global models, a complementary tool to improve our understanding of the Asian monsoon evolution in the Late Miocene.

scholarly journals High resolution simulation of the South Asian monsoon using a variable resolution global climate model

2013 ◽  
Vol 41 (1) ◽  
pp. 173-194 ◽  
Author(s):  
T. P Sabin ◽  
R. Krishnan ◽  
Josefine Ghattas ◽  
Sebastien Denvil ◽  
Jean-Louis Dufresne ◽  
...  
Keyword(s):  
High Resolution ◽  
South Asian ◽  
Asian Monsoon ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
South Asian Monsoon ◽  
The South ◽  
Variable Resolution ◽  
Resolution Simulation

scholarly journals On the Role of the African Topography in the South Asian Monsoon

2016 ◽  
Vol 73 (8) ◽  
pp. 3197-3212 ◽  
Author(s):  
Ho-Hsuan Wei ◽  
Simona Bordoni
Keyword(s):  
South Asian ◽  
General Circulation ◽  
Asian Monsoon ◽  
Circulation Model ◽  
Atmospheric Model ◽  
South Asian Monsoon ◽  
The South ◽  
East African Highlands ◽  
Somali Jet

Abstract The Somali jet, a strong low-level cross-equatorial flow concentrated in a narrow longitudinal band near the coast of Somalia, is a key feature of the South Asian monsoon (SAM) circulation. Previous work has emphasized the role of the East African highlands in strengthening and concentrating the jet. However, the fundamental dynamics of the jet remains debated, as does its relation to the SAM precipitation. In this study, numerical experiments with modified topography over Africa are conducted with the GFDL atmospheric model, version 2.1 (AM2.1), general circulation model (GCM) to examine the influence of topography on the Somali jet and the SAM precipitation. It is found that when the African topography is removed, the SAM precipitation moderately increases in spite of a weakening of the cross-equatorial Somali jet. The counterintuitive precipitation increase is related to lower-level cyclonic wind anomalies, and associated meridional moisture convergence, which develop over the Arabian Sea in the absence of the African topography. Potential vorticity (PV) budget analyses along particle trajectories show that this cyclonic anomaly primarily arises because, in the absence of the blocking effect by the African topography and with weaker cross-equatorial flow, air particles originate from higher latitudes with larger background planetary vorticity and thus larger PV.

scholarly journals Regional climate model experiments to investigate the Asian monsoon in the Late Miocene

2011 ◽  
Vol 7 (2) ◽  
pp. 841-886
Author(s):  
H. Tang ◽  
A. Micheels ◽  
J. Eronen ◽  
M. Fortelius
Keyword(s):  
Regional Climate Model ◽  
Summer Monsoon ◽  
Late Miocene ◽  
Asian Monsoon ◽  
Climate Model ◽  
Regional Climate ◽  
Regional Model ◽  
Global Model ◽  
Monsoon Climate ◽  
Northern Tibetan Plateau

Abstract. The Late Miocene (11.6–5.3 Ma) is a crucial period for the Asian monsoon evolution. However, the spatiotemporal changes of the Asian monsoon system in the Late Miocene are still ambiguous, and the mechanisms responsible for these changes are debated. Here, we present a simulation of the Asian monsoon climate (0 to 60° N and 50 to 140° E) in the Tortonian (11–7 Ma) using the regional climate model CCLM3.2. We employ relatively high spatial resolution (1° × 1°) and adapt the physical boundary conditions such as topography, land-sea distribution and vegetation in the regional model to represent the Late Miocene. As climatological forcing, the output of a Tortonian run with a fully-coupled atmosphere-ocean general circulation model is used. Our results show a stronger-than-present E-Asian winter monsoon wind in the Tortonian, as a result of the enhanced mid-latitude westerly wind of our global forcing and the lowered northern Tibetan Plateau in the regional model. The summer monsoon circulation is generally weakened in our regional Tortonian run compared to today. However, the changes of summer monsoon precipitation exhibit major regional differences. The precipitation decreases in N-China and N-India, but increases in S-China, the western coast and the southern tip of India. This can be attributed to the combined effect of both the regional topographical changes and the other forcings related to our global model. The spread of the dry summer conditions over N-China and NW-India further implies that the monsoonal climate may not be fully established over these regions in the Tortonain. Compared with the global model, the high resolution regional model highlights the spatial differences of the Asian monsoon climate in the Tortonian, and better characterizes the convective activity and its response to topographical changes. It therefore provides a useful and compared to global models complementary tool to improve our understanding of the Asian monsoon evolution in the Late Miocene.

scholarly journals The influence of vegetation on the ITCZ and South Asian Monsoon in HadCM3

2012 ◽  
Vol 3 (1) ◽  
pp. 91-111 ◽  
Author(s):  
M. P. McCarthy ◽  
J. Sanjay ◽  
B. B. B. Booth ◽  
K. Krishna Kumar ◽  
R. A. Betts
Keyword(s):  
Northern Hemisphere ◽  
South Asian ◽  
Vegetation Cover ◽  
Large Scale ◽  
Asian Monsoon ◽  
Global Dynamics ◽  
South Asian Monsoon ◽  
The South ◽  
Tropical Vegetation

Abstract. The role of extra-tropical vegetation on the large-scale tropical circulation is examined in the version 3 Hadley Centre Climate Model (HadCM3). Alternative representations of present day vegetation from observations and a dynamic vegetation model were used as the land-cover component for a number of HadCM3 experiments under a nominal present day climate state, and are shown to induce perturbations to the simulated global dynamics. This results in a shift in the location of the Inter Tropical Convergence Zone (ITCZ) and changes in the South Asian monsoon circulation. This has a significant impact on the Indian land precipitation compared to the standard configuration of HadCM3. This large-scale forcing is consistent with documented mechanisms relating to temperature and snow perturbations in the Northern Hemisphere extra-tropics. This analysis demonstrates that uncertainties in the representation of present day vegetation cover can result in significant perturbations to the simulated climate. The role of the Northern Hemisphere extra-tropics is further demonstrated with a fourth representation of vegetation cover produced by imposing simulated changes in Northern Hemisphere extra-tropical vegetation from the end of the 21st century on the present day climate. This experiment shows that through similar processes extra-tropical vegetation changes in the future contribute to a strengthening of the South Asian monsoon in this model, with a particular influence on the monsoon onset. These findings provide renewed motivation to give careful consideration to the role of global scale vegetation feedbacks when looking at climate change and its impact on the tropics and South Asian monsoon in the latest generation of Earth System models.

Late Cretaceous–Paleogene Indian monsoon climate vis-à-vis movement of the Indian plate, and the birth of the South Asian Monsoon

2021 ◽  
Vol 93 ◽  
pp. 89-100
Author(s):  
Harshita Bhatia ◽  
Mahasin Ali Khan ◽  
Gaurav Srivastava ◽  
Taposhi Hazra ◽  
R.A. Spicer ◽  
...  
Keyword(s):  
South Asian ◽  
Late Cretaceous ◽  
Asian Monsoon ◽  
Indian Monsoon ◽  
Indian Plate ◽  
South Asian Monsoon ◽  
Monsoon Climate ◽  
The South
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