The fidelity of a regional coupled model in capturing the relationship between intraseasonal variability and the onset/demise of the Indian summer monsoon

2020 ◽  
Vol 54 (11-12) ◽  
pp. 4693-4710
Author(s):  
Nirupam Karmakar ◽  
Vasubandhu Misra
Keyword(s):  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Intraseasonal Variability ◽  
Coupled Model ◽  
The Relationship ◽  
Regional Coupled Model

scholarly journals Study of the Indian summer monsoon using WRF-ROMS regional coupled model simulations

2013 ◽  
Vol 14 (1) ◽  
pp. 20-27 ◽  
Author(s):  
Basanta Kumar Samala ◽  
Nagaraju C ◽  
Sudipta Banerjee ◽  
Akshara Kaginalkar ◽  
Mohit Dalvi
Keyword(s):  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Coupled Model ◽  
Model Simulations ◽  
Regional Coupled Model

scholarly journals Barotropic Energy Conversion During Indian Summer Monsoon: Implication of Central Indian Ocean Mode Simulation in CMIP6

2021 ◽  
Author(s):  
Jianhuang Qin ◽  
Lei Zhou ◽  
Ze Meng ◽  
Baosheng Li ◽  
Tao Lian ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Kinetic Energy ◽  
Energy Conversion ◽  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Climate Models ◽  
Intraseasonal Variability ◽  
Coupled Model ◽  
Tropical Indian Ocean ◽  
Central Indian Ocean

Abstract The simulation and prediction of the Indian summer monsoon (ISM) and its intraseasonal component in climate models remain a grand scientific challenge for models. Recently, an intraseasonal mode was proposed over the tropical Indian Ocean, named central Indian Ocean (CIO) mode. The CIO mode index and with monsoon intraseasonal oscillations (MISO) have a high correlation. In this study, the simulations of the CIO mode in the sixth phase of the Coupled Model Intercomparison Project (CMIP6) models are examined. Although the coupled ocean-atmosphere feedbacks associated with the CIO mode are not fully reproduced, the results show that a better depiction of the CIO mode in CMIP6 models is favorable for a better simulation of northward-propagating MISO and heavy rainfall during the ISM. Dynamic diagnostics unveil that the rendition of the CIO mode is dominated by kinetic energy conversion from the background to the intraseasonal variability. Furthermore, kinetic energy conversion is controlled by the meridional shear of background zonal winds (\(\frac{\partial \stackrel{-}{u}}{\partial y}\)), which is underestimated in most CMIP6 models, leading to a weak barotropic instability. As a result, a better simulation of \(\frac{\partial \stackrel{-}{u}}{\partial y}\) is required for improving the CIO mode simulation in climate models, which helps to improve the simulation and prediction skill of northward-propagating MISO and monsoonal precipitation.

scholarly journals Oceanic factors controlling the Indian summer monsoon onset in a coupled model

2014 ◽  
Vol 44 (3-4) ◽  
pp. 977-1002 ◽  
Author(s):  
Chloé Prodhomme ◽  
Pascal Terray ◽  
Sébastien Masson ◽  
Ghyslaine Boschat ◽  
Takeshi Izumo
Keyword(s):  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Coupled Model ◽  
Monsoon Onset ◽  
Summer Monsoon Onset

Intraseasonal Teleconnection between the Summer Eurasian Wave Train and the Indian Monsoon*

2007 ◽  
Vol 20 (15) ◽  
pp. 3751-3767 ◽  
Author(s):  
Qinghua Ding ◽  
Bin Wang
Keyword(s):  
High Pressure ◽  
Central Asia ◽  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Wave Train ◽  
Intraseasonal Variability ◽  
The Other ◽  
Vertical Shear ◽  
Central Asian ◽  
Northeastern Atlantic

Abstract This study investigated the most recurrent coupled pattern of intraseasonal variability between midlatitude circulation and the Indian summer monsoon (ISM). The leading singular vector decomposition (SVD) pattern reveals a significant, coupled intraseasonal variation between a Rossby wave train across the Eurasian continent and the summer monsoon convection in northwestern India and Pakistan (hereafter referred to as NISM). The wave train associated with an active phase of NISM rainfall displays two high pressure anomalies, one located over central Asia and the other over northeastern Asia. They are accompanied by increased rainfall over the western Siberia plain and northern China and decreased rainfall over the eastern Mediterranean Sea and southern Japan. The circulation of the wave train shows a barotropic structure everywhere except the anomalous central Asian high, located to the northwest of India, where a heat-induced baroclinic circulation structure dominates. The time-lagged SVD analysis shows that the midlatitude wave train originates from the northeastern Atlantic and traverses Europe to central Asia. The wave train enhances the upper-level high pressure and reinforces the convection over the NISM region; meanwhile, it propagates farther toward East Asia along the waveguide provided by the westerly jet. After an outbreak of NISM convection, the anomalous central Asian high retreats westward. Composite analysis suggests a coupling between the central Asian high and the convective fluctuation in the NISM. The significance of the midlatitude–ISM interaction is also revealed by the close resemblance between the individual empirical orthogonal functions and the coupled (SVD) modes of the midlatitude circulation and the ISM. It is hypothesized that the eastward and southward propagation of the wave train originating from the northeastern Atlantic contributes to the intraseasonal variability in the NISM by changing the intensity of the monsoonal easterly vertical shear and its associated moist dynamic instability. On the other hand, the rainfall variations over the NISM reinforce the variations of the central Asian high through the “monsoon–desert” mechanism, thus reenergizing the downstream propagation of the wave train. The coupling between the Eurasian wave train and NISM may be instrumental for understanding their interaction and can provide a way to predict the intraseasonal variations of the Indian summer monsoon and East Asian summer monsoon.

scholarly journals Irrigation-Induced Land–Atmosphere Feedbacks and Their Impacts on Indian Summer Monsoon

2018 ◽  
Vol 31 (21) ◽  
pp. 8785-8801 ◽  
Author(s):  
Chihchung Chou ◽  
Dongryeol Ryu ◽  
Min-Hui Lo ◽  
Hao-Wei Wey ◽  
Hector M. Malano
Keyword(s):  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Land Surface ◽  
Large Scale ◽  
Coupled Model ◽  
North India ◽  
Shortwave Radiation ◽  
Surface Cooling ◽  
Limited Region ◽  
Feedback Mechanisms

From the 1980s, Indian summer monsoon rainfall (ISMR) shows a decreasing trend over north and northwest India, and there was a significant observed reduction in July over central and south India in 1982–2003. The key drivers of the changed ISMR, however, remain unclear. It was hypothesized that the large-scale irrigation development that started in the 1950s has resulted in land surface cooling, which slowed large-scale atmospheric circulation, exerting significant influences on ISMR. To test this hypothesis, a fully coupled model, the CESM v1.0.3, was used with a global irrigation dataset. In this study, spatially varying irrigation-induced feedback mechanisms are investigated in detail at different stages of the monsoon. Results show that soil moisture and evapotranspiration increase significantly over India throughout the summertime because of the irrigation. However, 2-m air temperature shows a significant reduction only in a limited region because the temperature change is influenced simultaneously by surface incoming shortwave radiation and evaporative cooling resulting from the irrigation, especially over the heavily irrigated region. Irrigation also induces a 925-hPa northeasterly wind from 30°N toward the equator. This is opposite to the prevailing direction of the Indian summer monsoon (ISM) wind that brings moist air to India. The modeled rainfall in the irrigated case significantly decreases up to 1.5 mm day−1 over central and north India from July to September. This paper reveals that the irrigation can contribute to both increasing and decreasing the surface temperature via multiple feedback mechanisms. The net effect is to weaken the ISM with the high spatial and temporal heterogeneity.

On the relationship between Indian summer monsoon withdrawal and Indo-Pacific SST anomalies before and after 1976/1977 climate shift

2011 ◽  
Vol 39 (3-4) ◽  
pp. 841-859 ◽  
Author(s):  
C. T. Sabeerali ◽  
Suryachandra A. Rao ◽  
R. S. Ajayamohan ◽  
Raghu Murtugudde
Keyword(s):  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Climate Shift ◽  
Before And After ◽  
The Relationship ◽  
Sst Anomalies

scholarly journals Role of the Indian Ocean in the Biennial Transition of the Indian Summer Monsoon

2007 ◽  
Vol 20 (10) ◽  
pp. 2147-2164 ◽  
Author(s):  
Renguang Wu ◽  
Ben P. Kirtman
Keyword(s):  
Indian Ocean ◽  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Indian Monsoon ◽  
Coupled Model ◽  
The Pacific ◽  
The Indian Ocean ◽  
Biennial Variability ◽  
Sst Anomalies

Abstract The biennial variability is a large component of year-to-year variations in the Indian summer monsoon (ISM). Previous studies have shown that El Niño–Southern Oscillation (ENSO) plays an important role in the biennial variability of the ISM. The present study investigates the role of the Indian Ocean in the biennial transition of the ISM when the Pacific ENSO is absent. The influence of the Indian and Pacific Oceans on the biennial transition between the ISM and the Australian summer monsoon (ASM) is also examined. Controlled numerical experiments with a coupled general circulation model (CGCM) are used to address the above two issues. The CGCM captures the in-phase ISM to ASM transition (i.e., a wet ISM followed by a wet ASM or a dry ISM followed by a dry ASM) and the out-of-phase ASM to ISM transition (i.e., a wet ASM followed by a dry ISM or a dry ASM followed by a wet ISM). These transitions are more frequent than the out-of-phase ISM to ASM transition and the in-phase ASM to ISM transition in the coupled model, consistent with observations. The results of controlled coupled model experiments indicate that both the Indian and Pacific Ocean air–sea coupling are important for properly simulating the biennial transition between the ISM and ASM in the CGCM. The biennial transition of the ISM can occur through local air–sea interactions in the north Indian Ocean when the Pacific ENSO is suppressed. The local sea surface temperature (SST) anomalies induce the Indian monsoon transition through low-level moisture convergence. Surface evaporation anomalies, which are largely controlled by surface wind speed changes, play an important role for SST changes. Different from local air–sea interaction mechanisms proposed in previous studies, the atmospheric feedback is not strong enough to reverse the SST anomalies immediately at the end of the monsoon season. Instead, the reversal of the SST anomalies is accomplished in the spring of the following year, which in turn leads to the Indian monsoon transition.

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