scholarly journals Indian Monsoon Low-Pressure Systems Feed Up-and-Over Moisture Transport to the Southwestern Tibetan Plateau

2017 ◽  
Vol 122 (22) ◽  
pp. 12,140-12,151 ◽  
Author(s):  
Wenhao Dong ◽  
Yanluan Lin ◽  
Jonathon S. Wright ◽  
Yuanyu Xie ◽  
Fanghua Xu ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Moisture Transport ◽  
Indian Monsoon ◽  
Low Pressure ◽  
Low Pressure Systems

Simulation of Monsoon trough and low pressure systems in CMIP6 models

2020 ◽  
Author(s):  
Praveen Veluthedathekuzhiyil ◽  
Ajayamohan Ravindran ◽  
Sabeerali Cherumadanakadan Thelliyil
Keyword(s):  
Climate Models ◽  
Monsoon Rainfall ◽  
Indian Monsoon ◽  
Low Pressure ◽  
Monsoon Trough ◽  
Warming Scenario ◽  
Wide Range ◽  
Future Warming ◽  
Dynamical Features ◽  
Low Pressure Systems

<p>Monsoon low pressure systems (LPS) contributes to more than half of the Indian monsoon rainfall. However most climate models fail to capture the characteristics of low pressure systems realistically. This aspect is scrutinized in a wide range of available CMIP6 model simulations using an objective LPS tracking algorithm. Broader features such as monsoon trough over which these systems forms are also analyzed. It has been found that, majority of the models fail to realistically represent these two important features. However few models that were able to capture these events in CMIP5 are able to simulate them in CMIP6 as well. We examine the dynamical features that lead to realistic simulation of LPS in these set of models. Selected good models are then used to study the characteristics of LPS in a future warming scenario. This study will help in judging the performance of models and for any future improvements.</p>

The structure of Indian monsoon low-pressure systems in the subseasonal-to-seasonal prediction models

2021 ◽  
Author(s):  
Akshay Deoras ◽  
Kieran M. R. Hunt ◽  
Andrew G. Turner
Keyword(s):  
Prediction Models ◽  
Indian Monsoon ◽  
Lower Troposphere ◽  
Seasonal Prediction ◽  
Low Pressure ◽  
Japan Meteorological Agency ◽  
Positive Temperature ◽  
Strong Positive Correlation ◽  
Cold Core ◽  
Low Pressure Systems

<p>Indian monsoon low-pressure systems (LPSs) are synoptic-scale cyclonic vortices that produce around half of the summer monsoon rainfall over India, and often cause catastrophic floods. Thus, accurate predictions of LPSs are crucial for disaster management and long-term planning. To improve the skill of LPS forecasts, it is important to understand how seasonal forecast models simulate the structure and behaviour of these weather systems. Here we examine in detail the simulation of the structure of LPSs by eleven models of the Subseasonal-to-Seasonal (S2S) prediction project. We use a feature-tracking algorithm to identify LPSs in all S2S models during a common re-forecast period of June–September 1999­­–2010. We then generate composite horizontal and vertical structures and compare them with those of LPSs in ERA-Interim reanalysis. <br><br>The results suggest that LPSs have the weakest intensity as well as precipitation in the Bureau of Meteorology (BoM), Australia, Hydrometeorological Centre of Russia (HMCR) and Japan Meteorological Agency models. Most S2S models simulate the warm-over-cold core structure that is commonly observed in LPSs, except for the BoM and HMCR models, which simulate weak positive temperature anomalies near the LPS centre in the lower troposphere. The vertical structure of relative vorticity is shallower and weaker in all S2S models than in ERA-Interim. In most S2S models, LPS composites feature a drier middle and upper troposphere than in ERA-Interim. There is a strong positive correlation between precipitation and the 925 hPa temperature anomaly in most S2S models and ERA-Interim supporting the hypothesis that evaporative cooling from precipitation and reduced insolation due to significant cloud cover are responsible for the lower-tropospheric cold core.</p>

Characteristics of Low Pressure Systems Associated with Intraseasonal Oscillation of Rainfall over Bangladesh during Boreal Summer

2014 ◽  
Vol 142 (12) ◽  
pp. 4758-4774 ◽  
Author(s):  
Daisuke Hatsuzuka ◽  
Tetsuzo Yasunari ◽  
Hatsuki Fujinami
Keyword(s):  
Indian Monsoon ◽  
Intraseasonal Oscillation ◽  
Low Pressure ◽  
Boreal Summer ◽  
Horizontal Scale ◽  
The North ◽  
Vertical Scale ◽  
Active Peak ◽  
The Ganges ◽  
Low Pressure Systems

Abstract Characteristics of low pressure systems (LPSs) responsible for submonthly-scale (7–25 days) intraseasonal oscillation (ISO) in rainfall over Bangladesh and their impact on the amplitude of active peaks are investigated for 29 summer monsoon seasons. Extreme and moderate active peaks are obtained based on the amplitude of 7–25-day-filtered rainfall series. By detecting the LPSs that formed over the Indian monsoon region, it was found that about 59% (62%) of extreme (moderate) active peaks of rainfall are related to LPSs. These LPSs have horizontal scale of about 600 km and vertical scale of about 9 km. For the extreme active peak, the locations of the LPS centers are clustered significantly over and around Bangladesh, accompanied by the maximum convergence in the southeast sector of the LPSs. After their formation, they tend to remain almost stationary over and around Bangladesh. In contrast, for the moderate active peak, the LPS centers are located over the Ganges Plain around 85°E, and the maximum convergence of the LPSs occurs around their centers. This difference in the convergence fields is closely associated with the geographical features to the north and east of Bangladesh and the horizontal scale of the LPSs. These features suggest that the amplitude of the active peaks in the submonthly-scale ISO is modulated by small differences in the locations of the LPS centers. These findings suggest that improved predictions of both genesis location and the tracks of the LPSs are crucial to forecasting seasonal rainfall over Bangladesh.

scholarly journals Comparison of the prediction of Indian monsoon low-pressure systems by Subseasonal-to-Seasonal prediction models

2021 ◽  
Author(s):  
AKSHAY DEORAS ◽  
KIERAN M. R. HUNT ◽  
ANDREW G. TURNER
Keyword(s):  
Disaster Preparedness ◽  
Prediction Models ◽  
Indian Monsoon ◽  
Seasonal Prediction ◽  
Low Pressure ◽  
China Meteorological Administration ◽  
Weather Forecasts ◽  
Forecast Lead Time ◽  
Resources Planning ◽  
Low Pressure Systems

AbstractThis study analyses the prediction of Indian monsoon low-pressure systems (LPSs) on an extended time scale of 15 days by models of the Subseasonal-to-Seasonal (S2S) prediction project. Using a feature-tracking algorithm, LPSs are identified in the eleven S2S models during a common re-forecast period of June September 1999-2010, and then compared with 290 and 281 LPSs tracked in ERA-Interim and MERRA-2 reanalysis datasets. The results show that all S2S models under-simulate the frequency of LPSs. They are able to represent transits, genesis and lysis of LPSs; however, large biases are observed in the AustralianBureau of Meteorology, China Meteorological Administration (CMA) and Hydrometeorological Centre of Russia (HMCR) models. The CMA model exhibits large LPS track position error and the intensity of LPSs is overestimated (underestimated) by most models when verified against ERA-Interim (MERRA-2). The European Centre for Medium-Range Weather Forecasts and UK Met Office models have the best ensemble spread-error relationship for the track position and intensity, whereas the HMCR model has the worst. Most S2S models are underdispersive - more so for the intensity than the position. We find the influence of errors in the LPS simulation on the pattern of total precipitation biases in all S2S models. In most models, precipitation biases increase with forecast lead time over most of the monsoon core zone. These results demonstrate the potential for S2S models at simulating LPSs, thereby giving the possibility of improved disaster preparedness and water resources planning.

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