Composite characteristics of Nor'westers based on observations and simulations

Das, Someshwar; Sarkar, Abhijit; Das, Mohan Kumar; Rahman, Md. Mizanur; Islam, Md. Nazrul

doi:10.1016/j.atmosres.2015.02.009

Cited by 35 publications

(26 citation statements)

References 49 publications

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“…The eastern and northeastern parts of India, Bangladesh, Bhutan, and Nepal are affected by severe thunderstorms during the premonsoon months (March-May). There are as many as 30-40 days of thunderstorms in parts of northeast India during this season (STORM 2005;Tyagi 2007;Das 2010;Yamane et al 2009a,b). Severe thunder clouds (cumulonimbus) are often arranged in long lines of 200-400 km in length and travel with speeds of about 50-60 km h -1 (Das et al 2009b).…”

Section: Severe Convective Storms Of South Asiamentioning

confidence: 97%

“…There are as many as 30-40 days of thunderstorms in parts of northeast India during this season (STORM 2005;Tyagi 2007;Das 2010;Yamane et al 2009a,b). Severe thunder clouds (cumulonimbus) are often arranged in long lines of 200-400 km in length and travel with speeds of about 50-60 km h -1 (Das et al 2009b). Figure 4a shows a typical nor'wester (squall line) observed by the DWR of Kolkata (22.57°N,88.37°E).…”

Section: Severe Convective Storms Of South Asiamentioning

confidence: 97%

“…Further, the diurnal variation shows their occurrences mostly in the late evening. In Sri Lanka, the highest frequencies of thunderstorms occur during the two intermonsoons from March to April and from October to November (Das 2010). The potential for thunderstorms is higher over the western d)…”

Section: Severe Convective Storms Of South Asiamentioning

confidence: 97%

“…Four pilot field experiments have been conducted so far during 1-31 May of 2009-12 jointly with the four countries to collect intensive observations of nor'westers in a coordinated way (Das et al 2009a(Das et al , 2011. Considering that the thunderstorms occur at a spatial scale ranging from a few kilometers to a few hundred kilometers, it was decided that a mesonet of automatic weather stations (AWS) would be set up over Bangladesh, Nepal, and Bhutan in a similar way as was done over West Bengal and the northeastern parts of India (Fig.…”

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confidence: 99%

See 3 more Smart Citations

The SAARC STORM: A Coordinated Field Experiment on Severe Thunderstorm Observations and Regional Modeling over the South Asian Region

Das

Mohanty

Tyagi

et al. 2014

Bull. Amer. Meteor. Soc.

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Section: Severe Convective Storms Of South Asiamentioning

confidence: 97%

Section: Severe Convective Storms Of South Asiamentioning

confidence: 97%

Section: Severe Convective Storms Of South Asiamentioning

confidence: 97%

mentioning

confidence: 99%

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The SAARC STORM: A Coordinated Field Experiment on Severe Thunderstorm Observations and Regional Modeling over the South Asian Region

Das

Mohanty

Tyagi

et al. 2014

Bull. Amer. Meteor. Soc.

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“…However, some works have been done regarding synoptic situation and composite characteristics of severe thunderstorms including tornadoes during pre-monsoon season over Bangladesh using FSU, MM5 and WRF model by Prasad 2006;Basnayake et al 2010;Islam 2007, 2009;Ahasan et al 2010;Das 2009Das , 2010 and SAARC-STORM 2013 etc. The above studies have been carried out based on the model simulation using FNL initial and lateral boundary condition data.…”

Section: Introductionmentioning

confidence: 97%

Impact of data assimilation in simulation of thunderstorm (squall line) event over Bangladesh using WRF model, during SAARC–STORM Pilot Field Experiment 2011

Ahasan

Debsarma

2014

Nat Hazards

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A widespread thunderstorm (squall line or multicell line) occurred over Bangladesh on 11 May 2011 during 0300 UTC to 1300 UTC. A north-south oriented wellestablished squall line of 400 km length was noticed to the center of Bangladesh at 0530 UTC and the vertical extend of this system was about 16-18 km. An attempt has been made to study the impact of data assimilation in simulation of the selected thunderstorm event of 11 May 2011 using Weather Research and Forecasting (WRF) model. The WRF model was run in STORM Phase-I domain at 9 km horizontal resolution using six hourly NCEP-FNL datasets from 0000 UTC of 11 May to 0000 UTC of 12 May 2011 as initial and boundary condition for control (CNTL) run. The 0300 UTC Synop, 0000 UTC Temp and 0300 UTC Khepupara DWR reflectivity and redial velocity of 11 May 2011 were assimilated in 3DVar with the first guess of WRF model for data assimilation (DA) run. Model outputs have been analyzed for CNTL and DA to compare and/or asses the model performance. It is found that the DA enhanced in the synoptic and environmental characteristics as compared to that of CNTL. The WRF model outputs with DA help to investigate the synoptic and environmental characteristics responsible for the occurring of this unusual event. The model products showed a cyclonic circulation over Gangetic West Bengal of India at 925 hPa and over Assam and adjoining areas of India at 500 hPa. Strong upward motion was noticed over Bangladesh. Significant moisture incursion was observed over center and southeast parts of Bangladesh at 925 and 850 hPa with southerly/southwesterly flow of 10-20 ms -1 (19-39 knots). Result showed that the WRF model with DA could capture thunderstorm event of 11 May 2011 in reasonably well though there are some spatial and temporal biases in the results.

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Orographic effects on droughts in a monsoon climate with the world's highest rainfall

Prokop,

Walanus

2024

Intl Journal of Climatology

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Drought, a recurring natural phenomenon in South Asia's monsoon climate, presents challenges in delineating its spatiotemporal patterns within complex topographies. This study investigated the impact of the orographic barrier in the rice‐dominated agricultural region of northeastern India and Bangladesh on drought characteristics during 1951–2020, employing the relative Standardized Precipitation Index (rSPI) and relative Standardized Precipitation‐Evapotranspiration Index (rSPEI) across 3‐, 6‐ and 12‐month scales. The results indicate that even in the rainiest region of the world, droughts extend beyond the limits of the dry season inherent in the monsoon regime. These mostly regional droughts exhibit weak correlations with the core of the Indian subcontinent and other parts of Bangladesh. The region's orographic barrier has a greater influence on drought intensity than on frequency. The rSPI index, which depends solely on rainfall, may overestimate drought intensity and frequency in regions with high seasonal/annual rainfall and substantial intermonthly variability. In contrast, the rSPEI index, which depends on both rainfall and potential evapotranspiration (PET), better reflects the spatial variation of drought in complex terrain, identifying the leeward hinterland of the orographic barrier as the most drought‐prone area. The two indices give similar results for drought characteristics away from the barrier. Furthermore, the orographic barrier exerts a negligible influence on the trends in rSPI and rSPEI. Principal component analysis (PCA) highlights the influences of the rainfall coefficient of variation and elevation on rSPI, while the PET coefficient of variation strongly influences rSPEI. Strategies to minimize the adverse effects of drought in complex topography and year‐round cropping should be local and season‐specific. These include using shorter‐growing, drought‐resistant rice varieties and adjusting planting schedules in rain shadow areas during the summer monsoon. These efforts should be complemented by integrating indigenous irrigation methods with modern practices such as roof water harvesting and tube wells in winter.

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Composite characteristics of Nor'westers based on observations and simulations

Cited by 35 publications

References 49 publications

The SAARC STORM: A Coordinated Field Experiment on Severe Thunderstorm Observations and Regional Modeling over the South Asian Region

The SAARC STORM: A Coordinated Field Experiment on Severe Thunderstorm Observations and Regional Modeling over the South Asian Region

Impact of data assimilation in simulation of thunderstorm (squall line) event over Bangladesh using WRF model, during SAARC–STORM Pilot Field Experiment 2011

Orographic effects on droughts in a monsoon climate with the world's highest rainfall

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