Dominant Synoptic Disturbance in the Extreme Rainfall at Cherrapunji, Northeast India, Based on 104 Years of Rainfall Data (1902–2005)

Murata, Fumie; Terao, Toru; Fujinami, Hatsuki; Hayashi, Taiichi; Asada, Hiroshi; Matsumoto, Jun; Syiemlieh, Hiambok Jones

doi:10.1175/jcli-d-16-0435.1

Cited by 23 publications

(21 citation statements)

References 47 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Negative rainfall anomalies over the central part of India ( Fig. 1c, d) are shown to have apparent associations with Rossby wave response induced by convectively stable anomalies seen over the Bay of Bengal (Krishnan et al 2000), and also in part with westward propagating lowlevel circulation anomalies from the western North Pacific (Murata et al 2017). The circulation anomalies seen over East Asia (Fig.…”

Section: Circulation and Rainfall Diagnosis Duringmentioning

confidence: 84%

“…While a decrease in upper tropospheric divergence during ISM breaks due to suppressed monsoon convection over the Indian subcontinent can induce a downstream Rossby wave response towards East Asia (Krishnan et al 2009), it is not yet clear if the monsoonal heating anomalies can have any further consequences on large-scale circulation patterns. Murata et al (2017) noted that extreme rain periods over Cherrapunji, the wettest place on Earth located over the CEH, had associations with westward propagating low-level circulation anomalies from the western North Pacific. Their results further indicated that a large number of extreme rain periods over Cherrapunji were coincident with ISM breaks.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Meridionally Extending Anomalous Wave Train over Asia During Breaks in the Indian Summer Monsoon

et al. 2019

View full text Add to dashboard Cite

Anomalous interactions between the Indian summer monsoon (ISM) circulation and subtropical westerlies are known to trigger breaks in the ISM on subseasonal time-scales, characterised by a pattern of suppressed rainfall over central-north India, and enhanced rainfall over the foothills of the central–eastern Himalayas (CEH). An intriguing feature during ISM breaks is the formation of a mid-tropospheric cyclonic circulation anomaly extending over the subtropical and mid-latitude areas of the Asian continent. This study investigates the mechanism of the aforesaid Asian continental mid-tropospheric cyclonic circulation (ACMCC) anomaly using observations and simplified model experiments. The results of our study indicate that the ACMCC during ISM breaks is part of a larger meridional wave train comprising of alternating anticyclonic and cyclonic anomalies that extend poleward from the monsoon region to the Arctic. A lead–lag analysis of mid-tropospheric circulation anomalies suggests that the meridional wave-train generation is linked to latent heating (LH) anomalies over the CEH foothills, Indo-China, and the Indian landmass during ISM breaks. By conducting sensitivity experiments using a simplified global atmospheric general circulation model forced with satellite-derived three-dimensional LH, it is demonstrated that the combined effects of the enhanced LH over the CEH foothills and Indo-China and decreased LH over the Indian landmass during ISM breaks are pivotal for generating the poleward extending meridional wave train and the ACMCC anomaly. At the same time, the spatial extent of the mid-latitude cyclonic anomaly over Far-East Asia is also influenced by the anomalous LH over central–eastern China. While the present findings provide interesting insights into the role of LH anomalies during ISM breaks on the poleward extending meridional wave train, the ACMCC anomaly is found to have important ramifications on the daily rainfall extremes over the Indo-China region. It is revealed from the present analysis that the frequency of extreme rainfall occurrences over Indo-China shows a twofold increase during ISM break periods as compared to active ISM conditions.

show abstract

Section: Circulation and Rainfall Diagnosis Duringmentioning

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Meridionally Extending Anomalous Wave Train over Asia During Breaks in the Indian Summer Monsoon

et al. 2019

View full text Add to dashboard Cite

show abstract

“…The subtropical westerly jet stream and tropical easterly jet stream together show a southward shift during extreme rainfall days and the axis of this couplet recedes north to the earlier position after the extreme activity; this result is consistent with the findings of Murata et al . (). The core of the negative relative vorticity during high rainfall activity lies around 25 ° N, and before and after the event the core is shifted farther north to north of 30 ° N. In general, the spatial structure of the wind pattern and vorticity explain the favourable conditions for enhanced rainfall activity over the northeast regions.…”

Section: Resultsmentioning

confidence: 99%

On the extreme rainfall events during the southwest monsoon season in northeast regions of the Indian subcontinent

Varikoden

Revadekar

2019

Meteorological Applications

View full text Add to dashboard Cite

Hydrological disasters are recurrent over the northeast Indian region (NEI) due to heavy downpours within a short span of time. Therefore, the characteristics of rainfall extremes during the southwest monsoon over the NEI, their evolution and dissipation features, are discussed using rainfall data from the Tropical Rainfall Measuring Mission (TRMM) 3B42 V7 and the Climate Prediction Center for 16 years from 2000 to 2015. Circulation features during the lead–lag of extreme events are also examined using the National Center for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis products. Thirty‐two extreme events such that rainfall of the day exceeds the 90th percentile were identified. During the extreme events, heavy rainfall is located mainly in the NEI without much spread in the aerial domain. The highest number of extreme rain events is found in July, followed by June and August. Trend analysis of the rainfall indicates a significant decrease in low rainfall events and this decreasing trend is compensated by the significant increasing trend in very heavy (>95 percentile) to extremely heavy (>99 percentile) rainfall events. The average life of the extreme rainfall events is found to be about 3 days during which the NEI receives more than 100 mm/day; however, on individual examination, this ranges from 2 to 5 days. A strengthening of the southerly component of lower level wind from the Bay of Bengal and an updraft due to convergence at 850 hPa over the region favours the rainfall peak. The sea level pressure anomaly gradient and vertical velocity show a sudden development of conditions favourable for a heavy downpour over the northeast region.

show abstract

“…In addition, intraseasonal variation (about 2~4 weeks) was found, with depletion occurring in mid-May, mid-June, early and late August, and early October. Fujinami et al (2011) and Murata et al (2017) showed that the intraseasonal variation of precipitation was dominant around Cherapunji in the northeastern part of India. These results indicate that the δ 18 O value of precipitation over Bangladesh can be controlled by seasonal and intraseasonal variations (e.g., the ISM and monsoon low-pressure system).…”

Section: Seasonal Variation In the Amount And Isotopic Composition Ofmentioning

confidence: 99%

Seasonal variation in isotopic composition and the origin of precipitation over Bangladesh

Tanoue

Ichiyanagi

Yoshimura

et al. 2018

Prog Earth Planet Sci

Self Cite

View full text Add to dashboard Cite

Water isotopic composition (δ 18 O and δD) in terrestrial proxies of past precipitation enable us to better understand and interpret variation in the Indian Summer Monsoon (ISM). Previous studies have suggested that the origin of precipitation is an important factor controlling the isotopic composition of precipitation around the Indian subcontinent; however, it is difficult to quantify using the Lagrangian approach because the approach does not satisfy the assumption of an adiabatic process over a convective area. We investigated the isotopic composition of precipitation at three sites over Bangladesh in 2010 and estimated the origins of precipitation by the Eulerian approach using an isotope-incorporating Atmospheric General Circulation Model. Our observations showed similar seasonal and intraseasonal variations in the δ 18 O values of precipitation among the sites, whereas the temporal characteristics of the precipitation amount differed among the sites. The isotopic composition was linked to the migration of organized convective activity around the region. The model showed that the pre-monsoon season (from mid-March to early June) was characterized by high δ 18 O values of precipitation originating from the Bay of Bengal and the Arabian Sea. In the ISM season (from mid-June to early October), the contribution of these sources to precipitation gradually decreased, while the contribution from the Indian Ocean increased, resulting in decreasing δ 18 O values of precipitation due to the enhanced rainout process during the transportation. These moisture contributed less to precipitation over Bangladesh in the post-monsoon season (from mid-October to November), whereas moisture originating from the Pacific Ocean and land surface (i.e., recycling of water) contributed to precipitation in the season. Because the recycling of water originated from past precipitation with low δ 18 O values in the ISM season, its contribution to precipitation reduced the δ 18 O values of precipitation in the ISM and post-monsoon seasons. These results suggest that the origins of precipitation and the migration of organized convective activity are the dominant factors controlling the isotopic composition of precipitation in the region. These characteristics can be used to identify monsoon onset and withdrawal based on water isotopic composition.

show abstract

Dominant Synoptic Disturbance in the Extreme Rainfall at Cherrapunji, Northeast India, Based on 104 Years of Rainfall Data (1902–2005)

Cited by 23 publications

References 47 publications

Meridionally Extending Anomalous Wave Train over Asia During Breaks in the Indian Summer Monsoon

Meridionally Extending Anomalous Wave Train over Asia During Breaks in the Indian Summer Monsoon

On the extreme rainfall events during the southwest monsoon season in northeast regions of the Indian subcontinent

Seasonal variation in isotopic composition and the origin of precipitation over Bangladesh

Contact Info

Product

Resources

About