On the anomalous precipitation enhancement over the Himalayan foothills during monsoon breaks

Vellore, Ramesh; Krishnan, R.; Pendharkar, Jayant; Ayantika, D. C.; Sabin, T. P.

doi:10.1007/s00382-013-2024-1

Cited by 67 publications

(70 citation statements)

References 54 publications

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“…In addition, physical mechanism responsible for enhancement of monsoon precipitation and extremes towards the central and eastern region of foothills of Himalayan region are normally associated with break/active monsoon condition in mainland India/Himalayan foothills (north ward migration of monsoon trough towards foothills of Himalaya from its normal position) during which interaction of southward migration of extratropical westerly troughs (dry air subsidence in Indian subcontinent at mid-to-upper troposphere) and weak monsoon circulation takes place [107]. The detail analysis of changing pattern of break monsoon situation and other physical mechanism responsible for changing extreme precipitation pattern over the whole monsoon season for Nepal is still lacking and it could be far from simple as the complex interaction of global, synoptic scale weather systems and topography takes place in the monsoon dominated region producing localized extreme precipitation.…”

Section: High-intensity-related Precipitation Extremesmentioning

confidence: 99%

Rising Precipitation Extremes across Nepal

Karki

Hasson

Schickhoff

et al. 2017

Climate

208

140

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Abstract:As a mountainous country, Nepal is most susceptible to precipitation extremes and related hazards, including severe floods, landslides and droughts that cause huge losses of life and property, impact the Himalayan environment, and hinder the socioeconomic development of the country. Given that the countrywide assessment of such extremes is still lacking, we present a comprehensive picture of prevailing precipitation extremes observed across Nepal. First, we present the spatial distribution of daily extreme precipitation indices as defined by the Expert Team on Climate Change Detection, Monitoring and Indices (ETCCDMI) from 210 stations over the period of . Then, we analyze the temporal changes in the computed extremes from 76 stations, featuring long-term continuous records for the period of 1970-2012, by applying a non-parametric Mann−Kendall test to identify the existence of a trend and Sen's slope method to calculate the true magnitude of this trend. Further, the local trends in precipitation extremes have been tested for their field significance over the distinct physio-geographical regions of Nepal, such as the lowlands, middle mountains and hills and high mountains in the west (WL, WM and WH, respectively), and likewise, in central (CL, CM and CH) and eastern (EL, EM and EH) Nepal. Our results suggest that the spatial patterns of high-intensity precipitation extremes are quite different to that of annual or monsoonal precipitation. Lowlands (Terai and Siwaliks) that feature relatively low precipitation and less wet days (rainy days) are exposed to high-intensity precipitation extremes. Our trend analysis suggests that the pre-monsoonal precipitation is significantly increasing over the lowlands and CH, while monsoonal precipitation is increasing in WM and CH and decreasing in CM, CL and EL. On the other hand, post-monsoonal precipitation is significantly decreasing across all of Nepal while winter precipitation is decreasing only over the WM region. Both high-intensity precipitation extremes and annual precipitation trends feature east−west contrast, suggesting significant increase over the WM and CH region but decrease over the EM and CM regions. Further, a significant positive trend in the number of consecutive dry days but significant negative trend in the number of wet (rainy) days are observed over the whole of Nepal, implying the prolongation of the dry spell across the country. Overall, the intensification of different precipitation indices over distinct parts of the country indicates region-specific risks of floods, landslides and droughts. The presented findings, in combination with population and environmental pressures, can support in devising the adequate region-specific adaptation strategies for different sectors and in improving the livelihood of the rural communities in Nepal.

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Section: High-intensity-related Precipitation Extremesmentioning

confidence: 99%

Rising Precipitation Extremes across Nepal

Karki

Hasson

Schickhoff

et al. 2017

Climate

208

140

View full text Add to dashboard Cite

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“…The greatest similarities in the response patterns of Figures and are outside of High Asia in the lowlands to the southwest. Although not the focus of our study, the last point reminds us that responses to large‐scale circulation variability can differ dramatically between the lowlands and the high‐altitude landscapes of High Asia (e.g., Vellore et al, ).…”

Section: A Note On the Forcings Of Westerly And Ism Influencesmentioning

confidence: 99%

Prominent Midlatitude Circulation Signature in High Asia's Surface Climate During Monsoon

et al. 2017

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High Asia has experienced strong environmental changes in recent decades, as evident in records of glaciers, lakes, tree rings, and vegetation. The multiscale understanding of the climatic drivers, however, is still incomplete. In particular, few systematic assessments have evaluated to what degree, if at all, the midlatitude westerly circulation modifies local surface climates in the reach of the Indian Summer Monsoon. This paper shows that a southward shift of the upper‐tropospheric westerlies contributes significantly to climate variability in the core monsoon season (July–September) by two prominent dipole patterns at the surface: cooling in the west of High Asia contrasts with warming in the east, while moist anomalies in the east and northwest occur with drying along the southwestern margins. Circulation anomalies help to understand the dipoles and coincide with shifts in both the westerly wave train and the South Asian High, which imprint on air mass advection and local energy budgets. The relation of the variabilities to a well‐established index of midlatitude climate dynamics allows future research on climate proxies to include a fresh hypothesis for the interpretation of environmental changes.

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“…Intense rainfall events can lead to flash floods, often resulting in infrastructure damage, considerable impact on natural ecosystems and even human casualties. Over the Asian domain, the largest socioeconomic losses are linked to floods attributed to these extreme rainfall events (Roxy et al 2017;Vellore et al 2014Vellore et al , 2016Goswami et al 2006;Krishnan et al 2015;Pai and Sridhar 2015;Rajeevan et al 2008). Understanding and quantifying their magnitude for the present and how they may change in the future is of immense importance to the society.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of precipitation extremes over the Asian domain: observation and modelling studies

et al. 2018

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In this study, a comparison in the precipitation extremes as exhibited by the seven reference datasets is made to ascertain whether the inferences based on these datasets agree or they differ. These seven datasets, roughly grouped in three categories i.e. rain-gauge based (APHRODITE, CPC-UNI), satellite-based (TRMM, GPCP1DD) and reanalysis based (ERA-Interim, MERRA, and JRA55), having a common data period 1998-2007 are considered. Focus is to examine precipitation extremes in the summer monsoon rainfall over South Asia, East Asia and Southeast Asia. Measures of extreme precipitation include the percentile thresholds, frequency of extreme precipitation events and other quantities. Results reveal that the differences in displaying extremes among the datasets are small over South Asia and East Asia but large differences among the datasets are displayed over the Southeast Asian region including the maritime continent. Furthermore, precipitation data appear to be more consistent over East Asia among the seven datasets. Decadal trends in extreme precipitation are consistent with known results over South and East Asia. No trends in extreme precipitation events are exhibited over Southeast Asia. Outputs of the Coupled Model Intercomparison Project Phase 5 (CMIP5) simulation data are categorized as high, medium and lowresolution models. The regions displaying maximum intensity of extreme precipitation appear to be dependent on model resolution. High-resolution models simulate maximum intensity of extreme precipitation over the Indian sub-continent, medium-resolution models over northeast India and South China and the low-resolution models over Bangladesh, Myanmar and Thailand. In summary, there are differences in displaying extreme precipitation statistics among the seven datasets considered here and among the 29 CMIP5 model data outputs.

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On the anomalous precipitation enhancement over the Himalayan foothills during monsoon breaks

Cited by 67 publications

References 54 publications

Rising Precipitation Extremes across Nepal

Rising Precipitation Extremes across Nepal

Prominent Midlatitude Circulation Signature in High Asia's Surface Climate During Monsoon

Evaluation of precipitation extremes over the Asian domain: observation and modelling studies

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