Delving into Recent Changes in Precipitation Patterns in the Western Himalayas under Global Warming (original) (raw)
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Theoretical and Applied Climatology, 2020
Events like melting glaciers, rising sea level, and changing weather patterns are being observed across the globe due to widely reported global warming. The monsoon season rainfall in the NorthWestern Himalayan region (NWH) becomes more uncertain as there is considerable variation between the duration of the monsoon season and the amount of rainfall during the season. The NWH region receives substantial amount of rainfall and witness various disasters during the monsoon season. In this context, the present study deals with the analysis of the rainfall patterns under various future warming scenarios (2076-2100), namely representative concentration pathway scenario 4.5 (RCP 4.5) and RCP 8.5 (RCP 8.5) with respect to the reference historical time period (1976-2000) during the principal monsoon season (i.e. 1st June to 30th September) of two Indian states (Uttarakhand and Himachal Pradesh) of the NWH region. To serve this purpose, six attributes are defined as follows; start date of the rainy season (SRS), date of the 50% of the seasonal total rainfall (HRS), end date of the rainy season (ERS), length of the rainy season (LRS), 1 day maximum intensity (MRS) and the day corresponding to the maximum rainfall intensity (MDRS). These attributes are estimated for both historical time period and various future warming scenarios based on the archives of five coupled climate models which participated in the Climate Model Inter-comparison Project Phase 5 (CMIP5). Considering huge inter-model variations amongst the CMIP5 models, results are presented here based on the multi-model mean (MME). Characteristics of various attributes of rainfall during the historical time period are compared with that of the two future warming scenarios viz.; RCP 4.5 and RCP 8.5 by means of statistical techniques. There is a possibility of early SRS, delayed ERS and extended LRS along with intense MRS under different future warming scenarios over Himachal Pradesh (HP) as compared with the historical time period; however, results are significant only for 1 day maximum rainfall under RCP 8.5. Similarly, over the Uttarakhand (UK) region, changes in the rainfall pattern are noted under two future warming scenarios viz.; RCP 4.5 and RCP 8.5 as compared with the historical time period; nonetheless, significant changes are noted in MRS and MDRS only under RCP 8.5. It is anticipated that both of the NWH states of HP and UK would experience enhanced MRS under the warmest future warming scenario (i.e. RCP 8.5). Based on the present analysis, intense rainfall events are expected which could act as an initiator for various meteorological hazards over the NWH region in future.
Non-monsoonal precipitation response over the Western Himalayas to climate change
Climate Dynamics, 2018
Winter-to-early spring non-monsoonal precipitation over the Western Himalayas (WH) primarily comes from eastward propagating synoptic-scale weather systems known as western disturbances (WDs). Earlier studies have noted that an increasing trend of synoptic-scale WD activity in the past few decades has contributed to enhanced propensity of daily precipitation extremes over the WH, although it remains unclear as to whether these regional changes are manifestations of climate change. This issue is addressed by conducting a suite of long-term climate experiments using a global variable-grid climate model with high-resolution telescopic zooming over the South Asian region. Our findings highlight that human-induced climate change has implications on the rising trend of synoptic-scale WD activity and precipitation extremes over the WH during the recent few decades, and these changes cannot be explained by natural forcing alone. A stronger surface warming, in response to climate change, is noted over the vast expanse of the high-elevated eastern Tibetan Plateau relative to the western side. The model simulations show that strengthening of positive east-west temperature gradient across the Tibetan Plateau tends to alter the background mean circulation in a manner as to favor amplitude enhancements of the synoptic-scale WDs and orographic precipitation over the WH. With continuation of global warming in future and enhancement in the east-west temperature gradient across the Tibetan highlands, the trend of precipitation extremes over the WH and synoptic-scale WD activity are projected to rise into the twenty-first century. While the high-resolution simulations of this study offers promising potential to understand changes in synoptic-scale WD activity and precipitation extremes over the WH, further investigations are necessary to decipher the multi-scale behavior and intricacies of the Himalayan precipitation variability under changing climate.
Journal of Water and Climate Change
Covering 60 years (1955–2016), this paper analyzed the spatio-temporal trends of daily annual and seasonal means of precipitation, temperature, and extreme climate indices. The long-term decadal change analysis was carried out in two timeframes for consecutive analysis periods of 1955–1985 and 1986–2016 to capture the relative regional variations. The trends were evaluated using the modified Mann-Kendall (MMK) and Sen's slope (SS) statistical tests. The pattern visualized on maps was assessed for regions and districts located in the four states of the Indian Himalayan Region. The results revealed significant increases in the annual mean precipitation (1.61 mm/year) and temperature (0.07°/year) in Uttarakhand, followed by Himachal Pradesh from 1986 to 2016. The seasonal monsoonal precipitation showed a significantly increasing trend in parts of Himachal Pradesh, followed by Uttarakhand. The maximum and minimum temperature values increased in all the states, increasing temperature...
The Hindu Kush-Himalayan (HKH) region epitomizes a geographic region where cryospheric processes coupled with hydrological regimes are under threat owing to a warming climate and shifts in climate extremes. In this study, we analyse global climate models in the Coupled Model Intercomparison Project phase 3 (CMIP3) and phase 5 (CMIP5) archives to investigate the qualitative aspects of change and trends in temperature and precipitation indices. Specifically, we examine and evaluate multi-model, multi-scenario climate change projections and seven extreme temperature and precipitation indices over the eastern Himalaya (EH) and western Himalaya-Karakoram (WH) regions for the 21st century. Density distribution plots of observed climate indices for meteorological stations and gridded indices are also analysed, which indicate significant negative trends in the annual number of frost days and significant increasing trends in warm nights in the EH region over the 1960–2000 period. Multi-model average (MMA) projections additionally indicate continued trends towards more extreme conditions consistent with a warmer, wetter climate. Precipitation projections indicate increased mean precipitation with more frequent extreme rainfall during monsoon season in the EH region, and a wetter cold season in the WH region. Time series of all MMA precipitation indices exhibit significant increasing trends over the 1901–2099 period. By comparison, time series of temperature indices show decreases in the intra-annual extreme temperature range and total number of frost days, as well as increases in warm nights. In general, these future projections point towards increases in summertime temperatures and modifications in precipitation across both regions.
Drivers of climate over the Western Himalayan region of India: A review
Earth-Science Reviews, 2019
The Himalayas popularly known as the 'Third Pole' and 'Water tower' of Asia has attracted global attention under the context of climate change as rainfall in this region has decreased drastically, and temperature has risen very rapidly in the last century. Present study was attempted to quantify such abnormal warming and unexpected declining trend of rainfall vis-à-vis to identify factors influencing such abnormal behavior over the complex physiographical region technically known as Western Himalaya Region (WHR) through the available literature therein. It was revealed that frequency and intensity of extreme rainfall and temperature events have risen due to the variation of local weather events while mean climate has altered due to the influence of large-scale circulations like the Indian monsoon, Western Disturbances, and change in teleconnection pattern. Why the WHR has been a hotspot of several hazards like the cloudburst, Glacial Lake Outburst Flood (GLOF), convective storms, and forest fires in the past have been answered with appropriate evidence. Feedback from different atmospheric factors like snow-albedo, black carbon, and other suspended particulates was discussed in details to understand the complex nature of the Himalayan climate. WHR may face higher magnitude of heavy and
Theoretical and Applied Climatology, 2003
This study presents the monthly climatology and variability of the INSAT (Indian National Satellite) derived snow cover estimates over the western Himalayan region. The winter=spring snow estimates over the region are related to the subsequent summer monsoon rainfall over India. The NCEP=NCAR data are used to understand the physical mechanism of the snow-monsoon links. 15 years (1986-2000) of recent data are utilized to investigate these features in the present global warming environment. Results reveal that the spring snow cover area has been declining and snow has been melting faster from winter to spring after 1993. Connections between snow cover estimates and Indian monsoon rainfall (IMR) show that spring snow cover area is negatively related with maximum during May, while snow melt during the February-May period is positively related with subsequent IMR, implying that smaller snow cover area during May and faster snow melt from winter to spring is conducive for good monsoon activity over India. NCEP=NCAR data further shows that the heat low over northwest India and the monsoon circulation over the Indian subcontinent, in particular the cross-equatorial flow, during May are intensified (weakened) when the snow cover area during May is smaller (extensive) and snow melts faster (slower) during the February-May period. The well-documented negative relationship between winter snow and summer rainfall seems to have altered recently and changed to a positive relationship. The changes observed in snow cover extent and snow depth due to global warming may be a possible cause for the weakening winter snow-IMR relationship.
Climate Dynamics
The frequency and severity of climatic extremes is expected to escalate in the future primarily because of the increasing greenhouse gas concentrations in the atmosphere. This study aims to assess the impact of climate change on the extreme temperature and precipitation scenarios using climate indices in the Kashmir Himalaya. The analysis has been carried out for the twenty-first century under different representative concentration pathways (RCPs) through the Statistical Downscaling Model (SDSM) and ClimPACT2. The simulation reveals that the climate in the region will get progressively warmer in the future by increments of 0.36–1.48 °C and 0.65–1.07 °C in mean maximum and minimum temperatures respectively, during 2080s (2071–2100) relative to 1980–2010 under RCP8.5. The annual precipitation is likely to decrease by a maximum of 2.09–6.61% (2080s) under RCP8.5. The seasonal distribution of precipitation is expected to alter significantly with winter, spring, and summer seasons markin...
Climate Change in Himalayas: Research Findings and Complexities
International Journal of Plant and Environment, 2018
Himalayas are important for its influence on the climate of much of Asia, and ecosystem services, which serve some 1.3 billion people living in 10 river basins that originate from the region. The region is warming rapidly and is highly vulnerable to climate change. This review (i) sheds light on some fairly well established facts about climate change in Himalayas, (ii) makes an attempt to give an integrated picture of its impact on various components, and (iii) discusses complexities in generalizing the findings. Himalayas are warming at 2-3 time higher rates than global average rate, at least in some areas. The rate of warming is increasing in time and with elevation. As for rainfall, uncertainty is high, but generally predictions are for more violent events. According to an analysis based on 75 glaciers, 63 glaciers are showing shrinkage and 12 growth, however, their (growing ones) measurements are of low confidence level. The contribution of glacier and snow melt to total river d...
Wintertime climatic trends in the western Himalayas
Climatic Change, 2012
Northern Indian rivers are primarily fed by wintertime (December, January, February-DJF) precipitation, in the form of snow-yielded by eastward moving synoptic weather systems called Western Disturbances (WDs), over the western Himalayas (WH). This accumulated snow melts during ablation period. In the context of today's warming atmosphere, it is imperative to study the changes in the temperature and precipitation patterns over the WH to assess the impact of global warming on climatic conditions of the region. Keeping that in mind, observational analysis of temperature and precipitation fields is planned. In the present study various climatic indices are analyzed based on wintertime (DJF) data of 30 years obtained from the Snow and Avalanche Study Establishment (SASE), India. Results indicate enhancement in the surface air temperature across the WH. Percent number of warm (cold) days have increased (decreased) during 1975-2006 over the WH. Further analysis of precipitation reveals slightly decreasing but inconsistent trends.
Climate change and the precipitation variations in the northwestern Himalaya: 1866–2006
Using available instrumental records, this paper examines the variation of precipitation from 1866 to 2006 in the northwestern Himalaya (NWH). The study indicates no trend in the winter precipitation but significant decreasing trend in the monsoon precipitation during the study period. Periodicities on a multi-decadal scale (29-34 years and 58-64 years) obtained in power spectrum analyses point towards epochal behaviour in the precipitation series. Analyses of the temperature data show significant increasing trends in annual temperature in all three stations in the NWH during the data period. Warming effect is particularly noteworthy during the winter season. Negative relationships between mean winter air temperature and snowfall amounts recorded at different meteorological stations in this period reveal strong effect of rising temperatures on the decreasing snowfall component in total winter precipitation, reducing effective duration of winter on the windward side of the Pir Panjal Himalayan Range.