Spatial Distribution of Extreme Precipitation Events and Its Trend in Nepal

Shrestha, Dibas; Sharma, Shankar; Hamal, Kalpana; Jadoon, Umair Khan; Dawadi, Binod

doi:10.12691/aees-9-1-8

Cited by 11 publications

(11 citation statements)

References 33 publications

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“…in the north. Being located in the tropical northern limit with diversified topography, the country features a very diverse climate from tropical savanna in low-elevation to polar frost in high-the Himalayas (Karki et al 2015;Nepal et al 2021;Shrestha et al 2021). Annual precipitation is predominately governed by the summer monsoon and westerly winter precipitation (Duncan et al 2013;Ehsan et al 2017;Kansakar et al 2004).…”

Section: Study Areamentioning

confidence: 99%

Projected Drought Conditions over Southern Slope of the Central Himalaya Using CMIP6 Models

et al. 2021

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Nepal is located on the southern slope of the Central Himalayas and has experienced frequent droughts in the past. In this study, we used an ensemble of 13 biased corrected models from the Coupled Model Intercomparison Project Phase 6 (CMIP6) to assess the future drought conditions over Nepal under three shared socioeconomic pathways (SSP126, SSP245, and SSP585) using the Standardized Precipitation Evapotranspiration Index (SPEI) at annual timescale. The monthly correlation between observed and CMIP6-simulated historical SPEI is 0.23 (p < 0.01), which indicates the CMIP6 model ensemble can simulate the drought characteristics over Nepal. In the future period (2020–2100), the duration and severity of droughts are projected to increase with higher emission scenarios, especially for SSP585. Our results indicate enhanced drought intensity under SSP126, whereas, under SSP245, the drought frequency will be slightly higher. The drought frequency is projected to increase in the early future (2020–2060), decreasing in the late future (2061–2100) under all SSP scenarios. The results further indicate more prolonged and severe droughts in the early future under SSP585 as compared to SSP126 and SSP245. The findings of the present study can help drought mitigation as well as long-term adaptation strategies over Nepal.

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Section: Study Areamentioning

confidence: 99%

Projected Drought Conditions over Southern Slope of the Central Himalaya Using CMIP6 Models

et al. 2021

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“…Several studies have recently examined the temperature and precipitation trend over the Himalayas and surrounding high altitude regions (Yue et al, 2019;Hamal et al, 2020a;Shrestha et al, 2021). Moreover, these studies indicate that the annual temperatures have generally increased in the region (Shrestha & Devkota, 2010;Shrestha & Aryal, 2011;Dibike et al, 2012;Kattel et al, 2013;Thakuri et al, 2019), and experiencing higher increase rates of temperature than the global average (Li et al, 2011;Poudel et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

Does the High Elevation Climate along Mt. Everest can be Represented by Lower Elevation Stations?

Dawadi¹,

Sharma²,

Hamal³

et al. 2021

J. Inst. Sci. Tech.

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Climate change studies of the high mountain areas of the central Himalayan region are mostly represented by the meteorological stations of the lower elevation. Therefore, to validate the climatic linkages, daily observational climate data from five automated weather stations (AWS) at elevations ranging from 2660 m to 5600 m on the southern slope of Mt. Everest were examined. Despite variations in the means and distribution of daily, 5-day, 10-day, and monthly temperature and precipitation between stations located at a higher elevation and their corresponding lower elevation, temperature records in the different elevations are highly correlated. In contrast, the precipitation data shows a comparatively weaker correlation. The slopes of the regression model (0.82–1.13) with (R2>0.74) for higher altitude (5050 m and 5600 m) throughout the year, 0.83–1.12 (R2>0.68) except late monsoon season for the station at 4260 m and 5050 m asl indicated the similar variability of the temperature between those stations. Similarly, Namche (3570 m) temperature changes by 0.81–1.32°C per degree change in corresponding lower elevation Lukla station (2660 m), except for monsoon season. However, inconsistent variation was observed between the station with a large altitudinal difference (2940 m) at Lukla and Kala Patthar (5600 m). In general, climate records from corresponding lower elevation can be used to quantitatively assess climatic information of the high elevation areas on the southern slope of Mt. Everest. However, corrections are necessary when absolute values of climatic factors are considered, especially in snow cover and snow-free areas. This study will be beneficial for understanding the high-altitude climate change and impact studies.

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“…Following the previous studies (Hamal et al, 2020c;Sharma et al, 2020a;Shrestha et al, 2021), four different statistical metrics are adopted to analyze the performance of four SBP products: correlation coefficient (CC, Equation 1), Normalized Root Mean Square Error (NRMSE, Equation 2), mean biases (MB, Equation 3), and absolute relative error (RE, Equation 4). CC measures the strength and direction of the linear association between SBP and observation, while NRMSE provides the averaged magnitude of the deviation of SBP from observation.…”

Section: Discussionmentioning

confidence: 99%

“…In contrast, the pre-monsoon and monsoon seasons are wet and humid (Shrestha, 2000;Sharma et al, 2021a). Low-land and Mid-Mountains receive large amounts of precipitation during the summer monsoon from July to September as part of the South Asian monsoon, which is the country's primary source of annual precipitation (Hamal et al, 2020a;Hamal et al, 2020b;Hamal et al, 2020c;Sharma et al, 2020b;Shrestha and Deshar, 2014;Shrestha et al, 2021). Meanwhile, the northern part of the high Himalayas, including trans-Himalayan regions, is relatively dry as mountains block the precipitation and are known as rain shadow areas (Dawadi et al, 2020;Pokharel et al, 2019;Talchabhadel and Karki, 2019;Talchabhadel et al, 2018).…”

Section: Study Areamentioning

confidence: 99%

Spatial Pattern of Precipitation in GPM-Era Satellite Products against Rain Gauge Measurements over Nepal

et al. 2021

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Precipitation in a mountainous region is highly variable due to the complex terrain. Satellite-based precipitation estimates are potential alternatives to gauge measurements in these regions, as these typical measurements are not available or are scarce in high elevation areas. However, the accuracy of these gridded precipitation datasets need to be addressed before further usage. In this study, an evaluation of the spatial precipitation pattern in satellite-based precipitation products is provided, including satellite-only (Integrated Multi satellite Retrievals for GPM IMERG-UCORR and Global Satellite Mapping of Precipitation (GSMaP-MVK) and gauge calibrated (IMERG-CORR and GSMaP-Gauge) products, with a spatial resolution of 0.1°, which is compared to 387-gauge measurements in Nepal from April 2014 to December 2016. The major results are as follows: (1) The gauge calibrated version 5 IMERG-CORR and version 6 GSMaP-Gauge are relatively better than the satellite-only datasets, although they all underestimate the observed precipitation. (2) The daily gauge calibrated GSMaP-Gauge performs fairly well in low and mid-elevation areas, whereas the monthly gauge calibrated IMERG-C performs better in high-elevation areas. (3) For the daily time scale, IMERG-CORR shows a better ability to detect the true precipitation (higher Probability of Detection (POD)) and (lowest False Alarm Ratio (FAR)) events among all datasets. However, all four satellite-based precipitation datasets accurately detect (Critical Success Index (CSI) >40%) precipitation and no-precipitation events. The results of this work provide the systematic quantification of IMERG and GSMaP of satellite precipitation products over Nepal using station observations and delivers a helpful statistical basis for the selection of these datasets for future scientific research.

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Spatial Distribution of Extreme Precipitation Events and Its Trend in Nepal

Cited by 11 publications

References 33 publications

Projected Drought Conditions over Southern Slope of the Central Himalaya Using CMIP6 Models

Projected Drought Conditions over Southern Slope of the Central Himalaya Using CMIP6 Models

Does the High Elevation Climate along Mt. Everest can be Represented by Lower Elevation Stations?

Spatial Pattern of Precipitation in GPM-Era Satellite Products against Rain Gauge Measurements over Nepal

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