Observed Climate Variability and Change over the Indian Region

2020

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The article reviews the issue of climate variability in the Indian context. In India, it is importance of studying climate variability and future climate change at local levels, given the substantial climatic variations across time and space. Climate variability refers to short-term (daily, seasonal, annual, inter-annual, several years) variations in climate, including the fluctuations associated with El Niño (dry) or La Niña (wet) events. Climate Variability may occur due to internal variability (natural internal processes within the climate system) or from the external variable (variations in natural or anthropogenic external forces). Internal variability is present on all time scales. Atmospheric processes that generate internal variability operate on time scales ranging from virtually instantaneous (condensation of water vapour in clouds) to long time scales (troposphere-stratosphere or inter-hemispheric exchange, ocean and the large ice sheets). In addition, internal variability is produced by coupling interactions between components, such as is the case with the El-Niño Southern Oscillation. There is consensus that climate change has set in, but it is not only a rise in temperature and rainfall; rather decrease in temperature and rainfall has also been projected. In this review paper, we discuss the results of regional climate model simulations for India, based on the second generation Hadley Centre regional climate model known as PRECIS (Providing Regional Climates for Impacts Studies). An evaluation of the model skills and biases is made by comparing with observed precipitation and temperature patterns with those in the baseline simulation.

Climate Change and Environmental Sustainability

The variabilities in maximum and minimum temperature, rainfall, relative humidity, wind speed, evaporation and sunshine hours were analysed from historical 30 years of meteorological data (1984-2013) recorded at Regional Research Station (Punjab Agricultural University), Ballowal Saunkhri, district SBS Nagar (Punjab). Two distinct crop growth seasons of kharif (1st May to 30th September) and rabi (1st October to 30th April) were characterised for seasonal trends. The analysis of data revealed that the climate had changed slightly over the past three decades. The annual maximum and minimum temperature in last three decades ranged from 28.5 to 31.0°C and 15.2 to 17.4°C. The annual average maximum temperature had shown increasing trends over the years and increase was non-significant in annual minimum temperature. The rainfall of this region ranges from 617 to 2,041 mm with average value of 1,067 mm, out of which about 80% was received during the monsoon period. The declining trend in average annual and kharif rainfall was observed over the years. The average annual relative humidity showed significant increase over the years and ranged from 58 to 71% with mean value of 64%. The significant decrease in wind speed was recorded from 1988 to 2000. The sunshine hours also showed significant decreasing trends over years.

Climate change worries the scientific community world over as the surface air temperature increased by 0.74 o C during . The impacts of warming in mountainous regions get magnified because of large variations in altitude within small distance. This study focuses on the variability and trends of air temperature and rainfall during 1951-2010 in Dharamsala, a hill station in Himachal Pradesh located in Western Himalaya , India. The results of the trend analysis show a statistically significant increase in monthly mean maximum temperature (, total monthly rainfall (June) and 24 hour heaviest rainfall (June). Statistically, significant decreasing trends are found in monthly mean minimum temperature (May to October), mean temperature (June), monthly rainfall (January and August) and rainy days (January). Seasonally, significant increasing trends are observed in mean maximum temperature (winter and post monsoon), mean temperature (winter) and diurnal temperature range (all seasons) and significant decreasing trends in minimum temperature for summer, monsoon and post monsoon. Annual mean maximum temperature and mean diurnal temperature range are significantly increasing at a rate +0.018 o C/year and +0.033 o C/year, respectively ,while annual mean minimum temperature is significantly decreasing by -0.018 o C/year. The trend analysis of air temperature and rainfall reveals a tendency of increase in maximum temperature, decrease in minimum temperature and rainfall , which may have impacts on agriculture, water resources, human health and natural environment in Dharamsala and surrounding region.

Mausam

To understand the climatic changes and variability in mid-Himalayan region, 22 to 28 years data on maximum and minimum temperatures and rainfall of Palampur, Bajaura, Dhaulakuan, Shimla and Salooni of Himachal Pradesh and Ranichauri of Uttarakhand were analysed. Highly significant positive trend (0.5 to 1.1 °C/decade) in annual maximum temperature at four locations, significant negative trend (-0.4 °C/decade) in annual minimum temperature at Ranichauri and highly significant increasing trend of rainfall (22 mm/year) at Shimla was observed. Maximum temperature in summer showed significant increasing trend at all the locations except Ranichauri. Maximum temperature showed significant increase in all the seasons at Shimla. During Rabi season, significant increasing trend in maximum temperature at Palampur, Bajaura and Shimla and significant decreasing trend in rainfall at Bajaura and Dhaulakuan was noticed. Both maximum and minimum temperatures in March registered significant increase ...

Natural Resources Conservation and Research, 2018

A trend analysis was performed for historic (1901-2002) climatic variables (Rainfall, Maximum Temperature and Minimum Temperature) of Uttarakhand State located in Northern India. In the serially independent climatic variables, Mann-Kendall test (MK test) was applied to the original sample data. However, in the serially correlated series, prewhitening is utilized before employing the MK test. The results of this study indicated a declining trend of rainfall in monsoon season for seven out of thirteen districts of Uttarakhand state. However, an increasing trend was observed in Haridwar and Udhamsingh Nagar districts for summer season rainfall. For maximum and minimum temperature, a few districts exhibited a declining trend in monsoon season whereas many districts exhibited an increasing trend in winter and summer season. Mountain dominated areas (as Uttarakhand state) are specific ecosystems, distinguished by their diversity, sensitivity and intricacy. Thus the variability of rainfall...

Landscape & Environment

Mountainous regions are considered highly vulnerable to the affects of climate change. The extent of change and variability of climatic parameters is still unexamined in many remote mountainous areas. This paper aims in understanding the change in pattern of rainfall and temperature for a period of 30 years in Mizoram. The analysis of time series changing trend in climatic variables is carried out by using Coefficient of Variation (CV), Mann-Kendall (M-K) and Sen’s Slope estimator. The analysis reveals that high variation is observed for both the variables in all the decadal, three decadal and seasonal change. The CV analysis shows that the highest seasonal rainfall variation occurs during winter and the highest seasonal temperature variation occurs during spring. Mann-Kendall test shows a significant change in rainfall with November showing the highest negative trend of rainfall. The temperature trend analysis in the study also reveals drastic change of temperature. An understandi...

Article, 2024

Himalaya – one of the pristine and ecologically fragile mountain ecosystem is highly vulnerable to any small changes in climatic system. Under changing climate conditions, assessing regional trends become more important owing to depen- dence of more than 1 billion people on Himalayas. To analyze the climatic trends and magnitude, this study utilized the long term meteorological data (1980–2022) for temperature and precipitation. Investigations were carried out for 11 mete- orological stations located in different topographical zones of Jammu, Kashmir and Ladakh region. The non-parametric Mann–Kendall test was used for significance of trends in precipitation and temperature data on monthly, seasonal, and annual scales, while Sen’s non-parametric estimator of the slope was used to estimate the magnitude of trend. For TMax, except Jammu plains (-0.018oC a− 1) all regions experienced increasing trend with annual rate of increase 0.018oC a− 1, 0.032oC a− 1 and 0.051oC a− 1 in Pir Panjal region, Kashmir valley and Ladakh region respectively. For annual TMin, all four geographical regions and individual stations have observed an increase. Ladakh region observed highest rate of increase (0.070oC a− 1) which was significant followed by Pir Panjal region (0.048oC a− 1), Kashmir valley (0.013oC a− 1) and the lowest rate was observed in Jammu Plains (0.006oC a− 1). Precipitation revealed a general decreasing trend with large inter annual variability. Seasonally, TMin has seen most significant changes across all topographical regions. Our results indicate that influence of Indian Summer Monsoon (ISM) was more towards the Jammu plains and its impact reduced towards Pir Panjal and Kashmir valley with increasing influence of Western Disturbances (WDs). Jammu plains received 75.8% precipitation from ISM while Kashmir valley received 72.4% precipitation from WDs. Shift in climatic variables could have serious environmental and socio-economic implications which can alter the regional ecological stability

Journal of Agrometeorology, 2021

Journal of Earth System Science, 2014

An investigation has been carried out to identify the trends in maximum, minimum and mean temperatures and temperature range over the Indian land mass during the winter (January, and February), premonsoon (March-May), southwest monsoon (June-September) and post-monsoon (October-December) seasons by using high resolution daily gridded data set prepared by India Meteorological Department for the period of 1969-2005. It has been observed that the maximum temperatures over the west coast of India show rising trend in winter, southwest monsoon and post-monsoon seasons but the maximum temperatures do not show any significant trend over the other parts of the country. Minimum temperatures show increasing trend over the North Indian states in all seasons and they show an increasing trend over the west coast of India in winter and southwest monsoon seasons. Mean temperature shows an increasing trend over the west coast of India during winter and southwest monsoon seasons. Decreasing trend is observed in the temperature range over North India in all seasons due to increasing trend in minimum temperature.