Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2018-201 Manuscript under review for journal Atmos. Chem. Phys. Discussion started: 22 May 2018 c Author(s) 2018. CC BY 4.0 License. 1 Climatic and extreme weather variations over Mountainous Jammu and Kashmir, 2 India: Physical explanations based on observations and modelling 3 4 Sumira N. Zaz1, Romshoo Shakil Ahmad1, Ramkumar Thokuluwa Krishnamoorthy2*, and 5 Yesu Babu Viswanadhapalli2 6 1. Department of Earth Sciences, University of Kashmir, Hazratbal, Srinagar, 7 Jammu and Kashmir-190006, India 8 9 2. National Atmospheric Research Laboratory, Dept. of Space, Govt. of India, Gadanki, Andhra 10 Pradesh 517112, India 11 12 Email: [email protected], [email protected], [email protected], 13 [email protected]; 14 15 *Corresponding author ([email protected]) 16 17 Abstract 18 19 The Himalaya is very sensitive to climatic variations because of its fragile environmental and 20 climatic settings. There are clear and strong indicators of climate change reported for the Himalaya, 21 particularly the Jammu and Kashmir region in the western Himalayas. In this study, the detailed 22 characteristics of long and short term as well as localized variations of temperature and precipitation are 23 analysed for six meteorological stations (Gulmarg, Pahalgam, Kokarnag, Quazigund, Kupwara and 24 Srinagar) over Jammu and Kashmir, India for a period of 37 years during 1980-2016 by making use of 25 observed stations data, WRF model downscaled monthly-averaged surface temperature and precipitation 26 and ERA-interim (ERA-I) reanalysis data. The annual and seasonal temperature and precipitation changes 27 were analysed by carrying out the Student’s t-test, Mann-Kendall, Spearman Rho and Cumulative deviation 28 statistical tests. The results show an increase of 0.8°C in average annual temperature over thirty years 29 during 1980-2016 with higher increase in maximum temperature (0.97°C) compared to minimum 30 temperature (0.76°C). Analyses of annual mean temperature at all the stations reveal higher rise at high- 31 altitude stations of Pahalgam (1.13°C) and Gulmarg (1.04°C) at the confidence level of S=99%. 32 Precipitation patterns in the valley show slight decrease in the annual precipitation at Gulmarg and 33 Pahalgam stations at the confidence level of S=90%.Seasonal analyses show increase in the winter and 34 spring temperature at all stations at the confidence level of S=95%with prominent decrease in spring 35 precipitation at S=99%. The present study reveals that variation in temperature and precipitation during 36 northern winter (December - March) has close association with the North Atlantic Oscillation (NAO). 37 Further, the observed temperature data (monthly averaged data for 1980-2016) at all the stations shows 38 good correlation of 0.86 with the results of WRF and therefore the model downscaled simulations can be 1 Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2018-201 Manuscript under review for journal Atmos. Chem. Phys. Discussion started: 22 May 2018 c Author(s) 2018. CC BY 4.0 License. 39 considered as a valid scientific tool for climatic change studies in this region. Using ERA-I potential 40 vorticities in the upper troposphere over the Jammu and Kashmir region, it is found that the extreme 41 weather event of September 2014occurred due to the breaking of intense Rossby wave activity over 42 Kashmir. As the wave could drag lots of water vapour from both the Bay of Bengal and Arabian Sea and 43 dump them in the region through wave breaking, resulting in the historical devastating flooding of the 44 whole Kashmir valley in the first week of September 2014 accompanied by the extreme rainfall events 45 measuring more than 620 mm in some parts of the Pir Panjal range in the South Kashmir. 46 47 1. Introduction 48 49 Climate change is a real Earth’s atmospheric and surface phenomenon and the influences of which 50 on all the spheres of life are considered significant everywhere in the world at least in the past few decades. 51 Extreme weather events like anomalously large floods and unusual drought conditions associated with 52 climate change play havoc with livelihoods of even established civilizations particularly in coastal and 53 high-mountainous areas. Jammu and Kashmir, India, located in the Western Himalayan region, is one such 54 cataclysmic mountainous region where the significant influence of climate change on local weather has 55 been observed for the last few decades;(1) shrinking and reducing glaciers,(2) devastating floods, (3) 56 decreasing winter duration and rainfall, (4) increasing summer duration and temperature etc.(Solomon et 57 al., 2007; Kohler and Maselli 2009; Immerzeel et al., 2010;Romshoo et al., 2015; Romshoo et al., 2017). 58 Western disturbances (WD) is considered as one of the main sources of precipitation(in the form of 59 rainfall/snowfall)for the Jammu and Kashmir region, which brings water vapour mainly from the tropical 60 Atlantic Ocean, Mediterranean Sea, Caspian Sea and Black sea. The Indian south-west and north-east 61 monsoons are other important sources during Northern summer and winter seasons respectively. Though 62 WD is perennial, but it is most intense during northern winter (December-February). Planetary-scale 63 atmospheric Rossby-waves have potential to significantly alter the distribution and movement of WD 64 according to their intensity and duration (few to tens of days). Since WD is controlled by planetary-scale 65 Rossby waves in the whole troposphere of the subtropical latitude region, diagnosing different kinds of 66 precipitation characteristics is easier with the help of potential vorticity (PV) at 350K potential temperature 67 (PT) and 200 mb level pressure surface(PS) as they are considered as proxies for Rossby wave activities 68 (Ertel, 1942; Bartels et al., 1998).For example, Postel and Hitchman (1999) studied the characteristics of 69 Rossby wave breaking (RWB) events occurring at 350K PT surface transecting the subtropical westerly 70 jets. Similarly, Waugh and Polvani (2000) studied RWB characteristics at 350K PT surface in the Pacific 71 region during northern fall–spring with emphasis on their influence on westerly ducts and their intrusion 72 into the tropics. Since PV is a conserved quantity on isentropic and isobaric surfaces (ISOES & ISOBS), it 73 is widely used for investigating large-scale dynamical processes associated with frictionless and adiabatic 2 Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2018-201 Manuscript under review for journal Atmos. Chem. Phys. Discussion started: 22 May 2018 c Author(s) 2018. CC BY 4.0 License. 74 flows. Moreover, all other dynamical parameters, under a given suitable balanced-atmospheric-background 75 condition, can be derived from PV and boundary conditions [Hoskins et al., 1985]. 76 77 Divergence of the atmospheric air flows near the upper troposphere is larger during precipitation, 78 leading to increase in the strength of PV. Because of which generally there will be a good positive 79 correlation between variations in the strength of PV in the upper troposphere and precipitation over the 80 ground provided that the precipitation is mainly due to the passage of large-scale atmospheric weather 81 systems like western disturbances, monsoons etc. Wind flows over topography can significantly affect the 82 height distribution of water vapour and precipitation characteristics.. Because of this, one can expect that 83 the positive correlation between variations in PV and precipitation be modified significantly depending 84 upon both the topography and wind flow strength. These facts need to be taken into account while finding 85 long-term climatic variations of precipitation near mountainous regions like the western Himalaya. The 86 interplay between the flow of western disturbances and topography of the western Himalaya can further 87 complicate the identification of source mechanisms of extreme weather events like the ones that occurred in 88 the western Himalayan region;2014 Kashmir floods, 2010 Leh floods, in the Jammu and Kashmir region 89 and 2013 in the Uttrakhand region. This necessitates making use of the proper surrogate parameters like 90 PV and distinguishing between different source mechanisms of extreme weather events associated with 91 both the long-term climatic impacts of remote origin and short-term localized ones like organized 92 convection. 93 94 The main aim of the present study is to investigate the climatic variation of surface temperature 95 and precipitation over the Jammu and Kashmir, India region of the western Himalayas in terms of 96 atmospheric Rossby wave activity in the upper troposphere. Since PV is considered as a measure of Rossby 97 wave activity, the present work analyses in detail, for a period of 37 years during 1980-2016, monthly 98 variation of PV (ERA-interim reanalysis data, Dee et al., 2001) in the upper troposphere (at 350 K potential 99 temperature and 200 mb pressure surfaces) and compares it with observed surface temperature and rainfall 100 (India Meteorological Department, IMD) at six widely separated mountainous locations with variable 101 orographic features (Srinagar, Gulmarg, Pahalgam, Qazigund, Kokarnag and Kupwara). There exist several 102 reports on climatological variation of hydro-meteorological parameters in various parts of the Himalayas. 103 For example, Kumar and Jain (2009) and Bhutiyani et al. (2010) found an increase in the temperature in the 104 north-western Himalayas with significant variations in precipitation patterns. Archer and Fowler (2004) 105 examined temperature data of seven stations in the Karakoram and Hindu Kush Mountains of the Upper 106 Indus River Basin (UIRB) in search of seasonal and annual trends using statistical test like regression 107 analysis. Their results revealed that mean winter maximum-temperature has increased significantly while 108 mean summer minimum-temperature declined consistently.