Monsoon, post monsoon rainy days analysis by using normal, binomial distribution and discrete probability for south Gujarat

The analysis will be conducted for standard weekly (SW) 22 to 47 of monsoon and post monsoon season at south Gujarat. The standard weekly rainy days analysis of binomial distribution for monsoon season of Navsari on chi-square test on binomial distribution was found in standard week (SW) 22 to 31, 33 and standard week (SW) 35 to 39 and post monsoon in standard week (SW) 41 to 44 shows significant. The result also reveals that the monsoon season SW 32 and 34 and post monsoon season SW 40, 45, 46 and 47 revealed non-significant result. Analysis reveals the rainfall is not equally distributed during SW 32, 34, 40, 45, 16 and 47, so that the test of binomial distribution is a good fit. Monsoon season rainfall data of Navsari, Bharuch and Valsad reveals that the normal distribution at 10, 20 and 30% probability levels for the month of June, July, August and September shows the possibility of increasing rainy days occurrence. The Navsari and Bharuch districts during post monsoon season rainfall of months of October and November reveals decreasing tendency except Valsad district. The binomial distribution fit only those standard weeks in which rainfall is not equally distributed. The standard weekly rainy days analysis of binomial distribution on chi-square test in Bharuch was found that standard week (SW) 25 only 10% of monsoon season and in post monsoon standard week (SW) 42 and 47 shows non significant (5 and 10% level of significant) result, but SW 25 found significant at 5% level. In case of Valsad district, standard week 22 to 39 of monsoon season and in post monsoon season 41, 42, 43 and 46 standard weeks shows significant result. The result reveals that the monsoon season of Bharuch standard weeks 22 to 39 except from 25 and post monsoon 40, 41, 43, 44, 45 and 46 shows significant result. Further, in Valsad district standard weeks 40, 44, 45 and 47 shows significant result. The trend analysis of rainy days shows that increasing trend in monsoon season and decreasing trend in post monsoon season of Navsari, Bharuch and Valsad districts. From above results observed that the rainfall distribution is not equally distributed so test of binomial distribution at above given standard week is a good fit. The data also shows that, decreasing tendency in rainfall was observed except Valsad district.

Recent trends in climate of Bangalore

The linear trends in the monthly, seasonal and annual mean maximum temperature, minimum temperature, average temperature, diurnal range of temperature, rainfall, relative humidities at 0830 & 1730 hr IST of Bangalore city and airport have been analysed based on the data for the period from 1960-95. The variation in surface wind over Bangalore during above period has also been studied to find out impact of urbanisation on weather parameters. It is found that Bangalore city is becoming warmer in terms of mean maximum & mean minimum temperatures. Rate of increase is significantly higher over Bangalore city (central observatory) than that over airport during winter months. Similarly the rising trend of average temperature of Bangalore city is higher than of Bangalore airport during October to April being significantly so during winter season. Also the diurnal range of temperature of Bangalore is becoming larger in winter months with the rising trend being higher over Bangalore city than over airport. Even though rainfall does not show any significant trend, the rising trend during monsoon & falling trend during post monsoon season over Bangalore city are higher than that of Bangalore airport. Also though both Bangalore city & airport show maximum rising trend in mean relative humidity at 0830 hr IST during winter, the rate of rise is less over Bangalore city. Similarly though the relative humidity at 1730 hr IST shows decreasing trend during all the seasons, the rate of decrease is less over Bangalore city for all seasons except post monsoon season. The mean maximum, minimum and average temperatures and relative humidities show cyclic variation of their monthly trend coefficients during the year.

Multi-Model Assessment of Streamflow Simulations under Climate and Anthropogenic Changes Exemplified in Two Indian River Basins

This study aims to evaluate the climate- and human-induced impacts on two contrasting river basins in India, specifically, the Ganges and the Godavari. Monthly discharge simulations from global hydrological models (GHMs), run with and without human influence using CMIP5 projections under the framework of the Inter-Sectoral Impact Model Intercomparison Project, are utilized to address the scientific questions related to the quantification of the future impacts of climate change and the historical impacts of human activities on these river basins. The five state-of-the-art GHMs were considered and subsequently used to evaluate the human and climate change impacts on river discharges (seasonal mean discharge and extreme flows) during the pre-monsoon, monsoon, and post-monsoon seasons under the RCP2.6 and RCP8.5 emission scenarios. Results showed that human impacts during the baseline period on long-term seasonal discharge in the Ganges and Godavari River basins for the pre-monsoon season are around 40% and 23%, respectively, and these impacts are stronger than the future climate change impact in the pre-monsoon season for the Ganges basin, whereas, for the Godavari basin, the same pattern is observed with some exceptions. The human impact in the course of the historical period on the pre-monsoon flows of both the Ganges and the Godavari are more significant than on the monsoon and post-monsoon flows. In the near future (2010–39) time slice, the impact of climate change on the streamflow of the Ganges is highest for the post-monsoon season (13.4%) under RCP 8.5 as compared to other seasons. For Godavari, in the near-future period, this impact is highest for the pre-monsoon season (18.2%) under RCP 2.6. Climate-induced changes in both of the basins during both the monsoon and post-monsoon seasons is observed to have a higher impact on future flows than direct human impact-induced changes to flow during the current period. High flows (31.4% and 19.9%) and low flows (51.2% and 36.8%) gain greater influence due to anthropogenic actions in the time of the pre-monsoon season compared to other times of year for the Ganges and Godavari basins, respectively. High flows for the Ganges during the near future time slice are most affected in the monsoon season (15.8%) under RCP 8.5 and, in the case of the Godavari, in the pre-monsoon season (18.4%) under the RCP 2.6 scenario. Low flows of the Ganges during the near-future period are most affected during the monsoon season (22.3%) and for the Godavari, low flows are affected most for the post-monsoon season (22.1%) under RCP 2.6. Uncertainty in the streamflow estimates is more pronounced for the Godavari basin compared to the Ganges basin. The findings of this study enhance our understanding of the natural and human-influenced flow regimes in these river basins, which helps the formation of future strategies, especially for inter-state and transboundary river management.

The relationship between geopotential height and movement & landfall of tropical cyclone in the Bay of Bengal region

In this paper a simple relationship is employed to investigate relative impacts on the movement and landfall of tropical cyclone in the Bay of Bengal region when geopotential height of different troposphere levels is used as an input. Five tropical cyclone during pre-monsoon and post-monsoon season over the Bay of Bengal region has been selected for the study. The RS/RW data of coastal stations namely Kolkata (Dumdum), Dhaka, Agartala, Bhubaneswar, Visakhapatnam, Machlipatnam, Chennai and Karaikal has been collected for the period of the cyclones under study. The geopotential height of different standard levels has been plotted against the time for the stations for every cyclone. The study suggests that the cyclone moves towards and cross near the station having relatively steeper decrease in geopotential height upto mid tropical level followed by increased in geopotential height.

A preliminary study about the prospects of extended range forecast of tropical cyclogenesis over the north Indian Ocean during 2010 post-monsoon season

o"kZ 2010 esa ekulwuksRrj _rq ds nkSjku nks pØokrh; rwQku fufeZr gq, FksA tSls ‘fxjh’ uked vfr izpaM pØokrh; rwQku ¼oh-,l-lh-,l-½ 19 vDrwcj dks fufeZr gqvk vkSj ;g 22 rkjh[k dks E;kaekj leqnz rV dks ikj dj x;k vkSj nwljk ‘tky’ uked izpaM pØokrh; rwQku ¼,l-lh-,l-½ 2 uoacj dks fufeZr gqvk vkSj ;g psUuS ds mRrjh Hkkx ds lehi mRrjh rfeyukMq & nf{k.kh vka/kz izns’k ds leqnzh rVksa dks 07 uoacj dks ikj dj x;k ftldh otg ls rfeyukMq vkSj nf{k.kh vka/kz izns’k ds leqnz rVh; {ks=ksa esa u dsoy rhoz iou ls cfYd mlls gqbZ Hkkjh o"kkZ ls Hkkjh {kfr gqbZA okLrfod le; foLr`r {ks= iwokZuqeku xR;kRed fHkUurkvksa ds lkIrkfgd vkSlr ds vk/kkj ij nks lIrkg ds fy, rS;kj fd, x, gSa tks- bZ- lh- ,e- MCY;w- ,Q-] ,u- bZ- lh- ih- rFkk nksuksa ds 2 ekWMYl vkSlr ¼2 ,e- ,- oh- bZ-½ ds ;qfXer ekWMy ifj.kke ij vk/kkfjr gSaA lkIrkfgd vkSlr] iou vkSj lkisf{kd Hkzfeyrk ds 5&11 fnuksa ds izpkyukRed iwokZuqeku 14 vDrwcj 2010 ds vkjafHkd fLFkfr ij vk/kkfjr gSa ftlls irk pyk gS fd 18&24 vDrwcj dh vof/k ds nkSjku e/; caxky dh [kkM+h ds Åij fuEu nkc dk pØokrh; ldqZys’ku Fkk tks vfr izpaM pØokrh; rwQku ‘fxjh’ ds leku FkkA ‘tky’ uked pØokr dh mRifRr dk 2 ,e- ,- oh- bZ- esa vPNh rjg irk yxk fy;k x;k FkkA bldk iwokZuqeku 12&18 fnuksa ds fy, oS/k Fkk vkSj ;g 21 vDrwcj 2010 dh vkjafHkd fLFkfr ij vk/kkfjr FkkA 2 ,e- ,- oh- bZ- iwokZuqeku 1&7 uoacj rd ds fy, oS/k Fkk tks 28 ,oa 21 vDrwcj dh vkjafHkd fLFkfr;ksa ij vk/kkfjr Fkk ¼buds iwokZuqeku dh vof/k Øe’k% 5&11 fnuksa rFkk 12&18 fnuksa dh Fkh½ ftlesa Li"V :i ls n’kkZ;k x;k gS fd rfeyukMq leqnz rV vkSj blls yxs gq, vka/kz izns’k ds {ks= esa izsf{kr dh xbZ folaxfr;ksa ls dkQh vf/kd ?kukRed o"kkZ folaxfr;k¡ ns[kh xbZ gSaA bl izkjafHkd v/;;u esa vkxs crk;k x;k gS fd lkIrkfgd pØokrh; Hkzfeyrk ds ekWMy iwokZuqekuksa dh vf/kdre folaxfr =qfV yxHkx &0-8 ls &1-0 × 10&5 izfr lSds.M dks fuEu LRkjh; vf“lj.k folaxfr yxHkx &0-8 ls &1-0 × 10&5 izfr lSds.M ds lkFk feyus ij m".kdfVca/kh pØokr cuus dh laHkkouk curh gSA rFkkfi bl flLVe ds pØokr ds :i esa rhozhdj.k gsrq Fkzs’kgksYM oSY;w dh igpku djus ds fy, vkSj vf/kd ekeyksa ds fo’ys"k.k djus dh vko’;drk gSA There were two cyclonic storms formed during the post monsoon season of 2010 viz., “Giri” a very severe cyclonic storm (VSCS) formed on 19th October and crossed the Myanmar coast on 22nd and the second system “Jal” a severe cyclonic storm (SCS) formed on 2nd November and crossed north Tamil Nadu-south Andhra Pradesh coasts, close to north of Chennai on 7th November, which caused lot of damage in Tamil Nadu and south Andhra Pradesh coast associated with not only strong wind but also due to associated heavy rainfall. The real time extended range forecasts in terms of weekly mean of dynamical variables are prepared for two weeks based on the coupled model outputs from ECMWF, NECP and the 2 models average (2MAVE) of both. The operational forecast for days 5-11 of weekly mean wind and relative vorticity based on 14th October, 2010 initial condition indicates cyclonic circulation at low level over the central Bay of Bengal during the period from 18-24 October associated with the very severe cyclone “Giri”. The genesis of the cyclone “Jal” was very much captured in the 2MAVE forecast valid for 12-18 days forecast based on the initial condition of 21st October, 2010. The 2MAVE forecast valid for 1-7 November based on 28 October and 21 October initial conditions (with forecast period of days 5-11 and days 12-18 respectively) also clearly indicated large positive rainfall anomalies over Tamil Nadu coast and adjoining coastal Andhra Pradesh region like that of observed rainfall anomalies. This preliminary study further indicates that the model forecasts anomaly of weekly cyclonic vorticity maximum of about 2.5´10-5 sec-1 combined with a low level convergence anomaly of about -0.8 to -1.0 ´ 10-5 sec-1 may lead to formation of a tropical cyclone. However, more number of cases required to be analysed for the proper identification of the threshold values for intensification of the system into a cyclone.