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Either naturally occurring process or human activities may have a significant impact on the quality of sub-surface waters which further limit its use. Multivariate statistical techniques such as factor analysis (FA), cluster analysis (CA) were applied for the evaluation of spatial variations and the interpretation of ground water quality data around Bacheli and Kirandul area. The major anions, cations and heavy metals were determined for each of 20 samples collected in pre-monsoon seasons. Hydrochemical parameters like EC, pH, TDS, TH, TA, Na+, K+, Ca2+, Cl-, F-, SO42-, As, Sb, Se, Pb, Cd, Zn, Cu were estimated in pre monsoon and post monsoon seasons. Different geochemical controls of the investigated parameters were also assessed. Factor 1 explains 33.47% of the total variance and indicates atmospheric controls and silicate mineral weathering process. Factor 2 explains 13.83% of total variance, indicating silicate mineral weathering process resulting in elevated pH. Generally, water types tend towards magnesium-bicarbonate-chloride.

Regional variation of electrical and lightning properties of thunderclouds is investigated by using simultaneous observations of electric field mill (EFM-100) and lightning detector (LD-350) in synergy with their radiance and bulk microphysical properties. The study is carried out over Kohima in the north-eastern and over Rampurhat in the eastern part of India (20o-30o N, 85o-96o E), during the pre-monsoon season (March–May) of 2017–2018. The occurrence of EFM-100 detected thunderclouds is found to be more over Kohima (111) compared to Rampurhat (88). Whereas, the average number of lightning flash is much higher over Rampurhat (~542 flash/thundercloud) compared to Kohima (~32 flash/thundercloud). Over both the regions, the maximum occurrence of thunderclouds is found during afternoon to evening hours. The upper whisker value in the box plot shows that thunderclouds over Rampurhat are associated with higher CAPE value (Kohima: 1100 J Kg−1; Rampurhat: 5000 J Kg−1). The diurnal variation of CAPE supports relatively early occurrence of thunderclouds over Kohima. Thunderclouds over Rampurhat persists for relatively longer duration. It is observed that overall percentage occurrence of CG lightning is more over Kohima (Kohima: −CG: 28.09% & +CG: 09.74%; Rampurhat (–CG: 12.33% & +CG: 08.60%), with relatively higher −CG lightning compared to +CG, over both the stations. On the contrary, the occurrence of IC lightning is more over Rampurhat (Rampurhat: −IC: 31.75% & +IC: 47.30%; Kohima: −IC: 36.44% & +IC: 25.72%). Over Kohima occurrence of −IC is more than the +IC, whereas over Rampurhat, the occurrence of +IC is more than −IC. The overall higher occurrence of total negative and positive discharges over Kohima and Rampurhat respectively is consistence with EFM observations. The prevalence of positive/negative discharge suggests the presence of a tripole charge structure within thunderclouds over both the regions. The upper whisker value in the box plots revels higher CG flash density, IC:CG and larger log(area) over Rampurhat (Kohima: 3.0 × 10−3 flash km−2 h−1 and Rampurhat: 4.25 × 10−3 flash km−2 h−1; Kohima: 7 and Rampurhat: 15; Kohima: 10.5 km2 and Rampurhat: 11.5 km2). The lower whisker value of cloud top temperature reveals prevalence of colder thunderclouds over Rampurhat (Kohima: 220 K; Rampurhat: 184 K). The thunderclouds over Rampurhat are found to be associated with stronger updrafts and mixed-phase processes. The study reveals that, over these two regions, the electrical and lightning properties have distinct characteristics.

The operational medium-range weather forecasting based on numerical weather prediction (NWP) models are complemented by the forecast products based on ensemble prediction systems (EPSs). This change has been recognised as an essentially useful tool for medium-range forecasting and is now finding its place in forecasting the extreme events. Here we investigate extreme events (heatwaves) using a high-resolution NWP model and its ensemble models in union with the classical statistical scores to serve verification purposes. With the advent of climate-change-related studies in the recent past, the rising number of extreme events and their plausible socio-economic effects have encouraged the need for forecasting and verification of extremes. Applying the traditional verification scores and associated methods to both the deterministic and the ensemble forecast, we attempted to examine the performance of the ensemble-based approach in comparison to the traditional deterministic method. The results indicate an appreciable competence of the ensemble forecast at detecting extreme events compared to the deterministic forecast. Locations of the events are also better captured by the ensemble forecast. Further, it is found that the EPS smoothes down the unexpectedly increasing signals, thereby reducing the false alarms and thus proving to be more reliable than the deterministic forecast.

Indoor radon and thoron measurements were carried out in 92 dwellings of Tiruchirappalli city employing single entry pin-hole dosimeter with a solid state nuclear track detector for a period of one year covering all four seasons. The results indicated that the indoor radon and thoron concentrations varied dynamically throughout the year. The maximum mean indoor radon concentration (42.1 ± 20 Bq m −3 ) and thoron concentration (98.2 ± 23 Bq m −3 ) were registered during monsoon season and minimum mean radon concentration (26.1 ± 14.5 Bq m −3 ) and thoron concentration (36.6 ± 18.8 Bq m −3 ) during pre monsoon season. Indoor radon and thoron concentrations are directly related to the types of building materials, ventilation rate and atmospheric temperature. The mean indoor radon concentration was 33.2 Bq m −3 which was within the safe limit of 300 Bq m −3 as set by WHO. Hence this study concluded that the indoor radon and thoron concentrations in the studied region did not pose any radiological hazard to dwellers.

An account of seasonal water quality variability has been taken as a proxy for the changes of environmental setting occurring in the catchment areas and helps to illustrate the ecological system processes associated with it. The present study in Meenachil River (L = 78 km, A = 1272 km2) comprising of stations from upstream to downstream for pre monsoon (PRM), monsoon (MON) and post monsoon (POM). Ca2+ and SO4 2− show an erratic trend while extreme deviations were observed at S6 and S7 stations. Na+, K+, Cl−, DIC and DOC showed a similar trend in most stations, i.e. (PRM > POM > MON). Significant rise of DIC and DOC at S7 during POM and PRM could explicate changes ensued in adjacent Vembanad lake system. Strong correlations of DIC and DOC for Na+, K+ and Cl− ions were noted in the study. HCA dendrogram reveals that ion chemistry in S6 and S7 was strictly controlled by neighbouring lake water dynamics. The results demonstrate high F1 variance of 73, 68 and 72% followed by F2 comprising of 17, 19 and 21% for PRM, MON and POM, respectively. General understanding into the autochthonous process associated within the river lake interface region was evident from the nutrient variability scenario.

Sea surface temperature (SST) plays a significant role in tropical cyclone (TC) formation and intensity evolution, while at the same time, TC induces SST changes during its life cycle. This work deals with the TC-induced SST changes associated with 21 TCs of Bay of Bengal (BoB) during 2006–2013. The SST analyses obtained from National Centre for Oceanic Information Services (INCOIS-SST) and real-time global SST (RTG-SST) are used along with buoy observations. Initial analyses reveal that INCOIS-SST is consistently better than RTG-SST with a good correlation and least root-mean-square error for both post- and pre-monsoon seasons. Overall results demonstrated that mean SST cooling decreases with increased translation speed of TCs within a radius of 50, 100 and 200 km from its centre. Further, a maximum SST cooling of ~2 and ~1.8 °C is noticed in pre- and post-monsoon, respectively, within the radial distance of 50–100 km from centre for slow-moving TCs, 1.2 and 1.0 °C for moderate and 0.9 and 0.7 °C for fast-moving TCs. The TCs formed over the southern BoB have a greater SST cooling up to 200 km radial distance followed by those formed over central and northern BoB in pre- and post-monsoon; however, the magnitudes of cooling in pre-monsoon seasons are greater than post-monsoon season. The minimum cooling over northern BoB may be attributed to the strong haline stratification as compared to the central and southern BoB during both seasons. However, there is a higher magnitude of stratification in post- compared to pre-monsoon, which might play a significant role in lesser SST cooling in post-monsoon season compared to pre-monsoon season.

Present study raises a serious issue of wetland loss and transformation due to damming and water diversion. At present study, it is noticed that overall rainfall trend (−0.006) of the study period (1978–2015) remains unchanged but riparian wetland area is attenuated after damming both pre monsoon (March to May) and post monsoon season (October to December). Total wetland area in pre- and post- monsoon seasons is respectively reduced from 42.2 km 2 to 27.87 km 2 , and from 277.85 km 2 to 220.90 km 2 in post dam period. Transformation of frequently inundated wetland area into sparsely inundated wetland is mainly triggered by flow modification due to installation of Komardanga dam and Barrage over Punarbhaba and its major tributary Tangon river. Sparsely inundated seasonal wetland area is rapidly reclaimed for agricultural practice. This extreme issue will invite instability in socio-ecological setup of the neighbouring region.

The present study focuses on a GIS-based assessment and characterization of groundwater quality using pre monsoon and post monsoon groundwater quality data. Spatio-temporal variations of water quality parameters in the study area were analysed by using GIS techniques. Maximum area of Jaisamand catchment showed the drinking water quality within permissible limit. EC somewhat extent within permissible limit during pre monsoon period. Sulphate content also exceeded from permissible limit some extent in pre monsoon period but in post monsoon period it was within permissible range. The maximum total dissolved solids were found in western site of study area during pre monsoon period whereas in post monsoon period maximum area showed total dissolved solids within permissible range.

The processes in Stratosphere and Troposphere are strongly correlated with each other and exchange of water vapor, momentum and energy between these two layers have much significance on climate. Recent studies indicate that stratospheric water vapor and its variability play an important role in changing climate. High-resolution data, even though available only at few locations, are highly useful for the analysis of stratosphere troposphere exchange. A stratosphere-troposphere (ST) radar (205 MHz) is operational at the Advanced Centre for Atmospheric Radar Research (10.04N; 76.33E), Cochin University of Science and Technology, India. This radar provides accurate measurements of upper troposphere-lower stratosphere (UTLS) region. Observations made during May 16 – 19, 2017, few days prior to the onset of Indian summer monsoon show that strong convection reached the tropopause height and disturbed the tropopause.

This study focuses on the seasonal variability of precipitation in the State of Karnataka, India over the period of 115 years (1901–2015). Gridded rainfall data of 0.5° × 0.5° resolution (CRU TS 4) was taken into account. The data were converted and rearranged into a 12 × 115 matrix form by using QGIS (2.18.24) and MATLAB. The processed data were then formulated into seasonal and annual series. Seasonal series were prepared based on the guidelines given by IMD, Karnataka. Based on this the seasons were divided as winter (Jan – Feb), pre monsoon (March – May), southwest monsoon (June – September), and northeast monsoon (October – December). For each grid point the annual and seasonal variations were observed by plotting them in QGIS.

Water of good drinking quality is of basic importance to physiology and man’s continued existence depends very much on its availability. The objective of this study is to understand the seasonal variations in the physiochemical parameters of the ground water of three sites of Sanganer Tehsil of Jaipur district, Rajasthan using statistical tools. The methodology utilized is to carry out the research ground water samples were collected for pre monsoon, monsoon and post monsoon period of a year. For this purpose five samples were collected from each location and the process of chemical analysis was conducted. With the help of one-way ANOVA test, the difference between the three locations based on the parameters were calculated. The findings of this paper was that the ground water of these three location shows seasonal variations in all eleven parameters using statistical methods like paired t-test and Analysis of Variance (ANOVA) tests. The groundwater of all the sites is not suitable for drinking & industrial purposes which will help the local government to take necessary action.

To combat the present COVID-19 pandemic, a countrywide lockdown (LD) was imposed in India from 25 March until 31 May 2020 This unique scenario brought a decline in various anthropogenic activities leading to a considerable decrease in the concentration of several atmospheric pollutants In this scenario, CSIR-IMMT Bhubaneswar carried out black carbon (BC), PM10 and PM2 5 analysis through optical and gravimetric measurements, respectively, during March-May 2020 followed by a comparison with previous years (2017-2018) of observation There was a reduction of similar to 33% in average overall BC concentration along with a significant drop in PM10 (33%) (P < 0 05) and PM2 5 (similar to 38%) (P < 0 05) during the entire LD period as compared to 2017-2018 During LD, contribution from biomass burning was enhanced by almost 3 times as compared to 2017-2018 However, the simultaneous meteorological variation during the LD period prevents clear distinction of the impact of lockdown on BC and PM

Thermodynamic indices have been used as a tool for nowcasting thunderstorms for decades. The present study deals with understanding the variations in threshold values of various thermodynamic indices during pre-monsoon season at two north-eastern Indian stations: Agartala and Guwahati. The study utilises thirty years (1987–2016) of radiosonde data, surface information about thunderstorms, and TRMM daily rainfall data. The threshold values for five years period interval each has been determined for fourteen thermodynamic indices to the whole period. The indices related to latent, potential and convective instability responded differently at both the sites.

The potential role of aerosol loading on the Indian summer monsoon rainfall during the El Nino years are examined using satellite-derived observations and a state of the art fully interactive aerosol-chemistry-climate model. The Aerosol Index (AI) from TOMS (1978–2005) and Aerosol Optical Depth (AOD) from MISR spectroradiometer (2000–2010) indicate a higher-than-normal aerosol loading over the Indo-Gangetic plain (IGP) during the pre-monsoon season with a concurrent El Nino. Sensitivity experiments using ECHAM5-HAMMOZ climate model suggests that this enhanced loading of pre-monsoon absorbing aerosols over the Indo-Gangetic plain can reduce the drought during El Nino years by invoking the ‘Elevated-Heat-Pump’ mechanism through an anomalous aerosol-induced warm core in the atmospheric column. This anomalous heating upshot the relative strengthening of the cross-equatorial moisture inflow associated with the monsoon and eventually reduces the severity of drought during El Nino years. The findings are subject to the usual limitations such as the uncertainties in observations, and limited number of El Nino years (during the study period).

All season multiyear characterization of the aerosol optical depths (AOD) & absorbing aerosol index (AI) was carried out over Indian subcontinent using simultaneous data from MODIS satellite sensors. Significant spatio-temporal heterogeneity was found in the aerosol optical depths over Indian subcontinent. Latitudinal, MODIS derived Aerosol optical depths (AOD), its Small mode fraction (SMF, except pre monsoon) has shown increasing trends towards northern latitudes of Indian subcontinent. Pre monsoon mean AI values were found to increase linearly from a minimum of ~0.52 over the southern India region to a maximum of 3 over the central India region head at around 26.50 N at a rate of 0.001 per degree latitude while there was an exponential decay during winter and post monsoon. Longitudinally, the variations in the aerosol properties are subdued comparatively. SMF values tend to increase weakly towards eastern longitudes during all the seasons. Variations in the aerosol properties are parameterised using best fit analytical functions. By simultaneous examination of AI, AOD and SMF, it was inferred that the aerosol load was found responsible for the higher values of AI over Indian subcontinent during pre-monsoon which was further dominated by the transported UV-absorbing dust.

Northeastern Region (NER) of India commonly experiences the occurrence of rigorous convective squalls, commonly known as Thunderstorms (TS) or Nor’westers through the months of March to May. This study utilizes satellite images of Kalpana-1 satellite in Thermal Infrared (TIR) and Water Vapor (WV) channels to identify TS genesis, frequency, and track over the NER. The results obtained have been compared with Indian Meteorological Department (IMD) reports to check the accuracy of satellite image interpretations. 81 TS were detected over NER of India with 38 in the month of April and 43 in the month of May. The duration of TS follows an exponential distribution with maximum TS having lifetime of an hour or less and a few having lifetime of about 8–9 h. The TS occurred almost during any time domain of a day with maximum number of them occurring between 16 and 20 UTC. Most of the systems were formed and dissipated over the NER, while some systems were formed over the northwestern parts of Bihar, Jharkhand, and West Bengal and moved toward the NER under the influence of the Nor’westers collecting moisture, maturing, and dissipating over the NER. The dominant wind was from the northwest during the season. The precipitation from these TS accounts for 20–25% of annual rainfall and is very important for the agrarian economy of this region. The interpreted TS was found to be lesser (67%) than the number of events reported by IMD reports primarily because of the limitations in spatial resolution of the sensor.

Geogenic arsenic (As) contamination in Bengal Delta Plain is a growing environmental and research concern. Cultivation of staple crops like paddy on these contaminated fields is one of the major routes for human dietary exposure. The present study investigates changes of arsenic concentrations in paddy plant parts, root soil and surface soil throughout the various phases of pre-monsoon (boro) cultivation. Arsenic uptake property of paddy plants collected from 10 fields was found to be dependent on the variety of paddy plant (like Minikit, Jaya) rather than arsenic levels in groundwater (0.074–0.301 mg/l) or soil (25.3–60 mg/kg). Arsenic is translocated from root to aerial parts in descending order. Leaf, stem, root, root soil and surface soil showed a similar trend in their change of arsenic concentration throughout the cultivation period. Arsenic concentration was highest in vegetative phase; sharply declined in reproductive phase; followed by moderate increase in ripening phase. The young root tissues in vegetative (primary) phase could uptake arsenic at a much faster rate than the older tissues in later phases. With the growth of the plant, higher concentrations of iron in root soil in the reproductive phase confirmed the formation of iron plaques on the surface of the root, which sequester arsenic and prevented its uptake by plants. Finally, co-precipitation of arsenic with iron released from crystallized iron plaques results in loosening of the iron plaques from root surface. Thus, soil arsenic concentration increases in the final phase of cultivation which in turn contributes to increased concentration in plant parts.

The study examines the impact of pre-monsoon rainfall deviation on maize yield in Manipur. Secondary data on rainfall was extracted from high resolution 0.50×0.50 daily gridded data obtained from India Meteorological Department for the period of twenty-eight years (1980-2007). The annual yield of maize was regressed on time trend and rainfall (January, February, March, April, May). Different regression models were worked out using different explanatory variables and functional form and the log-lin model turns out to be the best model based on logistic (sign and coefficients), statistical (p-value) and econometric (value of R-square) criteria. The regression model shows that time trend has positive and significant (1% level of significance) impact on yield of maize and March rainfall deviation has negative and significant (5% level of significance) impact on yield of maize. This is because, in Manipur, the tasseling and silking stage (critical stage of maize) falls during March. Hence, 1 per cent increase in March deviation leads to 5.6 unit decrease in yield of maize. The study recommended planting of drought-tolerant maize variety in the study area.

The medium range weather forecast issued from NCMRWF, Noida on rainfall, maximum temperature, minimum temperature and wind speed for the last 18 years (1999-2016) has been verified with observed weather parameters recorded at agrometeorological observatory, Sardarkrushinagar to known its accuracy. The results revealed that the usability of rainfall was higher in pre monsoon, post monsoon and winter seasons. However, during monsoon, the accuracy of rainfall forecast was 78 percent with RMSE value of 15.3 that indicated the lower accuracy. The maximum temperature forecast accuracy was very good varied from 76 to 88% in different seasons. Similarly, minimum temperature forecast was excellent in monsoon season (88%), and poor in winter season (57%). The wind speed forecast was excellent in all the seasons.

Available with full text.The Himalayan Physics Vol. 5, No. 5, Nov. 2014Page: 59-68

Ariyalur is one of the districts in Tamilnadu it is rich in limestone resource. A study on geochemical characterization of ground water and its suitability for drinking purposes was carried out. Twenty five groundwater samples were collected from bore wells and open wells during Pre monsoon seasons of 2014. Groundwater is the main principle source for drinking, irrigation water and other activities in our study area. It is an indispensable source of our life. The problem of groundwater quality obtains high importance in this present-day, whether in the study area or any other countries in the world. The present study was carried out to analyse and evaluate the groundwater samples collected from residential areas of Udayarpalyam Taluk. The analyzed physicochemical parameters such as pH, electrical conductivity, total dissolved solids, calcium, magnesium, sodium, potassium, bicarbonate, sulphate, phosphates, chloride, nitrate, and fluoride are used to characterize the groundwater quality and its suitability for drinking uses. Calcium, sodium, chloride and sulphate are the dominant ions in the groundwater chemistry. The Groundwater is not suitable for drinking purposes at several locations in this area. Each parameter was compared with its standard permissible limit as prescribed by WHO/BIS. The analytical results indicated that the ground water quality was found unsatisfactory for drinking purpose in some location.

Attempt has been made to characterize the hydrodynamic regime around the coastal waters of Goa for a pre-monsoon season, using MOHID, a two-dimensional finite volume model. The numerical model was forced with tides at open boundaries and calibrated using measured water levels and currents, during pre-monsoon season. The modeled water levels and currents were compared with field observations and found to be satisfactory, with correlation of 0.97 for water levels, 0.79 for zonal currents, and 0.84 for meridional currents. The ratio of diurnal (O1, K1) and semidiurnal (M2, S2) constituents was 0.63, suggesting that tides in this region are mixed, mainly semidiurnal in nature. The variation in amplitude of tidal constituents from the open boundary to the mouth and upstream of the Mandovi and Zuari estuaries has been modeled and compared with previous field studies and found to be satisfactory. The details of numerical scheme, methodology, and results are discussed in this paper.

Desert dust over the Indian region during pre-monsoon season is known to strengthen monsoon circulation, by modulating rainfall through the elevated heat pump (EHP) mechanism. In this context, an insight into long term trends of dust loading over this region is of significant importance in understanding monsoon variability. In this study, using long term (2000 to 2015) aerosol measurements from multiple satellites, ground stations and model based reanalysis, we show that dust loading in the atmosphere has decreased by 10 to 20% during the pre-monsoon season with respect to start of this century. Our analysis reveals that this decrease is a result of increasing pre-monsoon rainfall that in turn increases (decreases) wet scavenging (dust emissions) and slowing circulation pattern over the Northwestern part of the sub-continent.

Animal can respond to any environmental or non-environmental stress through several physiological mechanisms such as respiratory rate, heart rate and rectal temperature, which are excellent parameter to quantify the heat tolerance in any animal. The aim of the present study is to evaluate the effect of the variation of ambient temperature on the physiological mechanisms of the goat as well as using a geographical information system in the present study is to facilitate the spatial component of goat physiological parameters to be included in the reporting and analysis of animal health data. Different physiological parameters of Black Bengal goats have not any significant variation among the different study points within a specific region however these physiological parameters are significantly higher during in the pre-monsoon than the post monsoon season irrespective of the region. For the present study, the ability of GIS to link graphic and non-graphic data facilitates prevailing analysis of different non-spatial distribution and related issues. This model can be applied to animal disease control as an integral component of supporting system concerning decisions in the field of veterinary science.

In this study, the trends of seasonal maximum and minimum temperatures and rainfall time series were investigated for 9 selected stations in the north eastern India with the available data stretching between the years 1913-2012.During the period under study the minimum temperature has increasing trends in almost all the stations of north east India except Cherrapunji where it shows decreasing trend in all the season of the year. In case of maximum temperature Cherrapunji, Guwahati and Imphal show increasing trends during all the seasons. Agartala and Shillong show increasing trend of maximum temperature during monsoon and post monsoon season. Dibrugarh and Pasighat show decreasing trend during pre monsoon season and increasing trend during all other seasons of the year. Gangtok shows decreasing trend of maximum temperature during all the seasons where as Silchar shows no trend in maximum temperature.Out of all the selected nine stations, most of the stations show either decreasing trend or no trend of rainfall except Guwahati which shows significant increasing trend of rainfall during post monsoon season.

The pre-monsoon tropical cyclone (TC) activity and the monsoon evolution in the Bay of Bengal (BoB) are both influenced by the Madden–Julian Oscillation (MJO), but the two do not always occur in unison. This study examines the conditions that allow the MJO to modulate the monsoon onset in Myanmar and TC activity concurrently. Using the APHRODITE gridded precipitation and the ERA-Interim reanalysis datasets, composite evolutions of monsoon rainfall and TC genesis are constructed for the period of 1979–2010. It is found that the MJO exhibits a strong interannual variability in terms of phase and intensity, which in some years modulate the conditions for BoB TCs to shortly precede or form concurrently with the monsoon onset in Myanmar. Such a modulation is absent in years of weaker MJO events. Further understanding of the interannual variability of MJO activity could facilitate the prediction of the monsoon onset and TC formation in the BoB.

Prediction of thunderstorms is a challenging task for a forecaster as their spatial scale is small and lifespan is short. This study aims at evaluating the skill of stability indices with specific thresholds in relation to forecasting thundery and non-thundery days over Bangalore. A total of nine indices derived from radiosonde/radiowind data of Bangalore during 1991-2003 are treated as predictors and their statistical parameters were computed. The Z test (Zxy) was applied to find out significant predictors and the skill score method was used for finding the threshold value amongst the significant predictors. The threshold value of selected predictors is obtained by maximising normalised skill score. The results show that significant indices K (> 33 oC) and SHIm (< 3 oC) are most efficient predictors for 0000 UTC while SLI (< - 4 oC) and DCI (> 44 oC) are most efficient predictors for 1200UTC. These results were verified for pre-monsoon period of 2004-2006 over Bangalore.

The contributions of Coherent Structures (CS) to fluxes of momentum and heat have been analyzed for night time stable conditions during pre-monsoon thunderstorm periods over two tropical stations: Kharagpur and Ranchi. Fast response data recorded using sonic anemometers have been used for 2007, 2009 and 2010 for Kharagpur and 2008–2010 for Ranchi. The signals were decomposed in several time scales and then used for zero-crossing method using discrete wavelet transform. Significant contributions by CS have been found for both momentum and heat flux at both the sites and these contributions during night time stable conditions differs for days with a thunderstorm activity from a clear day with no activity, even though at both sites thunderstorm events are occurring during daytime unstable conditions.

A training period of lightning location data usage has been carried out in Nepal during the pre-monsoon season April–June 2012. The training was one part of a Finnish–Nepalese Project (FNEP) between the Department of Hydrology and Meteorology of Nepal (DHM) and the Finnish Meteorological Institute (FMI). FNEP aimed for the development of operational meteorological readiness in a developing country such as Nepal. The lightning location training included the introduction to lightning location techniques and principles and the actual hands-on training for the operational DHM forecasters. The lightning location system used was the Vaisala long range Global Lightning Dataset 360 (GLD360), which has practically a global coverage. During the three months of training, a dataset of Nepalese lightning was also collected, indicating the pre-monsoon thunderstorm characteristics of Nepal.

Aerosol optical and microphysical properties were studied at two major industrial cities (Delhi and Kanpur) of the Indo-Gangetic Basin (IGB) during three (2007-2009) consecutive pre-monsoon (PrM: March-May) seasons, using synergetic analyses of CALIOP, MODIS, AERONET and PARASOL observations. CALIOP-derived aerosol properties show vertically elevated aerosol profiles (up to 4 km altitude), majorly consisting of dust particles during all three PrM seasons with maximum loading in May, 2008. The above inference is well corroborated with columnar aerosol properties from MODIS and AERONET observations. The results also show higher aerosol optical depth (AOD) over Delhi as compared to Kanpur. The high aerosol loading found during the late PrM season at both locations can be attributed to the fact that dust/burning activities are at their peak in May during the PrM season over the IGB. The analyses of optical and microphysical parameters coupled with backward trajectory analyses indicate the presence of three different aerosol types (Type I, Type II and Type III) over both cities during PrM 2009. Type I is characterized as dust-dominated aerosols coming via long-range transportation from major dust sources (desert of Sahara, Iran, Afghanistan and western India), whereas a mixture of absorbing aerosols and dust coming from the Arabian Peninsula and the Thar Desert is characterized as Type II aerosols. The presence of highly absorbing, fine mode dominated Type III aerosols are categorized as urban-industrial/biomass burning aerosols, mainly locally originated and/or influenced by agriculture fires in the Himalayan foothills. A combination of CALIOP and PARASOL observations with ground-based measurements also highlights the dominance of biomass burning smoke (mixed with polluted continental) over the IGB during the middle of May in 2009. The variability in aerosol types found during the PrM season indicates the significant effect of natural/human activities, associated with different meteorological conditions, on aerosol behavior over the region.

Surface water samples were collected from 21 sampling sites throughout the Subarnarekha River during pre monsoon, monsoon and post monsoon seasons. The concentrations of metals were determined using inductively coupled plasma-mass spectrometry (ICP-MS) for the seasonal fluctuation, source apportionment and risk assessment. The results demonstrated that concentrations of the metals showed significant seasonality and most variables exhibited higher levels in the pre monsoon season. Principal component analysis (PCA) outcome of four factors together explained 76.9% of the variance with >1 initial eigenvalue indicated both innate and anthropogenic activities are contributing factors as source of metal profusion in Subarnarekha River. Risk of metals on human health was then evaluated using hazard quotients (HQ) by ingestion and dermal pathways for adult and child and it was indicated that As with HQingestion > 1, was the most important pollutant leading to non-carcinogenic concerns. The largest contributors to chronic risks were As, V and Co, in all the seasons. The HQdermal of all the elements for adult and child were below unity, suggesting that the metals posed little hazards via dermal absorption indicating that the oral intake was the primary exposure pathway.

Water quality rating methods provide a single number that reflects the combined influence of different water quality parameters and is of much significance in the sustainable development of a watershed. pH, EC, TDS, total alkalinity, total hardness, chloride, nitrate and sulphate were used to calculate WQI in weighted arithmetic index method. Accordingly water quality is classified as excellent, good, poor, very poor and unfit for drinking. Thematic maps for the study area were prepared from SOI toposheets and IRS P6 LISSIII image (P100/R67) using Arc GIS 9.2 software. Spatial distribution maps were prepared for both watersheds by adding WQI index values as attribute data. In both sub-watersheds, percentage of excellent category is higher during Post monsoon season compared to other two seasons. When both sub-watersheds are compared Vagamon has better water quality than Peermade sub-watershed. It is represented by 44.44% excellent, 44.44% good and 11.12% poor category of WQI during Pre monsoon season; 33.33% excellent and 66.67% good category of WQI during Monsoon season; and 77.78% excellent and 22.22% good category WQI during Post monsoon season. The corresponding values for Peermade sub-watershed, for different seasons are 36.36% excellent and good, 18.18% poor and 9.10% very poor WQI during Pre monsoon; 36.36% excellent, 54.55% good and 9.09% poor WQI during Monsoon; and 45.45% excellent and good and 9.10% very poor category WQI during Post monsoon season.

Heavy metal analysis of the surface waters from Vishwamitri River was conducted in pre-monsoon, monsoon and post-monsoon seasons during year 2015-2016. Samples were collected and analysed from various sampling stations along the Vishwamitri with a view to assess and analyse the concentration of various metals, i.e., Cd, Cu, Fe, Pb, Mn, Hg, Ni and Zn. The overall mean concentration revealed the toxicity level of heavy metals in the following order Pb>Fe>Hg>Cd>Ni>Cu>Mn>Zn. pH values were observed less than seven and consequently concentrations of most of the heavy metals were observed high in downstream stretch. Identification of point and non-point sources of heavy metal pollution in Vishwamitri is necessary. Suitability of Vishwamitri water is to be assessed for drinking purposes. Assessment regarding the biotoxic effects of heavy metals concentration and adoption of appropriate treatments and controlling measures to reduce metallurgical effluent load deposited into the river is need of the hour.

Heterogeneity in aerosol characteristics was studied at five different locations over the Indo-Gangetic Basin (IGB) region during the pre-monsoon period (April–June 2011) using concurrent measurements from sun/sky radiometer, which is hypothesized to affect the Indian monsoon circulation and also the global climate system. Based on the measured aerosol products, distribution of aerosols and the associated optical properties were examined over the entire region. The pre-monsoon mean aerosol optical depth (AOD) was found to be maximum at Lahore (0.78) and Kanpur (0.68); however, a minimum AOD (∼0.6) was observed at Karachi, Jaipur and Gandhi College, with relatively high variability at Karachi and low at Gandhi College. On the other hand, a significant gradient in Angstrom exponent (AE) from Karachi (0.30) in the west to Gandhi College (0.98) in the east IGB region suggests relative dominance of coarse particles over the western part and fine particles at the eastern part of the IGB. Results are confirmed with the aerosol size distribution and the air mass back-trajectory analysis at all the stations. The corresponding pre-monsoon mean single scattering albedo (SSA) shows relatively higher value at Karachi (0.94), suggests relative dominance of scattering type particles. On the other hand, lower SSA, ranging from 0.85 to 0.92, was observed at the other stations, with the lowest value at Gandhi College (0.85), which suggests absorbing aerosol distributions over the region.

In the present work turbulent kinetic energy (TKE) budget and boundary layer characteristics are studied for an Indian tropical station Ranchi (23A degrees 25N, 85A degrees 26E), situated over Chot ...

Summer monsoon rainfall which gives 75–90% of the annual rainfall plays vital role in Indian economy as the food grain production in India is very much dependent on the summer monsoon rainfall. It has been suggested by recent studies that aerosol loading over the Indian region plays significant role in modulating the monsoon circulation and consequent rainfall distribution over the Indian sub-continent. Increased industrialization and the increasing deforestation over past few decades probably cause a gradual increase in the aerosol concentration. A significant negative relationship between pre-monsoon (March–May i.e. MAM) aerosol loading over BOB and IGP regions and the forthcoming monsoon rainfall have been observed from the thorough analysis of the fifteen years (1997–2011) monthly Total Ozone Mapping Spectrometer (TOMS) Aerosol Index (AI) and All-India Summer Monsoon Rainfall (AISMR) data. Composite analysis revealed that AI anomalies during pre-monsoon season are negative for excess year and positive for deficient monsoon years over the Indian subcontinent, with strong variation over Bay of Bengal (BOB) and Indo-Gangetic Plain (IGP) regions from the month of March onwards. The correlation coefficients between AISMR and pre-monsoon AI over BOB and IGP regions are found to be negative and significant at 5% level. The study clearly brings out that the pre-monsoon aerosol loading over the BOB and IGP regions has a significant correlational link with the forthcoming monsoon intensity; however a further study of the aerosol properties and their feedback to the cloud microphysical properties is asked for establishing their causal linkage.

An attempt has been made to differentiate percentage contribution of coherent structures (CS) in the turbulent fluxes of heat and momentum during thunderstorm days (TD) and non-thunderstorm days (NTD) at two tropical sites. Pre-monsoon months (Marcha to May) fast response data (10Hz) of wind and temperature at Kharagpur (22 degrees 30N, 87 degrees 20E) for years 2007, 2009, and 2010, and at Ranchi (23 degrees 25N, 85 degrees 26E) for years 2008-2010 have been used. The contributions were calculated after decomposing the time series using wavelet technique by two methods: (1) the method of quadrant analysis for each scale, and (2) the method of zero-crossing. Contributions of CS in momentum flux are higher in TD than NTD, whereas for heat flux CS contribution is higher for NTD to that of TD at both sites; however, values are different at both sites and by each method as well. Significant percentages of contributions of CS to the total flux are noticed at both the sites.

Thunderstorms associated with severe gusty winds and lightening cause loss of life and property even though they last for an hour or so. Forecasting of these severe weather events is highly essential due to their impact on socioeconomic conditions of affected regions. Kharagpur (22°30′ N, 87°20′ E) is in the region of Gangetic West Bengal (GWB) affected by high frequency of occurrence of thunderstorms during pre-monsoon months. In the present study an attempt has been made to understand the performance of convective parameterization schemes (e.g. Kain-Fritsch, Grell-Devenyi ensemble and Betts-Miller-Janjic) of a meso-scale model WRF-ARW version 3.2 in simulating pre-monsoon thunderstorm events that occurred during 12 May 2009 and 5 May 2010 over Kharagpur. Numerical experiments are carried out by considering convection explicitly. The model simulations are compared with the available observations. Statistical evaluation of simulated parameters along with the observations revealed Grell-Devenyi ensemble and KainFritsch schemes performed reasonably well in representing the thermodynamical state of atmosphere during the thunderstorm events. General Terms Mesoscale model, Statistical evaluation, Simulation.

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