Identifying the various components contributing to river discharge can be challenging.This study relies on stable isotopes and electrical conductivity(EC)of water as tracers to distinguish the different components con...Identifying the various components contributing to river discharge can be challenging.This study relies on stable isotopes and electrical conductivity(EC)of water as tracers to distinguish the different components contributing to total river discharge.Additionally,we have made an effort to comprehend the processes that may influence glacier ice melt as well as the limits of oxygen-based hydrograph separation.Two distinct geographic domains in terms of climates and topographies were examined.The first study site represents the upper Ganga catchment(central Himalaya),while the second site is located in the Chandra sub-basin in western Himalaya.Errors in estimating the proportion of glacier melt in isotope mixing model are likely if end-member isotopic compositions,are not well defined,particularly for rainfall.Hydrograph separation results indicate that snowmelt is the largest contributor to total river flow in both regions.The contribution of snowmelt to the total runoff of the upper Ganga ranged from~60%to 70%.The estimated contributions of glacier melt varied from 36%to 63%in upper Ganga headwater to 6%to 15%at Devprayag and~8%at Rishikesh.In the Hamtah River,glacier and snowmelt contributions,quantified using a two-component mixing model,ranged from 10%to 14%during the pre-and postmonsoon seasons of 2013.The significant spatial and temporal variability,coupled with overlapping isotopic signatures,suggests complex glacio-fluvial interactions in these catchments.Local slow-moving air masses with whirling motion closer to the study area irrespective of the direction,and air parcels coming through Bay of Bengal branch are characterized by depleted isotopic rainfall compared to air masses originating from the Arabian Sea.展开更多
The first measurements of cloud condensation nuclei （CCN） at five supersaturations were carried out onboard the research vessel ＂Sagar Kanya＂ （cruise SK-296） from the south to the head-bay of the Bay of Bengal a...The first measurements of cloud condensation nuclei （CCN） at five supersaturations were carried out onboard the research vessel ＂Sagar Kanya＂ （cruise SK-296） from the south to the head-bay of the Bay of Bengal as part of the Continental Tropical Convergence Zone （CTCZ） Project during the Indian summer monsoon of 2012. In this paper, we assess the diurnal variation in CCN distributions at supersaturations from 0.2% to 1% （in steps of 0.2%） and the power-law fit at supersaturation of 1%. The diurnal pattern shows peaks in CCN concentration （NccN） at supersaturations from 0.2% to 1% between 0600 and 0700 LST （local standard time, UTC＋0530）, with relatively low concentrations between 1200 and 1400 LST, followed by a peak at around 1800 LST. The power-law fit for the CCN distribution at different supersaturation levels relates the empirical exponent （k） of supersaturation （%） and the Nccy at a supersaturation of 1%. The Nccy at a supersaturation of 0.4% is observed to vary from 702 cm-3 to 1289 cm-3, with a mean of 961 ＋ 161 cm-3 （95% confidence interval）, representing the CCN activity of marine air masses. Whereas, the mean Nccy of 1628 ＋ 193 cm-3 at a supersaturation of 1% is higher than anticipated for the marine background. When the number of CCN spectra is 1293, the value of k is 0.57 ± 0.03 （99% confidence interval） and its probability distribution shows cumulative counts significant at k ≈ 0.55 ± 0.25. The results are found to be better at representing the features of the marine environment （103 cm-3 and k ≈ 0.5） and useful for validating CCN closure studies for Indian sea regions.展开更多
The Mahanadi delta,deposited on a series of horst and graben basement structures,is considered an extension of the East Lambert Rift of Antarctica.Current study is based on the hydrogeochemical assessment of this delt...The Mahanadi delta,deposited on a series of horst and graben basement structures,is considered an extension of the East Lambert Rift of Antarctica.Current study is based on the hydrogeochemical assessment of this deltaic aquifer system and geospatial analysis thereof,to appreciate the basement structure influence on groundwater chemistry.Major ion chemistry of subsurface waters portrays a distinct saline contamination across the terrain and varied regimes of water types,specifically with respect to southern and northern parts of this aquifer system.Findings of the study indicate a general near surface saline horizon and significant fragmentation of the hydrostatic units.This,in turn,implies noteworthy influence of formational water to salinity regimes and basin structural changes for the escape of these waters to surroundings.A plot of recent low intensity earthquakes displays proximity of epicenters to the faults as well as striking similarity to the trend of terrestrial faults indicating multiple reactivations of the faults.To further corroborate the above findings,spatial pattern analysis of individual hydrochemical variables is carried out which reveals specific clusters of sources(groundwater mixing)and sinks(groundwater dispersion) in proximity to basement fault dispositions.While the faults can be disregarded as conduits or barriers owing to their great depth,the overlying sedimentary mass,particularly,the horizons with significant clayey content have been distorted due to post rift subsidence and fault reactivations.A proximity analysis of ionic clusters points towards a greater influence of longitudinal faults to that of the transverse ones on groundwater mixing or dispersion.展开更多
The authors report the results of aethalometer black carbon(BC)aerosol measurements carried out over a rural(pristine)site,Panchgaon,Haryana State,India during the winter months of 2021-2022 and 2022-2023.They are com...The authors report the results of aethalometer black carbon(BC)aerosol measurements carried out over a rural(pristine)site,Panchgaon,Haryana State,India during the winter months of 2021-2022 and 2022-2023.They are compared with collocated and concurrent observations from the Air Quality Monitoring Station(AQMS),which provides synchronous air pollution and surface meteorological parameters.Secular variations in BC mass concentration are studied and explained with variations in local meteorological parameters.The biomass burning fire count retrievals from NASA-NOAA VIIRS satellite,and backward airmass trajectories from NOAA-ERL HYSPLIT Model analysis have also been utilized to explain the findings.They reveal that the north-west Indian region contributes maximum to the BC mass concentration over the study site during the study period.Moreover,the observed BC mass concentrations corroborate the synchronous fire count,primary and secondary pollutant concentrations.The results were found to aid the development of mitigation methods to achieve a sustainable climate system.展开更多
基金the project entitled“Finger printing of glacial melt water in the Ganga basin-implications for modelling of hydrological cycle in a Himalayan River system”grant number NO.SR/DGH-46/2012 which supported work for this paper。
文摘Identifying the various components contributing to river discharge can be challenging.This study relies on stable isotopes and electrical conductivity(EC)of water as tracers to distinguish the different components contributing to total river discharge.Additionally,we have made an effort to comprehend the processes that may influence glacier ice melt as well as the limits of oxygen-based hydrograph separation.Two distinct geographic domains in terms of climates and topographies were examined.The first study site represents the upper Ganga catchment(central Himalaya),while the second site is located in the Chandra sub-basin in western Himalaya.Errors in estimating the proportion of glacier melt in isotope mixing model are likely if end-member isotopic compositions,are not well defined,particularly for rainfall.Hydrograph separation results indicate that snowmelt is the largest contributor to total river flow in both regions.The contribution of snowmelt to the total runoff of the upper Ganga ranged from~60%to 70%.The estimated contributions of glacier melt varied from 36%to 63%in upper Ganga headwater to 6%to 15%at Devprayag and~8%at Rishikesh.In the Hamtah River,glacier and snowmelt contributions,quantified using a two-component mixing model,ranged from 10%to 14%during the pre-and postmonsoon seasons of 2013.The significant spatial and temporal variability,coupled with overlapping isotopic signatures,suggests complex glacio-fluvial interactions in these catchments.Local slow-moving air masses with whirling motion closer to the study area irrespective of the direction,and air parcels coming through Bay of Bengal branch are characterized by depleted isotopic rainfall compared to air masses originating from the Arabian Sea.
文摘The first measurements of cloud condensation nuclei （CCN） at five supersaturations were carried out onboard the research vessel ＂Sagar Kanya＂ （cruise SK-296） from the south to the head-bay of the Bay of Bengal as part of the Continental Tropical Convergence Zone （CTCZ） Project during the Indian summer monsoon of 2012. In this paper, we assess the diurnal variation in CCN distributions at supersaturations from 0.2% to 1% （in steps of 0.2%） and the power-law fit at supersaturation of 1%. The diurnal pattern shows peaks in CCN concentration （NccN） at supersaturations from 0.2% to 1% between 0600 and 0700 LST （local standard time, UTC＋0530）, with relatively low concentrations between 1200 and 1400 LST, followed by a peak at around 1800 LST. The power-law fit for the CCN distribution at different supersaturation levels relates the empirical exponent （k） of supersaturation （%） and the Nccy at a supersaturation of 1%. The Nccy at a supersaturation of 0.4% is observed to vary from 702 cm-3 to 1289 cm-3, with a mean of 961 ＋ 161 cm-3 （95% confidence interval）, representing the CCN activity of marine air masses. Whereas, the mean Nccy of 1628 ＋ 193 cm-3 at a supersaturation of 1% is higher than anticipated for the marine background. When the number of CCN spectra is 1293, the value of k is 0.57 ± 0.03 （99% confidence interval） and its probability distribution shows cumulative counts significant at k ≈ 0.55 ± 0.25. The results are found to be better at representing the features of the marine environment （103 cm-3 and k ≈ 0.5） and useful for validating CCN closure studies for Indian sea regions.
文摘The Mahanadi delta,deposited on a series of horst and graben basement structures,is considered an extension of the East Lambert Rift of Antarctica.Current study is based on the hydrogeochemical assessment of this deltaic aquifer system and geospatial analysis thereof,to appreciate the basement structure influence on groundwater chemistry.Major ion chemistry of subsurface waters portrays a distinct saline contamination across the terrain and varied regimes of water types,specifically with respect to southern and northern parts of this aquifer system.Findings of the study indicate a general near surface saline horizon and significant fragmentation of the hydrostatic units.This,in turn,implies noteworthy influence of formational water to salinity regimes and basin structural changes for the escape of these waters to surroundings.A plot of recent low intensity earthquakes displays proximity of epicenters to the faults as well as striking similarity to the trend of terrestrial faults indicating multiple reactivations of the faults.To further corroborate the above findings,spatial pattern analysis of individual hydrochemical variables is carried out which reveals specific clusters of sources(groundwater mixing)and sinks(groundwater dispersion) in proximity to basement fault dispositions.While the faults can be disregarded as conduits or barriers owing to their great depth,the overlying sedimentary mass,particularly,the horizons with significant clayey content have been distorted due to post rift subsidence and fault reactivations.A proximity analysis of ionic clusters points towards a greater influence of longitudinal faults to that of the transverse ones on groundwater mixing or dispersion.
文摘The authors report the results of aethalometer black carbon(BC)aerosol measurements carried out over a rural(pristine)site,Panchgaon,Haryana State,India during the winter months of 2021-2022 and 2022-2023.They are compared with collocated and concurrent observations from the Air Quality Monitoring Station(AQMS),which provides synchronous air pollution and surface meteorological parameters.Secular variations in BC mass concentration are studied and explained with variations in local meteorological parameters.The biomass burning fire count retrievals from NASA-NOAA VIIRS satellite,and backward airmass trajectories from NOAA-ERL HYSPLIT Model analysis have also been utilized to explain the findings.They reveal that the north-west Indian region contributes maximum to the BC mass concentration over the study site during the study period.Moreover,the observed BC mass concentrations corroborate the synchronous fire count,primary and secondary pollutant concentrations.The results were found to aid the development of mitigation methods to achieve a sustainable climate system.
