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We investigated the effect of low-fat (2.5%) dahi containing probiotic Lactobacillus acidophilus and Lactobacillus casei on progression of high fructose-induced type 2 diabetes in rats. Diabetes was induced in male albino Wistar rats by feeding 21% fructose in water. The body weight, food and water intakes, fasting blood glucose, glycosylated hemoglobin, oral glucose tolerance test, plasma insulin, liver glycogen content, and blood lipid profile were recorded. The oxidative status in terms of thiobarbituric acid-reactive substances and reduced glutathione contents in liver and pancreatic tissues were also measured. Values for blood glucose, glycosylated hemoglobin, glucose intolerance, plasma insulin, liver glycogen, plasma total cholesterol, triacylglycerol, low-density lipoprotein cholesterol, very low-density lipoprotein cholesterol, and blood free fatty acids were increased significantly after 8 wk of high fructose feeding; however, the dahi-supplemented diet restricted the elevation of these parameters in comparison with the high fructose-fed control group. In contrast, high-density lipoprotein cholesterol decreased slightly and was retained in the dahi-fed group. The dahi-fed group also exhibited lower values of thiobarbituric acid-reactive substances and higher values of reduced glutathione in liver and pancreatic tissues compared with the high fructose-fed control group. The probiotic dahi-supplemented diet significantly delayed the onset of glucose intolerance, hyperglycemia, hyperinsulinemia, dyslipidemia, and oxidative stress in high fructose-induced diabetic rats, indicating a lower risk of diabetes and its complications.

The present study focuses on identifying the main atmospheric circulation characteristics associated with aerosol episodes (AEs) over Kanpur, India during the period 2001–2010. In this respect, mean sea level pressure (MSLP) and geopotential height of 700 hPa (Z700) data obtained from the NCEP/NCAR Reanalysis Project were used along with daily Terra-MODIS AOD₅₅₀ data. The analysis identifies 277 AEs [AOD₅₀₀ > [Formula: see text] ₅₀₀ + 1STDEV (standard deviation)] over Kanpur corresponding to 13.2 % of the available AERONET dataset, which are seasonally distributed as 12.5, 9.1, 14.7 and 18.6 % for winter (Dec–Feb), pre-monsoon (Mar–May), monsoon (Jun–Sep) and post-monsoon (Oct–Nov), respectively. The post-monsoon and winter AEs are mostly related to anthropogenic emissions, in contrast to pre-monsoon and monsoon episodes when a significant component of dust is found. The multivariate statistical methods Factor and Cluster Analysis are applied on the dataset of the AEs days’ Z700 patterns over south Asia, to group them into discrete clusters. Six clusters are identified and for each of them the composite means for MSLP and Z700 as well as their anomalies from the mean 1981–2010 climatology are studied. Furthermore, the spatial distribution of Terra-MODIS AOD₅₅₀ over Indian sub-continent is examined to identify aerosol hot-spot areas for each cluster, while the SPRINTARS model simulations reveal incapability in reproducing the large anthropogenic AOD, suggesting need of further improvement in model emission inventories. This work is the first performed over India aiming to analyze and group the atmospheric circulation patterns associated with AEs over Indo-Gangetic Plains and to explore the influence of meteorology on the accumulation of aerosols.

Aerosol particles can contribute to the Arctic amplification (AA) by direct and indirect radiative effects. Specifically, black carbon (BC) in the atmosphere, and when deposited on snow and sea ice, has a positive warming effect on the top-of-atmosphere (TOA) radiation balance during the polar day. Current climate models, however, are still struggling to reproduce Arctic aerosol conditions. We present an evaluation study with the global aerosol-climate model ECHAM6.3-HAM2.3 to examine emission-related uncertainties in the BC distribution and the direct radiative effect of BC. The model results are comprehensively compared against the latest ground and airborne aerosol observations for the period 2005–2017, with a focus on BC. Four different setups of air pollution emissions are tested. The simulations in general match well with the observed amount and temporal variability in near-surface BC in the Arctic. Using actual daily instead of fixed biomass burning emissions is crucial for reproducing individual pollution events but has only a small influence on the seasonal cycle of BC. Compared with commonly used fixed anthropogenic emissions for the year 2000, an up-to-date inventory with transient air pollution emissions results in up to a 30 % higher annual BC burden locally. This causes a higher annual mean all-sky net direct radiative effect of BC of over 0.1 W m−2 at the top of the atmosphere over the Arctic region (60–90∘ N), being locally more than 0.2 W m−2 over the eastern Arctic Ocean. We estimate BC in the Arctic as leading to an annual net gain of 0.5 W m−2 averaged over the Arctic region but to a local gain of up to 0.8 W m−2 by the direct radiative effect of atmospheric BC plus the effect by the BC-in-snow albedo reduction. Long-range transport is identified as one of the main sources of uncertainties for ECHAM6.3-HAM2.3, leading to an overestimation of BC in atmospheric layers above 500 hPa, especially in summer. This is related to a misrepresentation in wet removal in one identified case at least, which was observed during the ARCTAS (Arctic Research of the Composition of the Troposphere from Aircraft and Satellites) summer aircraft campaign. Overall, the current model version has significantly improved since previous intercomparison studies and now performs better than the multi-model average in the Aerosol Comparisons between Observation and Models (AEROCOM) initiative in terms of the spatial and temporal distribution of Arctic BC.

Ship-borne observations of spectral aerosol optical depth (AOD) have been carried out over the entire Bay of Bengal (BoB) as part of the W-ICARB cruise campaign during the period 27 December 2008–30 January 2009. The results reveal a pronounced temporal and spatial variability in the optical characteristics of aerosols mainly due to anthropogenic emissions and their dispersion controlled by local meteorology. The highest aerosol amount, with mean AOD500>0.4, being even above 1.0 on specific days, is found close to the coastal regions in the western and northern parts of BoB. In these regions the Ångström exponent is also found to be high (~1.2–1.25) indicating transport of strong anthropogenic emissions from continental regions, while very high AOD500 (0.39±0.07) and α380–870 values (1.27±0.09) are found over the eastern BoB. Except from the large α380–870 values, an indication of strong fine-mode dominance is also observed from the AOD curvature, which is negative in the vast majority of the cases, suggesting dominance of an anthropogenic-pollution aerosol type. On the other hand, clean maritime conditions are rather rare over the region, while the aerosol types are further examined through a classification scheme based on the relationship between α and dα. It was found that even for the same α values the fine-mode dominance is larger for higher AODs showing the strong continental influence over the marine environment of BoB. Furthermore, there is also an evidence of aerosol-size growth under more turbid conditions indicative of coagulation and/or humidification over specific BoB regions. The results obtained using OPAC model show significant fraction of soot aerosols (~6 %–8 %) over the eastern and northwestern BoB, while coarse-mode sea salt particles are found to dominate in the southern parts of BoB.

Diwali is one of the largest festivals for Hindu religion which falls in the period October–November every year. During the festival days, extensive burning of firecrackers takes place, especially in the evening hours, constituting a significant source of aerosols, black carbon (BC), organics, and trace gases. The widespread use of sparklers was found to be associated with short-term air quality degradation events. The present study focuses on the influence of Diwali fireworks emissions on surface ozone (O 3 ), nitrogen oxides (NO x ), and BC aerosol concentration over the tropical urban region of Hyderabad, India during three consecutive years (2009–2011). The trace gases are analyzed for pre-Diwali, Diwali, and post-Diwali days in order to reveal the festivity’s contribution to the ambient air quality over the city. A twofold to threefold increase is observed in O 3 , NO x , and BC concentrations during the festival period compared to control days for 2009–2011, which is mainly attributed to firecrackers burning. The high correlation coefficient (~0.74) between NO x and SO 2 concentrations and higher SO 2 /NO x (S/N) index suggested air quality degradation due to firecrackers burning. Furthermore, the Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observation-derived aerosol subtyping map also confirmed the presence of smoke aerosols emitted from firecrackers burning over the region. Nevertheless, the concentration level of pollutants exhibited substantial decline over the region during the years 2010 and 2011 compared to 2009 ascribed to various awareness campaigns and increased cost of firecrackers.

In the current study, atmospheric carbon dioxide (CO 2 ) data covering multiple locations in the Indian subcontinent are reported. This data was collected using a dedicated ground-based in-situ network established as part of the Geosphere-Biosphere Programme (CAP-IGBP) of the Climate and Atmospheric Processes of the Indian Space Research Organisation (ISRO). Data are collected over Ponmudi, Ooty, Sriharikota, Gadanki, Shadnagar, Nagpur, and Dehradun during 2014-2015, 2017–2020, 2012, 2011–2015, 2014–2017, 2017 and 2008–2011, respectively. The atmospheric CO 2 generated as part of the CAP−IGBP network would enhance the understanding of CO 2 variability in different time scales ranging from diurnal, seasonal, and annual over the Indian region. Data available under this network may be interesting to other research communities for modeling studies and spatiotemporal variability of atmospheric CO 2 across the study locations. The work also evaluated the CO 2 observations against the Model for Interdisciplinary Research on Climate version 4 atmospheric chemistry-transport model (MIROC4-ACTM) concentrations.

The present study focuses on analyzing the seasonal changes in aerosol characteristics using a classification scheme proposed by Gobbi et al. (2007). This scheme is based on the correlation between the Ångström exponent (α) in the 440–870 nm range and the difference in α values [dα = α (440–675 − α(675–870)] including the size of fine-mode particles (Rf) and the fine-mode fraction (η). The classification scheme can therefore provide information on the aerosol characteristics and their modification in transit. Spectral aerosol measurements using the Microtops-II sun photometer (MT-II) have systematically been conducted in Hyderabad, India during April 2009–March 2010 and analysed to study the seasonal effects. The results reveal a seasonal dependence, i.e. the presence of fine-mode aerosols under turbid atmospheres in winter and post-monsoon, a mixture of fine and coarse aerosol types in pre-monsoon and a significant influence of marine mixed with dust air masses during the monsoon season. The identification of the aerosol source type and the modification processes are discussed along with clustered air-mass trajectory analysis. Furthermore, we have also checked the consistency of this scheme with the findings arrived from the columnar size distributions (CSDs) computed by numerical inversion of spectral AOD using King's inversion algorithm and the scatter plot between AOD and spectral α. The comparison clearly demonstrates the usefulness of the classification scheme and highlights its advantages for the monitoring and study of seasonal variation of the aerosol types and the modification processes in the atmosphere.

This study is based on the analysis of the measurement of ozone and water vapor by airbus in-service aircraft (MOZAIC) data of vertical ozone (O 3 ) and carbon monoxide (CO) over Hyderabad during November 2005–March 2009. Measurements in the upper troposphere show highest values of O 3 (53–75 ppbv) and CO (80–110 ppbv) during the pre-monsoon and post-monsoon seasons, respectively. The episodes of strong wind shears (>20 ms −1 ) were frequent during the monsoon/post-monsoon months, while weak shear conditions (<10 ms −1 ) were prevalent during the winter season. The profiles of both O 3 and CO measured under southerly winds showed lower values than under northerly winds in each season. The strong and weak wind shears over the study region were associated with the El Niño and La Niña conditions, respectively. The outgoing long-wave radiation (OLR) and wind shear data indicate enhancement in the convective activity from monsoon to post-monsoon period. Higher levels of O 3 were measured under the strong shear conditions, while CO and H 2 O show enhancements under weak shear conditions. The near surface observation and simulations show increase of O 3 with increasing OLR, while insignificant relation in the upper region. In case of CO, the MOZAIC and CCM2 show weaker dependence while MOZART-4 shows rapid increase with OLR indicating large overestimation of convective transport. A modified Tiedtke convective scheme provides better representation compared to the Hack/Zhang-McFarlane schemes for both O 3 and CO during the monsoon season. The difference between observation and simulations were particularly large during transition from El Niño to La Niña phases. The different convection scheme and horizontal resolution in the MOZART-4 and CCM2 seem to be the major causes of disagreement between these models. Vertical profiles of both O 3 and CO during extreme events such a tropical cyclones (TCs) show strong influence of the convective-dynamics over Bay of Bengal (BOB).

An integrated campaign “Suryagrahan‐2019” with multi‐institutional support was conducted by launching a series of radiosondes/ozonesondes over 6‐different locations in India along with the operation of ST/MST radars and launching of RH‐200 rockets during the annular solar eclipse of 26 December 2019. We present the eclipse‐induced changes in the thermal structure, dynamics and trace gases in the lower and middle atmosphere. One of the novel findings is the formation of three step‐like isothermal structures in the lower stratosphere with a layer height of 1.4, 2.5, and 4 km, which is attributed to the adiabatic compression and expansion of the air parcel. These structures have both warming and cooling effect of the order of ±6 K. A significant increase of ozone by 20% in post‐eclipse scenario between 29 and 32 km is observed over Cochin. Strong downdrafts of ∼−0.25 m s−1 are observed between 12 and 16 km during the eclipse event, which is attributed to the atmospheric compression due to the sudden cooling during the eclipse event. Due to the changes in thermal structure, the atmospheric circulation changes are observed in the meridional wind. During the maximum obscuration, there is a sudden decrease in near‐surface and boundary layer ozone by 12–15 ppbv. The present study reiterates that the eclipse‐induced perturbations depend on the local time of the eclipse event and place of observations. It is envisaged that the results discussed in the study will improve our understanding of the eclipse induced perturbations in the Earth's atmosphere. Plain Language Summary Solar eclipse provides a well‐characterized reduction in solar radiation for a few hours, which provides a natural laboratory to understand and quantify the atmosphere's response to the abrupt cut‐off in the solar radiation. In this context, an integrated campaign “Suryagrahan‐2019” was conducted in India by launching a series of radiosonde/ozonesonde along with the operation of ST/MST radars during the annular solar eclipse event occurred on 26 December 2019. Several isothermal structures, followed by warming and cooling effect in the different stratospheric heights were observed. Alter in the ozone profile, especially in the lower stratosphere was one of the causative mechanism behind the modulations of thermal structure. Adiabatic compression and expansion of the air parcel in the lower stratosphere are explained in term of solar eclipse induced effects. Change in meridional circulation due to sudden solar cut‐off is reported. Key Points Solar eclipse induced isothermal structure and adiabatic compression and expansion in the lower stratosphere were observed Increase in ozone in the lower stratosphere during post‐eclipse scenario, whereas spontaneous decrease of surface ozone were reported Change in meridional circulation due to sudden cut‐off of solar radiation

The chemistry and variation in light molecular weight (C 2 –C 5 ) volatile organic compounds (VOCs) and nitrogen oxides (NO x  = NO + NO 2 ) over the formation of tropospheric ozone (O 3 ) was studied for a time period of 1 year (2013) at a tropical urban site located in Deccan plateau region of Hyderabad, India, with semi-arid climate. Diel pattern of hydrocarbons showed maxima in the morning and night and minima in the afternoon. Ethylene and propylene showed relatively larger diurnal amplitude than other hydrocarbons. Among the analyzed hydrocarbons, acetylene was the most abundant with an annual mean of 5.5 ± 1.3 ppbv. All the VOCs exhibited a seasonal variation with monsoon and summer minimum and winter maximum. Ozone formation potentials (OFP) and propylene-equivalents (propy-equiv.) were calculated to account the contribution of individual hydrocarbons towards formation of O 3 . Propylene had the highest contribution of propy-equiv. (34 %) and OFP (28.4 %) among the VOCs observed. The concentrations of VOCs and their reactivity with hydroxyl radicals played a significant role on the levels of propy-equiv. and OFP. Strong correlations 0.65 and 0.77 were observed between O 3 vs. propy-equiv. and O 3 vs. OFP, respectively. The crossover point relationship between NO x , VOCs, and O 3 showed enhancement of O 3 at lower levels and decreased at higher levels of NO x in the range of VOCs concentrations studied. Among hydrocarbons, propylene (10) and ethane (6.5) showed the highest and lowest crossover points, respectively.