scholarly journals Zonal variations of the vertical distribution of atmospheric aerosols over the Indian region and the consequent radiative effects

2021 ◽  
Author(s):  
Nair Krishnan Kala ◽  
Narayana Sarma Anand ◽  
Mohanan Remani Manoj ◽  
Harshavardhana Sunil Pathak ◽  
Krishnaswamy Krishna Moorthy ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Vertical Distribution ◽  
Atmospheric Aerosols ◽  
Seasonal Variations ◽  
Monsoon Season ◽  
Western India ◽  
Peninsular India ◽  
Dust Aerosols ◽  
Vertical Extent ◽  
North Western

Abstract. The vertical structure of atmospheric aerosols over the Indian mainland and the surrounding oceans and its spatial distinctiveness are characterized using long-term (2007–2020) spaceborne lidar observations, satellite-retrieved aerosol optical depths and assimilated aerosol single scattering albedo. The consequence of these on the spatial distribution of aerosol-induced atmospheric heating is estimated using radiative transfer calculations. The results show strong, seasonally varying zonal gradients in the concentrations and vertical extent of aerosols over the study region. In general, while over the oceans, aerosol concentrations decrease rather monotonically with increase in altitude (from its highest value near the surface), over the mainland, the concentrations initially increase from the surface to about 1 km before decreasing towards higher altitudes, in all seasons over Central India and during summer monsoon season in northern India. This is attributed to the seasonal variations in the source strengths and the atmospheric boundary layer dynamics. Compared to the surrounding oceans, where the vertical extent of aerosols is confined within 3 km, the aerosol extinction coefficients extend to considerably higher altitudes over the mainland, reaching as high as 6 km during pre-monsoon and monsoon seasons. Longitudinally, the vertical extent is highest around 75° E and decreasing gradually on either side over the peninsular India. In the west, the concentrations and vertical extent of aerosols are highest during summer/monsoon due to the lofting and strong advection of mineral dust and sea salt aerosols. Particulate depolarization ratio profiles affirm the ubiquity of dust aerosols in western India during monsoon. Dust aerosols are distributed all the way from surface to 6 km over the north-western semi-arid regions. While the presence of low-altitude dust aerosols decreases further east, the high-altitude (above 4 km) dust layers are observed to remain aloft throughout the year with seasonal variations in its zonal distribution over north-western India. Southern peninsular India and its surrounding oceans are marked with high-altitude (around 4 km) dust aerosols during the monsoon season. Radiative transfer calculations show that these changes in vertical distribution of aerosol loading and types result in enhanced atmospheric heating at the lower altitudes during pre-monsoon, with prominent heating within 2–3 km throughout the Indian region. These results will have large implications for aerosol-radiation interactions in regional climate simulations.

scholarly journals II. On the connexion of the Himalaya snowfall with dry winds and seasons of drought in India

1884 ◽  
Vol 37 (232-234) ◽  
pp. 3-22 ◽  
Keyword(s):  
Monsoon Season ◽  
India Meteorological Department ◽  
Climatic Conditions ◽  
General Idea ◽  
Annual Reports ◽  
Western India ◽  
The Subject ◽  
The Government ◽  
The Himalaya ◽  
North Western

The present paper, as regards its subject-matter though not in form, is part of a general investigation of the rainfall of India, which has occupied much of my spare time for some years past, and the results of which are already partly embodied in a memoir which I hope, in the course of a few months, to issue as an official publication of the Indian Meteorological Office. The idea that the snowfall of the Himalaya exercises a direct and important influence on the dry land winds of North-Western India is not now put forward for the first time. It has been the subject of frequent reference in the annual reports on the meteorology of India since 1876, as well as elsewhere; and in a report on the administration of the India Meteorological Department lately issued, I summarised very briefly those points in the experience of the previous five years which have seemed to justify its provisional adoption as a basis for forecasting the probable character of the monsoon rains. Relying on this experience, in the month of June last, I put forward in the Government Gazette, a note giving warning of the probability of a prolonged period of drought in the approaching monsoon season, and the result, if not in exact accordance with the terms of the forecast, has been so far confirmatory of the general idea, as to induce me to put the facts of past experience formally on record, and thereby challenge attention to the subject. If I am right in the inference that the varying extent and thickness of the Himalayan snows exercise a great and prolonged influence on the climatic conditions and weather of the plains of North-Western India, it is probable, that with more or less modification according to the local geography, causes of a similar character will be found equally operative in other regions, and perhaps on an even more extensive scale.

Effect of prolonged intermittent water restriction on the reproductive performance of ewes in the Indian desert

1986 ◽  
Vol 43 (2) ◽  
pp. 255-260 ◽  
Author(s):  
J. P. Mittal ◽  
P. K. Ghosh
Keyword(s):  
Reproductive Performance ◽  
Water Deprivation ◽  
Post Partum ◽  
Monsoon Season ◽  
Experimental Period ◽  
Control Group ◽  
Western India ◽  
Water Restriction ◽  
Desert Areas ◽  
North Western

ABSTRACTThe reproductive performance of female Magra and Marwari sheep of the desert areas of north-western India was studied in relation to intermittent water deprivation, for a period of 39 months during which four breedings were completed. The control group received an ad libitum supply of water every day, while the water-restricted group was provided with water on the same 2 days each week only throughout the experimental period, except during the monsoon season. All the ewes were maintained on cultivated Cenchrus ciliaris pasture. No ill effect was noticed on the general health of the animals. Reproductive measures such as incidence and duration of oestrus, length of the oestrous cycle, conception rate, lambing rate, length of gestation, post-partum interval, inter-lambing period, post-lambing weight of ewes and birth weight of lambs were not significantly affected by the imposed water deprivation. The dailywatered ewes had a slightly, but not significantly higher gain in body weight than the water-restricted ewes. It wa^ concluded that ewes of these two breeds could be maintained on a twice weekly watering schedule for prolonged periods of time without having any adverse effect on their reproductive performance.

scholarly journals Assessment of Spatiotemporal Variability and Rising Trends of Surface Ozone Over India

2021 ◽  
Author(s):  
Ravi Kumar Kunchala ◽  
Bhupendra Bahadur Singh ◽  
Karumuri Rama Krishna ◽  
Raju Attada ◽  
Vivek Seelanki ◽  
...  
Keyword(s):  
Time Series ◽  
Seasonal Variations ◽  
Anthropogenic Activities ◽  
Monsoon Season ◽  
Surface Ozone ◽  
Principal Component ◽  
Northern Region ◽  
Spatiotemporal Variability ◽  
Peninsular India ◽  
Second Mode

Abstract With rising anthropogenic activities, surface ozone levels have increased across different parts of the world including India. Studies have shown that surface ozone shows distinct characteristics across India, however these studies are mostly based on isolated locations. Any comprehensive and spatiotemporally consistent study on surface ozone is lacking thus far. Keeping these facts in mind, we utilize ground-based observations and reanalysis datasets to investigate the surface ozone variability, seasonality, and linkages with meteorology over India. A validation exercise shows that the Copernicus Atmosphere Monitoring Service Reanalysis (CAMSRA) reasonably compares against the ground-based observations. Results show that the CAMSRA ozone is in good agreement with the observations across India, where it shows better correlations (r>0.7) over southern regions and relatively lesser (> 0.5) over northern and eastern regions indicating larger variability and spread over these regions. We further quantify this agreement in terms of range, mean absolute error (MAE), and root mean square error (RMSE). Time series analysis shows that the CAMSRA captures seasonal variations irrespective of location. Spatial distribution of surface ozone shows higher (lower) concentrations of about 40-60 ppb (15-20 ppb) during pre-monsoon (monsoon) months over a broad region covering northern and western parts, and peninsular India. A prominent increase during May is noted over the northern region especially over Indo-Gangetic Plains (IGP). These seasonal variations are linked to solar radiation (SR), temperature, low-level circulation, and boundary layer height (BLH). Furthermore, Principal Component Analysis (PCA) is performed to understand the dominant patterns of spatiotemporal variability for different seasons. It is seen that the first (second) mode shows a high percentage variance explained ranging between 30-50% (10-20%). The time series of PCA-1 mode indicates an overall increasing trend across India with a notable increase over south and central India. The second mode indicates prominent variability over the IGP (southern India) in the pre-monsoon (post-monsoon) season, which shows significant interannual variability. During the monsoon season, an interesting dipole pattern is seen which closely resembles the active and break spell patterns of the Indian summer monsoon. Overall, the spatiotemporal variations in surface ozone are closely tied to meteorology while the rising trends indicate the potential role of increasing precursors across India.

Gastrointestinal Protective Effect of Zizyphus xylopyrus (Retz) Willd Leaf Extract Against Indomethacin and HCl-EtOH Induced Ulcers

2019 ◽  
Vol 5 (2) ◽  
pp. 140-146
Author(s):  
Shweta Jain ◽  
Sourabh Jain ◽  
Nagendra S. Chauhan ◽  
Ankur Vaidya
Keyword(s):  
Protective Effect ◽  
Ethanolic Extract ◽  
Negative Control ◽  
Gastric Epithelium ◽  
Gastric Ulcers ◽  
Western India ◽  
Skin Infections ◽  
Ulcer Index ◽  
Digestive Disorders ◽  
North Western

Background: Zizyphus xylopyrus (Retz.) Willd. (Rhamnaceae) is a straggling shrub or a small tree, armed with spines, found throughout north western India, Pakistan and China. Methods: The aerial and root barks, leaves and fruits of Zizyphus species are used in medicine for the treatment of various diseases such as weakness, liver complaints, obesity, diabetes, skin infections, fever, diarrhea, insomnia and digestive disorders. Ethanolic extract of leaves of Zizyphus xylopyrus (Retz) Willd was prepared by solvent extraction and subjected to study the protective effect against Indomethacin and HCl-EtOH induced ulcer using Ranitidine (100 mg/kg) and Omeprazole (8 mg/kg) as standard respectively. Results: Histopathological lesions with marked disorientation of the gastric epithelium was observed in negative control, while extract treated rats showed a better protected mucosa with intact epithelium in comparison to standard treated rats. Ulcer index and percentage ulcer protection also represent protecting effects of the extract. Conclusion: Ethanolic extract of Z. xylopyrus (Retz) Willd leaves extract was found to be significantly protective against gastric ulcers.

A case study on the vertical distribution and characteristics of aerosols using ground-based raman lidar, satellite and model over Western India

2021 ◽  
Vol 42 (17) ◽  
pp. 6421-6436
Author(s):  
Sourita Saha ◽  
Som Sharma ◽  
K. Niranjan Kumar ◽  
Prashant Kumar ◽  
Vaidehi Joshi ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Western India ◽  
Raman Lidar ◽  
The Vertical Distribution

scholarly journals Optical and Physical Properties of Atmospheric Aerosols over the Bay of Bengal during ICARB

2009 ◽  
Vol 66 (9) ◽  
pp. 2640-2658 ◽  
Author(s):  
Vijayakumar S. Nair ◽  
K. Krishna Moorthy ◽  
S. Suresh Babu ◽  
S. K. Satheesh
Keyword(s):  
Atmospheric Aerosols ◽  
Bay Of Bengal ◽  
Radiative Forcing ◽  
Latitudinal Gradients ◽  
Back Trajectory ◽  
Western India ◽  
Size Distributions ◽  
Average Mass ◽  
Scattering Coefficients ◽  
Vertical Heterogeneity

Abstract Simultaneous and collocated measurements of total and hemispherical backscattering coefficients (σ and β, respectively) at three wavelengths, mass size distributions, and columnar spectral aerosol optical depth (AOD) were made onboard an extensive cruise experiment covering, for the first time, the entire Bay of Bengal (BoB) and northern Indian Ocean. The results are synthesized to understand the optical properties of aerosols in the marine atmospheric boundary layer and their dependence on the size distribution. The observations revealed distinct spatial and spectral variations of all the aerosol parameters over the BoB and the presence of strong latitudinal gradients. The size distributions varied spatially, with the majority of accumulation modes decreasing from north to south. The scattering coefficient decreased from very high values (resembling those reported for continental/urban locations) in the northern BoB to very low values seen over near-pristine environments in the southeastern BoB. The average mass scattering efficiency of BoB aerosols was found to be 2.66 ± 0.1 m2 g−1 at 550 nm. The spectral dependence of columnar AOD deviated significantly from that of the scattering coefficients in the northern BoB, implying vertical heterogeneity in the aerosol type in that region. However, a more homogeneous scenario was observed in the southern BoB. Simultaneous lidar and in situ measurements onboard an aircraft over the ocean revealed the presence of elevated aerosol layers of enhanced extinction at altitudes of 1 to 3 km with an offshore extent of a few hundred kilometers. Back-trajectory analyses showed these layers to be associated with advection from west Asia and western India. The large spatial variations and vertical heterogeneity in aerosol properties, revealed by the present study, need to be included in the regional radiative forcing over the Bay of Bengal.

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