Urban Region Of Hyderabad Research Articles

Prevalence and Patterns of Refractive Errors in Children and Young Adults in an Urban Region in South India: the Hyderabad Eye Study

ABSTRACT Purpose To determine the prevalence of refractive error (RE) and associated risk factors for myopic refractive errors in children and young adults from the urban region of Hyderabad, South India. Methods Four thousand sixty-five (4,065) participants aged 6–22 years were enrolled and examined in this cross-sectional study conducted from October 2013 to January 2015. Participants were enrolled from a random sample of schools and universities in regions representative of urban Hyderabad. RE was determined using cycloplegic autorefraction. The association of demographic factors such as age, gender, and socio-economic category (SEC) (low/mid/high) with myopia was explored with logistic regression with robust standard error. Results Of the total participants, 2,259 were children aged 6–15 years and 1,806 were adolescents and young adults aged 16–22 years. Overall prevalence of myopia, high myopia (≤ −5.00D and ≤ −6.00 D), hyperopia, emmetropia, and astigmatism was 29.8% (95% CI: 26.0% to 33.6%, n = 1,216), 2.9% (95% CI: 1.9% to 3.9%, n = 120), 1.1% (95%CI: 0.7% to 1.5%, n = 46), 14.7% (95% CI: 12.4% to 17.0%, n = 599), 46.9% (95% CI: 43.7% to 50.1%, n = 1913) and 8.6% (95% CI: 7.4% to 9.9%, n = 352) respectively. A strong correlation existed between age and prevalence of myopia (R2 = 0.88, p < .001) and high myopia (R2 = 0.71, p < .001). Children from schools of low SEC (34.7%) had higher prevalence of myopia compared to the mid SEC (16.8%) (p = .043). Conclusion Myopia was the most prevalent refractive error and increased with age in this urban population. More myopia was observed in schools of low SEC.

Ventilation coefficient and boundary layer height impact on urban air quality

AbstractIn the present study, ventilation coefficient (VC) was estimated in order to understand the concentration of pollutants over the urban region of Hyderabad during 2009–2011. Nocturnal boundary layer height (BLH) was calculated using the accurate (0.2% for Refractivity Profiles) high vertical resolution global positioning system radio occultation (GPSRO), Constellation Observing System for Meteorology Ionosphere and Climate (COSMIC)-derived one-dimensional variational (1-DVAR) refractivity profiles, and observations of boundary layer LIDAR (BLL). The statistical results revealed that the coefficient of determination (R2) between LIDAR- and GPSRO-estimated BLH is 0.51, whereas that for VC is 0.68. The maximum BLH observed during the study period was maximum in the summer season and the minimum was observed in monsoon season, whereas the maximum VC was observed during summer and the minimum in winter. When the BLH and VC are low, the pollutant concentration of black carbon (BC) is higher and vice vers...

Variation in atmospheric aerosol properties over a tropical urban region associated with biomass-burning episodes – a study using satellite data and ground-based measurements

The change in aerosol properties and ground-reaching solar irradiance in different spectral bands associated with an intense biomass-burning episode has been examined in the present study. Synchronous ground-based measurements on aerosol optical depth (AOD), erythemal ultraviolet radiation (UVery), solar irradiance and light detecting and ranging (LIDAR) observations of aerosol backscatter were carried out in the urban region of Hyderabad, India. Air-mass back-trajectory analysis has been carried out to infer long-range transport of pollutants over the urban environment of Hyderabad. Ground-measured AOD showed ∼50% increase on 3 March 2009 compared to 2 March 2009, along with ∼13% and ∼31% increases in Angström's parameter (α) and turbidity coefficient (β). UVery and global solar irradiance showed ∼24% and ∼10% reduction, respectively, on a turbid day (3 March 2009) compared to a normal day (2 March 2009). The Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) AOD550 also showed higher values associated with long-range transport of aerosols from biomass burning over the region.

Influence of natural and anthropogenic emissions on aerosol optical properties over a tropical urban site — A study using sky radiometer and satellite data

Atmospheric aerosols are important aspects of climate research due to their impact on radiative forcing. In the present study, the aerosol optical depth (AOD), the Ångström exponent (α) and the single scattering albedo (SSA) over the urban region of Hyderabad, India, were examined using Sun/Sky radiometer measurements during January–December, 2008. AOD showed higher values on certain Julian days coinciding with the occurrence of wintertime dust storm events in the Gulf Region and biomass burning due to forest fires over Indian Region. The AOD values during wintertime dust event are about ~55% higher than those on normal days. The SSAs show positive and negative trends in α (R2=0.71) and black carbon (BC) aerosols (R2=0.44), respectively. The aerosol size distribution shows a bimodal pattern with fine (~0.15μm) and coarse (~>7μm) mode during January–December, 2008. The MODIS AOD showed positive correlation with sky radiometer-derived AOD values (R2=0.68).

Atmospheric correction to IRS-P6 AWiFS data and its validation with ground measurements: A study over the semi-arid region

In this study, we have implemented a fast atmospheric correction algorithm to IRS-P6 advanced wide field sensor (AWiFS) satellite data for retrieving surface reflectance under different atmospheric and surface conditions. The algorithm is based on MODIS climatology products and simplified use of Second Simulation of Satellite Signal in Solar Spectrum (6S) radiative transfer code. The algorithm requires information on aerosol optical depth (AOD) for correcting the satellite dataset. The atmospheric correction algorithm has been tested for IRS-P6 AWiFS False colour composites covering the International Crops Research Institute for the Semi-Arid Tropics Farm, Patancheru, Hyderabad, India, under varying atmospheric conditions. Ground measurements of surface reflectance representing different land use/land cover, i.e. red soil, chick pea, groundnut and pigeon pea crops were conducted to validate the algorithm. Terra MODIS AOD550 validated with Microtops-II sun photometer–derived AOD500 over the urban region of Hyderabad exhibited very good correlation of ∼0.92, suggesting possible use of satellite-derived AOD for atmospheric correction.

Fog Over Indo-Gangetic Plains—A Study Using Multisatellite Data and Ground Observations

Every year, fog formation over the Indo-Gangetic Plains (IGP) of Indian region during the winter months of December-January is believed to create numerous health hazards, economic loss, and cross-country transportation of aerosols. It has attracted the global scientific community's attention to address the uncertainties pertaining to its formation and physico-chemical properties. In this paper, we made an attempt to study the fog conditions that occurred over the north Indian region and long-range transport of aerosols from the fog region towards the southern region during November 2008, using multisatellite data sets and ground-based observations on aerosol properties and solar irradiance in the urban region of Hyderabad, India. Ground measurements showed a considerable increase in aerosol optical depth (AOD) at 500 nm ( ~ 30%) and a decrease in total solar irradiance ( ~ 7%) over Hyderabad, India, during the fog period compared to a normal day corresponding to 04 November 2008.

Impact of emissions from anthropogenic sources on satellite-derived reflectance

The present study deals with the impact of extensive anthropogenic activities associated with festivities and agricultural crop residues burning in the Indo-Gangetic Plains (IGP) on satellite-derived reflectance during November 2007. Intense smoke plumes were observed in the IRS-P4 OCM satellite data over IGP associated with agricultural crop residue burning during the study period. Terra-MODIS AOD and CALIPSO LIDAR backscatter datasets were analysed over the region to understand the spatial and temporal variation of the aerosol properties. Ground-based measurements on aerosol optical properties and black carbon (BC) mass concentration were carried out during 7–14 November 2007 over urban region of Hyderabad, India. Top of the Atmosphere (TOA) reflectance estimated from IRS-P4 Ocean Color Monitor (OCM) data showed large variations due to anthropogenic activities associated with crop residue burning and fireworks. Atmospheric corrections to OCM satellite data using 6S radiative transfer code with inputs from ground and satellite measurements could account for the variations due to differential aerosol loading. Results are discussed in this paper.

Effect of synoptic meteorological conditions on aerosol properties over urban environment: A study over tropical urban region of Hyderabad, India

Aerosol particle size distribution and chemical properties are important in studies related to human health and climate. The present study describes an analysis of aerosol mass loading, Aerosol Optical Depth (AOD), black carbon aerosol mass concentration and carbon monoxide over tropical urban region of Hyderabad, India, during March 2006, coinciding with active forest fires season over India. Aerosol optical depth, particulate matter mass loading and carbon monoxide were observed to be high on days with air mass coming from north of the study area.

Multiyear ground‐based and satellite observations of aerosol properties over a tropical urban area in India

AbstractAerosol particle size distributions along with their spatial and temporal variability are important for describing both direct and indirect radiative forcing. In this study, the variation of black carbon (BC) aerosols, total aerosol mass loading and aerosol optical depth (AOD) over an urban region of Hyderabad, south India, was analyzed for 3 consecutive years from 2003 to 2005. The AOD was measured using a handheld multichannel sun‐photometer at six wavelengths centered on 380, 440, 500, 675, 870 and 1020 nm and aerosol mass–size distribution was made using a quartz crystal microbalance (QCM) cascade impactor. In addition, satellite remote‐sensing data from nighttime DMSP‐OLS images were analyzed for inferring ancillary sources of aerosols. Results from temporal analysis (2004–2006) suggest that aerosol mass loading and BC mass concentration increased considerably over the 3‐year time‐period mainly due to increasing vehicular traffic from urban population growth. DMSP‐OLS nighttime images for different years suggested higher forest fire occurrences in the year 2004 compared to other years. The annual mean AOD at 550 nm from moderate resolution imaging spectroradiometer (MODIS) showed relatively high values during 2004. Copyright © 2007 Royal Meteorological Society