Vertical ozone variation in the lower troposphere of Delhi

Varshney, C. K.; Aggarwal, Maneesha

doi:10.1007/bf00549791

Cited by 4 publications

(1 citation statement)

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“…Measurements carried out at different altitudes along a mountain gradient in England (Gay, 1991), Japan ( Murao et al, 1990), Austria (Puxbaum et al, 1991) and Canada (Peake et al, 1983) gave some indication of the vertical variation of ozone but failed to provide accurate infor1nation because such measurements at different altitudes were made at the ground level and, thus, were not completely free from diverse infl uences operative at ground level and may not have truly represented the vertical ozone gradient. To eliminate such shortcomings, in a recent study, synoptic measurements were carried out in New Delhi at different heights from high rise buildings to determine the true vertical ozone variation in an urban environment exhibiting a positive trend (Varshney & Aggarwal, 1993). The work highlighted in this paper is an extension of the above mentioned work and is aimed at evaluating the seasonal influence on the vertical stratifi cation of ozone by carrying out synoptic measurements up to a height of 51 m.…”

Section: Introductionmentioning

confidence: 99%

Vertical Stratification of Ozone in Different Seasons in the Lower Troposphere of New Delhi

Aggarwal¹,

Varshney²

1995

Terr. Atmos. Ocean. Sci.

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Vertical ozone measurements were carried out in the urban environment of New Delhi, in three different seasons from 1989-1991. Air sampling was done synoptically at ground level, 23 m, 51 m, 57 m, 117 m and 153 m heights. A significant positive vertical gradient in the ozone concentration was observed at all sites. At any given time, ozone levels were lowest at the ground level and invariably increased with increasing distance from the ground. A� � . ... distinct seasonal variation in the vertical ozone profile was also observed'.'Ozone concentration was highest in summer at all heights. The peak in ozone concentration during the day, appeared. earlier at all heights in summers, in comparison to winter and spring. At the 51 m height in summers, the ozone concentration decreased rapidly during the late evening. Such vertical ozone stratification. may have severe implications for trees and residents of high rise buildings particularly in urban and industrial conglomerations which serve as the prime foci in the release of ozone forming substances.

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Section: Introductionmentioning

confidence: 99%

Vertical Stratification of Ozone in Different Seasons in the Lower Troposphere of New Delhi

Aggarwal¹,

Varshney²

1995

Terr. Atmos. Ocean. Sci.

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Analysis of long-term ozone trend over Delhi and its meteorological adjustment

Kumari

Jayaraman²,

Chirashree

2013

Int. J. Environ. Sci. Technol.

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Present study deals with the statistical analysis of long-term ground level ozone (O 3 ) trend and the influence of meteorological variables on its variation over Delhi, India. Daily mean and maximum of O 3 and meteorological data, obtained from India Meteorological Department, were arranged for the period of 9 years (1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006). Based on the preliminary correlation study of all the data with O 3 , six variables viz. daily maximum temperature, daily average relative humidity, dew point, wind speed, visibility, and total sunshine were selected. Classical additive time series decomposition technique was used to obtain seasonally adjusted long-term trend. To analyze the masking effect of meteorology, adjustment was made using Kolmogorov-Zurbenko filters followed by stepwise regression analysis to the smoothed series of O 3 maximum and meteorological variables, which showed that long-term trend was independent of sunshine duration. Results indicate a significant increasing trend with annual increase of 1.13 % for O 3 mean and 3 % for O 3 maximum. Annual deseasonalized trend for seasonal cycle shows bimodal oscillations. About 43 % of O 3 variation was explained by the selected meteorological factors and rest of variation attributed to factors like emission of precursor gases, pollutant transport, policy changes, etc. Among the three tested regression models, performance of Model 2 with variable temperature, wind speed, and visibility was found to be best that resulted in lowering of O 3 trend. Large variability (23 %) was explained by the variable visibility depicted that the emission of primary pollutants not only provides the precursor gases but also control the local photochemical reactions.

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