Ann Geophys 28 1879ndash1885 2010wwwann-geophysnet2818792010doi105194angeo-28-1879-2010copy Author(s) 2010 CC Attribution 30 License

AnnalesGeophysicae

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Tropospheric ozone (TOR) trend over three major inland Indiancities Delhi Hyderabad and Bangalore

Pavan S Kulkarni1 Sachin D Ghude2 and D Bortoli13

1Geophysics Centre of Evora (CGE) University of Ersquo vora 7000 Ersquo vora Portugal2Indian Institute of Tropical Meteorology Pune 411008 India3Institute for Atmospheric Science and Climate (ISAC-CNR) Bologna Italy

Received 13 July 2010 ndash Revised 26 August 2010 ndash Accepted 13 September 2010 ndash Published 12 October 2010

Abstract An analysis of tropospheric column ozone us-ing the NASA Langley TOR data during 1979ndash2005 hasbeen done to investigate the trend over major Indian citiesDelhi Hyderabad and Bangalore India was under socialdemocratic-based policies before 1990s Economic Liber-alization began in nineties which lead to a significant growthin industrial energy and transport sectors in major citiesOur analysis shows that there is a systematic increase in thenumber of months with higher tropospheric ozone values af-ter 1990 A comparison of TOR climatology before andafter 1990 over these cities shows evidence of increase inthe tropospheric ozone after 1990 Trend obtained from themodel shows significant change during monsoon over Delhiand during pre-monsoon and post-monsoon over Hyderabadand Bangalore The present analysis using TOR techniquedemonstrates the TOR potential to detect changes in tropo-spheric ozone over large cities which are impacted by largeanthropogenic pollution

Keywords Atmospheric composition and structure(Pollution-urban and regional)

1 Introduction

Tropospheric ozone (O3) is one of the most important green-house gases (Mickley et al 2001) and contributes to globalwarming and climate change Long-term changes in tropo-spheric ozone show a complex pattern over the globe that insome cases are driven by regional influences High amountsof volatile organic compounds (VOCs) and NOx from in-dustrial and traffic emissions lead to a fairly high concen-tration of surface ozone over the industrial cities (Sillman etal 1990) and can accumulate to a hazardous level during

Correspondence toPavan S Kulkarni(pavannplyahoocoin)

favourable meteorological conditions (Jain et al 2005) Itis now a major environmental concern in many big cities ofthe world with current concentrations being high enough toharm human health over wide areas (Klumpp et al 2006a bBeig et al 2008 Ghude et al 2009) Therefore the tempo-ral and spatial distribution of tropospheric O3 and the factorscontrolling its distribution have been a focus of atmosphericchemistry research

While numerous studies have been conducted in EuropeNorth America and Japan (Logan 1985 1994 Liu et al1987 Oltmans et al 1998 Monks 2000 Akimoto et al1994 Pochanart et al 2002) there is limited knowledge ofthe temporal and spatial distribution of tropospheric O3 inIndia where rapid urbanization and industrial developmentshave been taken place in the latest decades Recently avail-able satellite data have shown an increasing column concen-tration of nitrogen dioxide a precursor to O3 over major in-dustrial zones of India (Ghude et al 2008 2009) as well asover rural areas during the onset of rainy season (Ghude etal 2010) Available few scattered ground-based measure-ments within India have shown frequent O3 pollution dur-ing photo-chemically active seasons in urban areas (Naja andLal 2002 Jain et al 2005 Ghude et al 2006) How-ever all these studies seldom describe long term changesin tropospheric ozone except over cities like Ahamadebadand Delhi (Lal et al 2002 Ghude et al 2009) where in-creasing daytime surface ozone has been reported Hencemore efforts are needed to understand the temporal evalua-tion of tropospheric ozone over the large cities with respectto the increasing demand of energy consumptions and rapidurbanization Satellite observations of ozone (total columnstratospheric or tropospheric) offer the possibility to measurethe distribution over large areas and to study the temporaland spatial behaviour (Ahn et al 2003 Ghude et al 2009Kulkarni et al 2009a b) Rapid urbanization and indus-trialization in India have made Delhi Hyderabad and Ban-galore one of the most polluted cities in this region (Gurjar

Published by Copernicus Publications on behalf of the European Geosciences Union

1880 Pavan S Kulkarni et al TOR trend over three major inland Indian cities

22

465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503

Figure 1504 Fig 1 Map of India with three major inland cities Delhi Hyder-abad and Bangalore with adjacent region used in this study (markedwith red colour boxes) The inset shows the annual variation in av-eraged TOR over the three major inland cities Delhi Hyderabadand Bangalore of India for the period 1979ndash2005 The vertical barsshow one sigma standard deviation

et al 2008) Considering the potential of large economicdevelopment in and around the major cities Delhi Hyder-abad and Bangalore one can expect enhancement of anthro-pogenic activities such as increased consumption of fossilfuel and large scale industrialization This will result in extraburden of pollution in troposphere which can lead to fur-ther increase in ozone concentration over these cities Asa case study in this work we analyze monthly troposphericozone retrieved from Total Ozone Mapping Spectrometer(TOMS) and Solar Backscatter Ultraviolet (SBUV) measure-ments (TOMSSBUV) (1979ndash2005) to investigate temporalchanges in tropospheric O3 over Delhi Hyderabad and Ban-galore We examine the change in the climatology in tro-pospheric O3 between 1979ndash1989 and 1990ndash2005 and tem-poral distribution of O3 and trend during 1979ndash2005 overthese cities The most favorable situations to observe longterm changes in tropospheric ozone are the places where tro-pospheric ozone is impacted by the local pollution such aslarge cities In this work using multi-year observations forthe first time we have also demonstrate the TOR potentialto detect temporal changes in tropospheric ozone over largecities which are impacted by large industrial and vehiculargrowth

Table 1 Characteristics of Tropospheric Ozone Residual (TOR)dataset

Parameter Tropospheric ozoneTemporal coverage Jan 1979 to Dec 2005Temporal resolution Monthly dataData gap 57 Months 176

(Aug 1990 Mar 1991 May 1993 toSep 1997 and NovndashDec 1998)

Spatial coverage 50 S to 50 NSpatial resolution 100 latitude by 125 longitude

2 Dataset

The ozone (TOMSSBUV TOR) data over Delhi Hyderabadand Bangalore have been obtained from the web sitehttpasd-wwwlarcnasagovTORdatahtml Table 1 presentsthe details about the Tropospheric Ozone Residual (TOR)data used in the present analysis The TOR data are obtainedby empirically corrected tropospheric ozone residual tech-nique and measured in Dobson Unit (DU) The derivation ofthe TOR data is a two steps process First the empirically cor-rected stratospheric column ozone (SCO) is calculated fromSBUV profiles using the Eq (1) (Fishman et al 2003)

SCO= SBUV Total O3minusγClowastminusβBlowast

minusAlowast (1)

Where SBUV Total O3 is the total O3 column derived fromSBUV measurementsγ andβ lies between 0 and 1 and de-pends on the height of the tropopause andC B and Aare empirically corrected ozone layers using SBUV profileand Logan (1999) Climatology

Second the TOR is derived using following equation

TOR= TOMS Total O3minusSCO (2)

More details regarding the data retrieval methods are givenin Fishman et al (2003)

We select three major inland cities Delhi Hyderabad andBangalore where emission of ozone precursorrsquos (with rapidurbanization and industrialization) are thought to have in-creased significantly in and around the city Figure 1 givesthe locations of these cities on a geographical map of Indiaand inset shows tropospheric ozone climatology as a functionof months over selected locations To account for the spa-tial coverage these cities have been divided into four binseach of 125 longitudes by 100 latitude and labelled D1to D4 B1 to B4 and H1 to H4 as shown in Fig 1 The binsare chosen in such a way that they overlap exactly with theTOR grids Tropospheric ozone shows strong seasonal cycleover these cities with summer maximum and winter mini-mum The summer maximum (May and June) in TOR is at-tributed to the high solar intensity long daylight hours hightemperature and dryer synoptic conditions (Jain et al 2005)along with the availability of large amount of ozone precur-sors (NOx CO VOCrsquos etc) This leads to photochemical

Ann Geophys 28 1879ndash1885 2010 wwwann-geophysnet2818792010

Pavan S Kulkarni et al TOR trend over three major inland Indian cities 1881

production of ozone (Sillman et al 1990) in the planetaryboundary layer as well as in the free troposphere During thewinter period even with the availability of ozone precursorsthe other synoptic conditions are not favorable which resultsin reduced photochemical production of ozone throughoutthe troposphere Therefore lower amount of TOR is ob-served in the winter period Tropospheric ozone is highestin June over Delhi (sim 53 DU) and in May over Hyderabad(sim 38 DU) and Bangalore (sim 34 DU) It shows minimum inDecember (sim 31 DU) over Delhi and in February over Hy-derabad (sim 27 DU) and Bangalore (sim 23 DU) Such a meantropospheric O3 distribution is typical for locations in tropicsand mid-latitudes (Logan 1994 Monks 2000 Cooper et al2005 Anton et al 2010)

3 Trends in tropospheric O3

India was under social democratic-based policies from 1947to 1991 Economic Liberalization began in nineties and(since 1990) India has emerged as one of the fastest-growingeconomies in the developing world This lead to a signif-icant growth in industrial energy transport urban popula-tion agriculture and service sectors Accordingly we havedivided the total monthly TOR observation (from 1979ndash2005(267 months)) into two parts (1) before economic liberal-ization ie 1979ndash1989 period (132 months) and (2) fromeconomic liberalization ie 1990ndash2005 (135 months) Toexamine if there was any increase in tropospheric ozone dur-ing 1990ndash2005 we first did frequency distribution analysisby calculating the percent change in the frequency distribu-tion of monthly tropospheric ozone between 1979ndash1989 and1990ndash2005 periods Further we compare monthly tropo-spheric climatology between 1979ndash1989 and 1990ndash2005 Fi-nally we calculated the trends in tropospheric ozone by con-sidering monthly values from 1979ndash2005 We used the fol-lowing algorithm to derive decadal tendency of troposphericO3 over the cities considered in this study

C () = fra()minusfrb () (3)

wherefra () is the relative frequency distribution (percent)for the period 1990ndash2005 andfrb () is the relative fre-quency distribution (percent) for the period 1979ndash1989 forfrequency intervals of 5 DU If the output of this algorithm(C ()) is positive (negative) it shows percent increase (de-crease) in respective frequency interval Figure 2 shows fre-quency distribution of percentage change in the number ofmonth of tropospheric ozone concentration for Delhi (con-centration range from 20 DU to 60 DU) Hyderabad and Ban-galore (concentration range from 15 DU to 45 DU) This fig-ure reveals that all the three cities shows general tendencyof increase in number of months with higher troposphericozone values during 1990ndash2005 period (with correspondingdecrease in lower tropospheric ozone values) It can be seenthat percentage change in the number of months over Delhi in

23

505

506

507 508 509

Figure 2 510 511 512

Fig 2 Frequency distribution of change in the number ofmonths of tropospheric ozone concentration with frequency inter-val of 5 DU in the concentration range from 20 DU to 60 DU over(a) Delhi and in the concentration range from 15 DU to 60 DU over(b) Hyderabad and(c) Bangalore

general is negative below 35 DU frequency intervals and it isoverall positive between 35ndash60 DU frequency intervals Thisindicates that lower tropospheric ozone values (between 20to 35 DU) have decreased significantly whereas higher tro-pospheric ozone values have generally increased over Delhiduring 1990ndash2005 Similarly percentage change in the num-ber of months over Bangalore is negative between 15 and30 DU and it is evidently positive above 30 DU frequencyintervals This clearly indicates that there is a significant in-crease in higher tropospheric ozone values over Bangalore

wwwann-geophysnet2818792010 Ann Geophys 28 1879ndash1885 2010

1882 Pavan S Kulkarni et al TOR trend over three major inland Indian cities

24

513

514 Figure 3 515

516 517

Fig 3 Annual variation in averaged TOR over the three major in-land cities Delhi Hyderabad and Bangalore of India for the periods1979ndash1989 and 1990ndash2005 The vertical bars show one sigma stan-dard deviation

during 1990ndash2005 However it can be seen from Fig 2 thatover Hyderabad percentage change in the number of monthsis positive for frequency intervals between 20ndash25 DU 30ndash35 DU and 40ndash45 DU whereas it is negative for frequencyintervals between 23ndash30 DU and 35ndash40 DU Although sys-tematic change in tropospheric ozone values over Hyder-abad is not seen during 1990ndash2005 general tendency of fre-quency distribution shows that there is noticeable increasein the higher tropospheric values (40ndash45 DU) This analysisthus provides useful information on the changes in the tro-pospheric ozone over the selected cities during 1990ndash2005with respect to 1979ndash1989 Inspection of Fig 2 clearly re-veals that higher and extreme tropospheric ozone values overDelhi Hyderabad and Bangalore significantly increased dur-ing 1990ndash2005 compared to 1979ndash1989

To see if there is change in the tropospheric ozone levelsduring 1990ndash2005 in Fig 3 we compare the troposphericozone climatology between 1979ndash1989 and 1990ndash2005 forall the three cities considered in this study It shows lit-tle evidence of long-term changes in the tropospheric ozoneover all the cities Inspection of Fig 3 reveals that the in-crease in tropospheric ozone was not seen for all the sea-sons over Delhi Hyderabad and Bangalore A comparisonof tropospheric ozone over Delhi in particular show notice-able increase in ozone amount during monsoon (JJAS) post-monsoon (ON) and winter months (NDJ) in 1990ndash2005 pe-riod It does not show such an increase in ozone levels dur-ing pre-monsoon (MAM) months rather shows slight de-crease In contrast tropospheric ozone levels over Hyder-abad and Bangalore in 1990ndash2005 show marked increases

during pre-monsoon (MAM) months and do not show suchan increase in winter months Similar to Delhi it alsoshows marked increases over Hyderabad and Bangalore dur-ing post-monsoon season During monsoon troposphericozone levels over Bangalore do not show evidence of signifi-cant change However a noticeable decrease in troposphericozone levels during monsoon is seen over Hyderabad during1990ndash2005 Although Figs 2 and 3 show little evidence oflong term changes this result suggests that the troposphericozone levels over these cities appeared to be influenced bythe increased anthropogenic activities in and around the cityChandra et al (1999) estimated the changes in troposphericozone over 11-year solar cycle (minimum to maximum) us-ing Ottawa monthly-mean F107 cm solar flux (standard fluxunits (28 GHz frequency) which is apparently more closelyrelated to solar ultraviolet flux) They found mean annualsolar response for tropospheric ozone of aboutminus9 (plusmn3) (minus229plusmn101 DU) for an increase 100 units of F107 cm fluxWe observed that the change in F107 cm flux before and af-ter 1990 was about 1104 units at F107 cm flux This changeis primarily driven by the division of monthly mean solarcycle time-series before and after 1990 (between the period1979 and 2005) Therefore decrease of aboutsim 11 units ofF107 cm flux after 1990 may increase tropospheric ozoneby less than 1 However the difference observed in tropo-spheric ozone before and after 1990 is more that 3 (Fig 3)over the cities considered in our study Therefore we feelthat the effect of changes in short wave radiation before after1990 on TOR changes would be small

To examine if there was any long-term trends in tropo-spheric ozone over these cities we did regression analysisof tropospheric ozone using trend model details of whichare given elsewhere (Ziemke et al 1997) and hence de-scribed here briefly Error estimates are according to Neter etal (1985) In order to remove the effects of natural sourcesof ozone variability such as 11-year solar cycle as well as thelinear trend in solar irradiance we use a regression model Itconsists of seasonal cycle linear trend and solar cycle Thegeneral expression for the regression model equation can bewritten as follows

θ(t) = α(t)+β(t)Trend(t)+δ(t)Solar(t)+ resid(t) (4)

Whereα(t) andβ(t) are the time-dependent 12-month sea-sonal and trend coefficients respectively andδ(t) is 12-month coefficients corresponding to the ozone driving quan-tities such as solar flux Solar(t) is solar time series proxywhich is used in an effort to reduce errors in local ozonetrends Solar proxies have been used for Ottawa monthly-mean F107 cm solar flux (standard flux units (28 GHz fre-quency)) from January 1979 to December 2005 (ftpftpngdcnoaagov) which is apparently more closely related tosolar ultraviolet flux used in the model as solar proxy in-dices resid(t) represents the residues or noise Monthlymean tropospheric ozone over the cities (for each bean) from1979ndash2005 are used to obtained the time series These time

Ann Geophys 28 1879ndash1885 2010 wwwann-geophysnet2818792010

1882 Pavan S Kulkarni et al TOR trend over three major inland Indian cities

24

513

514 Figure 3 515

516 517

Fig 3 Annual variation in averaged TOR over the three major in-land cities Delhi Hyderabad and Bangalore of India for the periods1979ndash1989 and 1990ndash2005 The vertical bars show one sigma stan-dard deviation

during 1990ndash2005 However it can be seen from Fig 2 thatover Hyderabad percentage change in the number of monthsis positive for frequency intervals between 20ndash25 DU 30ndash35 DU and 40ndash45 DU whereas it is negative for frequencyintervals between 23ndash30 DU and 35ndash40 DU Although sys-tematic change in tropospheric ozone values over Hyder-abad is not seen during 1990ndash2005 general tendency of fre-quency distribution shows that there is noticeable increasein the higher tropospheric values (40ndash45 DU) This analysisthus provides useful information on the changes in the tro-pospheric ozone over the selected cities during 1990ndash2005with respect to 1979ndash1989 Inspection of Fig 2 clearly re-veals that higher and extreme tropospheric ozone values overDelhi Hyderabad and Bangalore significantly increased dur-ing 1990ndash2005 compared to 1979ndash1989

To see if there is change in the tropospheric ozone levelsduring 1990ndash2005 in Fig 3 we compare the troposphericozone climatology between 1979ndash1989 and 1990ndash2005 forall the three cities considered in this study It shows lit-tle evidence of long-term changes in the tropospheric ozoneover all the cities Inspection of Fig 3 reveals that the in-crease in tropospheric ozone was not seen for all the sea-sons over Delhi Hyderabad and Bangalore A comparisonof tropospheric ozone over Delhi in particular show notice-able increase in ozone amount during monsoon (JJAS) post-monsoon (ON) and winter months (NDJ) in 1990ndash2005 pe-riod It does not show such an increase in ozone levels dur-ing pre-monsoon (MAM) months rather shows slight de-crease In contrast tropospheric ozone levels over Hyder-abad and Bangalore in 1990ndash2005 show marked increases

during pre-monsoon (MAM) months and do not show suchan increase in winter months Similar to Delhi it alsoshows marked increases over Hyderabad and Bangalore dur-ing post-monsoon season During monsoon troposphericozone levels over Bangalore do not show evidence of signifi-cant change However a noticeable decrease in troposphericozone levels during monsoon is seen over Hyderabad during1990ndash2005 Although Figs 2 and 3 show little evidence oflong term changes this result suggests that the troposphericozone levels over these cities appeared to be influenced bythe increased anthropogenic activities in and around the cityChandra et al (1999) estimated the changes in troposphericozone over 11-year solar cycle (minimum to maximum) us-ing Ottawa monthly-mean F107 cm solar flux (standard fluxunits (28 GHz frequency) which is apparently more closelyrelated to solar ultraviolet flux) They found mean annualsolar response for tropospheric ozone of aboutminus9 (plusmn3) (minus229plusmn101 DU) for an increase 100 units of F107 cm fluxWe observed that the change in F107 cm flux before and af-ter 1990 was about 1104 units at F107 cm flux This changeis primarily driven by the division of monthly mean solarcycle time-series before and after 1990 (between the period1979 and 2005) Therefore decrease of aboutsim 11 units ofF107 cm flux after 1990 may increase tropospheric ozoneby less than 1 However the difference observed in tropo-spheric ozone before and after 1990 is more that 3 (Fig 3)over the cities considered in our study Therefore we feelthat the effect of changes in short wave radiation before after1990 on TOR changes would be small

To examine if there was any long-term trends in tropo-spheric ozone over these cities we did regression analysisof tropospheric ozone using trend model details of whichare given elsewhere (Ziemke et al 1997) and hence de-scribed here briefly Error estimates are according to Neter etal (1985) In order to remove the effects of natural sourcesof ozone variability such as 11-year solar cycle as well as thelinear trend in solar irradiance we use a regression model Itconsists of seasonal cycle linear trend and solar cycle Thegeneral expression for the regression model equation can bewritten as follows

θ(t) = α(t)+β(t)Trend(t)+δ(t)Solar(t)+ resid(t) (4)

Whereα(t) andβ(t) are the time-dependent 12-month sea-sonal and trend coefficients respectively andδ(t) is 12-month coefficients corresponding to the ozone driving quan-tities such as solar flux Solar(t) is solar time series proxywhich is used in an effort to reduce errors in local ozonetrends Solar proxies have been used for Ottawa monthly-mean F107 cm solar flux (standard flux units (28 GHz fre-quency)) from January 1979 to December 2005 (ftpftpngdcnoaagov) which is apparently more closely related tosolar ultraviolet flux used in the model as solar proxy in-dices resid(t) represents the residues or noise Monthlymean tropospheric ozone over the cities (for each bean) from1979ndash2005 are used to obtained the time series These time

Ann Geophys 28 1879ndash1885 2010 wwwann-geophysnet2818792010

Pavan S Kulkarni et al TOR trend over three major inland Indian cities 1883

Table 2 Trend regression coefficients ( per year) for tropospheric ozone residue (TOR) over the three tropical inland cities Delhi Hyder-abad and Bangalore for the period 1979ndash2005

Seasons Delhi Hyderabad BangaloreTrend ( yminus1) 2σ (plusmn) Trend ( yminus1) 2σ (plusmn) Trend ( yminus1) 2σ (plusmn)

Pre-monsoon (MAM) 004 03 047 025 050 027Monsoon (JJAS) 034 02 minus003 016 020 026Post-monsoon (ON) 032 03 034 02 078 03Winter (DJF) 056 048 005 022 013 03

series are then subjected to the multifunctional regressionmodel Monthly trend coefficients obtained from the model(for a bin) are then averaged to get a seasonal trend coef-ficient Similarly corresponding monthly two-sigma errorvalues are averaged to get a seasonal two-sigma error es-timate Seasonal trend coefficients are obtained separatelyfor each bin shown in Fig 1 Table 2 shows trends forDelhi (B3) Hyderabad (H2) and Bangalore (B2) for fourseasons The four seasons considered are as per the IndiaMeteorological Department (IMD) (MOEF 2004) winterfrom December-January-February pre-monsoon or summerfrom March-April-May monsoon from June-July-August-September and post-monsoon from OctoberndashNovember An-nually positive but insignificant trends of about 31plusmn32(2σ)

and 2plusmn 2(2σ) per decade are found over Delhi andHyderabad respectively A tropospheric ozone level overBangalore however shows a trend close to significance(4plusmn 28(2σ) per decade) during 1979ndash2005 Trend ob-tained from the model shows significant change during mon-soon over Delhi (+34plusmn2(2σ) per decade) during pre-monsoon over Hyderabad (+47plusmn 25(2σ) per decade)and Bangalore (+5plusmn27(2σ) per decade) It also showssignificant change over Hyderabad (+34plusmn 2(2σ) perdecade) and Bangalore (+78plusmn 2(3σ) per decade) andpositive but insignificant trend of about 32plusmn3(2σ) duringpost-monsoon season The highest trend is seen over Banga-lore despite the fact that growth in urban and vehicular pop-ulation is less compared to Delhi (Table 3)

This increase in trend is believed to be a result of increasedanthropogenic emission in and around Delhi Hyderabadand Bangalore Beig and Brasseure (2006) showed thatCO emission from Delhi Hyderabad and Bangalore haveincreased by approximately 35 25 and 20 respec-tively between 1991 and 2001 Similarly NOx emissionsfrom Delhi have increased by more that 100 and fromHyderabad and Bangalore it is increased by approximately65 (httphtaporgmeetings2008200810HTAP20Hanoi20PresentationsPostersGhudepdf) Power sta-tions road transport industries use of coal for domesticpurposes and burning of fossil fuels are the major sourcesof air pollution in these cities (Gurjar et al 2004) Therapid growth of economical activities in Delhi Hyderabad

Table 3 Urban and vehicular population in 1981 1991 and 2001

Delhi Hyderabad Bangalore

Population (in lakhs)a

1981 57 25 291991 84 42 412001 128 57 57

Vehicular population (in thousands)1981b 536 89 1751991b 1831 443 5772001 3456c 1450d 1950e

a wwwiipsenvisnicin b Ramanathan (2000)c wwwdelhiplanningnicin d Gertleret al (2009)e Sabapathy (2008)

and Bangalore in recent times has resulted in significantincrease in industrial and vehicular activities in and aroundthese cities Table 3 gives overview of urban and vehicularpopulation during 1981ndash2001 periods It can be seen thatrapid increase in urban population a number of vehiclesoccurred during 1981ndash2001 This resulted in significantchanges in anthropogenic emission during the study period(Garg et al 2001)

4 Conclusion

In this work we analyze troposphere ozone residual data from1979ndash2005 to examine the change in tropospheric ozonebefore and after 1990 over inland cities Delhi Hyderabadand Bangalore A frequency distribution of data before andafter 1990 shows that there is noticeable tendency of in-crease in the higher tropospheric values after 1990 Fur-ther a comparison of tropospheric ozone climatology be-fore and after 1990 over these cities shows evidence of in-crease in the tropospheric ozone after 1990 Finally to exam-ine if there were any long-term trends in tropospheric ozoneover these cities we did regression analysis of troposphericozone Trend obtained from the model shows significantchange during monsoon over Delhi during pre-monsoon andpost-monsoon over Hyderabad and Bangalore These results

wwwann-geophysnet2818792010 Ann Geophys 28 1879ndash1885 2010

1884 Pavan S Kulkarni et al TOR trend over three major inland Indian cities

suggest that tropospheric ozone levels over industrial citiesDelhi Hyderabad and Bangalore appeared to be influencedby the increased anthropogenic activities in and around thecity

The source of uncertainty in the long-term records of tro-pospheric ozone residue could be because of (a) the in-consistency between instruments (TOMS and SBUV) ortropopause height information which is derived from areanalysis of the meteorological data from NCEP and(b) degradation of the scanning mirror on the EP-TOMS in-strument occurring from the year 2000 onwards More im-portantly the shapes to the ozone profiles derived from theSBUV must be examined in the vicinity of the tropopauseover this entire period to ensure that no secular changesevolve during this time (Fishman et al 2003) Much workhas gone into making sure the TOMS total ozone data areconsistent between instruments The SBUV is taken from atleast four different instruments on different satellites Al-though care is taken to provide a consistent data set be-tween the four instruments which is done for the total ozonecolumns Careful analysis of the ozone amounts in thelower stratosphere is done for making sure they were asgood as possible because errors in this region of the at-mosphere would greatly discredit any conclusions about theTOR (Fishman et al 2003) Wozniak et al (2005) con-ducted a thorough study of the stratospheric column ozone(SCO) amounts that are generated by the residual techniqueand used SAGE profiles to assure that use of SBUV for de-riving TOR was justifiable However it is important to lookinto detail as to weather or not there are differences in theway these tropopause height analyses were made over the30-year period and trend analysis of the calculated SCO toreduce the uncertainty in the long-term TOR data Detailedanalysis by Anton et al (2010) shows that the degradation ofthe scanning mirror on the EP-TOMS instrument underesti-mates total column ozone measured by ground based Brewerand Dobson spectrophotometers bysim 1 to 3 This negativebias implies that the TOR values are underestimated and addsto uncertainties in the trend information This informationwill reduce the uncertainties in the trend information in theTOR data and needs to explore further In conclusion it canbe stated that the results obtained in this paper provide firsthand information on tropospheric trends over the big tropicalIndian cities which has seen large industrial and vehiculargrowth after 1990s It should be emphasized that althoughthe present analysis using tropospheric ozone residual tech-nique might influence the magnitude of the trend coefficientswe believe that it would not affect the general qualitative na-ture of the trend results

AcknowledgementsAuthor (Pavan S Kulkarni) is thankful to Geo-physics Centre of the University of Evora (CGE-UE) for the fellow-ship in the project ldquoSPATRAM-MIGE Polar Projectrdquo funded by thePortuguese Science Foundation ndash FCT Author (Sachin D Ghude)is thankful to the Director Indian Institute of Tropical Meteorol-ogy for encouragement during the progress of the work Thanks

are also due to ldquoTROPOSPHERIC OZONE RESIDUAL (TOR)HOMEPAGErdquo for the tropospheric ozone residual (TOR) data

Topical Editor P M Ruti thanks one anonymous referee forherhis help in evaluating this paper

References

Ahn C Ziemke J R Chandra S and Bhartia P KDerivation of tropospheric column ozone from the Earth ProbeTOMSGOES co-located data sets using the cloud slicing tech-nique J Atmos Solar-Terr Phys 65 1127ndash1137 2003

Akimoto H Nakane H and Matsumoto Y The chemistry ofoxidant generation tropospheric ozone increase in Japan inChemistry of the Atmosphere The Impact on Global ChangeCalvert J Blackwell Scientific Publications Oxford UK 261ndash273 1994

Anton M Lopez M Serrano A Banon M and Garcıa J ADiurnal variability of total ozone column over Madrid (Spain)Atmos Environ 44 2793ndash2798 2010

Anton M Koukouli M E Kroon M McPeters R D LabowG J Balis D and Serrano A Global validation of empir-ically corrected EP-TOMS total ozone columns using Brewerand Dobson ground-based measurements J Geophys Res 115D19305 doi1010292010JD014178 2010

Beig G Ghude S D Polade S D and Tyagi B Thresh-old exceedances and cumulative ozone exposure indices attropical suburban site Geophys Res Lett 35 L02802doi1010292007GL031434 2008

Beig G and Brasseur G P Influence of anthropogenic emissionson tropospheric ozone and its precursors over the Indian tropi-cal region during a Monsoon Geophys Res Lett 33 L07808doi1010292005GL024949 2006

Chandra S Ziemke J R and Stewart R W An 11-year solar-cycle in tropospheric ozone from TOMS measurements Geo-phys Res Lett 26 185ndash188 1999

Cooper O R Stohl A Eckhardt S Parrish D D Oltmans SJ Johnson B J Nedelec P Schmidlin F J Newchurch MJ Kondo Y and Kita K A springtime comparison of tro-pospheric ozone and transport pathways on the east and westcoasts of the United States J Geophys Res 110 D05S90doi1010292004JD005183 2005

Fishman J Wozniak A E and Creilson J K Global distributionof tropospheric ozone from satellite measurements using the em-pirically corrected tropospheric ozone residual technique Iden-tification of the regional aspects of air pollution Atmos ChemPhys 3 893ndash907 doi105194acp-3-893-2003 2003

Garg A Shukla P R Bhattacharya S and Dadhwal V K Sub-region (district) and sector level SO2 and NOx emissions for In-dia assessment of inventories and mitigation flexibility AtmosEnviron 35 703ndash713 2001

Gertler A Guttikunda S and Koppaka R The Impact of theTransport Sector on PM Levels in Hyderabad India in Proceed-ings of the International symposium Environment and Transportin different contexts Ghardaıa Algeria India 16ndash18 February2009 15ndash21 2009

Ghude S D Kulkarni P S Beig G Jain S L and Arya BC Global distribution of tropospheric ozone and its precursorsa view from the space Int J Remote Sensing 31(02) 485ndash495doi10108001431160902893519 2010

Ann Geophys 28 1879ndash1885 2010 wwwann-geophysnet2818792010

Pavan S Kulkarni et al TOR trend over three major inland Indian cities 1885

Ghude S D Lal D M Beig G Vander A R J and Sabale DRain-induced soil NOX emission from India during onset of thesummer monsoon A satellite perspective J Geophys Res 115D16304 doi1010292009JD013367 2010

Ghude S D Jain S L Arya B C Kulkarni P S Kumar Aand Ahammed N Temporal and Spatial Variability of SurfaceOzone at Delhi and Antarctica Int J Climatol 26 1367ndash13822006

Ghude S D Jain S L Beig G Arya B C Ahammed YN Arun Kumar and Bhisma Tyagi Ozone in ambient air attropical mega city Delhi characteristics trends and cumula-tive ozone exposure indices J Atmos Chem 60 237ndash252doi101007s10874-009-9119-4 2009

Ghude S D Fadnavis S Beig G Vander A R J and Polade SD Detection of surface emission hotspots trends and seasonalcycle from satellites retrieved NO2 over India J Geophys Res113 D20305 2008

Ghude S D Vander A R J Bieg G Fadnavis S and Polade SD Global distribution of tropospheric NO2and its trend duringpast decade over major source regions Environ Pollut 9 5253ndash5260 doi101016jenvpol200901013 2009a

Gurjar B R van Aardenne J A Lelieveld J and MohanM Emission estimates and trends (1990ndash2000) for megacityDelhi and implications Atmos Environ 38(33) 5663ndash5681doi101016jatmosenv200405057 2004

Gurjar B R Butler T M Lawrence M G andLelieveld J Evaluation of Emissions and Air Qual-ity in Megacities Atmos Environ 42(7) 1593ndash1606doi101016jatmosenv200710048 2008

Motor vehicle population in Delhi httpdelhiplanningnicinEconomic20SurveyEcosur2001-02PDFchap12(table)PDF3 May 2010

LRTAP httphtaporgmeetings2008 7 May 2010Distribution of Population Literacy Sex Ratio Workers

amp Non-Workers by sex-wise for Major Cities in In-dia 1981ndash2001 httpwwwiipsenvisnicinSDNPENVISProgramDataSheetsdatasheet7pdf 9 May 2010

Jain S L Arya B C Kumar A Ghude S D and Kulkarni PS Observational Study of Surface Ozone at New Delhi IndiaInt J Remote Sensing 26 3515ndash3526 2005

Klumpp A Ansel W Klumpp G Calatayud V Garrec J PHe S Pe˜nuelas J Ribas A Ro-Poulsen H Rasmussen SSanz M J and Vergne P Ozone pollution and ozone biomon-itoring in European cities Part I Ozone concentrations and cu-mulative exposure indices at urban and suburban sites AtmosEnviron 40 7963ndash7974 2006

Kulkarni P S Jain S L Ghude S D Arya B C Dubey PK and Shahnawaz On some aspects of tropospheric ozone vari-ability over the Indo-Gangetic (IG) basin India Int J RemoteSensing 30(15ndash16) 4111ndash4122 2009a

Kulkarni P S Ghude S D Jain S L Arya B C Dubey P Kand Shahnawaz Tropospheric ozone variability over the Indiancoastline and adjacent land and sea Int J Remote Sensing inpress 2009b

Lal S Naja M and Subbaraya B H Seasonal variations in sur-face ozone and its precursors over an urban site in India AtmosEnviron 34 2713ndash2724 2000

Liu S C and Trainer M Response of the tropospheric ozoneand odd hydrogen radicals to column ozone change J AtmosChem 6 221ndash233 1987

Logan J A Tropospheric ozone Seasonal behavior trends andanthropogenic influence JGeophys Res 90 10463ndash104821985

Logan J A Trends in vertical distribution of ozone An analysisof ozonesonde data JGeophys Res 99 25555ndash25585 1994

Logan J A An analysis of ozonesonde data for the troposphereRecommendations for testing 3-D models and development ofa gridded climatology for tropospheric ozone J Geophys Res104 16115ndash16149 1999

Mickley L J Murti P P Jacob D J Logan J A Koch DM and Rind D Radiative forcing from tropospheric ozonecalculated with a unified chemistry-climate model J GeophysRes 104 30153ndash30172 2001

MOEF Indiarsquos Initial National Communication to the United Na-tions Framework Convention on Climate Change Chapter 1 4Ministry of Environment and Forest Government of India 2004

Monks P S A review of the observations and origins of the springozone maximum Atmos Environ 34 3545ndash3561 2000

Naja M and Lal S Surface ozone and precursor gases at Gadanki(135 N 792 E) a tropical rural site in India J Geophys Res107(D14) 4197 doi1010292001JD000357 2002

Neter J Wasserman W and Kutner M H Applied linear statis-tical models Irwin Homewood IL 1985

Oltmans S J Lefohn A S Scheel H E Harris J M LevyII H Galbally I E Brunke E G Meyer C P Lathrop JA Johnson B J Shadwick D S Cuevas E Schmidlin F JTarasick D W Claude H Kerr J B Uchino O and MohnenV Trends of ozone in the troposphere Geophys Res Lett 25139ndash142 1998

Pochanart P Akimoto H Kinjo Y and Tanimoto H Surfaceozone at four remote island sites and the preliminary assessmentof the exceedances of its critical level in Japan Atmos Environ36 4235ndash4250 2002

Ramanathan R Link between population and number of vehiclesEvidence from Indian cities Cities 17(4) 263ndash269 2000

Sabapathy A Air quality outcomes of fuel quality and vehiculartechnology improvements in Bangalore city India Transporta-tion Research Part D Transport and Environment 13(7) 449ndash454 2008

Sillman S Logan J A and Wofsy S C The sensitivity of ozoneto nitrogen oxides and hydrocarbons in regional ozone episodesJ Geophys Res 95 1837ndash1851 1990

Wozniak A E Fishman J Wang P-H and Creilson J KDistribution of stratospheric column ozone (SCO) determinedfrom satellite observations Validation of solar backscattered ul-traviolet (SBUV) measurements in support of the troposphericozone residual (TOR) method J Geophys Res 110 D20305doi1010292005JD005842 2005

Ziemke J R Chandra S McPeters R D and Newman P ADynamical proxies of column ozone with applications to globaltrend models J Geophys Res 102 6117ndash6129 1997

wwwann-geophysnet2818792010 Ann Geophys 28 1879ndash1885 2010

Pavan S Kulkarni et al TOR trend over three major inland Indian cities 1885

Ghude S D Lal D M Beig G Vander A R J and Sabale DRain-induced soil NOX emission from India during onset of thesummer monsoon A satellite perspective J Geophys Res 115D16304 doi1010292009JD013367 2010

Ghude S D Jain S L Arya B C Kulkarni P S Kumar Aand Ahammed N Temporal and Spatial Variability of SurfaceOzone at Delhi and Antarctica Int J Climatol 26 1367ndash13822006

Ghude S D Jain S L Beig G Arya B C Ahammed YN Arun Kumar and Bhisma Tyagi Ozone in ambient air attropical mega city Delhi characteristics trends and cumula-tive ozone exposure indices J Atmos Chem 60 237ndash252doi101007s10874-009-9119-4 2009

Ghude S D Fadnavis S Beig G Vander A R J and Polade SD Detection of surface emission hotspots trends and seasonalcycle from satellites retrieved NO2 over India J Geophys Res113 D20305 2008

Ghude S D Vander A R J Bieg G Fadnavis S and Polade SD Global distribution of tropospheric NO2and its trend duringpast decade over major source regions Environ Pollut 9 5253ndash5260 doi101016jenvpol200901013 2009a

Gurjar B R van Aardenne J A Lelieveld J and MohanM Emission estimates and trends (1990ndash2000) for megacityDelhi and implications Atmos Environ 38(33) 5663ndash5681doi101016jatmosenv200405057 2004

Gurjar B R Butler T M Lawrence M G andLelieveld J Evaluation of Emissions and Air Qual-ity in Megacities Atmos Environ 42(7) 1593ndash1606doi101016jatmosenv200710048 2008

Motor vehicle population in Delhi httpdelhiplanningnicinEconomic20SurveyEcosur2001-02PDFchap12(table)PDF3 May 2010

LRTAP httphtaporgmeetings2008 7 May 2010Distribution of Population Literacy Sex Ratio Workers

amp Non-Workers by sex-wise for Major Cities in In-dia 1981ndash2001 httpwwwiipsenvisnicinSDNPENVISProgramDataSheetsdatasheet7pdf 9 May 2010

Jain S L Arya B C Kumar A Ghude S D and Kulkarni PS Observational Study of Surface Ozone at New Delhi IndiaInt J Remote Sensing 26 3515ndash3526 2005

Klumpp A Ansel W Klumpp G Calatayud V Garrec J PHe S Pe˜nuelas J Ribas A Ro-Poulsen H Rasmussen SSanz M J and Vergne P Ozone pollution and ozone biomon-itoring in European cities Part I Ozone concentrations and cu-mulative exposure indices at urban and suburban sites AtmosEnviron 40 7963ndash7974 2006

Kulkarni P S Jain S L Ghude S D Arya B C Dubey PK and Shahnawaz On some aspects of tropospheric ozone vari-ability over the Indo-Gangetic (IG) basin India Int J RemoteSensing 30(15ndash16) 4111ndash4122 2009a

Kulkarni P S Ghude S D Jain S L Arya B C Dubey P Kand Shahnawaz Tropospheric ozone variability over the Indiancoastline and adjacent land and sea Int J Remote Sensing inpress 2009b

Lal S Naja M and Subbaraya B H Seasonal variations in sur-face ozone and its precursors over an urban site in India AtmosEnviron 34 2713ndash2724 2000

Liu S C and Trainer M Response of the tropospheric ozoneand odd hydrogen radicals to column ozone change J AtmosChem 6 221ndash233 1987

Logan J A Tropospheric ozone Seasonal behavior trends andanthropogenic influence JGeophys Res 90 10463ndash104821985

Logan J A Trends in vertical distribution of ozone An analysisof ozonesonde data JGeophys Res 99 25555ndash25585 1994

Logan J A An analysis of ozonesonde data for the troposphereRecommendations for testing 3-D models and development ofa gridded climatology for tropospheric ozone J Geophys Res104 16115ndash16149 1999

Mickley L J Murti P P Jacob D J Logan J A Koch DM and Rind D Radiative forcing from tropospheric ozonecalculated with a unified chemistry-climate model J GeophysRes 104 30153ndash30172 2001

MOEF Indiarsquos Initial National Communication to the United Na-tions Framework Convention on Climate Change Chapter 1 4Ministry of Environment and Forest Government of India 2004

Monks P S A review of the observations and origins of the springozone maximum Atmos Environ 34 3545ndash3561 2000

Naja M and Lal S Surface ozone and precursor gases at Gadanki(135 N 792 E) a tropical rural site in India J Geophys Res107(D14) 4197 doi1010292001JD000357 2002

Neter J Wasserman W and Kutner M H Applied linear statis-tical models Irwin Homewood IL 1985

Oltmans S J Lefohn A S Scheel H E Harris J M LevyII H Galbally I E Brunke E G Meyer C P Lathrop JA Johnson B J Shadwick D S Cuevas E Schmidlin F JTarasick D W Claude H Kerr J B Uchino O and MohnenV Trends of ozone in the troposphere Geophys Res Lett 25139ndash142 1998

Pochanart P Akimoto H Kinjo Y and Tanimoto H Surfaceozone at four remote island sites and the preliminary assessmentof the exceedances of its critical level in Japan Atmos Environ36 4235ndash4250 2002

Ramanathan R Link between population and number of vehiclesEvidence from Indian cities Cities 17(4) 263ndash269 2000

Sabapathy A Air quality outcomes of fuel quality and vehiculartechnology improvements in Bangalore city India Transporta-tion Research Part D Transport and Environment 13(7) 449ndash454 2008

Sillman S Logan J A and Wofsy S C The sensitivity of ozoneto nitrogen oxides and hydrocarbons in regional ozone episodesJ Geophys Res 95 1837ndash1851 1990

Wozniak A E Fishman J Wang P-H and Creilson J KDistribution of stratospheric column ozone (SCO) determinedfrom satellite observations Validation of solar backscattered ul-traviolet (SBUV) measurements in support of the troposphericozone residual (TOR) method J Geophys Res 110 D20305doi1010292005JD005842 2005

Ziemke J R Chandra S McPeters R D and Newman P ADynamical proxies of column ozone with applications to globaltrend models J Geophys Res 102 6117ndash6129 1997

wwwann-geophysnet2818792010 Ann Geophys 28 1879ndash1885 2010