Detection of NO2 Emission Hotspots, Trend and Seasonal Variation over Indian Subcontinent Using TEMIS

tropospheric column NO2

Sachin D. Ghude

&

Suvarna Fadnavis, Yogesh K. Tiwari, G. Beig, Suraj Polade

Indian Institute of Tropical Meteorology, Pashan, Pune 411008 (INDIA)

In this study we focus on TEMIS tropospheric column NO2 retrievals from the GOME and SCIAMACHY satellite spectrometer over Indian Sub-continent for the period 1996-2006.

This data is obtained from the website:

http://www.temis.nl/airpollution/no2.html

GOME (ERS-2): 1996 – 2003 (0.25o * 0.25o, 1*e1013 Molecules/cm2)

SCIAMACHY (ENVISAT): 2003 – 2006(0.25o * 0.25o, 1*e1013 Molecules/cm2)(Version 1.1)

Objective:1. Identify the major NO2 emission hotspots2. Quantify the trend over major Industrial zone3. Identify the largest contributing regions 4. Seasonal Variation5. Comparison with in situ surface observation

India is second to China for various emission and energy consumption in the Asia region.

India has large variability in regional distribution of population and energy consumption patterns.

Over the past two decades rapid industrialization, urbanization and traffic growth due to economical development in India have believe to responsible for increasing emissions of gaseous pollutants in this region.

The varying sectoral growth rates, consumption patterns and resource endowments in India have led to widely different regional and sectoral emission distribution.

This variability is further creating pockets of heavy pollutant emitting regions like major industrial zones and metro-cities which has rapid rise in the vehicles number in the last decade.

Many thermal power plants have become operational in last two decades, which are consuming coal for electricity generation. Many large power plants have inefficient operations without advanced emission controls resulting in excessive emissions.

Therefore, a need arises for the policy makers to specially identify these regions of high pollution and target the sectors for mitigation, which are causing it.

Sectors and sub-sectors for major emissions over India:

The regional distributions for NO2 LPS (large Point Source) emissions corresponds to coal and petroleum consumption pattern for India.

Coal contributes 45 % of total NOx emission in India while, transport contributes 32% of NOx emission which mostly consist of small and dispersed sources.

The contribution of biomass burning to NOx production is less over the India which contributes 10-20% during March to May.

Electric power sector is the dominant component of Indian energy sector.

In India, coal is the primary fuel in thermal power plants, and gasoline and diesel are the primary fuels for automobiles.

About 70% of all India coal consumption is for power generation.

These plants generated almost 60% of total generated power for the nation.

Thermal power generation in India grew from 27030 MW in 1985 to 86014 MW in March 2007 out of which 26311 MW in 1985 to 71121 MW in March 2007 is due to coal used thermal power generation.

The present annual growth rate of electric power consumption in India is 4%

Large point source (LPS) for NOx emission are mostly power plant (Coal, Natural gas and Oil), Steel and cement plant, and large urban centers.

The regional distribution of these sector are well spread over the country.

However, the regional spread of overall NOx emission per unit area varies widely across the Indian districts and has a close correspondence with coal consumption pattern.

The emission also indicate a good correlation with population, level of economical and Industrial activity.

The emissions per unit power generated have increased for some LPS between 1990 and 1995 indicating a reduction in performance. It may be due to various reasons including high coal consumption per unit of power generated, poor quality of coal used, use of inefficient thermal generation technologies, etc.

Almost all the plants in India use sub-critical pulverized coal technology without any emission control equipment for SO2 and NOx. The newer plants contribute more to total power generation and therefore to emissions.

Regional distribution of per unit area coal consumption in India.

Regional distribution of per unit area NOx emissions in India

Sectoral contribution to Indian NOx emissions

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Electrical Power Generation Industry (energy use)

Road Transport Biomass burning

Other Transport Other Industries

Energy (47%)(Power and Indust)

Biomass peaking in March- May

The increasing population and urbanization result in a 4 to 6% annual growth rate of energy consumption in India, which enhances the emissions of NOx and other trace gases [UNEP, 2002].

Long-term air quality data over the residential and industrial locations of different Indian cities indicate that NO2 levels are increasing steadily over major cities, and some of them already exceed the permissible limits, as highas 100 to 240 mg/m3.

Different studies based on sector analysis and measurement campaigns show that NOx emissions over India are expected to increase in the forthcoming years, even though these estimates have large uncertainties for different sectors.

It is clear that more efforts are needed to understand the spatial and temporal evolution of regional NOx emissions over India with respect to the increasing demand of energy consumptions and rapid urbanization.

Data from satellites provide valuable information to improve estimates of NOx emissions as well as to identify the source regions and to study the regional O3 chemistry in light of seasonal meteorology.

Regional spread of LPS locations Major emission locations

Major Thermal Power Plants in India

Large number of TPP are observed to distributed over the Indo-Gangetic Basin.

Most of this TPP are located in Urban, sub-urban centers.

Near coal mines area.

Surrounded by Industrial area.

Density of the TPP and major industrial area is found to be higher in the northern part of India as compared to southern India.

Chandrapur, 2340 MW/day Ramagundam, 2600MW/day

Pune

Orba, Singrauli, Rihand (>4000MW/Day)

Kota

Bangalore

Kottagudem (1200MW/Day)Vijayawada (1300 MW/Day)

Raichur (1300 MW/Day)

Talcher (1500)

Vindhyachal (2300 MW/Day)

Korba (3200 MW/Day)

Nagpur, Korhadi (1200 MW/Day)

Bokaro, Chandrapura, Durgapur,Santaldih, Subermarekha, Culcutta

Wanakbori, Ukri, Bhurvaran(2700 MW/day)

Mumbai

Delhi

The location of emission hot spots correlates well with the location of mega thermal power plants, mega cities, urban and Industrial Region, emphasizing the contribution of emission through thermal power plants, transport sector, and Industrial sector.

Emission Intensities are particularly higher over densely populated Gangetic plains.

Satellite-retrieved NO2 columns shows maxima in the areas with mixed urban, industrial and TPP sources, such as Bombay-Gujarat urban corridor, and Punjab, Haryana, Uttar Pradesh, Zharkhand, West Bengal, northern part of Chhattisgarh and Orissa industrial corridor.

Retrieved NO2 also shows emission from the individual TPP not mixed with urban and industrial sources, such as Chandrapur (29, Installed capacity 2340 MW/day) and Ragundam (44, 2100MW/day)

Data and Regression Model:

NO2 Data set for 11 year period (1996-1006).

Regression model is applied for 5 different region

1. Mumbai Gujarat Golden Corridor (lon=72-74, lat=18-23)2. Delhi Region (lon=74-81, lat=26-32)3. Northeast and East India Industrial Sector (lon=81-91, lat=20-27)4. Southern Region (lon=77-80, lat=10-13)5. Central India (lon=79-80.5, lat=18-21.5)

General expression for the regression model used for trend analysis (Ziemke et al. [1997]) :

NO2(t) = b(t) + A(t).Trend(t) + Res(t)

Where, t = Month index (1996-2006)NO2(t) = Time series NO2.b(t) = Seasonal cycle coefficientA(t) = Seasonal trend coefficientRes(t) = Residual error time series for regression model

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1. Mumbai Gujarat Golden Corridor. (Urban centers, transport, Power, Industrial processes)

2. Delhi Region (Urban centers, transport, Power, Industrial processes, Biomass burning, Cement)

3. Northeast and East India Industrial Sector (near coal mine) (Power, Steel, Cement transport, Urban centers, Industrial process, Biomass burning,)

4. Southern Region (Power, Cement Urban centers)

5. Central India Power Plant region (near coal mine). (Power, Steel, Cement)

1.e1013 molecules/cm2

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10 20 30 40 50 60 70 80 90 100 110 120 130100150200250300350400450500550600

10 20 30 40 50 60 70 80 90 100 110 120 130100150200250300350400450500550600650

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Region 1: 2.4 %/Year (1)

Region 2: 3 %/Year (1.1)

Region 3: 1.6 %/Year (0.7)

Region 4: 1.55 %/Year (1.1)

Region 5: 1.3 %/Year (1.1)

All India : 1.4 %/Year (1)

However when October-March months are considered the NO2 show increase of about 3% and 4.7% / year over region 1 and 2 respectively. While over India it is observed 2.1 %/year.

Temporal evolution of tropospheric NO2 column from 1996-2006 period over the major emission region

• According to the study conducted by Garg et al. (2001), NOx emission over the Indian region growing at an annual rate of 5.5% /year, with a substantial heterogeneity.

• Similarly, Badhwar et al. (2006) computed that NO2 concentration over Delhi is growing at a rate of 3.8% /year (Vehicular growth during this period is 5.7% /year).

• Ghude et al (communicated 2007) computed that surface ozone concentration (based on monthly noontime and monthly mean of daily maximum values during 1997-2004 period) over Delhi is growing at the rate of 3.2% /year (Mega city in region 1).

• Whereas Naja and Lal (1996) showed that it is growing of about 1.45% /year at Ahamabad (Urban city in region 1).

• This suggests that the changes in NO2 column over the Indian region and majority of selected industrialized regions are consistent and not dominated by year to year variation.

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The annual cycle of the tropospheric column NO2 above the major emission region for the period 2003-2006 using SCIAMACHY

observations over India.

Pronounced seasonal variation in NO2 concentration is observed.

Minimum is observed during monsoon (JJAS) seasons over India.

maximum is observed during winter to pre-monsoon period

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Comparison between tropospheric column NO2 derived from the satellite measurement and in situ NOx measurements at surface level for

(using IR NOx analyzer) region 1 and 2.

Good agreement between the NO2 seasonal cycle measurements from satellite and from ground based stations, demonstrates well the ability of SCIAMACHY to detect pollution within the PBL.

Large seasonal variations of OH associated with photochemistry and moisture transport through the monsoon circulation can be generally seen over India. Over India strongest actinic fluxes are found in summer, leading to both high OH production rates and high NO2 loss by photolysis, and consequently to a reduced NO2 lifetime.

Biomass burning occurs mainly from January to may peaking in March and April, and maximum emission of NOx due to biomass burning are estimated to occur during this period. However, the contribution of biomass burning to NOx production is less over India than the other tropical regions during their biomass burning seasons. Biomass burned in the southern Indian states is very small (1.4 Tg/month) compared to eastern Indian states (6-7 Tg/months) and the western Indian states (4.6 Tg/month).

Whereas during spring (pre-monsoon) although the lifetime of NO2 starts decreasing (due to increase in solar actinic flux) biomass burning peaks (March-April) which sustain the higher NO2 concentration particularly over northern Indian region.

NO2 Column amount (1013 molec/cm2)

Maximum concentration of tropospheric column NO2 occurs over an IG plain despite moderate season to season variation.

Over middle to eastern part of IGP, western part of IGP (region 2 and 3) and Mumbai-Gujarat Industrial corridor (region 1) prominent high concentration of tropospheric column NO2 is observed during winter season.

A reasonable gradient of tropospheric column NO2 occur between southern part and northern plain of Indian subcontinent.

Conclusion:

The location of emission hot spots correlates well with the location of mega thermal power plants, mega cities, urban and Industrial Region, emphasizing the contribution of emission through thermal power plants, transport sector, and Industrial sector.

This suggests that the changes in NO2 column over the Indian region and majority of selected industrialized regions are consistent and not dominated by year to year variation.

Pronounced seasonal variation in NO2 concentration is observed with minimum during monsoon and maximum during winter.

Good agreement between the NO2 seasonal cycle measurements from satellite and from ground based stations, demonstrates well the ability of SCIAMACHY to detect pollution within the PBL.

Southern Indian region dose not seem to be a large source of emissions as compared to rest of the india.