aerosol climatology and intercomparisonweb.iitd.ac.in/~sagnik/sn1.pdf · western arid and desert...

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ASL-720

SATELLITE METEOREOLOGY AND REMOTE SENSING

PROJECT TITLE

AEROSOL CLIMATOLOGY AND INTERCOMPARISON

SUBMITTED TO

Dr. SAGNIK DEY Assistant Professor

Centre for Atmospheric Sciences Indian Institute of Technology Delhi

SUBMITTED BY

Gopinadh Rongali (2013CEZ8054) Pawan (2013ASZ8508) Siddhartha Shankar (2012AST2523) Jatin Anand (2013CEZ8430) April-2014

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CONTENTS

S. No. Title Page No.

Abstract 3

1 Introduction 3

2 Study Area 4

3 Data Used

5

4 Methodology 5

5 Results

5.1 New Delhi Comparison of MISR-MODIS 5.2 Eastern India Comparison of MISR-MODIS 5.3 Andhra Pradesh Comparison of MISR-MODIS 5.4 Thar Desert Comparison of MISR-MODIS

6-15

6 Conclusions

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7 References

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8 Individual Member Contributions

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ACKNOWLEDGEMENT

We have taken efforts in this project. However, it would not have been possible without the

kind of support and help of our course supervisor.

We are highly indebted to (Prof. (Dr.) Sagnik Dey) for his valuable guidance and constant

supervision as well as for providing necessary information regarding the project and also for

his support in completing the project.

Aerosol Climatology and Intercomparison Group

IIT Delhi

3

Abstract

In India population is increasing gradually day by day and it will become one of the most

populated countries in the world. The growing population, industrialization and urbanization,

the aerosol loading in India is increasing that has significant impact on the climatologic

conditions. The present report discuss among the two remote sensing satellite data sets of the

temporal and seasonal variations of aerosol optical depth (AOD) in the period of Jan-2005 to

Dec-2010. We have used aerosol optical depth (AOD) data over the Thar Desert, Eastern

India, New Delhi, and Andhra Pradesh, to validate Multiangle Imaging SpectroRadiometer

(MISR) and Moderate Resolution Imaging Spectroradiometer (MODIS) Terra level 3 AOD

products for the 2005–2010 summer, winter and monsoon seasons. MISR has been

underestimating when compare to MODIS during all seasons. In all seasons, the MODIS

level 3 product distinctly shows a large AOD. Maximum AOD for MODIS 1.7, 0.65,1.3 and

0.55 and Maximum AOD for MISR 0.8, 0.52,0.84 and 0.45and Minimum AOD for MODIS

0.45,0.55, 0.3,0.52 and Minimum AOD for MISR 0.3, 0.15,0.20 and 0.1 respectively for Thar

Desert, Eastren India, New Delhi and Andhra Pradesh during 2005-10. An increase in

satellite-derived aerosol loading over the 2005–2010 time period has been found over these

were taken for study. We have computed the correlation coefficient between MISR and

MODIS AOD during the 2005–2010 winter (November–January), summer (Aprl-June) and

monsoon (June-Sept) seasons. The overall MISR-MODIS correlation coefficient 0.721,

0.609, 0.45 and 0.80 for Thar Desert, Eastern India, New Delhi and Andhra Pradesh during

2005-10 has been found over India Subcontinent.

Keywords: India, MODIS, MISR, remote sensing, aerosol optical depth

1. Introduction

The aerosols signify the nature of the atmosphere and play a main role in climate processes.

The aerosol particles have strong influence on the climate system by reflecting, absorbing and

scattering radiation, where reflection and scattering mostly predominates. The presence of

aerosols controls the cooling/heating effect on the earth surface and in turn warming/cooling

of the atmosphere. Aerosol optical depth depends on three parameters those are 1) source of

aerosol 2) Meteorology of that region 3) Topography of that region.

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Mon-soon

SummerORPre Mon-soon

Winter

AOD Wind Direction

2. Study Area

We have selected four regions in Indian subcontinent to study the aerosol optical depth

(AOD) with respect climatology during the time period Jan2005 – Dec2010. Those areas are

Thar Desert (Latitude 28.3º N, Longitude 72.5º E), Andhra Pradesh (Latitude 19ºN,

Longitude 85ºE), New Delhi (Latitude 29ºN, Longitude 77.5º E) and Eastern India (Latitude

30ºN, Longitude 90º E).

Figure 1. Study areas shown in the square boxes in the above map

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3. Data Used We have carried out the comparison of monthly average time series Level 3 Terra-MODIS

AOD at 550 nm and MISR AOD at 555 nm over New Delhi, Eastern India, Andhra Pradesh

and Thar Desert for the summer (Aprl-Jun), winter (Nov-Jan) and monsoon (Jun-Sept)

seasons for the time period of 2005–2010. The level 3 monthly AOD data for MODIS and

MISR are available at 1° and 0.5° spatial resolution respectively.

4. Methodology

The aerosol optical depth (AOD) from (http://disc.sci.gsfc.nasa.gov/giovanni) MISR and MODIS data are downloaded. Here we are showing the steps for downloading the AOD data for a selected area.

Figure 2. Methodology for downloading the data from Giovanni website

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5. Results

5.1 New Delhi Comparison of MISR-MODIS

y = 0.280x + 0.275R² = 0.233

00.10.20.30.40.50.60.70.80.9

0 0.2 0.4 0.6 0.8 1 1.2 1.4

AO

D_

MIS

R (

55

5 n

m)

AOD_MODIS (550 nm)

Delhi_Monsoon

0

0.2

0.4

0.6

0.8

1

1.2

1.4

AOD

Monsoon_Delhi

MISR_555nm

MODIS_550nm

(A)

y = 0.549x + 0.082R² = 0.662

00.10.20.30.40.50.60.70.8

0 0.2 0.4 0.6 0.8 1 1.2 1.4

AO

D_M

ISR(

555

nm)

AOD_MODIS (550 nm)

Delhi_Summer

0

0.2

0.4

0.6

0.8

1

1.2

1.4A

OD

Delhi_Summer

MISR_555nm

MODIS_550nm

(B)

y = 0.576x + 0.030R² = 0.606

0

0.1

0.2

0.3

0.4

0.5

0.6

0 0.2 0.4 0.6 0.8 1

AO

D_

MIS

R (

55

5 n

m)

AOD_MODIS (550 nm)

Delhi_Winter

00.10.20.30.40.50.60.70.80.9

1

Jan-

05

Dec-

05

Nov

-06

Jan-

07

Dec-

07

Nov

-08

Jan-

09

Dec-

09

Nov

-10

AOD

Delhi_Winter

MISR_555nm

MODIS_550nm

(C)

Figure 3 (A, B, C). Comparison of Level 3 MODIS AOD with MISR AOD over Delhi, AOD at 550 nm, 555 nm during the summer (Aprl–June), monsoon (July–Oct), and winter (Nov–Jan) seasons in the period of 2005-10.

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Table 1. Correlation Coefficient analysis between MODIS and MISR AOD data over New Delhi for different seasons during 2005-10 Seasons Correlation Parameters

Correlation Coefficient(R2) Slope(m) Intercept(c) Summer 0.662 0.549 0.082

Winter 0.606 0.576 0.030

Monsoon 0.233 0.280 0.275

Overall(2005-10) 0.450 0.414 0.162

y = 0.414x + 0.162R² = 0.450

00.10.20.30.40.50.60.70.80.9

0 0.2 0.4 0.6 0.8 1 1.2 1.4

AO

D_

MIS

R (

55

5 n

m)

AOD_MODIS (550 nm)

Delhi_2005-2010

0

0.2

0.4

0.6

0.8

1

1.2

1.4

Jan

-05

Ma

y-0

5S

ep

-05

Jan

-06

Ma

y-0

6S

ep

-06

Jan

-07

Ma

y-0

7S

ep

-07

Jan

-08

Ma

y-0

8S

ep

-08

Jan

-09

Ma

y-0

9S

ep

-09

Jan

-10

Ma

y-1

0S

ep

-10

AO

D

Delhi MODIS & MISR

MODIS

MISR

(A) (B)

Figure 4 (A, B). Scatter, Linear plots between Level 3 MODIS AOD with MISR AOD over Delhi, AOD at 550 nm and 555 nm during 2005-10.

In the case of New Delhi, during the summer season MISR AOD increases rapidly. The high

AOD over the Delhi region can be attributed to the large influx of desert dust from the

western arid and desert regions of Arabia, Africa and Thar Desert (Rajasthan) during the pre-

monsoon season. The winter season is characterized by accumulation of aerosols over the

Delhi region due to unique topography as the alluvial basin valley (elevation b150 m from

mean sea level) is bounded by the towering Himalayas to the north and Vindhyan Mountains

to the south. MISR performs better than MODIS during both summer and winter seasons

owing to its unique multiangular and multispectral design. MODIS overestimates AOD

during the summer whereas both sensors underestimate it during the winter. Summer shows

high variability in both mean and standard deviation due to influence of dust storms coming

from western arid regions, and cloud cover affects monthly AOD during the monsoon season.

Thus, the winter season provides the best sampling with which to test the degree of MISR-

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MODIS correlation. As aerosol optical depth retrieval is sensitive to the vegetation cover

(dark and dense vegetation targets), particularly for MODIS, the relatively lower vegetation

cover over the Delhi region potentially explains the lower correlation between MISR and

MODIS AOD over the Delhi region.

5.2 Eastern India validation of MISR-MODIS

(A)

(B)

(C) Figure 5 (A, B, C). Comparison of Level 3 MODIS AOD with MISR AOD over Eastern India, AOD at 550 nm, 555 nm during the summer (Aprl–June), monsoon (July–Oct), and winter (Nov–Jan) seasons in the period of 2005-10.

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Table 2. Coefficients of correlation analysis between MODIS and MISR AOD data over Eastern India for different seasons during 2005-10 Seasons Correlation Parameters


Winter 0.854 0.506 0.117

Monsoon 0.630 0.441 0.134

Overall(2005-10) 0.609 0.824 0.134

(A) (B)

Figure 6 (A, B). Linear, Scatter plots between Level 3 MODIS AOD with MISR AOD over Eastern India, AOD at 550 nm and 555 nm during 2005-10.

In Eastern India aerosol climatology deals with interaction of various kinds of aerosol particle

with surroundings and its long term impact on climate of particular region over the period of

time. In this section we have compared the AOD value of two sensor MODIS and MISR for

555nm and over eastern India Region. It includes vast Indo Gangetic plane, Lower

Himalayan region and coastal areas of West Bengal..The linear plot Month vs AOD for

different period summer, winter and monsoon shows scatter plot MODIS is showing higher

value. This is due to dust aerosol in Indo-Gangetic plane .These dust particle comes from

nearby desert area due to long range transport .The pre monsoon period of Eastern India is

dominated by strong wind condition. The average wind speed is higher than winter season.

So this contributes long range transport beyond the Boundary layer.

The MONTH vs AOD plot is showing that average value of AOD is increasing for both the

sensor for the year 2005-2010. This fact is also supported by CPCB data that in these recent

years the pollution label has been increased sharply in this heavily populated plane. The

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MONTH vs AOD plot is showing peak value for each summer period for 2005-2010. Again

this is due to dust aerosol and pollutant particles. Winter month is dominated by pollutant

particles (sulphate and nitrate particle mostly) which is caused by anthropogenic activities

and in winter the average wind speed reduces and boundary layer thickness reduces which

leads to more concentration of pollutant aerosol near the surface.

In this scatter plot MODIS is showing higher value. This is due to dust aerosol in Indo-

Gangetic plane. The AOD value is increasing in pre-monsoon for all the years (2005-2010).

This is due to dust storm from desert and this effect in minimum in post monsoon but there is

rise in aerosol concentration due to anthropogenic activities fossil fuel burning and thermal

power plants. In these years the aerosol concentration has increased which is evident from

increasing slope of trend line for both MODIS and MISR.

5.3 Andhra Pradesh comparison of MISR-MODIS

(A)

(B)

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(C)

Figure 7 (A, B, C). Comparison of Level 3 MODIS AOD with MISR AOD over Andhra Pradesh, AOD at 550 nm, 555 nm during the summer (Aprl–June), monsoon (July–Oct), and winter (Nov–Jan) seasons in the period of 2005-10.

Table 3. Coefficients of correlation analysis between MODIS and MISR AOD data over Andhra Pradesh for different seasons during 2005-10 Seasons Correlation Parameters


Winter 0.803 0.793 0.054

Monsoon 0.806 0.570 0.130

Overall(2005-10) 0.801 0.737 0.081

(A) (B)

Figure 8 (A, B). Scatter, Linear plots between Level 3 MODIS AOD with MISR AOD over Andhra Pradesh, AOD at 550 nm and 555 nm during 2005-10.

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The south India seems to have less AOD when compared to that of the North India and it may

be due to the transport of Aerosols due to the Land-Sea winds. Main anthropogenic sources

of aerosols in the South India are the use of fossil fuels like coal, diesel, petrol, etc. (used for

transportation and electricity generation), biomass burning for cooking in rural areas,

agricultural waste-burning, forest fires and emissions from small industries. Seasonal

distribution of AOD over the study region for the entire period from 2005 to 2010 is shown in

Figure 7(A, B, C) and the overall distribution of AOD for Andhra Pradesh is shown in Figure

8(A, B).

In the case of Andhra Pradesh, there are very interesting points are observed, here in seasonal

vise in summer in giving less correlation when compare to winter and monsoon. In summer

R2 0.56 as in winter, monsoon R2 value is 0.803, 0.806. In summer AOD is high as compare

to other two seasons and winter is less AOD. In AP both MODIS and MISR is giving good

correlation and both are intersecting in some months. Some times MODIS is underestimating;

sometimes MISR is performing like MODIS (underestimation). This mainly due to Lad-

Ocean interaction. In AP study are we taken both land part (Andhra Pradesh), some part (Bay

of Bengal). In AP more things also is clearly shows about intersecting of MODIS, MISR

AOD values due to Eastern Ghats in AP. Sun glint reflectance from ocean surface due to

surface waves effect MISR AOD values it will take over estimation. In AP summer season

Dust plume incorrectly making due to high variability also affect MISR value. Metrology of

AP: In winter season winds come from N-E direction to Bay of Bengal (AP), in summer

peninsular to BB and in monsoon S-W to BB. Topography of AP: Eastern Ghats

5.4 Thar Desert Comparison of MISR-MODIS

(A)

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0

0.2

0.4

0.6

0.8

1

AO

DThar_Winter

Nov-Jan2005-10

MODIS_550nm

MISR_555nm

y = 0.300x + 0.096R² = 0.503

0

0.1

0.2

0.3

0.4

0.5

0 0.2 0.4 0.6 0.8 1

AO

D_M

ISR_

555n

m

AOD_MODIS_550nm

Thar_WinterMISR_vs_MODIS

(B)

0

0.5

1

1.5

2

AO

D

Thar_SummerApr-Jun-2005-10

MODIS_550nm

MISR_555nm

y = 0.311x + 0.148R² = 0.833

00.10.20.30.40.50.60.70.8

0 0.5 1 1.5 2

AO

D_M

ISR_

555n

m

AOD_MODIS_550nm

Thar_SummerApr-Jun-2005-10

(C) Figure 9 (A, B, C). Comparison of level 3 MODIS AOD with MISR AOD over Thar Desert, AOD at 550 nm, 555 nm during the summer (Aprl–June), monsoon (July–Oct), and winter (Nov–Jan) seasons in the period of 2005-10. Table 4. Coefficients of correlation analysis between MODIS and MISR AOD data over Thar Desert for different seasons during 2005-10 Seasons Correlation Parameters


Winter 0.503 0.300 0.096

Monsoon 0.570 0.346 0.159

Overall(2005-10) 0.721 0.405 0.077

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(A) (B)

Figure 10(A, B). Linear, Scatter plots between Level 3 MODIS AOD with MISR AOD over Thar Desert, AOD at 550 nm, 555 nm during 2005-10. In the case of Thar Desert: In summer season correlation Coefficient(R2) is high because their only dust that produced by dust storm in Thar during April to June and wind coming from middle east bring only dust not any type of pollution as we know in both MODI and MISR algorithm only dust can measure easily . In winter season wind direction is north–west so wind brings pollution produced in Pakistan

by fuel, biomass burning etc as we know in MISR algorithm in pollution is underestimation.

So that correlation Coefficient(R2) is low as compare to all three season.

In monsoon season wind direction is from south-west move some dust to other neighboring states and weather disturbances like depression change may affect the correlation Coefficient(R2) At Thar Desert two type of dust there one produced in Thar itself another transfer from middle east Asia both have different surface reflectance due to this MODIS and MISR measure different value. Meteorology of Thar Desert Low rain and high temperature are the most conspicuous characteristics of desert climate.

Thar desert in India receives considerable rainfall (100-300nm) west Rajasthan are the sand

dunes which contribute about 40% of area of the region. The Thar region is under the

influence of the Indian South-West monsoon during July and august and occasionally rain

producing weather disturbances like depressions and lows penetrate up to parts of Rajasthan

Triggering rain event in the Thar. Thus wind flow near the surface is from South –West

during the summer monsoon and from general North-West direction during the winter .At the

upper troposphere level wind flows from the east during summer monsoon and from west in

winter season in the transition month of October. and November. in autumn the pressure

gradient is very slack in the spring early summer during April and may intense heating during

the day coupled with existence of pressure gradient in the formative stage of the summer time

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heat low supports strong dust raising winds the almost clear weather pattern during late Jan.

to June is interrupted by the passage of a western disturbance which occasionally affects the

weather of western Rajasthan such that a few mild rain events occur during January march

and dust storms from April to June.

Rain fall The main rainy season during July and august when almost 80% of annual rain fall

occur the monsoon seasonal. Over western Rajasthan the rain fall is mostly convective in

nature such that an intense weather system even in one day produces 50% or higher of annual

rain fall in one day.

Stability and moisture content The Thar desert of India witness extreme surface air

temperature during the year . The maximum temperature in may and June touches 50 degree

and minimum temp in Jan Feb reach -3 degree or even less in extreme cold wave conditions.

The soil temp at the surface in summer is even 10 degree warm than the maximum surface air

temp near noon and it is about 3 degree colder than the minimum air temp in winter this

indicates the super adiabatic lapse rate prevails during day time in summer and a storm

inversion exists in winter the surface from dusk to early morning. Solar radiation decreases in

July and august and a secondary maximum occurs in October. Dust and clouds are major

factor in attenuation of solar radiation . maximum hours of bright sun shine reach 10 hours a

day occur in May and October. There is a decreasing trend in solar radiation perhaps due to

higher dust load

Surface wind At Thar desert surface winds reach a value of 25-30 km/hr on western

Rajasthan during May and June such strong wind rise tremendous dust from the loosely

sandy soil of the region and dust is transported eastward over the neighboring states of India.

Dust layer and dust storm A dust layer from ground from 8-9 km height is built gradually

from march to June which effect the horizontal and vertical visibility. Dust depletes solar

radiation by 30% . during intense episode of dust raising winds or following the dust storm

day the sun is obscured from view even during the mid day the dust raising capacity of

surface air is proportional to the cube of wind speed and hence the capacity of wind to rise

sand from the desert is increase shriply after the wind speed 10 km/h the average soil loss in

Thar desert vary between 30 to 60 kg per meter sq per day during April to June dust storm

also occur more frequently in Thar. During dust storm are often accompanied by thunder

storms (dry and wet) the annual no. of thunder storms days is about 10 over west Rajasthan

and increases about 40 over east Rajasthan .

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6. Conclusions The increase in concentration of air pollutants over major cities is growing due to

anthropogenic activities and rapid industrialization. In the Eastern India region have led to

increase in winter time aerosol loading from Delhi favored by topography, wind and other

meteorological conditions. In all plots MODIS is giving higher values of AOD as compared

to MISR. 1) It is overestimating due to algorithm of MODIS which takes higher values of

reflectance (as fixed) and MISR itself calculate surface reflectance 2) MISR calculate low

value at polluted region due to its algorithm.3) Different value of MODI and MISR due to

different algorithm eg. MISR not consider mixture of pollution and dust. 4) Surface

Reflectance changes according to seasons that are why the correlation coefficient is also

changing accourding to in different seasons. 5) The different camera-dependent effective path

lengths observed through the atmosphere, so MISR is giving better results. In all plots AOD

values increasing in consecutive years. This shows the increase in pollutant (sulphate and

nitrate) and dust. The Southern region AOD is less as compared to Northern region .It is due

to more population, urbanization and industrialization in north India. In summer period the

influxes of dust storm leading to higher value of AOD. Out of different region Delhi is

showing high values of AOD due to polluted dust and in Thar Desert it is due to dust. In

Andhra Pradesh in monsoon season surface reflectance change due to land cover will change

(vegetation). In this region basically land-ocean interaction in there that is why MODIS and

MISR is giving good correlation. In the monsoon winds directions come from Indian Ocean

to Indian subcontinent.

7. References

1. Anup K. Prasad and Ramesh P. Singh (2007) “Comparison of MISR-MODIS aerosol optical depth over the Indo-Gangetic basin during the winter and summer seasons (2000–2005)”. Remote Sensing of Environment 107, pp 109-119

2. S. Tiwari, A.K. Singh (2013)” Variability of Aerosol Parameters Derived from

Ground and Satellite Measurements over Varanasi Located in the Indio-Gangetic Basin”. Aerosol and Air Quality Research, 13: pp 627-6

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8. Individual Contribution of the Group Members Gopinadh Rongali (2013cez8054): Has downloaded the Level-3 Terra - MODIS (550nm) and MISR (555nm) AOD of time series data during the time period Jan 2005 –Dec 2010 of the Andhra Pradesh (lat , lon ) using the website link (http://disc.sci.gsfc.nasa.gov/giovanni). He plotted in between MODIS and MISR of scatter and liner plots of different seasons (monsoon ,summer ,winter) and analysis the data plots . He also contributed during the preparation of presentation and making the final report.

Pawan (2013asz8508): Has downloaded the Level-3 Terra - MODIS (550nm) and MISR (555nm) AOD of time series data during the time period Jan 2005 –Dec 2010of Thar Desert (lat, lon) using the website link (http://disc.sci.gsfc.nasa.gov/giovanni). He plotted in between MODIS and MISR of scatter and liner plots of different seasons (monsoon ,summer ,winter) and analysis the data plots . He also contributed during the preparation of presentation and making the final report.

Siddhartha Shankar(2012ast2523) :Has downloaded the Level-3 Terra - MODIS (550nm) and MISR (555nm) AOD of time series data during the time period Jan 2005 –Dec 2010of Eastern India (lat, lon) using the website link (http://disc.sci.gsfc.nasa.gov/giovanni). He plotted in between MODIS and MISR of scatter and liner plots of different seasons (monsoon ,summer ,winter) and analysis the data plots . He contributed during the preparation of presentation.

Jatin Anand (2013cez3) :Has downloaded the Level-3 Terra - MODIS (550nm) and MISR (555nm) AOD of time series data during the time period Jan 2005 –Dec 2010of New Delhi(lat, lon) using the website link (http://disc.sci.gsfc.nasa.gov/giovanni). He plotted in between MODIS and MISR of scatter and liner plots of different seasons (monsoon ,summer ,winter) and analysis the data plots .

aerosol climatology and intercomparisonweb.iitd.ac.in/~sagnik/sn1.pdf · western arid and desert...

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