Assessment of spatio-temporal trends of satellite-based aerosol optical depth using Mann–Kendall test and Sen’s slope estimator model

Figures & data

Figure 1. Geographical map of the study area, Jharkhand state and its major cities, India.

Figure 2. Flow chart of the methodology for assessing spatio-temporal trends of variation of AOD over Jharkhand state, India from 2000 to 2017.

Figure 3. Annual Spatial trends of aerosol optical depth over Jharkhand state from 2000 to 2017.

Figure 4. Time series and trend lines for annual AOD over Chaibasa, Jamshedpur, Ranchi, Dhanbad, Hazaribagh, and Sahibganj of Jharkhand state from 2000 to 2017.

Table 1. Result of Mann–Kendal trend test and Sen’s slope estimator of annual AOD over Chaibasa, Jamshedpur, Ranchi, Dhanbad, Hazaribagh, and Sahibganj of Jharkhand state from 2000 to 2017.

City name	Kendall’s tau	p Value (two-tailed)	Sen’s slope	Std. deviation	Std. error	Z- values	Significant levels
Chaibasa	0.582	.00000	0.011	0.080	0.004437	3.3332	***
Jamshedpur	0.686	.00000	0.015	0.092	0.005103	3.9393	***
Ranchi	0.556	.00000	0.009	0.064	0.003578	3.1817	***
Dhanbad	0.542	.00190	0.010	0.072	0.004014	3.106	**
Hazaribagh	0.660	.00000	0.011	0.072	0.004004	3.7878	***
Sahibganj	0.569	.00112	0.012	0.087	0.004848	3.2575	**

Showing Kendall’s tau, p value (two-tailed), Sen’s slope, Std. deviation, Std. Error, Z-Statistics, and Significant levels

** Statistically significant trends at the 99% confidence level;

*** Statistically significant trends at the 99.9% confidence level.

Figure 5. Annual distribution of aerosol optical depth over Jharkhand state from 2000 to 2017 in pre-monsoon and post-monsoon season.

Figure 6. Box and Whisker plots showing the variation of mean AOD for pre-monsoon (a) and post-monsoon (b) seasons from 2000 to 2017 of 6 major cities of Jharkhand state; Chaibasa, Jamshedpur, Ranchi, Dhanbad, Hazaribagh, and Sahibganj represented by A–F, respectively.

Figure 7. Pixel-based relative change of AOD for pre-monsoon (a–c) and post-monsoon (d–f) seasons over Jharkhand state for the periods between 2000 and 2017.

Figure 8. Seasonal Spatial trends of Aerosol Optical Depth of Pre-monsoon and Post-monsoon seasons over Jharkhand state; (a) Trends of AOD in Pre-monsoon season during 2000–2005, (b) Trends of AOD in Pre-monsoon season during 2006–2011, (c) Trends of AOD in Pre-monsoon season during 2011–2017, (d) Trends of AOD in Post-monsoon season during 2000–2005, (e) Trends of AOD in Post-monsoon season during 2006–2011, and (f) Trends of AOD in post-monsoon season during 2011–2017.

Table 2. Summary of Sen’s slope of aerosol optical depth for pre-monsoon and post-monsoon season of Jharkhand state.

Study periods	Pre-monsoon		Post-monsoon
	Highest	Lowest	Highest	Lowest
2000 to 2005	0.0794	−0.07058	0.09821	−0.05002
2006 to 2011	0.09484	−0.08291	0.10809	−0.03288
2012 to 2017	0.12288	−0.02587	0.11344	−0.09406

Figure 9. Seasonal time series and trend lines (Mann–Kendall Trend Test) of aerosol optical depth (AOD) for six major cities of Jharkhand state from 2000 to 2017 in Pre-monsoon (a–f) and post-monsoon (g–l); (a and g) Chaibasa, (b and h) Jamshedpur, (c and i) Ranchi, (d and j) Dhanbad, (e and k) Hazaribagh, and (f and l) Sahibganj.

Figure 10. Scatter plot matrix and wind rose showing the correlation between AOD and meteorological parameters of Jharkhand state from 2000 to 2017; (a) correlation between AOD, temperature, relative humidity (RH), wind speed, and wind direction; (b,c) Wind rose plot of pre-monsoon and post-monsoon season, respectively, over Jharkhand state.

Table 3. Result of Mann–Kendal trend test and Sen’s slope estimator of AOD of pre-monsoon season over Chaibasa, Jamshedpur, Ranchi, Dhanbad, Hazaribagh, and Sahibganj of Jharkhand state from 2000 to 2017.

City name	Kendall’s tau	p Value (two-tailed)	Sen’s slope	Std. deviation	Std. error	Z- values	Significant levels
Chaibasa	0.399	.02305	0.008	0.079	0.018705	2.2727	*
Jamshedpur	0.451	.01000	0.009	0.070	0.016616	2.5757	**
Ranchi	0.137	.44872	0.003	0.058	0.013749	0.75755	H0
Dhanbad	0.111	.54449	0.002	0.054	0.012614	0.60604	H0
Hazaribagh	0.163	.36332	0.004	0.066	0.015651	0.90906	H0
Sahibganj	0.359	.04082	0.008	0.085	0.020105	2.0454	*

Showing Kendall’s tau, p value (two-tailed), Sen’s slope, Std. deviation, Std. error, Z-Statistics, and Significant levels

* statistically significant trends at the 95% confidence level;

** Statistically significant trends at the 99% confidence level;

Table 4. Result of Mann–Kendal trend test and Sen’s slope estimator of AOD of post-monsoon season over Chaibasa, Jamshedpur, Ranchi, Dhanbad, Hazaribagh, and Sahibganj of Jharkhand state from 2000 to 2017.

City name	Kendall’s tau	p Value (two-tailed)	Sen's slope	Std. deviation	Std. Error	Z- values	Significant levels
Chaibasa	0.516	.00313	0.014	0.103	0.024186	2.9545	**
Jamshedpur	0.634	.00028	0.021	0.133	0.031407	3.6363	***
Ranchi	0.595	.00065	0.017	0.112	0.026512	3.409	***
Dhanbad	0.582	.00086	0.021	0.136	0.032005	3.3332	***
Hazaribagh	0.647	.00021	0.020	0.128	0.030123	3.712	***
Sahibganj	0.477	.00639	0.017	0.145	0.034229	2.7272	**

Showing Kendall’s tau, p value (two-tailed), Sen’s slope, Std. deviation, Std. error, Z-Statistics, and Significant levels

** statistically significant trends at the 99% confidence level;

*** statistically significant trends at the 99.9% confidence level.

Figure 11. Multi-year average AOD of Terra MODIS sensor for pre-monsoon and post-monsoon seasons over Jharkhand state from 2000 to 2017.

Figure 12. Comparative analysis of seasonal variation of AOD between pre and post-monsoonal seasons 2000, 2005, 2010, 2015, and 2017 over (a) Chaibasa, (b) Jamshedpur, (c) Ranchi, (d) Dhanbad, (e) Hazaribagh, and (f) Sahibganj of Jharkhand state.

Table 5. Averaged AOD of the year 2000, 2005, 2010, 2015, and 2017 over Chaibasa, Jamshedpur, Ranchi, Dhanbad, Hazaribagh, and Sahibganj of Jharkhand state in pre- and post-monsoonal periods.

Year		AOD_2000	AOD_2005	AOD_2010	AOD_2015	AOD_2017
City name	Season	Mean ± SD	Mean ± SD	Mean ± SD	Mean ± SD	Mean ± SD
Chaibasa	Pre-monsoon	0.24 ± 0.04	0.36 ± 0.04	0.35 ± 0.05	0.36 ± 0.04	0.33 ± 0.03
	Post-monsoon	0.22 ± 0.02	0.25 ± 0.03	0.38 ± 0.04	0.54 ± 0.05	0.37 ± 0.04
Jamshedpur	Pre-monsoon	0.28 ± 0.02	0.38 ± 0.04	0.39 ± 0.06	0.40 ± 0.03	0.38 ± 0.03
	Post-monsoon	0.32 ± 0.04	0.35 ± 0.02	0.53 ± 0.03	0.67 ± 0.04	0.55 ± 0.03
Ranchi	Pre-monsoon	0.23 ± 0.04	0.29 ± 0.03	0.27 ± 0.07	0.25 ± 0.03	0.29 ± 0.03
	Post-monsoon	0.26 ± 0.06	0.24 ± 0.06	0.36 ± 0.07	0.52 ± 0.07	0.36 ± 0.07
Dhanbad	Pre-monsoon	0.33 ± 0.03	0.38 ± 0.01	0.40 ± 0.05	0.31 ± 0.03	0.38 ± 0.04
	Post-monsoon	0.38 ± 0.04	0.34 ± 0.04	0.55 ± 0.04	0.71 ± 0.03	0.55 ± 0.04
Hazaribagh	Pre-monsoon	0.22 ± 0.02	0.32 ± 0.02	0.24 ± 0.04	0.28 ± 0.03	0.28 ± 0.03
	Post-monsoon	0.28 ± 0.01	0.25 ± 0.03	0.40 ± 0.03	0.59 ± 0.04	0.45 ± 0.07
Sahibganj	Pre-monsoon	0.32 ± 0.08	0.26 ± 0.09	0.33 ± 0.13	0.34 ± 0.13	0.44 ± 0.08
	Post-monsoon	0.49 ± 0.09	0.52 ± 0.11	0.58 ± 0.14	0.88 ± 0.10	0.53 ± 0.12

Figure 13. The geospatial pattern of average aerosol optical depth over Jharkhand state from 2000 to 2017.

Figure 14. ‘Most important parameters for the identification of sources of aerosols: (a) spatial distribution of average NDVI; (b) forest fire (constant occurrence from 2011-2017); (c) cement industries; (d) thermal power plants; (e) mines; (f) highly polluting industries; (g) road density; and (h) population density over Jharkhand state and surrounding areas (Census of India 2011)’ (Bandyopadhyay et al. 2021).

Census of India. 2011. Population density, Ministry of Home Affairs. http://censusindia.gov.in.

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Bandyopadhyay J, Mohammad L, Mondal I, Maiti KK, Al-Ansari N, Pham QB, Khedher KM, Anh DT. 2021. Identification and characterization the sources of aerosols over Jharkhand state and surrounding areas, India using AHP model. Geomat Nat Hazard Risk. 12(1):2194–2224.

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Availability of data and materials

The data that support the findings of this study are available from the author, [Lal Mohammad, [email protected] and Quoc Bao Pham, [email protected]], upon reasonable request.