Trends in aerosol optical depth for cities in India

Porch, W.M.; Chýlek, Petr; Dubey, Manvendra K.; Massie, Steven T.

doi:10.1016/j.atmosenv.2007.05.055

Cited by 31 publications

(15 citation statements)

References 16 publications

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“…In addition, there are reports on the continued decrease in surface‐reaching solar radiation over these regions, indicating a global dimming due to aerosols [ Wild et al ., ]. There are a few similar studies over Indian region based on the satellite data [ Massie et al ., ; Porch et al ., ; Dey and Girolamo , ]. However, none of these studies employed long‐term ground‐based AOD measurements from the networks.…”

Section: Introductionmentioning

confidence: 98%

Trends in aerosol optical depth over Indian region: Potential causes and impact indicators

et al. 2013

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[1] The first regional synthesis of long-term (back to~25 years at some stations) primary data (from direct measurement) on aerosol optical depth from the ARFINET (network of aerosol observatories established under the Aerosol Radiative Forcing over India (ARFI) project of Indian Space Research Organization over Indian subcontinent) have revealed a statistically significant increasing trend with a significant seasonal variability. Examining the current values of turbidity coefficients with those reported~50 years ago reveals the phenomenal nature of the increase in aerosol loading. Seasonally, the rate of increase is consistently high during the dry months (December to March) over the entire region whereas the trends are rather inconsistent and weak during the premonsoon (April to May) and summer monsoon period (June to September). The trends in the spectral variation of aerosol optical depth (AOD) reveal the significance of anthropogenic activities on the increasing trend in AOD. Examining these with climate variables such as seasonal and regional rainfall, it is seen that the dry season depicts a decreasing trend in the total number of rainy days over the Indian region. The insignificant trend in AOD observed over the Indo-Gangetic Plain, a regional hot spot of aerosols, during the premonsoon and summer monsoon season is mainly attributed to the competing effects of dust transport and wet removal of aerosols by the monsoon rain. Contributions of different aerosol chemical species to the total dust, simulated using Goddard Chemistry Aerosol Radiation and Transport model over the ARFINET stations, showed an increasing trend for all the anthropogenic components and a decreasing trend for dust, consistent with the inference deduced from trend in Angstrom exponent.

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Section: Introductionmentioning

confidence: 98%

Trends in aerosol optical depth over Indian region: Potential causes and impact indicators

et al. 2013

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“…Numerous studies using satellite observations and ground-based measurements have revealed an overall increase in aerosol optical depth (AOD) over India especially in IGP (Satheesh et al 2002, Massie et al 2004, Sarkar et al 2006, Porch et al 2007, Prasad and Singh 2007a, Lawrence and Lelieveld 2010, Dey and Di Girolamo 2011, Ramachandran et al 2012. Systematic aerosol observations via the well-calibrated AERONET instruments have played a vital role in the determination of the increase of anthropogenic aerosols, especially in developing countries (Yoon et al 2011, Xia 2011, Wang et al 2011.…”

Section: Introductionmentioning

confidence: 99%

Variability and trends of aerosol properties over Kanpur, northern India using AERONET data (2001–10)

Kaskaoutis

Singh

Gautam

et al. 2012

Environ. Res. Lett.

136

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Natural and anthropogenic aerosols over northern India play an important role in influencing the regional radiation budget, causing climate implications to the overall hydrological cycle of South Asia. In the context of regional climate change and air quality, we discuss aerosol loading variability and trends at Kanpur AERONET station located in the central part of the Indo-Gangetic plains (IGP), during the last decade (2001-10). Ground-based radiometric measurements show an overall increase in column-integrated aerosol optical depth (AOD) on a yearly basis. This upward trend is mainly due to a sustained increase in the seasonal/monthly averaged AOD during the winter (Dec-Feb) and post-monsoon (Oct-Nov) seasons (dominated by anthropogenic emissions). In contrast, a neutral to weak declining trend is observed during late pre-monsoon (Mar-May) and monsoon (Jun-Sep) months, mainly influenced by inter-annual variations of dust outbreaks. A general decrease in coarse-mode aerosols associated with variable dust activity is observed, whereas the statistically significant increasing post-monsoon/winter AOD is reflected in a shift of the columnar size distribution towards relatively larger particles in the accumulation mode. Overall, the present study provides an insight into the pronounced seasonal behavior in aerosol loading trends and, in general, is in agreement with that associating the findings with those recently reported by satellite observations (MODIS and MISR) over northern India. Our results further suggest that anthropogenic emissions (due mainly to fossil-fuel and biomass combustion) over the IGP have continued to increase in the last decade.

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“…The Indian subcontinent, home to 1.4 billion people (∼25% of the world's population) and the largest monsoon circulation in the world, is one region where the surface‐reaching solar radiation continues to decrease in recent times [ Wild et al , 2005; Kumari et al , 2007], implying a possible increase in aerosol loading. This has led to several studies examining regional trends of τ over India [ Porch et al , 2007; Streets et al , 2009; Zhang and Reid , 2010]. These studies either focused on the previous decade (e.g., Porch et al [2007] studied τ trend up to the year 2000), a particular region (e.g., Zhang and Reid [2010] focused on the oceanic region), or an average over the entire area of the Indian subcontinent [e.g., Streets et al , 2009].…”

Section: Introductionmentioning

confidence: 99%

A decade of change in aerosol properties over the Indian subcontinent

Dey

Girolamo

2011

Geophys. Res. Lett.

126

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[1] Changing atmospheric aerosol properties caused by anthropogenic activities carries serious implications for climate change and human health. The launch of the Multiangle Imaging SpectroRadiometer (MISR) onboard Terra spacecraft more than a decade ago provides the first capability to monitor several physical properties of aerosols over land from space. We use ten years (Mar 2000-Feb 2010 of observations from MISR to quantify seasonal linear trends of aerosol optical depth (t) segregated by particle size and shape over the Indian subcontinent. Here we show that many regions (referred to here as hotspots) have statistically significant (i.e., p < 0.05) seasonal linear trends in t, with seasonal t increasing in the range 0.1-0.4 in the last decade. These hotspots are associated with urban centers and densely-populated rural areas. Based on particle size and shape, we demonstrate that the trends, facilitated by topography and synoptic scale meteorology, are attributed to a significant rise in anthropogenic particles with additional contribution of natural particles in the rural and oceanic regions. The spatial and seasonal patterns of t trends suggest greater complexity in quantifying potential aerosolinduced regional climate and air quality effects, particularly at coarser scales. Citation: Dey, S., and L. Di Girolamo (2011), A decade of change in aerosol properties over the Indian subcontinent,

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Trends in aerosol optical depth for cities in India

Cited by 31 publications

References 16 publications

Trends in aerosol optical depth over Indian region: Potential causes and impact indicators

Trends in aerosol optical depth over Indian region: Potential causes and impact indicators

Variability and trends of aerosol properties over Kanpur, northern India using AERONET data (2001–10)

A decade of change in aerosol properties over the Indian subcontinent

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