K. V. S. Badarinath

Wintertime spatial characteristics of boundary layer aerosols over peninsular India

During an intense field campaign for generating a spatial composite of aerosol characteristics over peninsular India, collocated measurements of the mass concentration and size distribution of near-surface aerosols were made onboard instrumented vehicles along the road network during the dry, winter season (February-March) of 2004. The study regions covered coastal, industrial, urban, village, remote, semiarid, and vegetated forestlands. The results showed (1) comparatively high aerosol (mass) concentrations (exceeding 50 μ g m(-3)), in general, along the coastal regions (east and west) and adjacent to urban locations, and (2) reduced mass concentration ( 50% of the total) of coarse-mode aerosols (>1 μ m). The spatial composite of accumulation-mode share to the total aerosol mass concentration agreed very well with the monthly mean spatial composite of aerosol fine-mode fraction for February 2004, deduced from Moderate-Resolution Imaging Spectroradiometer data for the study region, while a point by point comparison yielded a linear association with a slope of 1.09 and correlation coefficient of 0.79 for 76 independent data pairs. Pockets of enhanced aerosol concentration were observed around the industrialized and urban centers along the coast as well as inland. Aerosol size distributions were parameterized using a power law. Spatial variation of the retrieved aerosol size index shows relatively high values (>4) along the coast compared to interior continental regions except at a few locations. Urban locations showed steeper size spectra than the remote locations.

Spatial characterization of electrical power consumption patterns over India using temporal DMSP-OLS night-time satellite data

Changes in electric power consumption patterns of a country over a period of time reflect on its socio‐economic development and energy utilization processes. In the present study, we characterized spatial and temporal changes in electric power consumption patterns over India during 1993 to 2002, using ‘night‐time lights’ data given by the Defense Meteorological Satellite Program–Operational Line Scan System (DMSP‐OLS) over the Indian region. The OLS operates in two bands: visible (0.5–0.9 µm) and thermal (10.5–12.5 µm) and has a unique capability of picking up faint sources of visible–near infrared emissions (lights) at night on the Earths surface including cities, towns and villages with a DN value ranging from 1 to 63. Night‐time light images for cloud‐free dates given by the DMSP‐OLS from 1993 to 2002 were segregated into respective years and were integrated to generate one ‘Stable light image’ per year. Changes in light scenarios over the Indian region in the decadal time frame were studied using stable lights datasets from 1993 to 2002. Information on changes in the light scenarios was integrated with demographic data to characterize developments in major cities and states of India. Results of the study suggested an increase in population by 170 million and power consumption from 44962 million kWh to 306355 million kWh over the country during 1993–2002, which was associated with an overall increase in number of night‐time lights of up to 26% in all states, indicating development in electric power consumption patterns. Correlation analysis between increase in population to the increase in night‐time lights and electric power consumption showed a coefficient of determination, R 2, of 0.59 and 0.56 respectively. Increase in light intensities along the peripheries of major Indian cities was observed, which indicated increased stress on the cities and corresponding development in power consumption patterns during the decadal time frame. Certain states, however, showed a decrease in night‐time lights in some areas, which are primarily attributed to the decreased economic growth trend and poverty and accounted to the scatter observed in the correlation analysis. Results are discussed in the paper.

Fire risk evaluation using multicriteria analysis - a case study.

Forest fires are one of the major causes of ecological disturbance and environmental concerns in tropical deciduous forests of south India. In this study, we use fuzzy set theory integrated with decision-making algorithm in a Geographic Information Systems (GIS) framework to map forest fire risk. Fuzzy set theory implements classes or groupings of data with boundaries that are not sharply defined (i.e., fuzzy) and consists of a rule base, membership functions, and an inference procedure. We used satellite remote sensing datasets in conjunction with topographic, vegetation, climate, and socioeconomic datasets to infer the causative factors of fires. Spatial-level data on these biophysical and socioeconomic parameters have been aggregated at the district level and have been organized in a GIS framework. A participatory multicriteria decision-making approach involving Analytical Hierarchy Process has been designed to arrive at a decision matrix that identified the important causative factors of fires. These expert judgments were then integrated using spatial fuzzy decision-making algorithm to map the forest fire risk. Results from this study were quite useful in identifying potential “hotspots” of fire risk, where forest fire protection measures can be taken in advance. Further, this study also demonstrates the potential of multicriteria analysis integrated with GIS as an effective tool in assessing “where and when” forest fires will most likely occur.

Hotspot Analysis of Vegetation Fires and Intensity in the Indian Region

In this study, we quantify vegetation fire activity in India using the MODerate resolution Imaging Spectroradiometer (MODIS) active fire datasets. We assessed different fire regime attributes, i.e., fire frequency, seasonality, intensity and the type of vegetation burnt in diverse geographical regions. MODIS data from 2002–2010 revealed an average of 63696 fire counts per year with the highest during 2009. Fire season in India extends from October to June with the peak during March. The K-means algorithm identified hotspot regions of fire clusters in diverse regions of India. We examined fire radiative power (FRP) data in the hotspot regions to address which fires burn intensively than others based on the vegetation type. We first assessed the best statistical fit distributions for the FRP data using the probability density functions (PDFs) and ranked them based on Kolmogorov-Smirnov statistic. We then described the fire intensities using empirical cumulative distribution functions (CDFs). Results suggest diverse pdfs for the FRP data that included Burr, Dagum, Johnson as well as Pearson distribution and they varied based on the vegetation type burnt. Analysis from empirical CDFs suggested relatively high fire intensity for closed broadleaved evergreen/ semi-deciduous forests than the other vegetation types. Although, annual sum of FRP for agricultural fires was less than the closed broadleaved evergreen forests, the values were higher than the mosaic vegetation category and broadleaved deciduous forests. These results on fire hotspots and FRP will be useful to address the impact of vegetation fires on air pollution and climate in India.

Biomass burning and related trace gas emissions from tropical dry deciduous forests of India: A study using DMSP-OLS data and ground-based measurements

Biomass burning is one of the major sources of trace gas emissions in the atmosphere. In India the major sources of biomass burning include deforestation, shifting cultivation, accidental fires, controlled burning, fire wood burning, burning from agricultural residues and burning due to fire lines. Studies on biomass burning practices gain importance due to increasing anthropogenic activities and increasing rates of deforestation. Satellite data have been widely used over the globe to monitor the rates of deforestation and also with respect to biomass burning studies. But, much of the polar orbiting satellites, due to their repetitive cycle, have limitations in observing such events and in the tropics, due to cloud cover, getting a cloud-free image during the daytime is difficult. In this study we used Defence Meteorological Satellite Program Operational Line Scanner (DMSP-OLS) night-time data to study the biomass burning events over a period of 10 years from 1987 to 1998 for the Eastern Ghats region, covering the northern part of Andhra Pradesh, India. Two ground-based experiments were carried out to quantify the emissions from biomass burning practices. The results of the study with respect to trace gases suggested emission ratios for CO, CH4, NOx and N20 during the burning to be about 12.3%, 1.29%, 0.29% and 0.07% at the first site and 12.5%, 1.59%, 0.29% and 0.05% at the second site, suggesting low inter-fire variability between the sites. The variation has been attributed to the fuel load, vegetation characteristics, site conditions and local meteorological parameters affecting the relative amounts of combustion. Using the DMSP OLS derived areal estimates of active fires, the trace gas emissions released from the biomass burning were quantified. The results suggested the emissions of 8.2 2 10 10 g CO 2, 1.8 2 10 8 g CO, 6.0 2 10 6 g N 2 O, 3.0 2 10 6 g NO x and 1.2 2 10 8 8 g CH 4 during March 1987. The emissions increased to 1.0 2 10 11 g CO 2, 2.3 2 10 g CO, 7.8 2 10 6 g N 2 O, 3.9 2 10 7 g NO x and 1.6 2 10 8 g CH 4, over a period of 10 years. The results of the analysis suggest the possible use of monitoring biomass burning events from DMSP-OLS night-time data.

Variation in aerosol properties over Hyderabad, India during intense cyclonic conditions

In this study, we examine the changes in aerosol properties associated with an intense tropical cyclone, the so‐called ‘Mala’, that occurred during April 2006, over the Bay of Bengal. This cyclone, accompanied by very strong surface winds reaching 240 km h−1, caused extensive disasters in houses and beach resorts in the coastal areas of Myanmar. Ground‐based measurements of aerosol optical depth (AOD), particle‐size distribution and erythemal UV radiation in the neighbouring urban environment of Hyderabad, India, showed significant variations due to changes in wind velocity and direction associated with the cyclone event. The results show an increase in ground‐measured PM1.0, PM2.5, and PM10 concentrations, probably associated with the strong surface winds on 28 April, the day on which the cyclone affected the study region. In contrast, the AOD on that day exhibited a significant decrease, since the winds probably acted as a ventilation mechanism for the atmosphere. The Terra‐MODIS satellite images showed a prevalence of dust particles over the study region on the next day of the cyclone. Results from ground‐based AOD sun‐photometer observations matched well with satellite AOD retrievals. Aerosol index obtained from Ozone Monitoring Instrument (OMI) during the cyclone events suggested increasing trend, indicating the presence of an elevated dust‐aerosol layer during and after the cyclone. Results on the effects of wind and air mass fields in affecting the AOD during cyclone events are also presented.

Studies on aerosol optical depth in biomass burning areas using satellite and ground-based observations

Biomass burning in the tropics is a source of trace gas fluxes and particulate matter. During the last decade, the shifting cultivation practices have been increased in the tropical forest of Eastern Ghats, Andhra Pradesh, India. In order to quantify the fluxes emitted from the biomass burning due to shifting cultivation practices, a field experiment has been conducted on February 16-25, 1999. The present study provides the variation of aerosol optical depth over the shifting cultivation areas of Rampa Revenue Division, Eastern Ghats using a sunphotometer in synchronism with satellite data. Optical depth values increased up to 2.0 during the burning phase and then returned to normal values (0.2-0.5). The atmospheric correction of the satellite data using the optical depth values suggested improvement in the overall contrast of the image and increase in the dynamic range of the normalized difference vegetation index (NDVI) values of various features in the image.

Active forest fire monitoring in Uttaranchal State, India using multi-temporal DMSP-OLS and MODIS data

This paper gives an account of day–night active forest fire monitoring conducted over the sub‐tropical and moist temperate forests of the Uttaranchal State, India, during 2005 using the Defence Meteorological Satellite Program – Operational Line Scan system (DMSP‐OLS) and Moderate Resolution Imaging Spectroradiometer (MODIS) satellite data. The state experienced heavy fire episodes during May–June 2005 and daily datasets of DMSP‐OLS (night‐time) and selected cloud‐free MODIS (daytime) datasets were used in mapping active fire locations. DMSP‐OLS collects data in visible (0.5 to 0.9 µm) and thermal (10.5 to 12.5 µm) bands and detects dim sources of lighting on the earths surface, including fires. The enhanced fire algorithm for active fire detection (version 4) was used in deriving fire products from MODIS datasets. Fire locations derived from DMSP‐OLS and MODIS data were validated with limited ground data from forest department and media reports. Results of the study indicated that the state experienced heavy fire episodes, most of them occurring during night‐time rather than daytime. Validation of satellite‐derived fires with ground data showed a high degree of spatial correlation.

Fog Over Indo-Gangetic Plains—A Study Using Multisatellite Data and Ground Observations

Every year, fog formation over the Indo-Gangetic Plains (IGP) of Indian region during the winter months of December-January is believed to create numerous health hazards, economic loss, and cross-country transportation of aerosols. It has attracted the global scientific communitys attention to address the uncertainties pertaining to its formation and physico-chemical properties. In this paper, we made an attempt to study the fog conditions that occurred over the north Indian region and long-range transport of aerosols from the fog region towards the southern region during November 2008, using multisatellite data sets and ground-based observations on aerosol properties and solar irradiance in the urban region of Hyderabad, India. Ground measurements showed a considerable increase in aerosol optical depth (AOD) at 500 nm ( ~ 30%) and a decrease in total solar irradiance ( ~ 7%) over Hyderabad, India, during the fog period compared to a normal day corresponding to 04 November 2008.

CH4 emissions from biomass burning of shifting cultivation areas of tropical deciduous forests – experimental results from ground-based measurements

Abstract Context Abstract : Tropical deciduous fires from shifting cultivation process in India are characterized by the highly differential nature of fire behavior due to fragmented burning patterns. Our study from ground-based experiments from biomass burning of tropical deciduous forest fires suggests smoldering combustion as the dominating process during biomass burning which leads to evolution of more incompletely oxidized products such as Methane when compared to other ecosystems such as Savannas. In the study, we report emission ratios and emission factors for methane from biomass burning of tropical deciduous forests. As tropical deciduous forests in India cover more than 50% of overall forests, the emission factors obtained in the present study can be used widely for methane emission estimation from forest biomass burning studies in other parts of India and in modeling studies of Methane from forest biomass burning in India. Main Abstract : Biomass burning is an important source of trace gas emissions to the atmosphere. Methane emitted from the biomass burning contributes to the atmospheric greenhouse effect and is sufficiently long-lived to enter the stratosphere and take part in the stratospheric ozone cycles. In India, though CH 4 emissions from the different sources such as rice paddy fields and domestic animals have been well studied, there are relatively no field-based studies with respect to CH 4 emissions from biomass burning. In the present study, we report for the first time, the CH 4 emissions from biomass burning of tropical deciduous forests cleared for shifting cultivation purposes. Trace gas emissions from the biomass burning plumes have been collected through grab sampling in canisters as well as from online measurements through instruments. Site characteristics with respect to species composition, amount of biomass burnt and relative amounts of combustion, viz., flaming, mixed and smoldering have been determined. Modified combustion efficiency has been used to differentiate relative amounts of combustion. Emission ratios were calculated with respect to CO 2 and emission factors based on the amount of biomass consumed. Results of the study with respect to biomass estimations prior to burning suggested values of 12–14 t ha −1 at the first site and 13.5–15.3 t ha −1 at the second site. The mean modified combustion efficiencies during flaming, mixed and smoldering combustion phases for the first site were found to be 95.7%, 91.1% and 74.4% and 95.31%, 90.63% and 72.89%, respectively, for the second site. The average biomass consumed during the fire ranged from 4.7 t ha −1 (site 1) to 3.4 t ha −1 (site 2), indicating low amount of biomass burnt during the first phase of burning in shifting cultivation areas. Results suggested the CH 4 emission ratios of 1.29% at the first site and 1.59% at the second site. The CH 4 emission ratios obtained in the present study are closer to the most accepted estimates of 1.2±0.5% obtained for tropical forests elsewhere. Using the emission ratios obtained in the study and estimating the amount of methane emissions from biomass burning suggests that nearly 0.99 Tg of methane is emitted annually from shifting cultivation process in India. Also, in the study, a detailed comparison of emission ratios and emission factors of CH 4 has been made.