Anup K. Prasad

Changes in aerosol parameters during major dust storm events (2001–2005) over the Indo‐Gangetic Plains using AERONET and MODIS data

[1] The Indo-Gangetic (IG) plains is one of the largest and most densely populated regions in the world. Recent studies over the IG plains using multi-year (2000-2004) satellite (including Moderate Resolution Imaging Spectroradiometer: MODIS) and ground Aerosol Robotic Network (AERONET) data show strong seasonal variability of aerosol optical depth (AOD) with maximum aerosol loading (>0.6-0.7 at 500 nm) during the pre-monsoon (summer) season. A number of major dust storms, originating from western arid and desert regions of Africa, Arabia and western part of India (Thar Desert), affect the whole IG plains during the pre-monsoon season (April-June). The mean AOD increases from 0.4-0.5 to more than 0.6-0.7 throughout the plains (>0.8-0.9 on the western side) as a result of the dust storm events. Pronounced changes in the aerosol optical parameters, derived from AERONET, have been observed over Kanpur (26.45°N, 80.35°E) during dust storm events (2001-2005). The maximum AOD (at 500 nm) during dust event days show increase from ∼1 to ∼2.4 with advance of the pre-monsoon season (April-June). The aerosol size distribution (ASD) shows increase in radius from 1.71 to 2.24 μm (in coarse fraction) and decrease in the distribution width from 3.76 to 2.56 μm showing changes in the aerosol characteristics during dust events. The aerosol parameters [ASD, single scattering albedo (SSA, total and coarse mode) and real and imaginary parts of the refractive index] change significantly during dust events. The National Oceanic and Atmospheric Administration (NOAA) Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model (5-day back-trajectory) and MODIS level-3 daily data (AOD and Angstrom exponent) have been used to trace the source, path and spatial extent of dust storm events. During major dust events, enhancement of the total column water vapor is observed from MODIS level-3 daily water vapor data (near-infrared clear column) showing a strong association (72% correlation) with the AOD along the track of dust storms over the IG plains. A significant rise of 50-100% is observed in the ground level respirable suspended particulate matter (RSPM) concentration showing alarming health risks to the people living in the IG plains during dust storm events.

Enhancement of oceanic parameters associated with dust storms using satellite data

over the Arabian Sea causes chlorophyll blooming (usually 10–22.43 mg/m 3 ) within a period of 1–2 to up to 3–4 days. However, we have also found significant anomalous cooling of the ocean surface (SST) and relatively higher ocean wind speeds (QuikSCAT) during dust storms that may lead to favorable conditions for blooming. Exact nature and cause of chlorophyll bloom in the semienclosed northern Arabian Sea, surrounded by one of the world’s major sources of dust storms (Africa, Middle East, Iran, and Afghanistan), are very important in understanding the productivity and the biogeochemical cycles of the marine ecosystem. The results have been validated using the Indian Remote Sensing Polar-4 Ocean Color Monitor (IRS P4 OCM) data.

Variability of Aerosol Optical Depth Over Indian Subcontinent Using MODIS Data

High AOD is observed over the Ganga basin throughout the year unlike southern India, is alarming as this basin is one of the most productive basins of Indian subcontinent having population of more than 460 million. AOD is found to be increasing rapidly since 2000 in summer season that may cause adverse effect to the agricultural crops and also to the human health. Increased aerosol loading may likely affect the rainfall which is responsible for the observed drought conditions over the Indian subcontinent. Detailed analysis of AOD, crop yields and rainfall data are required to understand the impact of increasing aerosol loading over the Indian subcontinent.

Seasonal climatology of aerosol optical depth over the Indian subcontinent: trend and departures in recent years

A. K. PRASAD*{{, R. P. SINGH{§ and A. SINGH{ {Department of Civil Engineering, Indian Institute of Technology, Kanpur, 208016, India {United Nations Environment Programme/Global Resources Information Database (UNEP/GRID), US Geological Survey/Earth Resources Observation Systems (USGS/EROS) Data Center, Sioux Falls, South Dakota 57198, USA §Center for Earth Observing and Space Research, George Mason University, Fairfax, Virginia 22030, USA

Multi-sensor studies of the Sumatra earthquake and tsunami of 26 December 2004

Multi sensor satellites are now capable of monitoring the globe during day and night and provide information about the land, ocean and atmosphere. Soon after the Sumatra tsunami and earthquake of 26 December 2004, multi‐sensors data have been analysed to study the changes in ocean, land, meteorological and atmospheric parameters. A pronounced changes in the ocean, atmospheric and meteorological parameters are observed while comparing data prior and after the Sumatra main event of 26 December 2004. These changes strongly suggest a strong coupling between land, ocean and atmosphere associated with the Sumatra event.

Use of vegetation index and meteorological parameters for the prediction of crop yield in India

Monsoon rainfall distribution over the Indian sub‐continent is inconsistent every year. Due to uncertainty and dependence on the monsoon onset and weather conditions, estimation of crop yield in India is difficult. In this paper, analyses of the crop yield, normalized difference vegetation index, soil moisture, surface temperature and rainfall data for 16 years (from 1984 to 1999) have been carried out. A non‐linear iterative multivariate optimization approach (quasi‐Newton method with least square loss function) has been used to derive an empirical piecewise linear crop yield prediction equation (with a break point). The derived empirical equation (based on 1984 to 1998 data) has been used to predict 1999 crop yield with R2>0.90. The model has been validated for the three years 1997, 1998 and 1999. A crop yield prediction equation has been obtained for each province in India (for wheat and rice) that accounts for>90% of the variance in the dataset.

EFFECT OF DUST STORM ON OCEAN COLOR AND SNOW PARAMETERS

ConclusionThe present study clearly shows the influence of dust storms on chlorophyll bloom in the offshore region of the Arabian Sea, with a time lag of few days, during the pre-monsoon season. Various satellite derived parameters over the Arabian Sea, Himalayan and Tibet snow covered regions show large changes due to the influence of dust storms. The MODIS snow albedo gives unreliable values under the influence of dust storms due to increase in the aerosol loading over these regions and snow albedo product must be used in combination with snow pixel counts during the dust storm season. A detailed study is required for the quantitative evaluation of dust storms on the chlorophyll blooms in the Arabian Sea region and on the snow parameters in the Himalayan region.

Changes in Himalayan snow and glacier cover between 1972 and 2000

Snow and glacier cover in the western Himalaya region are very important because four major rivers—the Indus, Ganga, Brahmaputra, and Yamuna—originate there. Changes in snow and glacier cover influence the discharge and flow of these perennial rivers, which together constitute one of the worlds largest alluvial river basins, the Indo-Gangetic (IG) basin. This basin is agriculturally fertile and densely populated with 700 million people. In the past, the basin has experienced numerous floods due to snow melting and also due to excessive monsoon rainfall. However, in recent years the areal extent of snow has been declining, especially in the western Himalayan region that has a direct influence over the hydrological regime of the basin and that also plays an important role in the changing climatic conditions of the Indian subcontinent.

Synergistic Use of Remote Sensing and Modeling for Tracing Dust Storms in the Mediterranean

This study focuses on the detection of the dust source region and monitoring of the transport of the dust plume from its primary outflow to final deposition. The application area is the Sahara desert and the eastern Mediterranean, where two dust events occurred during the period 4–6 February 2009, an unusual event for a winter period. The Aqua-MODIS and OMI observations clearly define the spatial distribution of the dust plumes, while the CALIPSO observations of total attenuated backscatter (TAB) at 532 nm, depolarization ratio (DR), and attenuated color ratio (1064/532 nm) on 5 February 2009 provide a clear view and vertical structure of the dust-laden layer. The dust source region is defined to be near the Chad-Niger-Libyan borders, using satellite observations and model (DREAM) output. This dust plume is vertically extended up to 2.5 km and is observed as a mass plume of dust from surface level to that altitude, where the vertical variation of TAB (0.002 to 0.2) and DR (0.2–0.5) implies dust-laden layer with non-spherical particles. CALIPSO profiles show that after the dust plume reached at its highest level, the dust particles start to be deposited over the Mediterranean and the initial dust plume was strongly attenuated, while features of dust were limited below about 1–1.5 km for latitudes northern of ~36° (Greek territory).

Seasonal variability of aerosol optical depth over indian subcontinent

Ganga basin extends 2000 km E-W and about 400 km N-S and is bounded by Himalayas in the north. This basin is unequivocally found to be affected by high aerosols optical depth (AOD) (>0.6) throughout the year. Himalayas restricts movement of aerosols toward north and as a result dynamic nature of aerosol is seen over the Ganga basin. High AOD in this region has detrimental effects on health of more than 460 million people living in this part of India besides adversely affecting clouds formation, monsoonal rainfall pattern and Normalized Difference Vegetation Index (NDVI). Severe drought events (year 2002) in Ganga basin and unexpected failure of monsoon several times, occurred in different parts of Indian subcontinent. Significant rise in AOD (18.7%) over the central part of basin (Kanpur region) have been found to cause substantial decrease in NDVI (8.1%) since 2000. A negative relationship is observed between AOD and NDVI, magnitude of which differs from region to region. Efforts have been made to determine general distribution of AOD and its dominant departure in recent years spatially using Moderate Resolution Imaging Spectroradiometer (MODIS) data. The seasonal changes in aerosol optical depth over the Indo-Gangetic basin is found to very significant as a result of the increasing dust storm events in recent years.