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Prakash, Satya
- Rainfall Estimation from Kalpana-1 Satellite Data over Indian Land and Oceanic Regions
Abstract Views :272 |
PDF Views:107
Authors
Affiliations
1 Atmospheric and Oceanic Sciences Group, Earth, Ocean, Atmosphere, Planetary Sciences and Applications Area, Space Applications Centre, Indian Space Research Organisation, Ahmedabad 380 015, IN
2 National Centre for Medium Range Weather Forecasting, Earth System Science Organization, Ministry of Earth Sciences, Noida 201 309, IN
1 Atmospheric and Oceanic Sciences Group, Earth, Ocean, Atmosphere, Planetary Sciences and Applications Area, Space Applications Centre, Indian Space Research Organisation, Ahmedabad 380 015, IN
2 National Centre for Medium Range Weather Forecasting, Earth System Science Organization, Ministry of Earth Sciences, Noida 201 309, IN
Source
Current Science, Vol 107, No 8 (2014), Pagination: 1275-1282Abstract
Rainfall, an integral component of the global water and energy cycle, is one of the critical weather elements. Reliable information of rainfall over India is crucial for food security and sustainable economic growth. The first Indian dedicated meteorological geostationary satellite Kalpana-1 was launched by the Indian Space Research Organisation in late 2002 to study the synoptic weather systems, monsoons and extreme weather events. Various geophysical parameters derived from this satellite measurements are operational and used for a wide range of applications. Two rainfall products, based on distinct algorithms, from this satellite are also available to users. These two algorithms after certain refinements are also applied to the recently launched INSAT-3D satellite measurements to estimate rainfall. In this article, the algorithms used for the development of these Kalpana-1-based rainfall products are summarized. The assessment of these rainfall products against standard multisatellite datasets and in situ observations are also outlined. Both the rainfall products are comparable with independent multisatellite datasets and have reasonable agreement with ground-based observations over the Indian land and oceanic regions. Limitations of these rainfall products are also presented; and future scope for further refinement of these products in perspective of upcoming Indian geostationary satellite missions is proposed.Keywords
Indian Monsoon, Kalpana-1 Satellite, Rainfall Estimation, Thermal Infrared.Full Text
- Nitrogen Uptake Rates and f-Ratios in the Equatorial and Southern Indian Ocean
Abstract Views :243 |
PDF Views:80
Authors
Affiliations
1 Physical Research Laboratory, Ahmedabad 380 009, IN
2 Department of Crop Physiology, University of Agricultural Sciences, Bengaluru 560 065, IN
3 National Centre for Antarctic and Ocean Research, Vasco-da-Gama, Goa 403 804, IN
1 Physical Research Laboratory, Ahmedabad 380 009, IN
2 Department of Crop Physiology, University of Agricultural Sciences, Bengaluru 560 065, IN
3 National Centre for Antarctic and Ocean Research, Vasco-da-Gama, Goa 403 804, IN
Source
Current Science, Vol 108, No 2 (2015), Pagination: 239-245Abstract
We report data on nitrate, ammonium and urea uptake rates from the Equatorial and Southern Indian Oceans. Productivity (0.81-2.23 mmol Nm-2 d-1) over the Equatorial Indian Ocean was low, but the f-ratio (0.13-0.45) was relatively high. In the Southern Indian Ocean total N-uptake rate varied from 1.7 to 12.3 mmol Nm-2 d-1; it was higher in the Antarctic coast (69°S) and lower over most of the Southern Ocean, the lowest being at 58°S. The f-ratio also showed significant spatial variation, but was higher compared to values at the Equatorial Indian Ocean. The mean f-ratio in the Southern Indian Ocean was 0.50. The nitrate-specific uptake rates and f-ratios appear to have increased significantly in the recent past relative to earlier estimates. While productivity in the Southern Ocean is comparable to that in the Equatorial Indian Ocean, higher f-ratios in the former underscore its importance in the uptake of CO2.Keywords
Carbon Sequestration, f-Ratio, Nitrogenuptake, Primary Productivity, Southern Ocean.Full Text
- An Assessment of Terrestrial Water Storage, Rainfall and River Discharge over Northern India from Satellite Data
Abstract Views :227 |
PDF Views:104
Authors
Affiliations
1 National Centre for Medium Range Weather Forecasting,Earth System Science Organization, Ministry of Earth Sciences, Noida 201 309, IN
2 Atmospheric and Oceanic Sciences Group, Space Applications Centre, Indian Space Research Organisation, Ahmedabad 380 015, IN
3 Institut de Recherche pour le Developpement (IRD), LEGOS, Toulouse 31400, FR
1 National Centre for Medium Range Weather Forecasting,Earth System Science Organization, Ministry of Earth Sciences, Noida 201 309, IN
2 Atmospheric and Oceanic Sciences Group, Space Applications Centre, Indian Space Research Organisation, Ahmedabad 380 015, IN
3 Institut de Recherche pour le Developpement (IRD), LEGOS, Toulouse 31400, FR
Source
Current Science, Vol 107, No 9 (2014), Pagination: 1582-1586Abstract
Terrestrial water storage (TWS) plays a key role in the global water cycle and is highly influenced by climate variability and human activities. In this study, monthly TWS, rainfall and Ganga-Brahmaputra river discharge (GBRD) are analysed over India for the period of 2003-12 using remote sensing satellite data. The spatial pattern of mean TWS shows a decrease over a large and populous region of Northern India comprising the foothills of the Himalayas, the Indo-Gangetic Plains and North East India. Over this region, the mean monthly TWS exhibits a pronounced seasonal cycle and a large interannual variability, highly correlated with rainfall and GBRD variations (r > 0.8) with a lag time of 2 months and 1 month respectively. The time series of monthly TWS shows a consistent and statistically significant decrease of about 1 cm year-1 over Northern India, which is not associated with changes in rainfall and GBRD. This recent change in TWS suggests a possible impact of rapid industrialization, urbanization and increase in population on land water resources. Our analysis highlights the potential of the Earth-observation satellite data for hydrological applications.Keywords
Earth-Observation Satellites, Rainfall, River Discharge, Terrestrial Water Storage.Full Text
- Revisiting the Noctiluca scintillans Paradox in Northern Arabian Sea
Abstract Views :273 |
PDF Views:94
Authors
Affiliations
1 ESSO-Indian National Centre for Ocean Information Services, Pragathi Nagar, Nizampet, Hyderabad 500 090, IN
2 Ocean Sciences Group, Earth and Climate Science Area, National Remote Sensing Centre, Indian Space Research Organisation, Hyderabad 500 037, IN
1 ESSO-Indian National Centre for Ocean Information Services, Pragathi Nagar, Nizampet, Hyderabad 500 090, IN
2 Ocean Sciences Group, Earth and Climate Science Area, National Remote Sensing Centre, Indian Space Research Organisation, Hyderabad 500 037, IN
Source
Current Science, Vol 113, No 07 (2017), Pagination: 1429-1434Abstract
In 2015, a Noctiluca scintillans bloom and associated water column properties were studied in the northern Arabian Sea. Our observations showed photic depth limited to 30 m with uniform oxygen concentration of ~223 μM. In general, the dissolved oxygen ranged between 180 and 223 μM within the top 80 m indicating saturated mixed layer. Chlorophyll a varied between 0.24 and 2.4 mg m–3 within the core of the bloom and <0.1mg m–3 outside. We further examined Argo oxygen data from 2006 to 2013 to delineate possible surface water hypoxia associated with the initiation of N. scintillans bloom. Oxygen profiles from Argo data suggest oxic upper water column (~ 50 m) with strong seasonal shoaling. Our results do not indicate any mixed layer oxygen depletion associated with the N. scintillans bloom or any evidence of surface water hypoxia in the past. However, examination of silicate/nitrate (Si/N) climatology suggests strong longitudinal variation. The silicate in the surface waters in the northwestern Arabian Sea is depleted much earlier (Si/N < 1) compared with the eastern part, resulting in a strong spatial trend. This presumably facilitates easy community transition to a N. scintillans bloom. This is supported by the heterotrophic nature of the species which, under detectable and below-detectable nitrate conditions, gives it a competitive advantage over other phytoplankton communities.Keywords
Hypoxia, Monsoon, Noctiluca scintillans, Oxygen, Silicate/Nitrate Ratio.Full Text
References
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- Capabilities of Satellite-Derived Datasets to Detect Consecutive Indian Monsoon Droughts of 2014 and 2015
Abstract Views :280 |
PDF Views:84
Authors
Affiliations
1 Divecha Centre for Climate Change, Indian Institute of Science, Bengaluru 560 012, IN
1 Divecha Centre for Climate Change, Indian Institute of Science, Bengaluru 560 012, IN
Source
Current Science, Vol 114, No 11 (2018), Pagination: 2362-2368Abstract
India received anomalously deficit southwest monsoon rainfall during 2014 and 2015, which resulted in consecutive droughts across the country. Reliable detection and monitoring of droughts are crucial for the reduction in drought vulnerability and associated socio-economic impacts. In this study, the potential of multiple high-resolution satellite datasets is examined using distinct drought indices over India for these two successive monsoon seasons. The satellite-derived precipitation, soil moisture and land surface temperature estimates are capable of depicting the anomalous drought conditions with some exceptions. A non-parametric multivariate standardized drought index, based on precipitation and soil moisture estimates is proven to be better in the detection of droughts when compared to conventional standardized drought indices. Overall, remote sensing satellite datasets provide immense opportunity to detect and monitor different kinds of droughts using a composite of indices. However, limited temporal records of these high-resolution satellite datasets restrain their applicability from the climatological perspective.Keywords
Drought, Multi-Satellite Product, Non-Parametric Multivariate Drought Index, Southwest Monsoon.Full Text
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