The Indian sub-continent is one of the most adversely affected TC active basins that experience o... more The Indian sub-continent is one of the most adversely affected TC active basins that experience on an average 4–5 TCs every year. In comparison to other TC basins, this region is the most vulnerable due to relatively dense coastal population, shallow bottom topography and coastal configuration. Though the TCs formed in this region are considered to be much weaker in intensity and smaller in size as compared to other region, yet the number of deaths in the region is highest in the globe (300,000 human deaths were estimated from TC associated storm surge in Bangladesh in 1970). Out of nine recorded cases of heavy loss of human lives (~40,000) by TCs during last 300 years, seven cases (77 %) occurred in Indian sub-continent (Frank and Hussain, Bull Amer Meteor Soc 52:438–445, 1971). To overcome such loss, the advance predictions of TC in terms of their genesis, track and intensity is highly important. These advance timely information can save the life of people and help in decision mak...
ABSTRACT http://www.tandfonline.com/eprint/INyQrTTBpV9p9t2yK9RB/full Subsequent to the launch of ... more ABSTRACT http://www.tandfonline.com/eprint/INyQrTTBpV9p9t2yK9RB/full Subsequent to the launch of the Sondeur Atmosphérique du Profil d’Humidité Intertropicale par Radiométrie (SAPHIR) sensor on board the Megha-Tropiques satellite on 12 October 2011 from Satish Dhawan Space Centre, Indian Space Research Organization (ISRO), Shriharikota, India, the validation of layer averaged relative humidity (LARH) retrieved from SAPHIR has been initiated in different phases along with other retrieved parameters. The Megha-Tropiques is a joint satellite mission executed by the Indian Space Research Organization (ISRO) and the Centre National d’Etudes Spatiales (CNES), and is primarily devoted to study the tropical atmospheric processes influencing both weather and climate. The present study focuses on a validation campaign, where the validation of LARH derived from SAPHIR is carried out with three different numerical model analyses: the European Centre for Medium Range Weather Forecasts (ECMWF) model, the National Centers for Environmental Prediction (NCEP) model, and the National Centre for Medium Range Weather Forecasting (NCMRWF) model, over a period of six months from January 2013 to June 2013. It is observed that the root mean square difference (RMSD) of LARH has improved considerably for layers 1, 2, 3, and 6, and some marginal changes for layers 4 and 5, when a bias correction is applied to the data. The RMSD of SAPHIR LARH after correcting for bias is well within the range of the mission goal of 20% accuracy.
Possible causes behind the unusual cooling by summer monsoon clouds over India are investigated. ... more Possible causes behind the unusual cooling by summer monsoon clouds over India are investigated. Results suggest that the causes behind the cooling over the Bay of Bengal, India (BBI) and Arabian Sea (AS) within the Indian monsoon region are different. Over the BBI, clouds are tall. A unique upper tropospheric easterly jet stream exists over India during the summer monsoon
India’s polar orbiting satellite Oceansat-2 was launched by Indian Space Research Organisation on... more India’s polar orbiting satellite Oceansat-2 was launched by Indian Space Research Organisation on 23 September 2009 for applications pertaining to ocean studies and meteorology. The wind scatterometer aboard the Oceansat-2 satellite (OSCAT) covers 90 % of the global ocean within a day. In the present study, the OSCAT-derived wind fields are used to predict the genesis of tropical cyclones over the North Indian Ocean using a new technique based on data mining. The technique is based on the premise that there is some degree of similarity in low-level wind circulation among developing systems, which can be utilized to distinguish them from non-developing systems. This similarity of wind patterns has been measured quantitatively by computing the “matching index” between the given wind pattern and the wind signatures of developing systems available from the past observations. The algorithm is used to predict the tropical cyclogenesis of cyclones formed during the period 2009–11 in the North Indian Ocean. All the tropical disturbances that developed into tropical storms during the above period (2009–11), viz. PHYAN, WARD, LAILA, BANDU, PHET, GIRI, JAL, KEILA, FOUR, FIVE and THANE were predicted using the proposed method. The mean prediction lead time of the technique was 63 h. Probability of detection of the technique was 100 %, while the false alarm ratio was 2 %.
... pages 2429-2440. Available online: 24 Jun 2011. ... Velden, CS, Olson, WS and Roth, BA Tropic... more ... pages 2429-2440. Available online: 24 Jun 2011. ... Velden, CS, Olson, WS and Roth, BA Tropical cyclone centre fixing using DMSP SSM/I data. 4th Conference on Satellite Meteorology . ... Available online at http://cimss.ssec.wisc.edu/tropic/aodt View all references, 200612. ...
ABSTRACT The Megha-Tropiques (MT) satellite, a joint Indo-French mission, was launched by ISRO’s ... more ABSTRACT The Megha-Tropiques (MT) satellite, a joint Indo-French mission, was launched by ISRO’s PSLV-C18 on 12 October 2011 from Sriharikota, India. SAPHIR, a microwave humidity sounder on-board Megha Tropiques operates in six channels with frequencies around 183.31 GHz. A radiative transfer simulationbased operational algorithm has been developed to retrieve layer-averaged relative-humidity (LARH) for six atmospheric layers from the surface to nearly 12 km using SAPHIR observations over land and ocean under non-rainy conditions. SAPHIR-derived LARH for the period July to November 2012 has been validated with concurrent quality-controlled radiosonde observations as well as with ECMWF analysis data. Global validation with radiosonde and ECMWF data shows that root mean square deviation in LARH for all the six layers is nearly 20% and 15% respectively, after bias correction.
Soil moisture at different temporal and spatial scales is very important for various applications... more Soil moisture at different temporal and spatial scales is very important for various applications. At smaller spatial scales it has importance for the agro-meteorological applications, whereas at large spatial scales it is an important boundary parameter in the numerical prediction models of atmosphere for monthly to seasonal time-scale integrations. Frequent in situ global measurements of soil moisture at these spatial scales are virtually impossible because large heterogeneity of soil types makes these observations highly expensive and time consuming. Satellite based microwave radiometers can provide indirect estimates of soil moisture at resolutions compatible to that of climate models (50-100 km). In this paper the potential of Multi-frequency Scanning Microwave Radiometer (MSMR) onboard Indian satellite IRS-P4 is assessed for large area averaged soil moisture estimation. These are compared with the weekly-observed in situ soil moisture data over a few observatories of India Met...
Rainfall, an integral component of the global water and energy cycle, is one of the critical weat... more 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 multisate...
Journal of Geophysical Research: Atmospheres, 2013
ABSTRACT 1] This study presents an initial assessment of the quality of radiances measured from S... more ABSTRACT 1] This study presents an initial assessment of the quality of radiances measured from SAPHIR (Sounder for Probing Vertical Profiles of Humidity) on board Megha-Tropiques (Indo-French joint satellite), launched by the Indian Space Research Organisation on 12 October 2011. The radiances measured from SAPHIR are compared with those simulated by the radiative transfer model (RTM) using radiosondes measurements, Atmospheric Infrared Sounder retrievals, and National Centers for Environmental Prediction (NCEP) analyzed fields over the Indian subcontinent, during January to November 2012. The radiances from SAPHIR are also compared with the similar measurements available from Microwave Humidity Sounder (MHS) on board MetOp-A and NOAA-18/19 satellites, during January to November 2012. A limited comparison is also carried out between SAPHIR measured and the RTM computed radiances using European Centre for Medium-Range Weather Forecasts analyzed fields, during May and November 2012. The comparison of SAPHIR measured radiances with RTM simulated and MHS observed radiances reveals that SAPHIR observations are of good quality. After the initial assessment of the quality of the SAPHIR radiances, these radiances have been assimilated within the Weather Research and Forecasting (WRF) three-dimensional variational data assimilation system. Analysis/forecast cycling experiments with and without SAPHIR radiances are performed over the Indian region during the entire month of May 2012. The assimilation of SAPHIR radiances shows considerable improvements (with moisture analysis error reduction up to 30%) in the tropospheric analyses and forecast of moisture, temperature, and winds when compared to NCEP analyses and radiances measurement obtained from MHS, Advanced Microwave Sounding Unit-A, and High Resolution Infrared Sounder. Assimilation of SAPHIR radiances also resulted in substantial improvement in the precipitation forecast skill when compared with satellite-derived rain. Overall, initial results show the usefulness of SAPHIR radiances in the numerical weather prediction data assimilation systems.
Ocean surface wind vectors retrieved from the Oceansat-2 scatterometer (OSCAT) are used in this s... more Ocean surface wind vectors retrieved from the Oceansat-2 scatterometer (OSCAT) are used in this study to evaluate their impact on Thane cyclone simulation. The Weather Research and Forecasting (WRF) model and its three-dimensional variational (3D-Var) data assimilation system are adapted to evaluate the sensitivity of OSCAT observations. Simulated track error and landfall forecast are considered as standard measurements to assess the impact of 50 km and ~15 km spacing grid OSCAT winds along and across the swath. Significant improvement is obtained in track forecasting, when high-resolution vector winds (HVW; composite slice-level winds, ~15 km) are used for assimilation rather than coarser-resolution (50 km) operational OSCAT winds. Forecasting sensitivity to observations (OSCAT winds) using WRF tangent linear and adjoint modelling is used to quantify the impact of two different resolutions of OSCAT winds. WRF adjoint modelling is used here as a diagnostic tool, which indicates that high-resolution OSCAT winds have a more positive impact on the track prediction of Thane tropical cyclone.
Present study describes a methodology to establish an empirical expression to estimate the upper ... more Present study describes a methodology to establish an empirical expression to estimate the upper tropospheric humidity (UTH) from brightness temperature observations in water vapour channel of Very High Resolution Radiometer (VHRR) onboard Indian geostationary satellites INSAT-3A and Kalpana. Radiative transfer simulations for VHRR water vapour channel were made using SBDART model for tropical atmosphere with different upper tropospheric relative humidity
The Indian sub-continent is one of the most adversely affected TC active basins that experience o... more The Indian sub-continent is one of the most adversely affected TC active basins that experience on an average 4–5 TCs every year. In comparison to other TC basins, this region is the most vulnerable due to relatively dense coastal population, shallow bottom topography and coastal configuration. Though the TCs formed in this region are considered to be much weaker in intensity and smaller in size as compared to other region, yet the number of deaths in the region is highest in the globe (300,000 human deaths were estimated from TC associated storm surge in Bangladesh in 1970). Out of nine recorded cases of heavy loss of human lives (~40,000) by TCs during last 300 years, seven cases (77 %) occurred in Indian sub-continent (Frank and Hussain, Bull Amer Meteor Soc 52:438–445, 1971). To overcome such loss, the advance predictions of TC in terms of their genesis, track and intensity is highly important. These advance timely information can save the life of people and help in decision mak...
ABSTRACT http://www.tandfonline.com/eprint/INyQrTTBpV9p9t2yK9RB/full Subsequent to the launch of ... more ABSTRACT http://www.tandfonline.com/eprint/INyQrTTBpV9p9t2yK9RB/full Subsequent to the launch of the Sondeur Atmosphérique du Profil d’Humidité Intertropicale par Radiométrie (SAPHIR) sensor on board the Megha-Tropiques satellite on 12 October 2011 from Satish Dhawan Space Centre, Indian Space Research Organization (ISRO), Shriharikota, India, the validation of layer averaged relative humidity (LARH) retrieved from SAPHIR has been initiated in different phases along with other retrieved parameters. The Megha-Tropiques is a joint satellite mission executed by the Indian Space Research Organization (ISRO) and the Centre National d’Etudes Spatiales (CNES), and is primarily devoted to study the tropical atmospheric processes influencing both weather and climate. The present study focuses on a validation campaign, where the validation of LARH derived from SAPHIR is carried out with three different numerical model analyses: the European Centre for Medium Range Weather Forecasts (ECMWF) model, the National Centers for Environmental Prediction (NCEP) model, and the National Centre for Medium Range Weather Forecasting (NCMRWF) model, over a period of six months from January 2013 to June 2013. It is observed that the root mean square difference (RMSD) of LARH has improved considerably for layers 1, 2, 3, and 6, and some marginal changes for layers 4 and 5, when a bias correction is applied to the data. The RMSD of SAPHIR LARH after correcting for bias is well within the range of the mission goal of 20% accuracy.
Possible causes behind the unusual cooling by summer monsoon clouds over India are investigated. ... more Possible causes behind the unusual cooling by summer monsoon clouds over India are investigated. Results suggest that the causes behind the cooling over the Bay of Bengal, India (BBI) and Arabian Sea (AS) within the Indian monsoon region are different. Over the BBI, clouds are tall. A unique upper tropospheric easterly jet stream exists over India during the summer monsoon
India’s polar orbiting satellite Oceansat-2 was launched by Indian Space Research Organisation on... more India’s polar orbiting satellite Oceansat-2 was launched by Indian Space Research Organisation on 23 September 2009 for applications pertaining to ocean studies and meteorology. The wind scatterometer aboard the Oceansat-2 satellite (OSCAT) covers 90 % of the global ocean within a day. In the present study, the OSCAT-derived wind fields are used to predict the genesis of tropical cyclones over the North Indian Ocean using a new technique based on data mining. The technique is based on the premise that there is some degree of similarity in low-level wind circulation among developing systems, which can be utilized to distinguish them from non-developing systems. This similarity of wind patterns has been measured quantitatively by computing the “matching index” between the given wind pattern and the wind signatures of developing systems available from the past observations. The algorithm is used to predict the tropical cyclogenesis of cyclones formed during the period 2009–11 in the North Indian Ocean. All the tropical disturbances that developed into tropical storms during the above period (2009–11), viz. PHYAN, WARD, LAILA, BANDU, PHET, GIRI, JAL, KEILA, FOUR, FIVE and THANE were predicted using the proposed method. The mean prediction lead time of the technique was 63 h. Probability of detection of the technique was 100 %, while the false alarm ratio was 2 %.
... pages 2429-2440. Available online: 24 Jun 2011. ... Velden, CS, Olson, WS and Roth, BA Tropic... more ... pages 2429-2440. Available online: 24 Jun 2011. ... Velden, CS, Olson, WS and Roth, BA Tropical cyclone centre fixing using DMSP SSM/I data. 4th Conference on Satellite Meteorology . ... Available online at http://cimss.ssec.wisc.edu/tropic/aodt View all references, 200612. ...
ABSTRACT The Megha-Tropiques (MT) satellite, a joint Indo-French mission, was launched by ISRO’s ... more ABSTRACT The Megha-Tropiques (MT) satellite, a joint Indo-French mission, was launched by ISRO’s PSLV-C18 on 12 October 2011 from Sriharikota, India. SAPHIR, a microwave humidity sounder on-board Megha Tropiques operates in six channels with frequencies around 183.31 GHz. A radiative transfer simulationbased operational algorithm has been developed to retrieve layer-averaged relative-humidity (LARH) for six atmospheric layers from the surface to nearly 12 km using SAPHIR observations over land and ocean under non-rainy conditions. SAPHIR-derived LARH for the period July to November 2012 has been validated with concurrent quality-controlled radiosonde observations as well as with ECMWF analysis data. Global validation with radiosonde and ECMWF data shows that root mean square deviation in LARH for all the six layers is nearly 20% and 15% respectively, after bias correction.
Soil moisture at different temporal and spatial scales is very important for various applications... more Soil moisture at different temporal and spatial scales is very important for various applications. At smaller spatial scales it has importance for the agro-meteorological applications, whereas at large spatial scales it is an important boundary parameter in the numerical prediction models of atmosphere for monthly to seasonal time-scale integrations. Frequent in situ global measurements of soil moisture at these spatial scales are virtually impossible because large heterogeneity of soil types makes these observations highly expensive and time consuming. Satellite based microwave radiometers can provide indirect estimates of soil moisture at resolutions compatible to that of climate models (50-100 km). In this paper the potential of Multi-frequency Scanning Microwave Radiometer (MSMR) onboard Indian satellite IRS-P4 is assessed for large area averaged soil moisture estimation. These are compared with the weekly-observed in situ soil moisture data over a few observatories of India Met...
Rainfall, an integral component of the global water and energy cycle, is one of the critical weat... more 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 multisate...
Journal of Geophysical Research: Atmospheres, 2013
ABSTRACT 1] This study presents an initial assessment of the quality of radiances measured from S... more ABSTRACT 1] This study presents an initial assessment of the quality of radiances measured from SAPHIR (Sounder for Probing Vertical Profiles of Humidity) on board Megha-Tropiques (Indo-French joint satellite), launched by the Indian Space Research Organisation on 12 October 2011. The radiances measured from SAPHIR are compared with those simulated by the radiative transfer model (RTM) using radiosondes measurements, Atmospheric Infrared Sounder retrievals, and National Centers for Environmental Prediction (NCEP) analyzed fields over the Indian subcontinent, during January to November 2012. The radiances from SAPHIR are also compared with the similar measurements available from Microwave Humidity Sounder (MHS) on board MetOp-A and NOAA-18/19 satellites, during January to November 2012. A limited comparison is also carried out between SAPHIR measured and the RTM computed radiances using European Centre for Medium-Range Weather Forecasts analyzed fields, during May and November 2012. The comparison of SAPHIR measured radiances with RTM simulated and MHS observed radiances reveals that SAPHIR observations are of good quality. After the initial assessment of the quality of the SAPHIR radiances, these radiances have been assimilated within the Weather Research and Forecasting (WRF) three-dimensional variational data assimilation system. Analysis/forecast cycling experiments with and without SAPHIR radiances are performed over the Indian region during the entire month of May 2012. The assimilation of SAPHIR radiances shows considerable improvements (with moisture analysis error reduction up to 30%) in the tropospheric analyses and forecast of moisture, temperature, and winds when compared to NCEP analyses and radiances measurement obtained from MHS, Advanced Microwave Sounding Unit-A, and High Resolution Infrared Sounder. Assimilation of SAPHIR radiances also resulted in substantial improvement in the precipitation forecast skill when compared with satellite-derived rain. Overall, initial results show the usefulness of SAPHIR radiances in the numerical weather prediction data assimilation systems.
Ocean surface wind vectors retrieved from the Oceansat-2 scatterometer (OSCAT) are used in this s... more Ocean surface wind vectors retrieved from the Oceansat-2 scatterometer (OSCAT) are used in this study to evaluate their impact on Thane cyclone simulation. The Weather Research and Forecasting (WRF) model and its three-dimensional variational (3D-Var) data assimilation system are adapted to evaluate the sensitivity of OSCAT observations. Simulated track error and landfall forecast are considered as standard measurements to assess the impact of 50 km and ~15 km spacing grid OSCAT winds along and across the swath. Significant improvement is obtained in track forecasting, when high-resolution vector winds (HVW; composite slice-level winds, ~15 km) are used for assimilation rather than coarser-resolution (50 km) operational OSCAT winds. Forecasting sensitivity to observations (OSCAT winds) using WRF tangent linear and adjoint modelling is used to quantify the impact of two different resolutions of OSCAT winds. WRF adjoint modelling is used here as a diagnostic tool, which indicates that high-resolution OSCAT winds have a more positive impact on the track prediction of Thane tropical cyclone.
Present study describes a methodology to establish an empirical expression to estimate the upper ... more Present study describes a methodology to establish an empirical expression to estimate the upper tropospheric humidity (UTH) from brightness temperature observations in water vapour channel of Very High Resolution Radiometer (VHRR) onboard Indian geostationary satellites INSAT-3A and Kalpana. Radiative transfer simulations for VHRR water vapour channel were made using SBDART model for tropical atmosphere with different upper tropospheric relative humidity
Uploads
Papers by Pradip Pal