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Shukla, Bipasha Paul
- Top of Atmosphere Flux from the Megha-Tropiques ScaRaB
Abstract Views :249 |
PDF Views:79
Authors
V. Sathiyamoorthy
1,
Bipasha Paul Shukla
1,
Rajesh Sikhakolli
1,
Sasmita Chaurasia
1,
Baby Simon
1,
B. S. Gohil
1,
P. K. Pal
1
Affiliations
1 Atmospheric and Oceanic Sciences Group, Earth, Ocean, Atmosphere, Planetary Sciences and Applications Area, Space Applications Centre (ISRO), Ahmedabad 380 015, IN
1 Atmospheric and Oceanic Sciences Group, Earth, Ocean, Atmosphere, Planetary Sciences and Applications Area, Space Applications Centre (ISRO), Ahmedabad 380 015, IN
Source
Current Science, Vol 104, No 12 (2013), Pagination: 1656-1661Abstract
One of the important payloads on-board the joint Indo- French Megha-Tropiques satellite is the Scanner for Radiation Budget (ScaRaB). It is dedicated for monitoring the Earth Radiation Budget (ERB) parameters at Top of Atmosphere (TOA). In this article, details of the algorithm used for computing two important ERB components, namely TOA reflected shortwave and emitted longwave fluxes from ScaRaB radiance measurements are presented along with preliminary crosssatellite validation results.
The ScaRaB flux computation algorithm is similar to the one used in the ERB Experiment. The maximum likelihood estimation algorithm is used for identification of different Earth scenes and cloud types. First, the raw radiances are corrected for spectral filtering effects followed by implementation of scene-type dependent angular correction to deduce shortwave and longwave fluxes. The instantaneous TOA flux data derived from ScaRaB radiance measurements are compared with similar data available from Clouds and Earth's Radiant Energy System (CERES) onboard Aqua and Terra satellites. Preliminary comparison confined to two months period (September- October 2012) using the two satellites suggests that the ScaRaB data are in good agreement with the CERES data. The bias-corrected ischolar_main mean square difference in ScaRaB longwave flux is 4.7 and 5.3 Wm-2 with respect to CERES on-board Aqua and Terra satellites respectively. For ScaRaB shortwave flux, it is 25.9 Wm-2 and 25.5 Wm-2 with respect to CERES onboard Aqua and Terra satellites respectively. A detailed comparison of ScaRaB TOA flux data with more than one-year of CERES data is already initiated. Results from the preliminary comparison exercise suggest that the ScaRaB data can be used with confidence for ERB studies.
Keywords
Atmosphere, Computation Algorithm, Megha-Tropiques Mission, Scarab Instrument.Full Text
- Cloud Microphysical Characterization during AVIRIS-NG Campaign
Abstract Views :199 |
PDF Views:78
Authors
Affiliations
1 Atmospheric Sciences Division, Atmosphere and Oceanic Sciences Group, Space Applications Centre, Indian Space Research Organisation, Ahmedabad 380 015, IN
2 Department of Physics, Electronics and Space Sciences, Gujarat University, Navrangpura, Ahmedabad 380 009, IN
1 Atmospheric Sciences Division, Atmosphere and Oceanic Sciences Group, Space Applications Centre, Indian Space Research Organisation, Ahmedabad 380 015, IN
2 Department of Physics, Electronics and Space Sciences, Gujarat University, Navrangpura, Ahmedabad 380 009, IN
Source
Current Science, Vol 116, No 7 (2019), Pagination: 1196-1200Abstract
Airborne Visible/Infrared Imaging Spectrometer-Next Generation (AVIRIS-NG) air campaign has provided a unique opportunity to characterize the properties of tropical clouds at microscale. A novel approach based on spectral matching technique has been used to derive the cloud microphysical parameters (CMPs) such as optical thickness and effective radius over campaign sites of Kurnool (Andhra Pradesh) and Chilika (Odisha) region in India. It is found that the derived CMPs correspond to medium opacity and effective radius ranging from 4 to 18 μm. The hyperspectral bands coupled with high spatial resolution of the observations make it possible to identify pockets populated densely with large particles within a cloud. This has great applications for picking up fast developing convective cloud cells. More insight with different cloud type observations is anticipated with AVIRISN G phase-2 campaign.Keywords
Cloud Microphysical Parameters, Hyperspectral Imaging, Remote Sensing, Spectral Matching.Full Text
References
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- Development of Windspeed Retrieval Model using RISAT-1 SAR Cross-Polarized Observations
Abstract Views :167 |
PDF Views:87
Authors
Affiliations
1 Earth, Ocean, Atmosphere, Planetary Sciences and Applications Area, Space Applications Centre, Indian Space Research Organisation, Ahmedabad 380 015, IN
1 Earth, Ocean, Atmosphere, Planetary Sciences and Applications Area, Space Applications Centre, Indian Space Research Organisation, Ahmedabad 380 015, IN
Source
Current Science, Vol 118, No 8 (2020), Pagination: 1282-1286Abstract
In this study, a method for retrieving ocean surface wind speed using C-band cross-polarization SAR observations has been outlined. A linear least square technique has been used to develop a Geophysical Model Function (GMF), C2P. The GMF was derived using NRCS observations from RISAT-1 and wind-speed observations from ASCAT. The correlation between observed and simulated NRCS values obtained from C2P was 0.66, with a negative bias of 0.01 dB and the corresponding ischolar_main mean square difference of 1.13 dB. Subsequently, the developed GMF was tested with 774 RISAT-1 MRS datasets to retrieve wind speed along the Indian coast and also of the tropical cyclone ‘Megh’. The measured intensity and radius of maximum wind speed were 30 m s–1 and 16.65 km respectively. Subsequently, the retrieved wind speed was validated with ASCAT wind-speed observations. The statistical comparison of RISAT-1 and ASCAT observed wind speed showed negative biases of 0.90 and 0.34 m s–1 with the corresponding RMSD of 2.11 and 1.77 m s–1 respectively, for CMOD5.N and C2P. The developed GMF C2P showed 16% more accuracy than that of CMOD5.N.Keywords
Cross-polarization, Geophysical Model Function, Ocean Surface, Wind Speed Retrieval.Full Text
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