Abstract 1 Development of humidity profile retrieval algorithm for humidity sounder (saphir) onboard Megha-Tropiques

Abstract 1
Development of humidity profile retrieval algorithm for humidity sounder (SAPHIR) onboard Megha-Tropiques
A K Mathur and B S Gohil

Geophysical Retrieval Division, Atmospheric and Oceanic Sciences Group

Space Applications Centre ( ISRO ), Ahmedabad-380015, India
([e-mail])
Indo-French satellite Megha-Tropiques carrying onboard a six-channel humidity sounder (SAPHIR) alongwith a radiometer (MADRAS), radiation budget instrument (SCARAB) and radio occultation sounder (ROSA) is scheduled to be launched next year. An algorithm has been developed for retrieval of humidity profiles from SAPHIR observations. Emission based radiative transfer simulations for six water vapor absorbing channels around 183 GHz have been carried out to retrieve the relative humidity in six layers from surface to 100 mb. The algorithm has been tested with the observations of Humidity Sounder of Brazil (HSB) onboard AQUA satellite yielding encouraging results. With the availability of additional channels in SAPHIR, the retrieval accuracy is expected to improve.


Abstract 2

Development of millimeter-wave temperature sounder onboard LEO

B S Gohil and R K Gangwar

Geophysical Retrieval Division, Atmospheric and Oceanic Sciences Group

Space Applications Centre ( ISRO ), Ahmedabad-380015, India

([e-mail])
ISRO is planning to develop a microwave temperature sounder to be carried onboard a LEO satellite. Its baseline design has been developed. The temperature sounding unit will have 15 channels with a set of 12 channels distributed over off-resonance wings in the 50-60 GHz Oxygen absorption spectrum for sounding upto 40 kms in the atmosphere. In addition three radiometer channels (23.8, 31.5 and 89 GHz) are selected for surface and other atmospheric corrections. The system design adheres to a total power radiometer configuration because of its better noise performance than a Dicke-switched receiver.

Abstract 3
Atmospheric profiles from INSAT-3D Sounder: Algorithm and Simulation Studies
P. K. Thapliyal , M. V. Shukla, A.K.Mitra

Atmospheric Sciences Division

Atmospheric and Oceanic Sciences Group

Space Applications Centre (ISRO),Ahmedabad-380015,India.and

India Meteorological Department, New Delhi-110003
([e-mail])

The information on atmospheric profiles over Indian region is currently available from polar orbiting satellites - NOAA, EOS-Aqua and METOP having 1-2 days repetivity. USA has sounding capability from geostationary satellite GOES over but that is limited to the observations over continental USA and the surrounding regions. To obtain the high temporal resolution data over Asian monsoon region, India is scheduled to launch a geostationary satellite, INSAT-3D, in the first quarter of 2011. INSAT-3D will carry an 18-channel infrared Sounder along with a 6 channel Imager. The spatial resolution of INSAT-3D Sounder observation is approximately 10 km at sub-satellite point. The active scan coverage of the Sounder can be selected to a minimum of 64 lines by 64 pixels and a multiple thereafter, with a maximum of 640 lines by 640 pixels. The scan time varies from ~2 minute for 64 x 64 pixels coverage and 180 minutes for 640 x 640 pixels.

The retrieval algorithm for atmospheric temperature and moisture profiles along with total column ozone has been developed for INSAT-3D Sounder under clear-sky conditions. The algorithm includes generation of the hybrid first guess atmospheric profiles using a linear combination of regression retrieval and NWP model forecast. This is followed by a non-linear physical retrieval procedure to make the first guess consistent with the Sounder observations. The PFAAST atmospheric radiative transfer model has been used for the forward computation of sounder channel radiances alongwith their Jacobians which is used in the physical retrieval. The regression coefficients for different zenith angle and latitude zone classifications have been computed from radiosonde database (SeeBor dataset, University of Wisconsin). The simulated accuracy of the retrieved temperature profile is ~2-3 K in the lower atmosphere and ~1.5 K in the mod-tropospheric layers, 20-30 % for the retrieved humidity profile and 14 Dob for the total column integrated ozone. These accuracies are comparable to those retrieved from similar sounding platforms presently operational in the orbit.


Abstract 4
Cloud properties from INSAT-3D Sounder observations
M. V. Shukla and P. K. Thapliyal

Atmospheric Sciences Division

Atmospheric and Oceanic Sciences Group

Space Applications Centre (ISRO),Ahmedabad-380015,India.

([e-mail],[e-mail])
Satellite derived parameters like temperature and humidity profiles, cloud top pressure, cloud top temperature, total precipitable water etc. are very crucial for the improvement in weather forecasting. India is scheduled to launch INSAT-3D in a geostationary orbit with 18 channel infrared (plus a visible channel) sounder. The sounder on board INSAT-3D will play a major role in providing observations over extended regions particularly measurements over data sparse Indian Ocean region. In addition to it INSAT-3D sounder will also give the information regarding the cloud cover and cloud top pressure and temperature, which in turn will be very helpful for nowcasting and for severe weather prediction.
This working paper is aimed at cloud detection and computation of cloud top pressure using INSAT-3D Sounder observations. For this purpose, various threshold tests have been formulated for the cloud detection and CO₂-slicing technique has been used for the computation of cloud top pressure. The algorithm has been tested with GOES sounder dataset over Continental US region. For cloud detection we have tried minimal use of the ancillary dataset to avoid the effect of ancillary data bias on the cloud flag. The cloud flag tests were validated with MODIS cloud flag and cloud top pressure has been validated with CALIPSO data.
Abstract 5

Atmospheric Motion Vectors (AMV) retrieval from Kalpana/INSAT
C. M. Kishtawal , S. K. Deb , V.R.rao and R. K.Giri

Atmospheric Sciences Division

Atmospheric and Oceanic Sciences Group ,Space Applications Centre (ISRO),Ahmedabad-380015,India. And

India Meteorological Department , New Delhi-110003

([e-mail],[e-mail])
The operational derivation of atmospheric motion vectors from infrared (10.5-12.5 m) and water vapor (6.3 –7.1 m) channel of three successive geo-stationary satellite images started in the early seventies. However, for the last decade the extraction of atmospheric motion vectors from satellite images has become most important component for operational numerical weather prediction (NWP) and a significant contribution of atmospheric wind information are derived from satellite observations by considering the movement of cloud and water vapor tracers to determine wind operationally several times a day. This working paper focuses on attempts to improve the existing triplet based (Kishtawal et al. 2009) operational derivation of atmospheric motion vectors from the observations of Indian geostationary satellite, Kalpana-1. The significant improvements are achieved by considering false vector elimination and buffer optimization. In the present technique, false vectors appearing in the clear-sky regions are removed for cloud motion vectors and a wind buffer is created using last 8-images between a pair of images (viz. between 1-2, 2-3, 3-4, 4-5, 5-6, 6-7 and 7-8) and stored in a file. For every new vector under consideration, (from current image-pair), its vector difference from the buffer is computed at the same as well as 3X3 neighborhood, provided, the vectors to be compared show similar BT characteristics (e.g. similar levels). Each vector difference (magnitude of complex number) is weighed according to distance and time difference from the current vector. If the difference of top 30% weighted differences is less than 1.1-pixel, the new vector is accepted, otherwise it is rejected. An empirically derived height assignment technique based on genetic algorithm is used to derive the height of cloud water vapor tracers. The Mean-Vector-Difference (MVD) values of few months validation of new CMV products are 6.9 m/s for High level, 6.8 m/s for Mid-level and 6.2 m/s for low-level respectively. While the MVD values of water vapor winds is 6.7 m/s. These values are comparable to the accuracies of AMV’s from the other operational agencies. The similar method will be applied for INSAT-3D which is going to be launched next year.
Abstract 6
Land Surface Products Using Observations from Suite of Indian Geostationary Satellites : Current Status and Future Opportunities
Bimal K Bhattacharya and V.R.Rao

Agro-ecosystems Division, Agriculture-Biosphere and Terrestrial Hydrology Group (ABHG), EPSA, Space Applications Centre (ISRO), Ahmedabad, India-380015,India.

and India Meteorological Department, New Delhi-110003
([e-mail])
Land-atmosphere energy and mass (water, CO2) exchange processes need to be characterized to quantify vegetation (Agriculture, Forests, grasslands) responses (photosynthesis and primary productivity) and feedbacks (evapotranspiration and rainfall) at regional to continental scales. Diurnal observations from imager, radiometer and sounder at constant view direction from geostationary satellite platform provide opportunity to retrieve core land surface radiation budget variables either to model processes or to assimilate them into climate models. The retrieval of surface albedo and land surface temperature (LST) using broad visible (VIS) and thermal infrared (IR) bands of currently operational Kalpana-1 (K1) VHRR has been demonstrated using contrast ratio and mono-window algorithms, respectively. An integrated spectral irradiance and three-layer cloudy scheme has been tested to estimate incident solar radiation from K1VHRR. A normalized difference vegetation index (NDVI) product from INSAT 3A CCD multi-spectral observations is being operationally generated at India Meteorological Department (IMD). A simplified evaporative fraction model was implemented to estimate regional evapo-transpiration process in clear skies using land surface radiation and energy budgeting with above K1VHRR based products. Impact of deficit south-west monsoon rainfall in 2009 over agricultural region could be captured through substantial reduction in CCD NDVI. One dimensional sensitivity analysis showed that the retrieval accuracy of core radiation budget variables determines accuracy of process variables. The presence of split window thermal bands, broad VIS, short-wave (SWIR) and middle infrared (MIR) bands in the “Imager’ and vertical atmospheric (temperature, water vapour) profiles from ‘Sounder’ in future INSAT 3D would enhance the accuracy of land surface radiation and energy-water budgeting.
Abstract 7
Validation of Geophysical products of the forthcoming satellite missions for weather and climate studies.
B Simon and A.K.Sharma

Space Applications Centre (ISRO),Ahmedabad-380015,India.

And India Meteorological Department , New Delhi-110003

([e-mail],[e-mail] and [e-mail])

Detailed Validation activities are planned during pre-launch and post-launch periods. These include the selection of observations needed, instruments to be used, selection of validation sites and the approach for validation. The INSAT-3D imager products are Atmospheric Motion Vectors (AMV), Outgoing longwave radiation (OLR), Upper tropospheric Humidity (UTH), Rain, Sea Surface Temperature (SST), Fire, snow, Fog etc. The sounder will provide data for the derivation of vertical profiles of temperature and humidity, total ozone content, and Application products at a 10 km spatial resolution.

MT retrieved parameters (data products) are integrated water vapor, humidity profile temperature profile, cloud liquid water content, wind speed, precipitation, short wave and long wave radiation. The validation will also include intense observation periods (IOPs) to collect in-situ and other ancillary data.
The results of validation will be provided as feedback to data products for fine-tuning the retrieval algorithm and generation of final operational data products. Since a number of international satellites is also likely to provide some of these parameters, inter-satellite comparison will provide important results on performance of MT and INSAT vis-à-vis other sensors.
Abstract 8
Near Real Time Data Processing of INSAT Data and Dissemination of Data Products
R.Ramakrishnan

Data Products Software Group

Signal and Image Processing Area

Space Applications Centre

Ahmedabad,380015, INDIA
{[e-mail]}

INSAT-3D Meteorological Satellite has been planned to be launched in the first Quarter of 2011 one of the ground segment system is the data Processing and Products Generation system. The Data Processing System will cater to the requirements of a Near Real Time INSAT-3D Meteorological Data Processing System (IMDPS) which includes data acquisition and quick look processing (DAQLS) of all data transmitted by the Imager and Sounder payloads of INSAT-3D (6 channels IMAGER : VIS, SWIR, MIR, WV, TIR1, TIR2; SOUNDER of 19 Channels ), VHRR (VIS, WV, TIR) and CCD (VIS, NIR, SWIR) payloads of INSAT-3A and VHRR payload of KALPANA-1 satellites.

The proposed system will acquire raw data from serial data streams, producing quality Data Products (DP) and generate various quantitative Geo-Physical products (GPR) from the As a part of space mission for weather and climate studies India will be launching INSAT-3D next year which will be an exclusive meteorological satellite carrying advanced meteorological payloads, viz. a 6-channel imager and a 19-channel sounder. We are also planning a satellite Mega-Tropiques (MT), a joint India-France (ISRO-CNES) mission to study the convective system , and their influence on tropical weather system and climate. The MT satellite payloads are high-technology sensors viz. Microwave Analysis and Detection of Rain and Atmospheric Structures (MADRAS), a millimeter wave humidity profiler, SAPHIR, an optical-IR radiometer for radiation budget (ScaRAB) and an Integrated GPS Occultation Receiver (GPS-RO) . The MT mission has been accordingly planned for a specific coverage of tropical region ( 30 in the north-south direction about the equator) and a higher sampling frequency than the normal twice a day. The mission sensors have been planned in a way that they will complement the existing /or about to be processed data for operational utilization by various users. The Products thus produced are being operationally displayed for the current KALPANA-1, INSAT-3A missions by the indigenous designed Satellite Imagery Display System throughout the campus of IMD, Delhi, SAC-BOPAL,Ahmedabad on an 24 x 7 basis for every half hour images processed. Additionally, the system is capable of processing, ingesting and analyzing Automatic Weather Station (AWS) and Global Telecommunication System (GTS) data. A large number of meteorological parameters and application-products are required to be derived from the raw data of satellite-sensors, AWS and GTS data as well as conventional meteorological data. Some of the application-specific retrievals and validation exercise is necessary and being carried out in operational meteorology.
The deliverables will include Data acquisition quick display system, Data products generation, Parameter retrieval and image processing and Visualization display system solutions, data visualization comprising of both hardware and software systems for the near real time Data Processing and dissemination of Meteorological Data Products on the WEB. The Radiometric calibration as part of data pre-processing is carried out based on the extensive ground calibration data supported by ground and on-board calibration techniques, which tracks changes in the instrument response due to in-orbit thermo-mechanical environment, radiation effects and aging. The geometric correction, resampling is performed on the radiometric corrected pixel-data based on static and dynamic models of the instrument and satellite as well as orbit and attitude parameters available simultaneously with the imaging data and produces various levels of data products. A further precision/improved accuracy is necessary which requires in registering the image-pixels on fixed lat-long grids would be achieved through image navigation and registration algorithm in an automatic/interactive approach. The Data Products Software providing the capability for generation of Various levels of Data Products ( LEVEL-0, LEVEL-1 , LEVEL-2 and LEVEL-3) on the user requested media and in the required formats HDF-5 and also in the generic binary format.

Abstract 9
Development of Rainfall Algorithm for Monitoring Rainfall Events over India Using KALPANA-IR on Various Temporal and Spatial Scales
R.M Gairola and Atul Kumar Varma

Geophysical Retrieval Division, Atmospheric and Oceanic Sciences Group

Space Applications Centre ( ISRO ), Ahmedabad-380015, India
([e-mail],[e-mail])

Accurate estimation of rainfall at small spatial and temporal scales has many applications in meteorology and hydrology. Using combination of ground based radars and dense network of rain gauges such information is available but only over the limited areas. Continuous high temporal resolution satellite data uniformly over large area is available only from instruments onboard geostationary platforms in the infrared (IR) and visible (VIS) part of electromagnetic spectrum. Precipitation Radar (PR) onboard TRMM is the first spaceborne Radar that gives the three dimensional structure of rainfall. PR is able to provide significantly more accurate estimation of rain rates but suffer from poor temporal sampling associated with platforms in low earth orbits.

An attempt has been made to analyze the IR radiances from Kalpana/INSAT data along with the high resolution, rainfall estimates from PR. Contrary to the IR, microwave rain rates are based on measurements that sense precipitation in clouds and do not rely on cloud top temperature. The combination of the broad coverage and frequent refresh of the geostationary satellites with the sparse but more accurate active microwave rain rates has been used for the characterization of precipitation-bearing systems over Indian land from adjoining oceans. It has been named as INSAT Multispectral Rainfall Algorithm (IMSRA) as it makes use of both IR and MW sources of measurement from different satellite sensors of both low earth orbiting and geostationary platforms.
As IMSRA depends upon contemporary measurements from microwave observations, it is desired to have an only IR based algorithm. Hence a new technique called Hydro-Estimator (H-E) is developed that blends the thermal IR measurements from Kalpana/INSAT with NWP model derived fields and surface elevation model. The H-E method provides most precise measurement of precipitation at pixel-scale at every IR observations (presently 30 minutes from Kalpana/INSAT). The important features of this scheme include provision to measure rain based on cloud growth and availability of moisture in the atmosphere, adjustments for orographic rain and the warm rain by using wind laced topography and atmospheric equilibrium level, and wet atmospheric correction. The scheme is presently under operational implementation.

Abstract 10

Ocean Surface Vector Wind Products from Oceansat-2 Scatterometer
B.S. Gohil and Rajesh S.

Geophysical-parameter Retrievals Division

Atmospheric and Oceanic Sciences Group (EPSA)

Space Applications Centre (ISRO),Ahmedabad-380015, India

([e-mail])

Oceansat-2 satellite was successfully launched on 23rd September 2009 with a two-day repeat cycle, carrying three instruments, namely, a Ku-band Wind Scatterometer (SCAT), an Ocean Colour Monitor (OCM), and a Radio Occultation Sounder for Atmosphere (ROSA - developed by the Italian Space Agency ASI). Oceansat-2 aims at unique suite of meteorological, physical and biological ocean applications with the Scatterometer and the Ocean Colour Monitor. Availability of ROSA will supplement with meteorological parameters of the overlying atmosphere.

Subsequent to the completion of commissioning phase also involving initial quality assessment and preliminary verification, the ocean surface wind vector products are being operationally generated and made available at NRSC-ISRO website. At present, the wind products are available at 50 km wind-cells in orbit-wise product and the day-wise product at 0.5 deg global grid. Also available are the daily means of backscatter data at 0.5 deg global grid. The data is presently updated twice in a day and envisaged to be updated more frequently after the commissioning of links with other Space Agencies under different MoUs.
Abstract 11
Retrieval of Atmospheric Profiles from Radio Occultation Technique
Abhineet Shyam & B.S.Gohil and N. Puviarasan

Geophysical-parameter Retrievals Division

Atmospheric and Oceanic Sciences Group (EPSA)

Space Applications Centre (ISRO),Ahmedabad-380015, India

And India Meteorological Department , New Delhi-110003
([e-mail]; [e-mail])
Retrieval of geophysical parameters viz. Temperature and humidity from RO-derived refractivity is done using an iteration-based “Refined temperature technique”. The methodology is currently applied on a limited set of COSMIC refractivity profiles of Jan 2010 and is compared with the corresponding products retrieved by COSMIC processing software based on 1DVariational (1DVAR) technique. The accuracy achieved with the “Refined temperature technique” making no use of external information is found to be within acceptable limits above 5-6 kms, while degrading rather rapidly for the levels below. A significant improvement in the accuracy is expected to occur by ingesting temperature external information (at a few vertical levels) from NWP model analysis into the retrieval software. With this modification the methodology is applied on 3 COSMIC profiles of Jan 2010. The bias is upto 2% for temperature and less than 1-2% for water vapour pressure.

Retrieval using the popular methodology of 1DVAR is being initiated. A feasibility study to understand various issues in the execution of 1DVAR technique for retrieval from RO refractivity has been done and an interim result was obtained with quasi-realistic error estimate in the background and observation. Errors of representativeness and forward model error were not considered. Such issues, apart from realistic estimate of background error covariance matrix are now being addressed. The methodologies are being developed for retrieval from the refractivity derived from ROSA sensor aboard Megha-Tropiques mission.

Abstract 12
Calibration Assessment of INSAT Satellite data

A.K.Sharma and Baby Simon

India Meteorological Department and Indian Space Research Organization

([e-mail] and [e-mail],[e-mail])

An attempt has been made to intercalibrate INSAT satellites data with the NOAA AVHRR channel 4 data as done in International Satellite Cloud climatology Project (ISCCP) . Inter-calibration is based on common principles of collocation , transformation , comparison and are analyzed to produce calibration correction functions . In this attempt Kalpana-1 and INSAT-3A satellites data in compared with NOAA polar orbiting satellite . The clinear least square fit equation and its coefficients are computed and applied to the INSAT data and various products with the calibrated data e.g. OLR and QPE etc. are obtained


Abstract 13
Current Status of INSAT Meteorological Satellites
A.K.Sharma and P. K.Pal
India Meteorological Department, New Delhi-110003 and

Space Application Centre (ISRO) Ahmedabad-380015

At present India has two geosynchronous satellites in orbit for meteorological purposes namely Kalpana-1 and INSAT-3A. kalpana -1 was launched in 2002 and INSAT-3A in 2003 . Both these satellites have a 3-channel very high resolution Radiometer (VHRR) scanning the earth in visible (0.55 -0.75 um) , water vapour (5.7 -7.1 um) and Thermal infra red ( 10.5 -12.5 um) bands . The instrument has 2 km. resolution in visible and 8 km. resolution in water vapour and thermal infra red bands. It has three modes of operation namely Full frame of 33 minutes, normal frame of 23 minutes and sector scan of 7 minutes duration . In addition to VHRR , INSAT-3A has a 3 channel CCD payload which scans the earth in visible , near infra red and shortwave infra red and has resolution of 1 km. in all three bands .