Gnerally discussed about four types of resolution in remote sensing and its trade off. then discussed about wind speed and the satellite that can be used to retrieve the wind speed data.
Sea Surface Salinity
Project 1 : Windspeed, Sea Surface Temperature & Salinity Mapping
Group Members : ABDUL AZIM BIN ABDUL TAHRIM NOOR HAZWANI BINTI ZUNAZRI SITI MARYAM BINTI BAKRI WAN MOHAMAD AMIRUL HAKIM B WAN MOHAMED NUR RITASHA BINTI TARIDI Resolution?Spatial?Temporal?Spectral?Radiometric?You just cant have it all2SpatialThe ability to refers to the size of the smallest possible feature that can be detectedWhat??depends primarily on theirInstantaneous Field of View (IFOV).If a sensor has a spatial resolution of 20 metres means each pixel represents an area of 20m x 20m on the ground
comparing a high and low spatial resolution3SpectralThe ability of a sensor to define fine wavelength intervalsWhat??The finer the spectral resolution, the narrower the wavelength range for a particular channel or band.Advanced multi-spectral sensors calledhyperspectralsensors contains hundreds bands
comparing a 2-bit image with an 8-bit image4TemporalThe ability to collect imagery of the same area of the Earth's surface at different periods of timeWhat??to monitor the changes that take place on the Earth's surfaceBy collecting and comparing multi-temporal imagery
5RadiometricWhat??The ability to describe the actual information content in an imageFiner = the more sensitive it is to detecting small differences in reflected or emitted energy
comparing a 2-bit image with an 8-bit imageUse number of bits
(e.g. 1 bit=2 1=2)6Trade-OffHigh Spatial = Small IFOV , Low Radiometric = Reduce amount of energy
High Radiometric = Broaden wavelenght range , Low Spectral =
Thus, these three types of resolution must be balanced against the desired capabilities and objectives of the sensor.7
Wind Speed8Introduction to Wind SpeedWhat is Wind Speed?the measure motion of the air with respect to the surface of the earth covering a unit distance over a unit timeWind speed directly affects aviation, maritime and construction activities.. An Earth-observing satellite that has provided early detection of ocean storms, including tropical cyclones9Common RS satellites used to retrieve wind speedQuickScatRapidScatWindSat
Vector = DirectionMagnitude = Speed11QuikSCATThe QuikSCAT nominal mission ended on November 23, 2009. QuikSCAT was launched in 1999 and was already operating 7 years beyond its design life.
The RapidSCAT is improvement of QuickScat, which is scheduled launch in next year (2014)13WindSatDeveloped by the Naval Research Laboratory, it is one of the two primary instruments on the Coriolis satellite launched on 6th January 2003. WindSat is continuing to outlive its three year design life, with data free of charge to scientists
14ComparisonResolutionQuickSCATRapidSCATWindSatSpatialStandard = 25 kmSpecial = 5 km and 12.5 km 10 to 15 km25kmSpectral13.402 GHz (Ku Band)13.402 GHz (Ku Band)5 bands(125, 300, 750, 500 2000 MHz)TemporalDaily coverage includes four browse images per dayDaily8 days15Comparison (Cont`)CharacteristicQuickSCATRapidSCATWindSatAltitude824 kmAltitude of 435 km (highest expected) compared to QuikSCAT830 km Operational Lifetime19 July 1999 to 21 November 2009
One month of post-installment checkout and two years of operations.Planned 3 years from 6 January 2003 (Still Operating)Sensor UsedSeaWinds scatterometerScatterometerPolarimetric Microwave Radiometer16ConclusionWind speed measurement is vital for the computer models that forecast hurricanes, since hurricanes typically move over data-poor ocean areas
Sea Surface Salinity19Introduction to salinityWhat is Salinity?Think salt = we use it to add flavor to our food, or to keep our sidewalks free of ice in the winterThe concentration of salt in the ocean, called salinity, is a key variable for understanding global ocean circulation and the movement of freshwater in the ocean.But salt in our natural environment impacts = important role in Earths climate.20Common RS satellites used to retrieve sea surface salinitySMOS (ESA and partners)
Aquarius / SAC-D (NASA)
Aquarius Salinity Microwave InstrumentLaunch VehicleService Platform and SAC-D Science InstrumentsMission Operations & Ground System
International Partnership between United States Argentina
Mission Partnership of Aquarius22Aquarius / SAC-D
24Common points between SMOS and Aquarius missions?Produce global salinity maps on a monthly basis with a spatial resolution of ~100 km with an accuracy of 0.2-0.3 psuBoth radiometer measuring radiation at 1.4 GHzPhysical laws ( Kirchhoff's law of thermal radiation, planck law)8 months period of SSS products25What are the differences? (SMOS and Aquarius)Instrument design and accuracySpatial and temporal samplingAscending passes (6am for SMOS vs 6pm for Aquarius)Forward model (or contamination corrections) and auxiliary parameters (SST,wind speed) used to retrieved salinity26SMOS vs Aquarius InstrumentResolutionSMOSAquariusSpatial30-55 km90 x 130kmSpectralL-band (1.4 GHz)L-band (1.4 GHz)Temporal(Global Coverage)3 days7 daysRadiometric0.8 - 2.2 K0.4 KScanning SystemInterferometerPush broomOperatingModePassiveActive and Passive27Discussion (SSS)SMOS has higher spatial, temporal and radiometric resolution in comparison to Aquarius.In contrast, Aquarius has higher spectral resolution compare to SMOS.Both of them are complementary by way of their spatial and temporal coverage and their viewing angles. By combining their data, maps of ocean salinity will be even more accurate and robust.
Sea Surface Temperature30Common RS sensors used to retrieve SSTNOAA- AVHRRGOESMODIS3132
Comparison of Satellites (SST)ResolutionMODISGOESNOAA-AVHRRSpatial1km4km1 - 4kmSpectral36 bands5-band (0.6, 3.9, 6.7, 10.7, 12 or 13.3 micron) and 4-band (0.6, 3.9, 6.7, 10.7. or 13.3 micron) 6 bands(band 3B, 4 and 5 for SST)TemporalDaily, weekly (8 day), monthly and annual.3 hour and 24 hour Averages4 dayRadiometric12 bits11 bits10 bits35Discussion (SST)Radiometric Most of the instruments have almost same radiometric resolution.Images such as these from polar-orbiting satellites are available less frequently that those from GOES, but they offer a more detailed view of cloud features due to improved spatial resolution. The more modern instruments such as MODIS also contain many more channels (or spectral bands) than are available from the current generation of GOES satellites. These additional bands allow the creation of a variety of quantitative satellite products.36Discussion Validation (SST)MODIS provides, as well, the first opportunity to obtain SST using exclusively bands in the medium IR atmospheric window. This window is more transparent and provides the opportunity to derive more accurate SST fields, however this spectral interval suffers from the contamination of the reflected solar radiation in the daytime, limiting its applicability to night-time or where the risk of solar contamination can be confidently discounted.37According to Marcello, J., Validation of MODIS and AVHRR/3 sea surface temperature retrieval algorithms, IGARSS 2004