Remote Sensing of Ocean-Atmosphere - UPRM遠程海洋大氣遙感UPRM

1、1Dr. Sandra Cruz PolMicrowave Remote Sensing INEL 6069Dept. of Electrical & Computer Engineering,UPRM, Mayagez, PRFall 20212lWhat is radiometry?lImportance of MicrowaveslRadar vs. Radiometer lBrief history lRecent applications: DCASlPlane WaveslAntennas3lAll objects radiate EM energy. lRadiometr

2、y measures of natural EM radiation from objects; earth, ice, plants.45lCapability to penetrate clouds and, to some extent, rain.lIndependence of the sun as a source of illumination.lProvides info about geometry and bulk-dielectric properties. salinity)3 stages of El Nio6lEstudio de contenido de vapo

3、r de agua en nubes tipo stratus (NASA - TCESS)lEstudio de deteccin de razn de lluvia usando radares banda S y W. (NASA)lEstudio de reflectividad de cristales de hielo que componen las nubes tipo cirrus. (NSF).7lMeasures rain rate using the difference in radar reflectivity between two frequencies.8v(

4、D)=9.251-e)Doppler radar is used to measure rain rate. The Doppler frequencyis related to the terminal velocity of the raindrops. We can alsoestimate from this the particle size distribution.D2 91011Earth curvature effects prevent 72% of the troposphere below 1 km from being observed12lAffect Earths

5、 radiation budgetlImprove global climate models (GCM)lImprove reliability of forecastsAbsorbed(blue area)Transmitted(white) WKaAtmospheric Windows13lPenetrate more deeply into vegetation than optical waves.lPenetrate into ground (more into dry than wet soil).Visible and IR sensors can sometimes be u

6、sed to complement this information14151617 BANDDesignationNominalFrequency RangeSPECIFICBandsHF3-30 MHz0VHF30-300 MHz138-144 MHz216-225UHF300-1000MHz420-450 MHz890-942L1-2 GHz1.215-1.4 GHzS2-4 GHz2.3-2.5 GHz2.7-3.7 C4-8 GHz5.25-5.925 GHzX8-12 GHz8.5-10.68 GHzKu12-18 GHz13.4-14.0 GHz15.7-17.7K18-27 G

7、Hz24.05-24.25 GHzKa27-40 GHz33.4-36.0 GHzV40-75 GHz59-64 GHzW75-110 GHz76-81 GHz92-100millimeter110-300 GHz(millimeter)18lEnergy (EM waves) received at the Earth from the Sun is absorbed (atmosphere , clouds, earth, ocean) scattered transmitted lAbsorbed energy is transformed into thermal energy.lTh

8、ermodynamic balance through emission, absorption,RT19Passive uses of radiometers to study the EarthPassive sensors are called microwave radiometers, which receive and detect the radiation emitted from various objects on the earth Active uses RADAR (RAdio Detection And Ranging) to study EarthActive m

9、icrowave remote sensor illuminates the ground with microwave radiation and then receives the back-scattered energy from the object. Some of the active microwave remote sensors are : lRadars: CW, Pulse, Doppler, FMlSide looking airborne radar (SLAR) lSynthetic aperture radar (SAR) lWind scatterometer

10、 lAltimeter lPolarimeter 20Microwave Radiometer (most of the time)(Arecibo Observatory)Microwave Radar(Tropical Rainfall Measuring Mission (TRMM) satellite)2122lHenry Hertz, 1886 1st radio experiment, reflections detected 200MHz, confirmed experimentally that an electric spark propagates electromagn

11、etic waves into space.l1890, Tesla illuminated a vacuum tube wirelesslyhaving transmitted energy through the air using a Tesla coil to change 60Hz into hi-freq.l1895 Marconi patent for radio, 1986 in England, using 17 patents from Tesla.l1925- Pulse radars to measure height of ionosphere.l1930- unin

12、tentional detection of airplanesl1943 the Supreme Court overturned Marconis patent in in favor of Tesla.lWWII- detecting ships and aircraft. Used PPI displays.lMIT- developed magnetron hi-power Tx and klystron Lo-power sourcel1938 Altimeter airborne FM radars at 400MHz to measure altitude.l1950 SLAR

13、 finer resolution cause antennas length up to 15 m fixed | to fuselage. Airplane motion produced a scan.Side Looking Aperture Radar (SLAR)Range resolution =pulse widthAzimuth resolution= antenna size23lLight blue sea ice with open water displayed in green :/24l1952- 54 SAR fine resolution Doppler, p

14、ixel dimension in the along track direction independent of distance from radar, and antenna could be much smaller. Complex processing to produce an image.lScatterometer radar that measures scattering coefficient. (In ocean, scatter is proportional to wind speed.)l1970 Doppler becomes major technique

15、 for meteorology.RADARSAT is a Synthetic Aperture Radar (SAR) at C-band. Used for oceanic oil spill and ice sheet monitoring.A targets position along the flight path determines the Doppler frequency of its echoes: Targets ahead of the aircraft produce a positive Doppler offset; targets behind the ai

16、rcraft produce a negative offset. As the aircraft flies a distance (the synthetic aperture), echoes are resolved into a number of Doppler frequencies. The targets Doppler frequency determines its azimuth position. 25l1930s- First radiometers used for radio-astronomyl1950s- First radiometers used for

17、 terrestrial observations26circa 1945 lA Radiation Laboratory roof-top crew use microwave radiometer equipment pointed at the sun to measure water absorption by the atmosphere. Atop Building 20 (from left): Edward R. Beringer, Robert L. Kyhl, Arthur B. Vane, and Robert H. Dicke (Photo from Five Year

18、s at the Radiation Laboratory) 27lWater vapor is one of the most significant constituents of the atmosphere since it is the means by which moisture and latent heat are transported to cause weather. lWater vapor is also a greenhouse gas that plays a critical role in the global climate system. This ro

19、le is not restricted to absorbing and radiating energy from the sun, but includes the effect it has on the formation of clouds and aerosols and the chemistry of the lower atmosphere. lDespite its importance to atmospheric processes over a wide range of spatial and temporal scales, it is one of the l

20、east understood and poorly described components of the Earths atmosphere. 281965 lOn location at the National Center for Atmospheric Research (NCAR) in Texas. A launch crew prepares a 60-GHz atmospheric sensing receiver. Once lofted airborne by balloon, the receiver remotely sensed the temperature p

21、rofile at different altitudes. lThese experiments evolved into the Nimbus series of NASA satellites, which later became part of the National Oceanic and Atmospheric Administrations (NOAA) satellite weather forecasting system, also used by NASA.291977 lChecking an instrument that is the direct foreru

22、nner of todays operational satellite microwave atmospheric imagers used by NOAA30l Provides time-series measurements of column-integrated amounts of water vapor and liquid water. The instrument itself is essentially a sensitive microwave receiver. That is, it is tuned to measure the microwave emissi

23、ons of the vapor and liquid water molecules in the atmosphere at specific frequencies. (22 GHz)H2O31 ://CAMPAIGN_DOCS/SGP97/slmr.html#100 This truck-mounted microwave radiometer system measures surface soil moisture at L, S and C bands.32lMicrowave Radiometry can be used for the de

24、tection of different diseases. Madison, WI- tumor-detection system exploits the large dielectric contrast between normal tissues and malignant tumors at microwave frequencies. Clinical trials at Moscow oncological centers, conducted in over 1000 patients have shown that breast cancer detective abili

25、ty of microwave radiometry is 90%.lMicrowave Radiation used for treatment. The microwave procedure used a finely focused beam which heats up and kills tumour cells. The trial is being organised at two centres in the US, in Palm Beach, Florida, and the Harbor UCLA Medical Centre in California. 33is a

26、 microwave radiometer that measures thermal emission from oxygen molecules along a line of sight that is scanned in elevation angle. lKnowledge gained in developing this radiometers are useful in developing radiometers for unstart-prevention systems in high-speed (up to mach 2.4) civil-transport aircrafts. 34lOne of the contributions to the altimetric delay is the wet path delay caused by tropospheric water vapor in the altimetric signal path. lThe wet path delay is the additio