07-PassiveMicrowave - 1 ESM 266 Passive microwave ESM 266...

Unformatted text preview: 1 ESM 266: Passive microwave ESM 266: Passive microwave remote sensing remote sensing Jeff Dozier 2 Frequency-wavelength relation Frequency-wavelength relation Generally in the microwave part of the spectrum we use frequency instead of wavelength Typically measured in s 1 , called Hertz (Hz) Most often Gigahertz (GHz) = 10 9 Hz 8-1 Frequency where speed of light =3.00 10 m s c c = = 3 Microwave band codes Microwave band codes Band Wavelength, cm Frequency, GHz Mid-IR (3-5) 10 4 100,000-60,000 Thermal IR (8-15) 10 4 37,500-20,000 K a 0.75-1.18 40.0-26.5 K 1.19-1.67 26.5-18.0 K u 1.67-2.4 18.0-12.5 X 2.4-3.8 12.5-8.0 C 3.9-7.5 8.0-4.0 S 7.5-15.0 4.0-2.0 L 15.0-30.0 2.0-1.0 P 30.0-100 1.0-0.3 4 Advantages of passive microwave remote Advantages of passive microwave remote sensing sensing Sees through clouds at lower frequencies Long heritage, various instruments since 1978 Emissivity sensitive to state of surface, particularly moisture Soil moisture Snow-water equivalent (water is ~80 as absorptive as ice at these frequencies, whereas in visible through infrared, water and ice have similar absorption coefficients) But, because of small amount of energy emitted, pixel size must be large Characteristics of major passive microwave Characteristics of major passive microwave instruments instruments Footprint (km) Frequency (GHz) SSM/R 1978-85 SSM/I 1987-pres AMSE-E 2002-pres AMSR 2002-pres 6.6-6.9 148 95 75 43 70 40 10.7-10.9 91 59 51 29 46 27 18.7-19.4 55 41 69 43 27 16 25 14 22-23.8 46 30 60 40* 32 18 29 17 36-37 27 18 37 29 14 8 14 8 50.3/52.8 10 6* 85-89 15 13 6 4 6 3 *V-polarization only 6 Planck equation frequency form...
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