Lecture 4b: Meteorological Satellites and Instruments. Acknowledgement: Dr. S. Kidder at Colorado State Univ.

Transcription

1 Lecture 4b: Meteorological Satellites and Instruments Acknowledgement: Dr. S. Kidder at Colorado State Univ.

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3 US Geostationary satellites - GOES (Geostationary Operational Environmental Satellites)

4 US Goestationary Satellites The US GEO started from Sunsynchronous Meteorological Satellite 1 (SMS 1) in 1974, which was originally operated by NASA as experimental satellites. The follow-ups are the Geostationary Operational Environmental Satellites (GOES) series that transitioned to NOAA The current generation (GOES 8-13) has: 1. Imager 2. Sounder

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6 The three most common channels on meteorological satellites are: 1) visible (~ 0.6 µm) 2) infrared (~ 11 µm) and 3) water vapor (~ 6.7 µm) channels.

7 GOES Sounder Courtesy: U. Wisconsin

8 Differing roles of GOES and NOAA polar orbiters in weather service 1. GOES is for short-range warning and nowcasting, that is, forecasting of weather in the 0-12 hr time framework (it is the range that human forecaster does a better job than computer NWP or numerical weather prediction models) 2. Polar-orbiting satellites are for longer-term forecasting. Longer-term forecasting is performed by computers through solving the evolution equations of the atmospheric motions. Polar orbiters provide the temperature/moisture profiles of the atmosphere (outside the reach of weather balloons), which are needed by the NWP models as initial conditions.

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10 Operational Vs Experimental Operational: designed for day-to-day operations of weather services. High requirements on reliability and availability. In USA, the agency that administrates operational MetSat is NOAA (National Oceanic & Atmospheric Administration). DoD also has its own operational MetSat. Experimental: designed to test new concept or technology. May find its use in meteorological service in the future. NASA is the main space agency of this country that develops experimental satellites.

11 Experimental Meteorological Satellites/Instruments There are just too many to name. The following are worth noting: 1. ERBE (Earth Radiation Budget Experiment) 2. MODIS (Moderate-Resolution Imaging Spectroradiometer) 3. AIRS (Atmospheric Infrared Sounder) 4. TRMM (Tropical Rainfall Measuring Mission) 5. CloudSat /CALIPSO (Cloud-Aerosol Lidar & Infrared Pathfinder Satellite Observations)

12 Earth s Radiation Budget

13 Outgoing Longwave Radiation Earth Radiation Budget Satellite + π B v (T)dv = σt 4 0

14 Bright Spots: Clouds because they are reflective (evidence: clouds are white in visible wavelengths) Cold Spots: Clouds because they are located where temperatures are colder than the surface. Higher clouds appear colder than lower clouds

15 MODIS (Moderate-Resolution Imaging Spectroradiometer) The MODIS instrument provides high radiometric sensitivity in 36 spectral bands ranging in wavelength from 0.4 µm to 14.4 µm. Two bands are imaged at a nominal resolution of 250 m at nadir, with five bands at 500 m, and the remaining 29 bands at 1 km. Dust in the middle East A ±55-degree scanning pattern at the EOS orbit of 705 km achieves a 2,330-km swath and provides global coverage every one to two days. Courtesy: MODIS Team

16 AIRS (Atmospheric Infrared Sounder) Like HIRS, AIRS mainly measures temperature and water vapor profiles. But with 2378 spectral channels, AIRS has a spectral resolution more than 100 times greater than previous IR sounders (such as HIRS) and provides more accurate information on the vertical profiles of atmospheric temperature and moisture. Courtesy: AIRS Team

17 TRMM (Tropical Rainfall Measuring Mission) Precipitation Radar (the first spaceborne precipitation radar) ; Microwave Imager; Visible/IR imager Courtesy: TRMM Team

18 CloudSat: the first space-borne cloud radar

19 Cross section of a hurricane. Brighter colors indicate heavy precipitation.

20 CloudSat Vs TRMM: differences btw cloud (3 mm) and precipitation (1.5 cm) radars

21 CALIPSO (Cloud-Aerosol Lidar & Infrared Pathfinder Satellite Observations) Space-borne lidar

22 CloudSat Vs CALIPSO: difference in attenuation