instruments:hatpro:hatpro
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instruments:hatpro:hatpro [2016/06/05 22:01] – susanne | instruments:hatpro:hatpro [2016/06/11 21:11] – susanne | ||
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- | [[http:// | + | Fig. 1: [[http:// |
===== History of microwave radiometer measurements ===== | ===== History of microwave radiometer measurements ===== | ||
First developments of microwave radiometer were dedicated to the measurement of radiation of extraterrestrial origin in the 1930s and 1940s [1]. The first operational microwave radiometer was designed by [[https:// | First developments of microwave radiometer were dedicated to the measurement of radiation of extraterrestrial origin in the 1930s and 1940s [1]. The first operational microwave radiometer was designed by [[https:// | ||
- | Soon after satellites were first used for observing the atmosphere, MW radiometers became part of their instrumentation. In 1962 the [[https:// | + | Soon after satellites were first used for observing the atmosphere, MW radiometers became part of their instrumentation. In 1962 the [[https:// |
Here we could keep the graphic from the original article | Here we could keep the graphic from the original article | ||
https:// | https:// | ||
+ | Fig. 2 | ||
===== Principle of operation ===== | ===== Principle of operation ===== | ||
- | Solids, liquids (e.g. the earth' | + | Solids, liquids (e.g. the earth' |
- | The emission and absorption of hydrometeors does not provide characteristic absorption line features as found for atmospheric gases. Liquid hydrometeors (small cloud and rizzle drops) are efficient emitters in the microwave. | + | Besides the distinct absorption features of molecular transistion lines, there are also non-resonant |
- | Larger rain drops as well as larger frozen hydrometeors (snow, graupel, hail) also scatter microwave radiation especially at higher frequencies (>90 GHz). These scattering effects can be used to distinguish between rain and cloud water content [10] but also to constrain the columnar amount of snow and ice particles from space [11] and from the ground [12]. | + | Larger rain drops as well as larger frozen hydrometeors (snow, graupel, hail) also scatter microwave radiation especially at higher frequencies (>90 GHz). These scattering effects can be used to distinguish between rain and cloud water content |
- | + | {{: | |
- | {{ : | + | Fig. 3: Microwave spectrum: The black lines show the simulated spectrum (in brightness temperatures TB) for a ground-based receiver; the colored lines are the spectrum obtained from a satellite instrument over the ocean measuring at horizontal (blue) and vertical (red) linear polarization. Solid lines indicate simulations for clear-sky (cloud-free) conditions, dotted lines show a clear-sky case with a single layer liquid cloud. The vertical lines indicate typical frequencies used by satellite sensors like the [[https:// |
- | Microwave spectrum: The black lines show the simulated spectrum (in brightness temperatures TB) for a ground-based receiver; the colored lines are the spectrum obtained from a satellite instrument over the ocean measuring at horizontal (blue) and vertical (red) linear polarization. Solid lines indicate simulations for clear-sky (cloud-free) conditions, dotted lines show a clear-sky case with a single layer liquid cloud. The vertical lines indicate typical frequencies used by satellite sensors like the [[https:// | + | |
===== Design ===== | ===== Design ===== | ||
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The principal components of a microwave radiometer often follow a similar design and can be grouped into: antenna system, microwave radio-thermal receiver, recording and storage devices and a final processing unit. Usually ground-based radiometers are also equipped with environmental sensors (rain, temperature, | The principal components of a microwave radiometer often follow a similar design and can be grouped into: antenna system, microwave radio-thermal receiver, recording and storage devices and a final processing unit. Usually ground-based radiometers are also equipped with environmental sensors (rain, temperature, | ||
- | {{ : | + | {{: |
- | Schematic | + | Fig. 2Schematic |
===== Calibration ===== | ===== Calibration ===== | ||
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[4] Passive Microwave Remote Sensing of the Earth, Physical Foundations, | [4] Passive Microwave Remote Sensing of the Earth, Physical Foundations, | ||
- | - Cimini et al., 2009 | + | [5] Czekala et al. (2001), Discrimination of cloud and rain liquid water path by groundbased polarized microwave radiometry, |
- | - Klein and Gasiewski, 2000 | + | |
- | - Eugene A. Sharkov, “Passive Microwave Remote Sensing of the Earth”, Physical Foundations, | + | [6] Bennartz, R., and P. Bauer (2003), Sensitivity of microwave radiances at 85–183 GHz to precipitating ice particles, Radio Sci., 38(4), 8075, doi: |
- | - http:// | + | |
- | - Czekala et al., Discrimination of cloud and rain liquid water path by groundbased polarized microwave radiometry, | + | [7| Kneifel et al. (2010), Snow scattering signals in ground-based passive microwave radiometer measurements, |
- | | + | |
- | | + | |
instruments/hatpro/hatpro.txt · Last modified: 2021/01/22 22:17 by 127.0.0.1