instruments:hatpro:hatpro
Differences
This shows you the differences between two versions of the page.
Both sides previous revisionPrevious revisionNext revision | Previous revisionNext revisionBoth sides next revision | ||
instruments:hatpro:hatpro [2016/05/24 17:31] – stefan | instruments:hatpro:hatpro [2016/06/05 22:01] – susanne | ||
---|---|---|---|
Line 6: | Line 6: | ||
===== Introduction ===== | ===== Introduction ===== | ||
- | The atmosphere in the [[https:// | + | Microwave radiometers are very sensitive receivers designed to measure thermal electromagnetic radiation emitted by material media like the atmosphere. They are usually equipped with multiple receiving channels |
+ | |||
+ | Using the [[https:// | ||
For weather and climate monitoring, microwave radiometers are operated from space [1] [2] as well as from the ground [3]. As [[https:// | For weather and climate monitoring, microwave radiometers are operated from space [1] [2] as well as from the ground [3]. As [[https:// | ||
Line 15: | Line 17: | ||
===== 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:// | ||
- | 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 | + | Here we could keep the graphic from the original article |
+ | https:// | ||
===== 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. | + | 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. |
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 [10] but also to constrain the columnar amount of snow and ice particles from space [11] and from the ground [12]. | ||
Line 40: | Line 44: | ||
===== Calibration ===== | ===== Calibration ===== | ||
+ | The calibration of MWRs sets the basis for accurate measured TB and therefore, for accurate retrieved atmospheric parameters as temperature profiles, integrated water vapor and liquid water path. The simplest version of a calibation is a so-called „hot-cold“ calibration using two reference blackbodies at known, but different, „hot“ and „cold“ temperatures, | ||
+ | |||
+ | The temperatures of the calibration targets should be chosen such that they span the full measurement range. Ground-based radiometers usually use an ambient temperature target as „hot“ reference. As a cold target one can use either a liquid nitrogen cooled blackbody (77 K) [e.g. Ulaby] or a zenith clear sky TB that was obtained indirectly from radiative transfer theory [Paper Westwater]. Satellites use a heated target as „hot“ reference and the cosmic background radiation as „cold“ reference. To increase the accuracy and stabiltity of MWR calibrations further calibration targets, such as internal noise sources, can be used. | ||
===== | ===== | ||
Line 61: | Line 68: | ||
===== References ===== | ===== References ===== | ||
+ | [1] Microwave Remote Sensing—Active and Passive”. By F. T. Ulaby. R. K. Moore and A. K. Fung. (Reading, Massachusetts: | ||
+ | |||
+ | [2] Thermal Microwave Radiation: Applications for Remote Sensing, C. Matzler, 2006, The Institution of Engineering and Technology, London, Chapter 1. | ||
+ | |||
+ | [3] http:// | ||
+ | |||
+ | [4] Passive Microwave Remote Sensing of the Earth, Physical Foundations, | ||
- | - http:// | ||
- | - http:// | ||
- | - http:// | ||
- | - Thermal Microwave Radiation: Applications for Remote Sensing, C. Matzler, 2006, The Institution of Engineering and Technology, London, Chapter 1. | ||
- | - Eugene A. Sharkov, “Passive Microwave Remote Sensing of the Earth”, Physical Foundations, | ||
- Cimini et al., 2009 | - Cimini et al., 2009 | ||
- Klein and Gasiewski, 2000 | - Klein and Gasiewski, 2000 | ||
- | - Eugene A. Sharkov, “Passive Microwave Remote Sensing of the Earth”, Physical Foundations, | + | - Eugene A. Sharkov, “Passive Microwave Remote Sensing of the Earth”, Physical Foundations, |
- http:// | - http:// | ||
- | - Czekalla | + | - Czekala |
- Bennartz, R., and P. Bauer (2003), Sensitivity of microwave radiances at 85–183 GHz to precipitating ice particles, Radio Sci., 38(4), 8075, doi: | - Bennartz, R., and P. Bauer (2003), Sensitivity of microwave radiances at 85–183 GHz to precipitating ice particles, Radio Sci., 38(4), 8075, doi: | ||
- Kneifel et al., Snow scattering signals in ground-based passive microwave radiometer measurements, | - Kneifel et al., 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