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Instruments of RG Crewell

The Institute for Geophysics and Meteorology operates an array of remote sensing instruments suited for measuring the thermodynamic state of the atmosphere. Our main remote sensing instruments are shortly described below. The complete list of meteorological instruments at IGMK is located here. Also, you can find an overview of some live measurements here.

Atmospheric Emitted Radiance Interferometer AERI
  • The AERI measures downwelling infrared radiation from 3-25 µm at less than one wavenumber resolution every ten minutes.
  • It has potential for deriving profiles of tropospheric temperature and humidity and is also sensitive to low liquid water content clouds als well as to the CO2 column.
Ceilometer
  • Our ceilometer CT25K is based on the light detecting and ranging (LIDAR) principle: it sends out laser pulses and measures the backscattered light (at 905 nm).
  • From the time delay it derives cloud base height (i.e. the ceiling in aviation) as well as boundary layer structures.
Cloud radar MIRA
  • IGM's cloud radar MIRA is a pulsed Doppler radar which measures vertical profiles of reflectivity, Doppler velocity, Doppler spectral width, and linear depolarization ratio at 35.5 GHz and can scan freely in elevation and azimuth.
  • Various macro- and microphysical properties of clouds and precipitation can be derived
Infrared Pyrometers
  • IGM's infrared pyrometers (or just infrared thermometer IRT) measure downwelling sky brightness temperatures in atmospheric IR windows.
  • One IRT is mounted on SUNHAT and measures IR brightness temperature between 9.6 aund 11?m with a dynamic range of -100-200°C.
  • Two IRTs are mounted on TOPHAT (IRT1 bandpass 10.2 – 11.9 ?m and IRT2 bandpass 11.1 – 12.8 ?m) for improved retrievals of cloud optical depth and effective radius during low-LWP clouds.
Microwave Radiometers
  • Microwave radiometers measure spectral radiance emitted and scattered by atmospheric gases and hydrometeors.
  • IGM operates three Humidity And Temperature PROfilers HATPRO (TOPHAT, SUNHAT, SNOHAT) which are suited for continuously monitoring the hemispheric distribution of cloud liquid water path (LWP) and integrated water vapor (IWV) as well as tropospheric temperature profiles.
  • Additionally IGM operates the Dual Polarization Radiometers DPR which measures in mm wavelength atmospheric windows for snowfall and super-cooled liquid water retrieval.
Micro Rain Radar MRR
  • The MRR is a vertically pointing FM-CW Doppler radar operating at K-band. From the Doppler spectra the radar reflectivity factor (Ze) and the terminal fall velocity distribution can be derived.
  • In case of rain the Doppler spectra can be used to derive vertical profiles of microphysical rain properties like drop size distribution and rain rate.
Scintillometer
  • Our scintillometer measures the path-averaged structure parameter of the refractive index of air over horizontal path.
  • In combination with standard meteorological observations (air temperature, wind speed, and air pressure) this can be used to derive the surface sensible heat flux.
Sodar
  • A SODAR is a wind profiler based on the SOnic Detecting And Ranging principle. A sound is emitted and backscattered at inhomogeneities of the temperature field. Travel time of the backscattered sound signal is related to distance, Doppler shift gives the wind speed along the sound beam.
  • Several tilted sound beams allow to infer the vector components of the wind.
Total Sky Imager TSI
  • The TSI is used to identify cloud types and cloud coverage and complements our cloud liquid water observations.

Specifications

Beam width 4 - 2 deg FWHM ~0.6 mrad 2 deg 90 FWHM
Instrument HATPRO CT25K MRR TSI SODAR
Manufacturer Radiometer Physics Vaisala Metek YES Metek
Principle passive active active passive active
Wavelength / Frequency 22-31 & 51-59 GHz 905 nm 24.1GHz visible light 1400-3000 Hz accoustic
Integration time 1 s 15 s 15 s 1Img/20s 10min
Elevation angle 0-90 deg. ~90 deg. 90 deg. 0-90 deg. 90~25 deg.