EN-SCI Cryogenic Frost
Point Hygrometer
A sonde that accurately and precisely measures water vapor at elevations from the earth’s surface to the mid-stratosphere.
Applications
- To study the upper and lower troposhpere.
- Measure the amount of water vapor inside ice clouds
- Dehydration studies (particularly in the tropical upper troposphere)
- Validation of satellite measurements and radiosonde humidity sensors
Advantages
- Measure water vapor at the parts-per-million level
- Avoid the costs associated with aircraft-mounted instruments
- Simple operation
- Lightweight design with minimal power requirements
- Can be launched with small balloons
- Perform accurate measurements during ascent as well as descent
- Software included for easy monitoring of the CFH unit
- Compatible with EN-SCI ECC Ozonesondes
How it Works
The CFH operates by maintaining a small mirror at the precise temperature necessary to generate a thin, constant layer of condensate on the mirror. When this layer exists, the mirror temperature is the same as the ambient frost or dew point temperature. An LED emits light that is reflected off the mirror, and a photodetector senses this reflected light, which varies with the amount of frost present. The photodetector signal is then used to adjust the mirror temperature. The mirror is heated with a heater coil and/or cooled with a cryogenic liquid. These mechanisms allow the mirror to be heated and cooled quickly so that its temperature reflects the current frost or dew point.
Product Details
Specifications
| Parameter | Specification |
|---|---|
| Measured Parameters | Ambient Frost Point |
| Derived Parameters | Relative Humidity, Mixing Ration |
| Technique | Temperature-controlled chilled mirror |
| Uncertainty Measurement | 4% in tropical lower troposphere, 10% in middle stratosphere, 9% in tropopause |
| Altitude Range | 0 - 25 km (all climates) |
| Weight | < 400 g (without coolant) |
| Instrument Dimensions | 7.6 cm x 7.6 cm x 13.3 cm |
| Dimensions (in Flight Box) | ~12" W x 12" D x 12" H (~39cm x 39cm x 39cm) |
Included Items
- EN-SCI CFH Sonde
- Polystyrene Foam Flight Box
- Lithium Metal Batteries
- Inlet Tubes
- Technical Support
Warranty
EN-SCI warrants this product to be free of defects in material and workmanship for up to one year from the shipped date or first flight, whichever comes first. See full warranty for details and limitations.
Preparation Equipment
( Sold Separately )
-
CFH Full Test Kit
This kit has all the materials to prepare the Cryogenic Frost Point Hygrometer (CFH) sonde before flight. Included Items USB Drive with software to track data points from the CFH Allen wrench screwdriver 200ml of ethanol Bag of cotton-tipped applicators Insolated Glove Brass tubing Cylinder can
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Published Articles
Absolute accuracy of water vapor measurements from six operational radiosonde types launched during AWEX‐G and implications for AIRS validation
Miloshevich, L. M., H. Vömel, D. N. Whiteman, B. M. Lesht, and F. J. Schmidlin (2006). “Absolute accuracy of water vapor measurements from six operational radiosonde types launched during AWEX and implications for AIRS validation,” Journal of Geophysical Research, 111, D09S10, doi:10.1029/2005JD006083.
Increase in lower-stratospheric water vapor at a mid-latitude Northern Hemisphere site from 1981 to 1994
Oltmans, S. J., and D. J. Hofmann (1995), “Increase in lower-stratospheric water vapour at a mid-latitude Northern Hemisphere site from 1981 to 1994,” Nature, 374, 146– 149.
Tropical cirrus clouds near cold point tropopause under ice supersaturated conditions observed by lidar and balloon-borne cryogenic frost point hygrometer
Shibata, T., H. Vömel, S. Hamdi, S. Kaloka, F. Hasebe, M. Fujiwara, and M. Shiotani (2007), “Tropical cirrus clouds near cold point tropopause under ice supersaturated conditions observed by lidar and balloon-borne cryogenic frost point hygrometer,” Journal of Geophysical Research, 112, D03210, doi:10.1029/2006JD007361.
Accuracy of tropospheric and stratospheric water vapor measurements by the cryogenic frost point hygrometer: Instrument Details and Observations
Vömel, H., D. E. David and K. Smith (2007). “Accuracy of tropospheric and stratospheric water vapor measurements by the cryogenic frost point hygrometer: Instrument Details and Observations.” Journal of American Geophysical Research, Vol. 12, D08305, doi:10.1029/2006JD007224.
Intercomparisons of stratospheric water vapor sensors: FLASH-B and NOAA/CMDL frost point hygrometer
Vömel, H., V. Yushkov, S. Khaykin, L. Korshunov, E. Kyrö , and R. Kivi (2007). “Intercomparisons of stratospheric water vapor sensors: FLASH-B and NOAA/CMDL frost point hygrometer.” J. Atmos. Ocean. Technol, Vol. 24, doi: 10.1175/JTECH2007.1.