EN-SCI Cryogenic Frost Point Hygrometers
Precision Water Vapor Sondes
The EN-SCI Cryogenic Frost Point Hygrometer (CFH) line represents the gold standard for high-accuracy, in-situ atmospheric water vapor measurements. Trusted by researchers globally, these robust, balloon-borne sondes deliver reliable humidity data essential for understanding complex atmospheric processes from the surface through the mid-atmosphere. Recognizing diverse operational and environmental requirements, EN-SCI offers specialized variants built on the same proven core technology.
Primary Applications
- Conduct detailed Atmospheric Profiling & Process Studies, investigating water vapor structure, transport, and key processes like TTL dehydration.
- Perform Cloud Physics & In-Cloud Measurements, obtaining direct, in-situ water vapor data within various cloud types, including ice clouds.
- Serve as a reference standard for Sensor Validation & Intercomparison, crucial for validating satellite retrievals and assessing radiosonde humidity sensor performance.
How the CFH Measures Frost Point – All EN-SCI CFH models utilize the gold-standard temperature-controlled chilled mirror technique. The instrument actively cools a small mirror surface using a cryogenic liquid while precisely controlling its temperature via an integrated heater. This process maintains a constant, thin layer of frost (or dew) in equilibrium with the surrounding air. The measured mirror temperature directly corresponds to the ambient frost point (or dew point) temperature – a fundamental measurement of water vapor content. An LED emits light reflected off the mirror; a photodetector senses this light, varying with the frost amount, and provides feedback to the controller to precisely adjust the mirror temperature. This allows the CFH to achieve exceptional sensitivity down to parts-per-million levels, with derived parameters including Relative Humidity and Water Vapor Mixing Ratio. A forced-freezing algorithm ensures clear interpretation between dew and frost points.
CFH Models
CFH (Standard R23 Variant)
The foundational instrument in the CFH line, utilizing Trifluoromethane (R23) cryogen. This model has a long operational history and is backed by extensive validation in numerous field campaigns and peer-reviewed studies. It delivers benchmark performance for demanding atmospheric research requiring the highest fidelity water vapor data.
CFH-LN2 (Liquid Nitrogen Variant)
Addressing the growing need for sustainable research tools, the CFH-LN2 operates using readily available Liquid Nitrogen (LN2), an environmentally friendly cryogen with zero Global Warming Potential (GWP). This variant features an optimized design specifically engineered for reliable operation with LN2’s unique thermal properties. It aims to deliver accuracy and sensitivity comparable to the standard CFH model, providing a green alternative without compromising data quality.
Choosing Your CFH Model – Selecting the right CFH variant depends on your specific research goals, operational logistics (cryogen availability), and environmental considerations. Contact EN-SCI today to discuss your application and determine the optimal solution.
Product Details
Key Capabilities
- High Quality Data: Achieve high accuracy with sensitivity down to parts-per-million (ppmv) levels.
Wide Operational Profiling: Reliably operates through the mid-atmosphere across diverse climate conditions. - Optimized For Balloon Sounding: Lightweight design and low power consumption enable deployment on various meteorological balloon configurations.
- Versatile Data Collection: Capable of continuous, accurate measurements during both balloon ascent and descent phases.
- Requires Radiosonde Integration: Designed to interface with standard radiosondes for essential pressure, temperature, GPS data, and telemetry.
- Ozonesonde Compatible: Fully compatible with EN-SCI ECC ozonesondes for simultaneous water vapor and ozone profiling.
- Software Support: Includes software for pre-flight instrument setup/checks and operational monitoring.
- Reusable Design: Instruments are designed to be retrieved and reused, requiring cleaning and replacement of consumable supplies between flights.
Specifications Overview
CFH | CFH-LN2 |
|
|---|---|---|
| Measurement Technique | Temp-controlled Chilled Mirror | Temp-controlled Chilled Mirror |
| Cryogen Used | Trifluoromethane (R23) | Liquid Nitrogen (LN2) |
| Operational Range | 0 - 25 km (all climates) | 0 - 25 km (all climates) |
| Instrument Dimensions | 7.6 x 7.6 x 13.3 cm | coming soon |
| Flight Box Dimensions | ~ 39 x 39 x 39 cm | coming soon |
| Package Weight (without coolant) | < 400 g | coming soon |
What’s Included
- EN-SCI CFH Sonde Unit (Specific variant as ordered)
- Durable Polystyrene Foam Flight Box
- Lithium Metal Batteries
- Operator Manual
- (Please Note: Cryogenic coolant is specific to the model ordered and must be sourced and supplied by the user.)
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.
Expert technical support via email and phone from EN-SCI specialists is included to assist with your operations.
Required Preparation Supplies
( Sold Separately )
Operating the CFH sonde requires specialized supplies for essential pre-flight preparation that are sold separately.
Get the complete CFH Full Test Kit. This convenient bundle contains all the durable tools, software, safety items, and consumable supplies you need to perform your initial pre-flight preparations and get started quickly.
Ongoing Flights? For subsequent deployments, ensure you have the necessary consumable items readily available.
Replenish CFH Consumable Supplies
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.