Tipping Radiometers for Tau / Opacity Measurements
Tau-225 / Tau-350 Radiometer
The RPG-Tau-225 and RPG-Tau-350 radiometers are designed for the estimation of atmospheric opacity (optical thickness, tau) in the observation bands of radio astronomy applications. Both of these sub-mm frequencies can easily be combined in single instrument. Other frequencies are available.Technical Specifications
- Optical resolution: 3.5° HPBW at 23.8 GHz
- Radiometric resolution: 0.2 K RMS at 1.0 s integration time
- Absolut system stability: <1.0 K
- Receiver and antenna thermal stabilization: < 0.02 K
- Environmental temperature range for operation: -30 °C to +45 °C
- Automatic rain-detection system (including a dew-blower)
- Integrated PC on-board
- Full internal retrieval algorithm, retrieval data and raw data output
- GPS clock
- Additional external meteorological sensors: barometric pressure, humidity, temperature
- Connection of optional IR-radiometer possible, software already designed for IR-data input
- Customized retrieval software available
- Frequency extension possible by tandem operation (adding a second radiometer unit, plug and play)
- Stand alone operation
- Data storage and backup on-board, power-failure safe-guard
- Low maintenance (3 months intervall for absolute calibration using LN)
- Power supply: 85 to 265 V AC (at 47 to 63 Hz)
- Power consumption: 350 W turn-on power, 150 W under stabilized conditions
- Weight: 60 kg
- Dimensions: 63 × 40 × 105 cm (H × W × L without stand)
- Low cost!
Description
This Tau-225 radiometer is an upgraded version of the above LWP two-channel radiometer.
By including a high frequency channel at 90 GHz the sensitivity
to thin cloud (small LWP) is significantly improved:
Instead of approximately 30 g/m^2 the three channel version has a detection limit
of 5 to 10 g/m^2.
The three channel version is using the same housing as the standard LWP radiometer.
The instrument is a stand-alone system for automated weather-station use
under nearly all environmental conditions.
The total (integrated) amounts of water vapor and liquid water in the vertical column above
the radiometer are retrieved from the two-channel brightness temperature mesurements.
A variety of retrieval algorithms (custom designed or global standard algorithms) can be selected.
- Frequencies:
- 3 channels at 23.8, 31.4 and 90 GHz
- Retrieved data types:
-
- Liquid Water path (LWP)
- Integrated Water Vapor (IWV)
- wet delay
- dry delay
- Documentation:
- Technical Note (brochure) on LWP Radiometers RPG Standard MWR Installation and Maintenance Manual RPG Standard MWR Software and Operations Manual RPG Standard MWR Technical Specifications and References RPG Standard MWR Guide to Measurements and Deployment
