CLAMPS: Instrumentation
CLAMPS-1 was funded by the NSF, NSSL, and OU, and was constructed in 2015. It is collaboratively maintained and operated by OU and NSSL. CLAMPS-2 was built in early 2016 with funding from NSSL. It is maintained and operated by NSSL and CIMMS scientists, but collaborates often with CLAMPS1. The systems were designed and continue to be maintained as sibling systems. Throughout their history, they have not always had identical configurations, but the aim is to operate them in as similar fashion as possible. The instrumentation that makes up the CLAMPS concept is described here. Changes throughout the history of the CLAMPS facilities are detailed, pointing out times when the two systems were not operating matching instruments.
Doppler LIDAR
Doppler LIDAR measures the radial velocity of atmospheric scatterers, which are primarily small aerosol particles that trace atmospheric motion, as a function of distance from the lidar. Measurements along different azimuth and elevation directions using the 3d scanner allow horizontal wind speed and direction to be derived. Turbulence profiles can also be derived using repeated vertically pointing measurements. CLAMPS1 is equipped with a Halo Photonics Streamline Doppler lidar. CLAMPS2 has a similar, but newer and more powerful system: a Halo Photonics Streamline XR+ Doppler lidar. Both are fully-scanning, eye-safe, lidar operating at 1.9 µm. The CLAMPS1 system has been upgraded to be nearly equivalent in practice to the system onboard CLAMPS2. The lidar systems are capable of 18-m gate resolution, have a 38 m/s nyquist limit, and have a max range of 7-10km (CLAMPS1) or 12km (CLAMPS2). Scan stategies are entirely user configurable.
Atmospheric Emitted Radiance Interferometer
The Atmospheric Emitted Radiance Interferometer (AERI) measures downwelling infrared radiance from 3-19 µm at high spectral resolution. Profiles of temperature and water vapor are retrieved from these observations, as well as cloud properties and trace gas information. Two blackbody targets maintain calibration to better than 1%. These measurements are used in a thermodynamic retreival algortihm called TROPoe (previously known as AERIoe). AERI systems are essentially identical between the CLAMPS facilities. AERI systems are similar in principle to the LR-Tech ASSIST platform some users may know.
Microwave Radiometer
The Microwave Radiometer measures downwelling microwave radiance from 22 to 60 GHz in 10-20 channels (depending on model/configuration). Profiles of temperature and water vapor are retrieved from these observations. The MWR has lower vertical resolution than the AERI, but is able to get some information through clouds. These measurements are used in a thermodynamic retreival algortihm called TROPoe. CLAMPS1 is equiped with a RPG HATPRO-G4 microwave radiometer. CLAMPS2 is equipped with a similar micrwave radiometer, but the G5 model. From 2016-2019, a Radiometrics MP-3000A operated in the CLAMPS2, and during 2020 CLAMPS2 was without a microwave radiometer.
Additional Capabilities
CLAMPS also includes a surface meteorological station, and supports radiosonde ballooning. It is an air-conditioned trailer with room for up to 4 people to work. An integrated generator is able to supply system power during short deployments and during transit. For longer deployments, CLAMPS operates on 220V/50A shore power. The CLAMPS onboard datasystem ingests and processes instrument data feeds in real-time.