NWB
Sensors, Inc.
Infrared Cloud Imager (ICI)
The All-Sky Infrared Cloud Imager (ICI) provides real-time images of clouds over the full sky using a calibrated long-wave infrared (LWIR) thermal imaging camera. The ICI produces consistent data products across day and night unlike visible band systems. The calibrated camera and proprietary data processing can detect thin clouds and in some cases cloud precursors, moist air masses.
​
The ICI features a ruggedized design. Instruments have supported research and free-space laser communication ground terminals in high-mountain, desert, highly-humid, and extreme winter environments. An automated hatch system provides protection for the imager’s lens during rain, snow, and high winds. An integrated weather station connects to the Camera Enclosure and collects atmospheric wind velocity, temperature, humidity, and pressure data. In addition, the system provides real-time atmospheric precipitable water vapor (PWV) observations that are derived using an integrated Global Navigation Satellite System (GNSS) receiver (see PWV Whitepaper). The system consists of an environmentally stabilized Camera Enclosure which mounts outdoors and is powered and controlled by a Power Enclosure which mounts in a climate-controlled environment.
Example ICI Data
The ICI generates several image data products. An example time lapse video of the total sky radiance, residual (sky - model) radiance, cloud probability, and cloud mask data products are shown below. This video was generated from data collected on May 26, 2023 during a deployment of an ICI to the US Department of Energy Atmospheric Radiative Measurement (ARM) User Facility at Southern Great Plains (SGP). This day exhibited rich cloud diversity with multiple layer heights and velocities. Times shown are in UTC. The sun rises around 12:00 and is visible throughout the remainder of the video. Two radiosonde (weather balloon) launches are visible in the upper right near 17:30 and 21:30. The moon is visible after 22:00 starting in the bottom center. The small but noticeable effect of residue on the lens is visible as a persistent spot in the cloud probability image to the lower right of center. A time lapse video of the entire 9-month deployment and associated netCDF data products can be downloaded from ARM here. (You will need to create an ARM login to access the data.)
Data Validation
The data products generated by the ICI were validated during the SGP campaign mentioned above.
A report summarizing the radiometric and clear sky model accuracy as established during this campaign can be downloaded here:
​
ICI Radiometric Calibration and Model Accuracy Validation.pdf
​​
A report summarizing the validation of the real-time precipitable water vapor (PWV) observations provided by the ICI can be downloaded here:
​
ICI Precipitable Water Vapor Retrieval Algorithm Accuracy.pdf