Radiometric cloud imaging with an uncooled microbolometer thermal infrared camera

Abstract

An uncooled microbolometer-array thermal infrared camera has been incorporated into a remote sensing system for radiometric sky imaging. The radiometric calibration is validated and improved through direct comparison with spectrally integrated data from the Atmospheric Emitted Radiance Interferometer (AERI). With the improved calibration, the Infrared Cloud Imager (ICI) system routinely obtains sky images with radiometric uncertainty less than 0.5 W/(m(2 )sr) for extended deployments in challenging field environments. We demonstrate the infrared cloud imaging technique with still and time-lapse imagery of clear and cloudy skies, including stratus, cirrus, and wave clouds.

Retrieval of sulfur dioxide from a ground-based thermal infrared imaging camera

“…The error on the retrieval was estimated to be ±20 %, due mostly to the NE T error, but with a significant error to due to inaccurate measurement of the plume temperature. The bias error is estimated to be variable within the range −5 to +6 %, which is slightly poorer than the calibration errors reported by Shaw et al (2005) for their broadband camera.…”

“…Other factors may also limit achieving the ideal image capture rate: for example, extracting the image frame data rapidly requires fast electronics and a good microprocessor and communications hardware and software. Shaw et al (2005) describe an uncooled thermal imaging camera for use in atmospheric studies. This camera has a single passband (∼ 8-14 µm) and is used to view the sky overhead for studies of clouds.…”

Correcting for focal-plane-array temperature dependence in microbolometer infrared cameras lacking thermal stabilization

“…4,5 However, many other applications become viable if they can be deployed without on-board calibration sources or temperature stabilization, such as sensing in agriculture and food processing, 6 airborne remote sensing of streams and rivers, 7 face recognition in thermal imagery, 8 noninvasive monitoring of beehive populations, 9 vegetation imaging to detect leaking CO 2 gas, 10 and many others. 11 Yet other applications may be feasible with on-board calibration sources, but still benefit from the smaller size and lower cost associated with the use of microbolometer imagers without external calibration sources or camera temperature stabilization, such as infrared imaging polarimetry, 12 cloud imaging in climate studies, 13 and characterizations of Earth-space optical communication paths. 14 Radiometric calibration typically requires quantitatively relating the camera output to source radiance or temperature.…”

Radiometric calibration of infrared imagers using an internal shutter as an equivalent external blackbody

“…13 Our motivation for pursuing high-accuracy and high-precision calibration of compact, TEC-less thermal imagers was provided by research into the use of microbolometer imagers to implement infrared cloud imager (ICI) systems for measuring the spatial and temporal variations of clouds and their radiative properties. [14][15][16][17][18] The ICI data are calibrated radiometrically to allow removal of the atmospheric emission to isolate the cloud signature. Previous versions of this system used a blackbody calibration source to track the changes in camera calibration over time, [15][16][17] but in the newer, compact ICI systems there is no room for a blackbody.…”

“…[14][15][16][17][18] The ICI data are calibrated radiometrically to allow removal of the atmospheric emission to isolate the cloud signature. Previous versions of this system used a blackbody calibration source to track the changes in camera calibration over time, [15][16][17] but in the newer, compact ICI systems there is no room for a blackbody. 14,18 Furthermore, in many other remote sensing applications, it is desirable to use a compact system that does not include a large, heavy, and expensive large-area blackbody source.…”