BAECC-TWST

This deployment emphasized collaboration with other ARM sensors so as to take advantage of TWST’s combined features of fast sample rate, narrow FOV, and simultaneity in all spectral bands. These features make TWST relevant to DOE’s goals in understanding the impact of clouds and aerosols on climate change. TWST contributes significantly to the body of data used for extracting cloud microphysical properties as opposed to outputting only stand-alone COD results as in prior deployments. TWST directly collects calibrated spectral radiance at zenith for the spectral range of 350 – 1000 nm at ~2 nm spectral resolution. In stand-alone mode it retrieves Cloud Optical Depth (COD) at a sample rate of 1 Hz using the spectral radiance at 440 nm and the equivalent width of the oxygen A-band at 760 nm. When used in concert with other AMF instruments, namely the MWR, HSRL, W-Band cloud radar and Ka-Band zenith radar, it contributed to the retrieval of Liquid Water Path (LWP), vertical profiles of the effective radius of cloud droplets (re), and cloud droplet number concentration (Nd). The many instances of sensitivity to aerosols found in data collections to date give us reason to expect that TWST's high SNR and full spectral coverage support the extension of TWST capabilities to the measurement of aerosol properties. In addition to contributing to the BAECC campaign objectives, the TWST sensor itself benefited from this deployment, making the technique more useful for subsequent campaigns. This was an opportunity to test and refine the TWST nonlinear filter algorithms designed to automatically resolve the thin cloud/thick cloud ambiguity using the equivalent width of the oxygen A-band. By examining the large body of BAECC cloud radar and lidar data we were able to immediately quantify, and improve if needed, the performance of our decision algorithms. This was a significant step toward the goal of TWST being capable of long term unattended autonomous operation in the field. Once again, TWST spectral radiance and COD results were compared to a collocated CIMEL Sunphotometer operating independently in cloud mode to confirm the accuracy and calibration stability of TWST.

Timeline

Campaign Data Sets

TMP Data Sources