Northern Alaska Site Science: Instrument quality and data stream developments

Description

This poster will provide an overview of instrument quality assessments and data stream developments produced by the Northern Alaska Site Science Team. At Oliktok Point (OLI), ground clutter is a significant problem in the recorded KAZR Doppler spectra. Since the standard ARM processing cannot distinguish ground clutter from atmospheric signals, a clutter mitigation methodology was developed to remove ground clutter before estimating multiple peaks in the spectra and calculating high-order spectral moments. Two years of KAZR spectra have been processed and multiple peak high-order moments are available on the ARM Archive as a PI product. At the North Slope of Alaska (NSA) site, a new scanning routine for the X-band ARM precipitation radar (X-SAPR) has been recently implemented. We present an initial analysis of X-SAPR measurements and assess the data quality. Further, multiple years of the ShupeTurner cloud microphysics PI product have been produced for both OLI and NSA which provides a cloud phase classification and microphysical properties. We compare the results of both sites and identify differences. Based on the KAZR and ShupeTurner PI products, we evaluated the calibration of the KAZRs at NSA and OLI by observing microphysical processes of liquid clouds. Specifically, we studied the relationships between the reflectivity and three variables not affected by absolute calibration: skewness, mean Doppler velocity, and liquid water path (LWP). We identified reference points of these relationships and evaluated their potential for calibration. We found that the LWP-based method performed best and estimated that the radar reflectivity at NSA was about 1 ± 1 dB too low in 2016. For OLI, we identified serious problems with maintaining an accurate calibration including a sudden decrease of 5 to 7 dB in June 2016. In order to evaluate ventilation and heating technologies developed to mitigate icing of shortwave and longwave radiometers, we ran the De-Icing Comparison Experiment (D-ICE) campaign at Utqiaġvik, AK, from August 2017 to July 2018. D-ICE consisted of 20 pyranometers and 5 pyrgeometers operating in various ventilator housings alongside operational stations run by NOAA and the ARM NSA and OLI sites. All radiometers were monitored continuously using cameras. We investigated the effectiveness of the ventilators in mitigating ice formation as well as biases associated with icing that does occur and formulated recommendations for the user community.