Quality Control of Pyranometer Data during Winter for the New York State Mesonet

Winter weather impacts field instrumentation in the Northeast for 5-6 months out of the year. Some instrumentation manufacturers have taken steps towards incorporating features on sensors that help to prevent damage to instruments as well as data interference. Although this is appropriate for some measured parameters, there are still others that require a manual procedure and algorithm for maintaining the best quality of data. The New York State Mesonet (http://nysmesonet.org) consists of 126 standard stations with at least one station deployed in each of New York’s counties and boroughs. One instrument that is highly affected by winter weather is the pyranometer, which measures solar irradiance values every 3 seconds. Being affected by lake effect snow, winter ice storms, and nor’easters, New York experiences frequent snow and ice events. When snow and ice are covering the pyranometer, it becomes difficult to maintain accurate solar irradiance values. A multi-step, multi-sensor quality-control process has been created to identify and confirm these scenarios using archived satellite imagery, archived radar imagery, temperature measurements, precipitation type, and camera images. In the case of an event on 11-14 January 2019, it was clear that using this procedure would verify confidently that snow and ice were the cause of abnormal solar irradiance values. This information allows data quality analysts to make better decisions about data that can be used by the public and is more accurately representative of the entire state’s solar irradiance.