Corrected distorted flow quality metrics in 2D wind speed and direction product
March 17, 2022
A previous data notification warned of an error remaining in the computation of the distorted flow quality metrics in the 2D wind speed and direction data product (DP1.00001.001). This error has been corrected. Provisional data (collected on/after July 1, 2021) were reprocessed and are available now. Updated data collected prior to July 1, 2021 will become available when RELEASE-2023 is issued in January 2023. The error most often resulted in over-flagging (indicating that the wind measurements were impacted by tower infrastructure when they were actually not), and had no impact on the wind direction statistics themselves. Only data from terrestrial sites were impacted, and mostly prior to 2018. Please see the issue log on the data product page (https://data.neonscience.org/data-products/DP1.00001.001) for a full list of impacted sites and time periods. Until the full corrected dataset is available in RELEASE-2023, we recommend that users download the expanded download package and use other quality metrics to inform data filtering.
Separately, and impacting all terrestrial sites and time periods, characterization of distorted flow was tightened to include only the main tower structure plus a smaller buffer of 5 degrees on either side. Previously, winds passing through the main tower structure as well as across perpendicular tower booms on other tower faces, plus a buffer of 10 degrees on either side were characterized as distorted flow. This often resulted in 90 degrees of angular width characterized as distorted flow and flagged as suspect data. Given that the sensors on perpendicular booms on other tower faces are small and several meters away, and the booms themselves are slender, their impact on measurements of wind direction is insignificant. This change reduced the angular width of wind directions characterized as distorted flow by up to 55 degrees, improving data usability. Provisional data and forward processing (collected on/after July 1, 2021) now use this tightened characterization of distorted flow. The change will be available in the full dataset when RELEASE-2023 is issued in January 2023.