Aquatic instrument data product corrections

Recent updates in the algorithms that generate some of our aquatic instrument data will improve published data products by fixing erroneous data. The updates will address the following issues with each of these data products at all sites where they are collected:

1. Nitrate in Surface Water - DP1.20033.001 (all Aquatic sites): Data averaged over 15 minutes were inappropriately published on 30-second intervals. Because the SUNA nitrate sensor generally takes between 30 - 60 seconds to collect 21 data points (known as a burst), published data at 30-second intervals generally included two records with data values. The remaining 30-second time stamps at times outside of the burst reported NA, which created excessive null quality flags. The updated algorithm will generate SUNA nitrate data at 15-minute intervals. In other words, only one row of data should exist every 15 minutes, rather than 30 rows of mostly NA data every 15 minutes. Also, automated quality flagging algorithms (e.g. spikes, steps) would flag suspect data within each 15-minute period’s burst of data points, but the flagged data were not excluded from the data averaging. The updated algorithm will exclude flagged points from averaging.
2. Windspeed and direction above water on-buoy - DP1.20059.001 (all Aquatic sites with buoys): Time averaging window errors resulted in inappropriate statistics in published data. This adversely affects data at 30-minute intervals.
3. Temperature at specific depth in surface water – DP1.20264.001 (all Aquatic sites with buoys): Time averaging window errors resulted in inappropriate statistics in published data. This adversely affects data at 30-minute intervals.
4. Water quality – DP1.20288.001 (all Aquatic sites): Uncertainty estimates corresponding to each data stream from the multisonde became incorrect beginning on July 16, 2019 due to a mistake in the uncertainty coefficients. Water quality uncertainty estimates from July 16, 2019 to present day should not be used until data are republished.
5. Elevation of groundwater - DP1.20100.001 (all 30-minute data, beginning Jan 1, 2018): An error for all 30-minute averaged groundwater elevation data beginning on Jan 1, 2018 accidentally includes anomalous data points in the averages. We recommend using the 5-minute groundwater elevation data product until we announce this fix.

At the time of this posting, the algorithm updates are not reflected in published data. Data are being re-processed and will be corrected. We will announce when these corrected data have been republished.