Entries with tag data quality .

Upcoming corrections to 2D wind direction data

In March of 2017 the terrestrial instrument system (TIS) team identified that the 2D anemometers on the NEON towers were producing 2D wind data that did not correlate with 2D wind data collected at NEON meteorological stations nearby. At first this was assumed to only be an issue at a handful of sites. However, as time progressed it was evident that this was an issue at nearly all operational sites. The North Transducer head of the 2D anemometers at the TIS sites listed below were not oriented consistently and all 2D wind direction data were offset from 90 to 270 degrees from 'truth'. The deviation from truth is a function of site and measurement level. The TIS team is in the process of identifying site- and measurement-level--specific dates of incorrect anemometer orientation so that these data can be corrected. The process of identifying the orientation of each 2D anemometer, the corrective action, and reprocessing the data should be completed by Spring 2020. We will provide a more specific completion date in February 2020. Please use the data portal contact form for further inquiries; please select DP1.00001.001 in the Data Product dropdown list and include the term "INC0033824" in the body of your request.

Issues with infrared gas analyzer pressure data stream mapping

We have identified issues with infrared gas analyzer pressure data stream mapping processed through October 28, 2019 (irrespective of data collect date). This led to differential pressure (Head Pressure) being subtracted from Box Pressure and accounted for twice when calculating Total Pressure. This problem affects the following data products and all previously processed site-months.

  • H2O concentration – turbulent (DP1.00035.001)
  • CO2 concentration – turbulent (DP1.00034.001)
  • Carbon dioxide flux (DP4.00067.001)
  • Latent heat flux (DP4.00137.001)
  • Sensible heat flux (DP4.00002.001)

All of these data products are solely available within the Bundled Data Products - Eddy Covariance (DP4.00200.001).

A fix has been implemented as of October 29th, 2019 at 2:00 p.m. MDT. All data processed after this time have the correct values. Assessment of the scientific impact of this error is in progress. Within two weeks we will update this message regarding scientific impact and reprocessing time.  Please use the data portal contact form for further inquiries; select DP4.00200.001 in the Data Product dropdown list.

Update 2019-12-19

H2O and CO2 concentration measurements were not impacted by the error. Flux data median error resulting from this issue is between 1 and 5 percent, and is proportional to site elevation. The timeline for reprocessing will be determined following discussion with the Surface-Atmosphere Exchange Technical Working Group.

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.

Surface water and groundwater elevation data improvements

In-the-field infrastructure upgrades will improve NEON water elevation data products at many aquatic sites. To date, all NEON groundwater and surface water elevation data has had high uncertainty due to unstable survey reference points and delays in reporting field-based sensor position adjustments. Permanent benchmarks are in the process of being installed at all NEON aquatic sites to serve as controlled location reference points. Site resurveys in relation to these benchmarks will impact the published water elevations derived from pressure transducers. Elevations will be updated and reported to a much greater certainty. This will require republishing groundwater and surface water elevation data products. In addition to these updates, past field-reported sensor position adjustments will be included in the data republication.

Sites that have or will be improved with permanent benchmarks include: POSE, LEWI, SUGG, BARC, CRAM, KING, MCDI, MAYF, PRPO, PRLA, BLDE, WLOU, FLNT, LIRO, BLUE, GUIL, ARIK, CUPE, PRIN, MART, BIGC, REDB, HOPB, COMO, SYCA, WALK, TOMB, BLWA, MCRA.

This issue affects the following data products:

Updates to the groundwater and surface water elevation data products will be republished in batches as post-benchmark installation surveys are processed and integrated with raw pressure transducer data.

Additionally, 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.

Occasional high soil moisture values

We recently discovered that unreasonably high soil moistures are sometimes being reported in the soil water content and salinity data product (DP1.00094.001) at many terrestrial sites. The issue is caused when the sensor reports a value above the high end of the calibration data used to generate the soil-specific calibration and when the calibration equation had a shallow slope at those high soil moistures. The threshold that this impact begins to impact the soil moisture data varies among sites and depths, but in general soil water content values above ~0.4 cm3 cm-3 should be treated with caution while we address this issue (values below this threshold are typically not affected). We are in the process of developing a solution to correct this issue for all future and previously collected data, but we do not currently expect this to be implemented until March 2020 at the earliest. In the meantime, we will adjust the high-end range threshold in the automated QA/QC tests to flag the affected data. Please use the data portal contact form for further inquiries; please select DP1.10094.001 in the Data Product dropdown list and include the term "INC0033810" in the body of your request.

Removal of instrumented data processed with incorrect calibration information

We recently discovered that calibration information was incorrectly applied to a number of instrumented systems data products (list of affected products below) from Feb 26, 2018 to present. All potentially affected data have been removed from the data portal and will be reprocessed with appropriate calibration information. Reprocessing will likely begin mid-December and continue through mid-January. Data will be published as it is reprocessed. The error resulted from a manual database procedure that updated calibrations after a sensor change. We are automating this procedure to avoid this problem as we transition to a fully operational observatory in the near future.

We apologize for any inconvenience this may cause. For further inquiries please use the Feedback Form.

List of affected data products
DP1.00002      Single aspirated air temperature
DP1.00003      Triple aspirated air temperature
DP1.00004      Barometric pressure
DP1.00005      IR biological temperature
DP1.00006      Precipitation
DP1.00014      Shortwave radiation (direct and diffuse pyranometer)
DP1.00022      Shortwave radiation (primary pyranometer)
DP1.00023      Shortwave and longwave radiation (net radiometer)
DP1.00024      Photosynthetically active radiation (PAR)
DP1.00041      Soil temperature
DP1.00066      Photosynthetically active radiation (quantum line)
DP1.00095      Soil CO2 concentration
DP1.20004      Barometric pressure above water on-buoy
DP1.20015      Specific conductivity in groundwater
DP1.20016      Elevation of surface water
DP1.20032      Shortwave and longwave radiation above water on-buoy (net radiometer)
DP1.20042      Photosynthetically active radiation at water surface
DP1.20053      Temperature (PRT) in surface water
DP1.20059      Windspeed and direction above water on-buoy
DP1.20100      Elevation of groundwater
DP1.20217      Temperature of groundwater
DP1.20261      Photosynthetically active radiation below water surface
DP1.20264      Temperature at specific depth in surface water
DP1.20288      Water quality
DP4.00001      Summary weather statistics

— 20 Items per Page
Showing 6 results.