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Enter Sandmass Data

Approximately once a month during the dust season, field personnel visit each sand motion monitor site and replace the inner tubes in the Cox Sand Catchers. The collected tubes are corked and taken to the lab, where the contents is dried (if necessary), cleared of large debris (such as insects), and weighed. These "sand masses" are entered in sheet and emailed to an analyst for entry.

The OLIVE system automatically determines when new sand mass entries are needed on the Field Data Page, Sandmasses tab. The Weigh Data sub-tab displays a data grid with collection periods for each sand motion site that need a mass entry for the time period selected on the page filters tray. Click the edit button to the right and enter:

  • Tare Weight (empty bag weight)
  • Total weight (weight of sand + bag)
  • Collection number (the system will attempt a best guess, but adjust if needed)

The system automateically calculates the net weight of sand. Entered data will then disappear from the Weigh Data sub-tab and will appear on the Sandmasses sub-tab.

Collection periods that appear on the Weigh Data sub-tab are automatically determined by the system based on the intervals of site visits of type "Collection."

If expected collection periods are not showing up on the Weigh Data sub-tab, check that the latest site visits show up on the Sensit Site Visits tab and are of type "Collection." Also check that the selected time period encompasses the start AND end of the collection period.

Sand Flux Calculations

Sand flux is automatically calculated by the OLIVE system using particle count data from Sensits and sand mass data from Cox Sand Catchers (CSCs). There are several configurations that need to be properly in place for this to function properly.

  • A station must be configured with a default met station name. If the station is CSC-only (i.e. there is no co-located Sensit), it must also have an Alt Sensit name. These are configurable on the Stations Page.
  • For True Sand Flux, site visits of type Collection must be entered, and sand masses for the collection periods entered.

True Sand Flux

True sand flux is calculated using Sensit particle counts and sand mass entries. The total mass for each collection period is distributed proportionally across all valid, hourly particle count sums that are greater than zero during the period. True flux is indicated by closed circles on the Sand Flux Page timeseries plot.

Virtual Sand Flux

Virtual sand flux is calculated using the average ratio of particle count to sand mass for all valid collection periods at a given station for a specific Sensit. Virtual flux is used to issue sand motion alerts witin the OLIVE system. Virtual flux is indicated by closed circles on the Sand Flux Page timeseries plot, and in most circumstances will be used for any plots displaying real-time data.

If a Sensit is replaced, the ratio calculations start over. To maintain accurate virtual flux estimates, it is critical to keep up with entering Asset Deployments.

Sand Flux Calculation Schedule

Sand flux calculations are updated and stored in the OLIVE database twice a day starting at 12:33 and 00:33 Pacific Standard Time. During this time, for about 2 minutes, sand flux data are unavailable from the database.

On the Sand Flux Page, Matrix tab, there is a Refresh Data button that will trigger re-calculation on-the-fly. Be sure to coordinate with others who may be working in the system at the time, as multiple concurrent refreshes can lock up the database.