The Energy Balance Bowen Ratio (EBBR) system produces 30-min estimates of the vertical fluxes of sensible and latent heat at the local surface. Flux estimates are calculated from observations of net radiation, soil surface heat flux, and the vertical gradients of temperature and relative humidity.
A unique aspect of the system is the automatic exchange mechanism (AEM), which helps to reduce errors from instrument offset drift.
The EBBR timestamp is at the end of the averaging period (i.e. 1630 covers 1600-1630), whereas the ECOR timestamp is at the beginning of the averaging period.
* For more information see EBBR
30 Minute Averaged EBBR Metrics
The 30 minute averaged EBBR data has the most information with it. This will be the main metrics/plots to look at. The metrics table includes
5 Minute Averaged EBBR Metrics
The 5 minute averaged data has mostly surface meteorological variables, radiation data, and diagnostic information.
15 Minute Averaged EBBR Metrics
The 15 minute data only has battery voltage and soil moisture data.
Flux and Soil Data (flux_soil)
This plot includes the flux data (latent heat, sensible heat, net radiation, and average soil heat flux) in the top panel (1). The rest of the panels include (2) Soil Temperature, (3) Soil Moisture, (4) Soil Heat Flow, and (5) Corrected Soil Hear Flow. There are 5 different soil sensors in various placements around the instrument. Depending on the medium above the soil sensor, the measurements could be very different between sensors.
Surface Meteorology Variables (ebbr)
There are multiple temperature and relative humidity sensors,
Each of the meteorological variables plots have the corresponding MET data plotted alongside it. Since the EBBR data is averaged over 30 minutes, it will not be nearly as noisy as the MET data. There will also be biases between the MET and EBBR due to the fact that they have different sensors and are measuring at different levels. The wind speed and direction should match up very closely. The net radiation plot includes data from the SIRS as well.
Home Signal (home_signal)
The home signal is the position indicator of the automatic exchange mechanism (AEM). The AEM helps to reduce errors from instrument offset drift. If it is outside of the limits indicated in the plot, there is a problem and a DQPR should be submitted.
Battery Voltage (bat)
Battery voltage of the instrument/logger. It normally goes up during the day due to increased temperatures.
Soil Moisture Resistance (solm)
Plot of the soil moisture resistance. This is used in calculating the soil moisture in the 30EBBR data.
The 5 minute EBBR data has the same plots as the 30 minute data. In order to reduce redundancy, these plots will only be listed below.
EBBR - SIRS Net Radiation
The 30 minute EBBR net radiation data is compared with the co-located SIRS data (if available). There will be a little offset, but should follow the same trend for the most part.
From the Mentor:
The net radiation measurements for the two systems are being measured by very different instruments, hence the differences.
The EBBR net radiometer does not respond to as far into the IR range as does the SIRS IR instrument, so the EBBR nighttime net will usually be higher and the daytime net during clear skies may be different as well. The EBBR and SIRS tend to be more similar when the sky is cloudy.
The EBBR is located at SGP.
Known issues that may not need to be mentioned in DQAs are mentioned below:
Some conditions do not require Data Quality Reports (DQRs) because they occur somewhat frequently. These conditions include spikes in the sensible and latent heat fluxes when the Bowen ratio is near -1, short periods when the AEM is not functioning properly (this can be detected from the quality control [QC] checks in the data files), and short periods of missing data. Common instrumentation problems include:
Preventative maintenance visits every two weeks and instrument mentor quality assurance activities are designed to detect and correct these problems to reduce the amount of incorrect data collected.
Past problems that do need to be mentioned in DQAs are mentioned below:
There have already been a lot of problems documented with the EBBR please see the following. NOTE: Many of the problem descriptions in the following link use plots and metrics from our older software. These issues may not be present in the latest data.
AEM Normal Operation vs Failure
Net Radiation above 1000 W/m3