SGP/EBBR/E13  - Water in Net Radiometer, Surface Fluxes Incorrect

The net radiometer top dome was punctured by migrating birds.  This alone does not cause 
incorrect net radiation measurements.  However, when it subsequently rains, water collects 
in the bottom dome, causing the net radiation measurements to be too large during the 
day and too small at night.

• net_radiation_mv

• Radiation, net(net_radiation)

• Radiation, net(net_radiation)
• Heat flux, sensible, at 1.5-m height, 30-min intervals(sensible_heat_flux)
• Heat flux, latent, at 1.5-m height, 30-min intervals(latent_heat_flux)

SGP/EBBR/E13 - Improved EBBR CR10 Program

Effective 20050331.2100, the EBBR.E13 CR10 program was revised to improve the quality of 
the primary measurements as follows:

1) An RMS procedure is used to determine max and min limits of acceptable soil heat flow.  
This is applied to the individual soil sets.  Measurements outside the limits are 
rejected and the measurements within the limits are used to calculate the average soil heat flow.

2) Max and min limits are used to determine incorrect values of net radiation, sensible 
heat flux (h), latent heat flux (e), and automatic exchange mechanism (AEM) signal.  If AEM 
signal is outside the limits, h and e are set to 999s.  If net radiation is outside the 
limits, h and e are set to 999s. If h or e are outside the limits, h and e are set to 999s.

Virtually no incorrect soil measurement will affect the primary measurements of h and e.

By setting h and e to 999s, it can be easily seen that the primary variables are 
incorrect; no other interpretation is possible.

Prior to 20050331, the improved CR10 program was NOT in effect.  DQRs have been submitted 
for known instances of incorrect soil measurements which affected the quality of the 
primary measurements of h and e.

Note: the DQR begin date is the begin date of the sgp30ebbrE13.b1 data stream.  The 
earlier version of the CR10 program was also used on previous EBBR datastream names (e.g. 
sgp30ebbrE13.a1).

• Heat flux, sensible, at 1.5-m height, 30-min intervals(sensible_heat_flux)
• Average soil heat flow at the surface(surface_soil_heat_flux_avg)
• Heat flux, latent, at 1.5-m height, 30-min intervals(latent_heat_flux)

SGP/EBBR/E13 - Wind Direction Dependency of Surface Fluxes and General Data Quality 
Information

Beginning in FY2006, Data Quality Reports are not written for missing 
data or for situations when qc flags clearly show that the data is 
incorrect (this is true for most of the conditions listed below).  
DQRs are written for periods when data is incorrect, when the situation 
is not represented by qc flags in the data, and it's not obvious that 
the data should have been flagged as incorrect.

The EBBR data is only useful for particular wind directions at each 
Extended Facility.  Please use the following resources to help in 
interpreting the EBBR data.

1) qc flags in the EBBR data.

2) Instrument Mentor Monthly Summaries (IMMS) at http://www.db.arm.gov/IMMS/

3) SGP EF Surface Conditions Observations (EFSCO) at 
http://198.124.96.210:591/sfc_cond1/default.htm

4) Surface fluxes are valid only for the following wind directions
(in degrees):

0-52, 142-194, 328-360

Note that there are wind directions at most sites for which the fetch
is insufficient and therefore EBBR data is invalid.  Appropriate 
fetch was determined from a 1/40 measurement height to fetch ratio, 
resulting in a required minimum fetch of 120 m.  Particular attention 
should be paid to the limited valid wind directions for the Central 
Facility EBBR.  The surface vegetation type for the EBBRs is grazed 
or ungrazed grassland (refer to the EFSCO for state).

5) Some conditions that commonly cause the EBBR primary measurements to 
be incorrect or missing follow:

a) Sensible and latent heat fluxes are not accurate during times when 
the Automatic Exchange Mechanism (AEM) is not functioning properly.  
The AEM switches the gradient measuring instrumentation between the 
top and bottom positions every 15 minutes; this reduces the effects of 
instrument offsets.  Sometimes the AEM does not reach it's full extent 
of travel, resulting in the home signal being zero.  

b) Sensible and latent heat fluxes are sometimes incorrect when surface 
soil heat flow is out of range, as seen in the average soil heat flux 
(ave_shf).

c) Very light winds may be seen at nights for brief periods. Wind 
direction flops around a lot during low wind conditions (< 1.5 m/s) 
and is often unreliable during those periods.

d) Missing data periods occur at times; this is usually a site data 
system collection/communication problem; it can also occur during 
replacement of the system with a newly calibrated unit.  Missing data 
is sometimes filled in later from manual or automatic re-collection of 
the data.

• Wind speed vector mean(wspd_vec_mean)
• Heat flux, sensible, at 1.5-m height, 30-min intervals(sensible_heat_flux)
• corr_soil_heat_flow_4
• home_signal_30
• corr_soil_heat_flow_3
• energy_storage_change_4
• corr_soil_heat_flow_5
• energy_storage_change_5
• corr_soil_heat_flow_2
• Heat flux, latent, at 1.5-m height, 30-min intervals(latent_heat_flux)
• corr_soil_heat_flow_1
• temp_air_bottom
• Wind direction, vector, lower, 1-min avg(wdir_vec_mean)
• surface_soil_heat_flux_5
• lon
• Average soil heat flow at the surface(surface_soil_heat_flux_avg)
• temp_air_top
• temp_trh_top
• base_time
• soil_heat_flow_1
• soil_heat_flow_3
• soil_moisture_1
• soil_heat_flow_2
• soil_moisture_2
• soil_heat_flow_5
• soil_heat_flow_4
• energy_storage_change_1
• soil_moisture_5
• soil_moisture_3
• energy_storage_change_3
• energy_storage_change_2
• soil_moisture_4
• time_offset
• Barometric Pressure(atmos_pressure)
• temp_reference
• vapor_pressure_top
• soil_heat_capacity_1
• soil_heat_capacity_5
• Soil temperature mean 2(soil_temp_2)
• soil_heat_capacity_4
• Soil temperature mean 1(soil_temp_1)
• soil_heat_capacity_3
• soil_heat_capacity_2
• home_signal_15
• Soil temperature mean 5(soil_temp_5)
• Soil temperature mean 4(soil_temp_4)
• Soil temperature mean 3(soil_temp_3)
• Wind speed, lower, 1-min avg(wspd_arith_mean)
• wdir_vec_std
• bowen_ratio
• surface_soil_heat_flux_3
• alt
• surface_soil_heat_flux_4
• surface_soil_heat_flux_1
• surface_soil_heat_flux_2
• rh_bottom_fraction
• lat
• vapor_pressure_bottom
• Radiation, net(net_radiation)
• temp_trh_bottom
• rh_top_fraction