| Description: | EDITOR'S NOTE: This DQR refers to data collected by the EBBR at E20 prior
to the begin date of regular ARM data. At that time, the data streams which
contain the EBBR.E20 data were named
Dsgp15ebbr6.a0
Dsgp30ebbr6.a1
Dsgp5ebbr6.a0
These data are not readily available from the ARM archive, but can be
made available by special request. The actual time range of the problem
described here is 930405.0000-930429.2359.
Soil heat flux sensor #3 of EBBR6, at Meeker, Ok extended site was
determined by me to have one heat flux plate whose output was out of phase
with the other four. The absolute value of the soil heat flux value
produced by the plate was good. Normally, this condition is caused either
by improper wiring of the sensor into the data acquisition system (this was
checked by site operations personnel on 29 April; wiring convention was
correct) or by the plate being installed upside down. The latter seems
fairly obvious, although the plate was not dug up to check it's orientation;
that is not neccesary and would be detrimental since it takes time for such
sensors to acclimate themselves to their soil environment.
The consequence of this problem is that 5 soil heat flux plate outputs were
being averaged, with one of the outputs being of opposite sign from the
other four. Since the outputs are similar, in absolute terms, this
essentially resulted in an average soil heat flux plate value that is 40%
too low. In terms of output, this a reduction of around 10 W per meters
squared, or 1-2% of the RN+G term during maximum solar insolation. This is
clearly a small error.
Site operations personnel switched the soil heat flux plate leads to give
the proper sign of output, on 29 April 1993, time unknown (this can be
determined from looking at the ingested data later; it hasn't been ingested
yet). The instrument operated properly at that point. Thus, the problem
has been corrected. |