Start Date | Start Time | End Date | End Time | Data Quality Metric |
---|---|---|---|---|
09/22/1993 | 1630 | 11/03/1993 | 1730 | Suspect |
Subject: | SGP/EBBR/E8 - Drop in atmospheric pressure |
DataStreams: | sgp30ebbrE8.b1, sgp15ebbrE8.b1, sgp5ebbrE8.b1 |
Description: | Beginning September 22, 1993, the atmospheric pressure sensor at the E8 EBBR began showing drops of as much as 5 kPa for about half a day. These could be easily seen in comparisons with the SMOS pressure sensor. The drops were diurnal and occurred during daytime, at the same time as other quantities such as temperature, net radiation, and battery voltage were at the highest levels of the day. It is unclear what exactly caused this situation. Replacement of the Campbell multiplexer to which the pressure sensor was connected caused the problem to go away. The same multiplexer was then used as a replacement for the other multiplexer in the E8 EBBR and has not shown any odd behavior on the channel that previously served the pressure sensor. My conclusion is that there was poor electronic contact of the pressure sensor to the multiplexer. Affected pressure data can only be easily seen by comparison with SMOS pressure data. No EBBR data other than pressure is affected by the pressure problem; calculations of specific heat at constant pressure (which includes the term 1/(p-vp)) times other terms (including p-.378*vp) result in a very small error in the resulting Bowen Ratio. For example; assume a common vapor pressure (vp) of 2.0 kPa, a common atmospheric pressure of 97.0 kPa, and a corrupted atmospheric pressure of 92.0 kPa. Uncorrupted Corrupted (97.0-.378*2.0)/(97.0-2.0) = 1.0131 (92.0-.378*2.0)/(92.0-2.0) = 1.0138 1.0138/1.0131 = 1.00069 or 0.069% increase in the Bowen Ratio as a result of the corruption Therefore, no correction to the quantities calculated using pressure is warranted. |
Suggestions: | This DQR was originally PIF No. P931115.3 |
Measurements: | sgp5ebbrE8.b1: more
sgp15ebbrE8.b1: more sgp30ebbrE8.b1: more |