NCAR/RAP
                      
 

 
Sensors at the BNL/NCAR Ceiling & Visibility site

 
Timeline of sensor installation and logs of known problems
 
        [Note: : problem detected;  : problem fixed]
  • Sept. 12th 2003: Final installation of surface-based instrumentation (including soil sensors) completed.
  • Nov. 13th 2003: Deployment of instrumentation on 90m tower completed.
  • December 5th 2003: Data acquisition system for tower and surface measurements stable.
  • Nov. 11th 2003: Correction for wind sensor alignment w.r.t. True North (-95o) implemented in data acquisition procedure.
  • Problems with the upward (reflected) shortwave radiation at 70m since the beginning of the experiment.
  • 2m temperature HMPC35C probe not working since the beginning of the experiment (but RH ok).
  • January 14th 2004: Topmost (3cm) soil volumetric water content (ECH2O) probe not working properly starting at 2151UTC. For reasons unknown, voltage suddenly dropped from 459mV to less than 150mV at that time and remained lower than expected thereafter.
  • March 29th 2004: Broken soil volumetric water content (ECH2O) probe at 3cm replaced with new one at 1900 UTC. No probe-specific calibration was performed. Assume that the calibration relationship derived previously (see this link) can be applied without a significant error. Caution about this needs to be taken into account while analyzing the data.
  • March 29th 2004: 2m temperature probe fixed. Valid data starting at 2045 UTC.
  • March 29th 2004: Sonic/krypton : lenses of krypton at 32m (K1482 w/ sonic "whiskey") cleaned at 1605 UTC  (Julian day 089).
  • March 29th 2004: Glass bead calibration verification performed on fog monitor at 16:14:37 UTC.
  • April 14th 2004: Malfunction of soil volumetric water content (ECH2O) probe P04-3 (at 15cm depth) starting at 0148 UTC. Voltage suddenly dropped from ~840 mV to ~480 mV. Soil very wet, as 3 inches of rain fell day before.
  • April 15th 2004: Problems of unknown source with the 70m datalogger. Data from the upper levels of the tower contaminated on an intermittent basis since 0407 UTC. Other than the 45m T/RH probe, all other data stopped showing intermittent erratic behavior by the 23rd. Continuously bad data from the 45m T/RH probe since the 15th.
  • April 27th 2004: ECH2O probe at 15cm replaced with new one. Good data starting at 2300 UTC. No probe-specific calibration was performed.
  • April 28th 2004: Optics of the fog monitor cleaned. Performed "before and after" bead calibration checks (see this link).
  • April 28th 2004: Lenses on both krypton hygrometers cleaned w/ distilled water.
  • April 28th 2004: Lenses on the 3 HSS cleaned.
  • May 1st 2004: Laser power low on ceilometer starting at 0949 UTC. Problem with laser board. Instrument shipped back to Boulder for repair.
  • May 4th 2004: 45m T/RH sensor fixed. Good data starting at 1721 UTC.
  • May 11th 2004: Microwave Radiometer stopped working. Power supply "fried", probably due to lightning strike.
  • June 27th 2004: ECH2O probe at 8cm stopped providing good data at 1018 UTC. Likely same problem as with the other probes (see above).
  • June 30th 2004: Power supply on Microwave Radiometer replaced & instrument now functioning with updated neural net file for the retrievals (scanning procedure).
  • June 30th 2004: Beginning of the summer "stand down" period.
    • Fog spectrometer de-activated to maximize the lifetime of its components
    • Krypton hygrometers taken down from the tower and shipped back to NCAR for an updated calibration in ATD's humidity chamber
    • CNR1 radiation sensor at 70 m taken down from the tower and shipped back to Kipp and Zonen for repair.
    • All other sensors are expected to continue operating throughout the summer.
  • October 19th 2004: Beginning of the "back to full operation" period.
    • Ceilometer re-installed and began operating at 1407 UTC.
    • Replaced 8cm soil moisture probe. Valid data available again starting at 1812 UTC. 
    • Performed "end point" LN2 calibration of the profiling microwave radiometer.
    • GEONOR rain gauge emptied.
  • October 20th 2004:
    • Profiling microwave radiometer taken down and shipped back to Boulder for upgrade and testing at Radiometrics.
    • Lenses cleaned on the 4 m and 32 m HSS
    • 32 m krypton hygrometer re-installed and functional.
  • October 21st 2004:
    • 70 m krypton hygrometer re-installed and functional.
    • 70 m CNR1 net radiometer re-installed and functional starting at 1724 UTC.
    • Fog spectrometer taken off the tower and shipped back to Boulder for maintenance. Glass bead calibration tests showed significant under-sizing of the particles.

  • April 5th 2005:
    • 32 m hygrometer lenses cleaned at 1430 UTC, 70 m hygrometer lenses cleaned at 1445 UTC
    • HSS lenses also cleaned.
    • Fog monitor re-installed and functional. Bead (20 microns) calibration performed.
    • Microwave radiometer re-installed and functional. Level checked and LN2 calibration performed. But clock set 1 hour ahead w.r.t. correct time.
    • Geonor gauge emptied.
    • Ceilometer lenses cleaned.
  • April 29th 2005:
    • 40 m temperature probe shows intermittent spurious values starting on this date. The problem seems to appear during wet periods. Sensor seems to settle down during drier periods, but now has a +2 to +3oC bias (see potential temperaure profiles from 2005-06-06). The RH measurements look ok.
  • May 18th 2005:
    • Clock on radiometer set to actual GMT time at 23 GMT. Clock had been erroneously set 1 hour ahead than actual GMT since April 3rd (Daylight Saving). 
  • May 23rd 2005:
    • New LN2 calibration performed on the microwave radiometer between 1815 UTC and 1900 UTC. Differences in Tnd (between current calib. and previous calib. are significant for channels 9 to 12 (4 to 5 % increase).
  • August 2nd 2005:
    • Ceilometer lenses cleaned
    • Drained and re-leveled the Geonor gauge bucket
    • HSS leanses cleaned
    • 45 m T/RH probe repaired (connector re-sealed)
    • Krypton hygrometers removed for repair (sent back to manufacturer for source replacement and re-cal)
    • Fog monitor cleaned (inlet, pitot tube and optics)
  • October 19th 2005:
    • New LN2 calibration performed on the microwave radiometer. 
    • Geonor : drain, level and put antifreeze and oil back in gauge.
    • Lenses on HSS at  4m and 32m cleaned.
    • All lenses on 32m CNR1 cleaned.
    • 32m T/RH checked: cleaned Gortex screen.
    • 32m RM Young wind sensor checked, bearings and propeller.
    • 32m krypton hygrometer re-installed after being sent to manufacturer for new light source and re-cal.
    • Fog monitor: cleaned inlet, Pitot tube and lenses. Bead calibration check performed with 15 micron beads.
  • October 20th 2005:
    • Fog monitor: Bead calibration check performed with 15 micron beads.
    • Lenses on HSS at 70m cleaned.
    • 70m krypton hygrometer re-installed after being sent to manufacturer for new light source and re-cal.
    • 45m T/RH re-cabled (moisture in cable once again).
    • 2m, 10m, 15m,  20m, 45m, 70m and 85m  T/RH checked: cleaned Gortex screen.
    • 10m, 15m,  20m, 45m, 70m and 85m  RM Young wind sensor checked, bearings and propeller.
    • All lenses on 70m CNR1 cleaned. 
  •  November 30th 2005:
    • Microwave radiometer taken down and shipped back to manufacturer.
    • New blower on fog monitor installed, inlet and sampling tube cleaned.
  • July 24th 2006:
    • Geonor : drain, clean and level, gauge.
    • Clean 32 m HSS lenses (1730 UTC).
    • Clean ceilometer windows (1845 UTC)
    • Fog monitor: Bead calibration check performed with 20 micron beads before cleaning of the instrument. Inlet, sampling tube and lenses cleaned. Bead calibration check performed with 20 micron beads after the cleaning. Problem detected with the inlet de-icing heater (remains on all the time). Not clear what the problem could be. May affect the ambient temperature readings. Instrument taken down from the tower for the remainder of the summer season.
  • July 25th 2006:
    • Bearings on all of the RM Young wind sensors were replaced. It was found that old ones were still in fairly good shape, except for the sensor at 20 m. Wind measurements could be affected at that level, particularly in low wind speeds.
    • Clean 4 m and 70 m HSS lenses (2030 UTC).
    • Clean radiometers domes (32m at 1554 UTC and 70 m at 1603 UTC).
    • Lenses on the krypton hygrometers were cleaned and the data was checked. The sensor at 32 m ("whiskey") seems in good shape after the cleaning. The sensor at 70 m ("jig") seems out of commission, with very low voltage readings after the lense cleaning. Both sensors taken down for the remainder of the summer season.

 


 

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