TWP/VCEIL/C2 - Time offset

On 7/14/2006, I found that the ceilometer time was 8m 36s slow, the PC time display (lower 
right taskbar) was frozen at "22:24", and AboutTime was not running. Corrected it on 
7/17 by running AboutTime so that 19:03:29 became 19:12:05. This also corrected the frozen 
display on the Windows98 taskbar. 

I am not sure of the start time of this problem but there were several other Windows 
related issues that had to be corrected on 5/14 with indications of inappropriate access via 
Remote Administrator on 5/13. I do not know if the time offset was a sudden or gradual 
change.

• Aerosol backscatter coefficient at 355 nm(backscatter)
• Flag indicating aeri retrieval status(status_flag)
• Percentage of nominal factory setting (0 to 999%)(laser_pulse_energy)
• Third cloud base height(third_cbh)
• Time offset of tweaks from base_time(time_offset)
• base time(base_time)
• Lowest cloud base height detected.(first_cbh)
• Warning and alarm status bits(status_string)
• range(range)
• Millivolts at internal ADC input (0 to 2500)(background_light)
• Percentage of nominal factory setting (0 to 999%)(receiver_sensitivity)
• Vertical visibility(vertical_visibility)
• Laser temperature(laser_temperature)
• Altitude of highest signal(alt_highest_signal)
• 6 character string describing instrument measurement parameters(measurement_parameters)
• Second lowest cloud base height(second_cbh)
• Degrees from vertical (0 to +90)(tilt_angle)
• Detection status. See details(detection_status)
• Millivolts at internal ADC input(window_contamination)
• Backscatter sum(sum_backscatter)

TWP/SMET/C2 - Reprocess: Tipping bucket rain gauge added

A tipping bucket rain gauge was added to the TWP.C2 SMET suite of instruments on 20061129. 
Effective 20060926, two new variables (count and rain amount) were added to the end of 
the twpsmet60sC2.b1 datastream.  Between 9/26 and 11/29, the data for these two variables 
are filled with zeros.  Users should not use the data during this period as the zeros are 
not representative of the rain fall at the site.  When reprocessing of this datastream 
occurs these variables will be added for the 19981021-20060926 and data from 
19981021-20061129 will be filled with -9999 (missing).

• base time(base_time)

TWP/SMET/C2 - Wind Speed data contain offset due to induced voltage

The marine model of the RM Young wind sensor needs twisted pair shielded cable.  The 
manufacturer did not originally supply the pigtail with twisted pair shielded cable.  Use of 
twisted pair shielded cable for the rest of the cable run to the logger was also not 
specified.  This caused an induced voltage in the wind speed line from the wind direction 
excitation.  The induced voltage varied from sensor to sensor and probably changed anytime 
the cable was replaced or parts of the wind sensor were repaired or replaced. The induced 
voltage has been seen to vary from 0.15 m/s to as much as 1.08 m/s.

• Upper sensor, wind speed vector average(up_spd_vec_avg)
• Upper sensor, wind speed minimum(up_spd_min)
• Lower sensor, wind speed minimum(lo_spd_min)
• Upper sensor, wind speed maximum(up_spd_max)
• Lower sensor, wind speed arithmetic average(lo_spd_arith_avg)
• Lower sensor, wind speed maximum(lo_spd_max)
• Lower sensor, wind speed vector average(lo_spd_vec_avg)
• Lower sensor, wind speed standard deviation(lo_spd_sd)
• Upper sensor, wind speed arithmetic average(up_spd_arith_avg)
• Upper sensor, wind speed standard deviation(up_spd_sd)