TWP/C2/SMET Temperature spike

There was a brief -4 C spike in the temperature at approximately
21.5 Z on December 3.  This spike also showed up in the vapor pressure
which is calculated from the temperature and relative humidity.

• vappress_sd
• Temperature maximum(temp_max)
• temp_sd
• Vapor pressure mean(vappress_mean)
• Temperature minimum(temp_min)
• Mean Air Temperature or Hardware Error(temp_mean)

• Mean Air Temperature or Hardware Error(temp_mean)
• temp_sd
• Vapor pressure mean(vappress_mean)
• Temperature maximum(temp_max)
• vappress_sd
• Temperature minimum(temp_min)

TWP/SKYRAD/C2 - Solar tracker failure

During Reset7 (8/6) the skytracker firmware was upgraded for Y2K.  While still at the 
site, the mentor noted that the tracker was sticking and replaced it on 8/8/99. The 
replacement tracker also failed.  Repeated attempts through 8/13 were not successful.  After 8/13, 
the tracker was not operational.

It was found that the problem was the result of bugs in the Y2K compliant version (2.44) 
of the firmware.  On 10/14, Jeff Zirzow installed a new tracker with the Y2K non-compliant 
version (2.43) of the firmware.  It was correctly assumed that the Y2K issues would only 
be apparent at the 19991231-20000101 time boundary.

Exact times of changes are not known; noon GMT (midnight Local) was used to adequately 
window the time period of the changes.

• psps_max
• psps_min
• nip_mean
• pirs_sd
• psps_mean
• nip_sd
• pirs_max
• nip_min
• pirs_mean
• nip_max
• pirs_min
• psps_sd

• Radiation, shortwave, downwelling diffuse hemispheric irradiance, 1-min avg(down_short_diffuse_hemisp)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer2(down_long_hemisp2)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Maxima(short_direct_normal_max)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Minima(short_direct_normal_min)
• short_direct_normal_std
• Radiation, shortwave, direct normal irradiance, 1-min avg(short_direct_normal)
• down_long_hemisp2_max
• down_long_hemisp2_min
• down_long_hemisp2_std
• down_short_diffuse_hemisp_std
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Minima(down_short_diffuse_hemisp_min)
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Maxima(down_short_diffuse_hemisp_max)

TWP/SKYRAD/C2 - UVB Data questionable/incorrect due to uncontrolled sensor temperature

The UVB was not temperature controlled to 25C as required
to ensure accurate data.  UVB data should ONLY be used after 
checking both the bit_data and twpskyrad20sC1.a1 uvb_temp
or inst_down_uvb_temp.  UVB data where the UVB temperature
was outside the range of 24-26C should not be used.

• Downwelling Ultra-Violet Irradiance, UV Biometer, Minima(down_uvb_min)
• uvb_min
• down_uvb_std
• uvb_mean
• Downwelling Ultra-Violet Irradiance, UV Biometer, Maxima(down_uvb_max)
• Downwelling Ultra-Violet Irradiance, UV Biometer(down_uvb)
• uvb_sd
• uvb_max

• Downwelling Ultra-Violet Irradiance, UV Biometer, Maxima(down_uvb_max)
• down_uvb_std
• uvb_max
• uvb_sd
• uvb_mean
• uvb_min
• Downwelling Ultra-Violet Irradiance, UV Biometer, Minima(down_uvb_min)
• Downwelling Ultra-Violet Irradiance, UV Biometer(down_uvb)

• uvb_uncorr_irradiance
• Irradiance, ultraviolet, downwelling (UV Biometer)(inst_down_uvb_irradiance)
• uvb_temp
• inst_down_uvb_temp

TWP/SKYRAD/C2 - IRT affected by rain or shutter

During this time period, the SKYRAD IRT data was affected by rain events due to a shutter 
which was installed to protect the optics from being emersed in rainwater.  While the 
shutter was closed, or if water got on the lens, the IRT data was invalid.  If water did get 
on the lens, the contamination usually persisted until an operator cleaned the optics.

The configuration of the IRT was changed Oct 29, 2001.
The IRT was mounted such that the field of view is directed downward at a 30 degree 
elevation angle and reflected to the vertical by a front-surfaced, gold-plated mirror. This 
configuration prevents rain from directly striking the lens and collecting in the lens barrel.

Data from 11/98-2/99 were examined and times when the data are invalid are identified 
below.	Data from 3/99-10/01 also contain periods of invalid data, but it is left to the data 
users to identify those periods and filter the data according to their needs.

12/10/1998 04:30 - 12/10/1998 05:30 
12/10/1998 11:30 - 12/10/1998 12:30 
12/10/1998 13:00 - 12/10/1998 17:00 
12/17/1998 02:30 - 12/17/1998 04:00 
12/17/1998 13:00 - 12/17/1998 15:00 
12/23/1998 18:00 - 12/23/1998 20:00 
12/30/1998 21:00 - 12/31/1998 03:00 
01/12/1999 22:35 - 01/12/1999 23:45
01/13/1999 14:16 - 01/13/1999 16:35
01/13/1999 21:41 - 01/13/1999 23:30

• irt1_sd
• irt1_min
• irt1_mean
• irt1_max

• IR Brightness Temperature(sky_ir_temp)
• sky_ir_temp_std
• sky_ir_temp_max
• sky_ir_temp_min

TWP/SMET/C2 - Negative rainfall rates

Due to limitations of the Zeno dataloggers all voltage measurements
from the optical rain gauge (ORG) were converted to rainfall rates. 
This resulted in negative values for rain rates.  Any value below
0.10 mm/hr should be considered to be 0 mm/hr.  New dataloggers 
alleviated this problem.

• Precipitation mean(precip_mean)
• Precipitation minimum(precip_min)
• Precipitation maximum(precip_max)
• precip_sd

TWP/SMET/C2 - Reprocess: Barometric pressure units change

Barometric pressure data during this time period is reported in hPa.  After this time, the 
data have been converted to kPa to standardize the measurement units among ARM sites and 
to conform to accepted standard units determined by the scientific community.

• Barometric Pressure(atmos_pressure)

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

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.

• lo_spd_arith_avg
• lo_spd_min
• lo_spd_vec_avg
• up_spd_min
• up_spd_arith_avg
• lo_spd_max
• up_spd_max
• up_spd_sd
• lo_spd_sd
• up_spd_vec_avg