TWP/SKYRAD/C1 - Comparison between shaded and unshaded PIRs

We notice a clear-sky diurnal pattern which shows PIR_shaded > PIR_total in the morning 
with a maximum difference of about 2.5 W/m^2. They are equal at about 10AM local time, 
PIR_total > PIR_shaded from 10AM until about 2PM reaching a max difference of about 5W/m^2 at 
noon. PIR_shaded > PIR_total after 2PM, reaching a max difference of about 2.5 W/m^2 
around 4PM. During the night, PIR_shaded is typically about 0.5 W/m^2 greater than 
PIR_total. We have thought about the difference at noon, and think that this difference may be due 
to a heating of the dome of the unshaded PIR, or perhaps a contribution from the IR 
portion of the solar spectrum.  Initial simple calculations show that this solar contribution 
may be of the magnitude as the difference in the two PIRs (consultation with Tom Stoffel 
at NREL indicates that the source of the discrepancy is likely the solar IR).  We cannot 
explain the structure over the remainder of the day.

There are also some general trends that should be noted: (1)cloudy conditions result in 
PIR_shaded > PIR_total (2)Larger positive spikes in PIR_total - PIR_shaded occur in rain, 
particularly when the rain rate >10mm/hr (even for a very short period).

In brief, the two radiometers usually agree within 1 W/m^2  at night and under cloudy 
conditions.  The two instruments tend to deviate during sunny conditions. The descrepancy 
between the shaded and unshaded instruments generally peaks around 5 W/m^2 near local noon 
with the unshaded instrument reporting higher values. 

Note: the unshaded PIR is incorrectly named "shaded2" during this time period.  This is 
covered in a separate DQR.

• down_long_hemisp1_min
• down_long_hemisp1_std
• down_long_hemisp2_max
• down_long_hemisp1_max
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer1(down_long_hemisp1)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer2(down_long_hemisp2)
• down_long_hemisp2_std
• down_long_hemisp2_min

• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer1)(inst_down_long_hemisp_shaded1_tp)
• inst_down_long_shaded1_dome_resist
• inst_down_long_shaded2_case_resist
• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer2)(inst_down_long_hemisp_shaded2_tp)
• inst_down_long_shaded1_case_resist
• inst_down_long_shaded2_dome_resist

TWP/SKYRAD/C1 - Change in relationship between shaded and unshaded PIRs

As before, there is good agreement between the two up-looking
PIRs.  However, there has been an unusual change in the relationship
between the two instruments.  Prior to the RESET visit at the end of
August, the two instruments agreed to within 1 W/m^2 at night and
on sunny days, the unshaded radiometer reported higher values during
the day.  The difference between the two instruments exhibited a
cosine-like diurnal curve peaking at about 5 W/m^2 near solar noon. 
On 970830, the data logger was reconfigured and since that time,
the behavior has been different.  Now, there is a 5-10 W/m^2
difference between the two radiometers with the *shaded* instrument
reading higher than the unshaded during the day.  At night, the two
still agree within about 1 W/m^2.  There is still a cosine-like
diurnal dependance to the instrument discrepancy during the day - with
the offset, this actually results in closer agreement between the two
radiometers near solar noon than in the morning or afternoon.

Note: the unshaded PIR is incorrectly named "shaded2" during this
time period.  This is covered in a separate DQR.

• down_long_hemisp_shaded2_min
• down_long_hemisp_shaded2_std
• down_long_hemisp_shaded1_min
• down_long_hemisp_shaded2_max
• down_long_hemisp_shaded1_std
• Irradiance, longwave, downwelling, hemispheric, shaded pyrgeometer2(down_long_hemisp_shaded2)
• down_long_hemisp_shaded1_max
• Irradiance, longwave, downwelling, hemispheric, shaded pyrgeometer1(down_long_hemisp_shaded1)

• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer1)(inst_down_long_hemisp_shaded1_tp)
• inst_down_long_shaded1_dome_resist
• inst_down_long_shaded2_case_resist
• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer2)(inst_down_long_hemisp_shaded2_tp)
• inst_down_long_shaded1_case_resist
• inst_down_long_shaded2_dome_resist

TWP/SKYRAD/C1 - Shaded vs. unshaded radiometer comparison

The daily average difference between the shaded and unshaded PIRs
reversed on 19980428.  Previous to then, the unshaded PIR was typically
about 2 Wm-2 less than the shaded PIR.  Since the 28th, the unshaded
PIR has been averaging about 4-5 Wm-2 greater than the shaded PIR.
This latter difference worsened for the period 5/25 to 5/31, when the
daily average difference increased to between 8-10 Wm-2.    The
disagreement is typically greater at night, reaching differences of
greater than 12 Wm-2 during the period 5/25-5/31.  The cause for the
switch in sign of the difference can most likely be attributed to
instrument replacement, however the (in general) larger absolute
disagreement after Apr 28th indicates a possible calibration problem.
The cause of the large discrepancies from 5/25 to 5/31 is unknown.

I noticed that the daylight differences increased slightly, with an
attendant slight decrease in the night differences. This daylight
difference is on the order of an additional 1 Wm-2.

Note: the unshaded PIR is incorrectly named "shaded2" during this
time period.  This is covered in a separate DQR.

• down_long_hemisp_shaded2_min
• down_long_hemisp_shaded2_std
• down_long_hemisp_shaded1_min
• down_long_hemisp_shaded2_max
• down_long_hemisp_shaded1_std
• Irradiance, longwave, downwelling, hemispheric, shaded pyrgeometer2(down_long_hemisp_shaded2)
• down_long_hemisp_shaded1_max
• Irradiance, longwave, downwelling, hemispheric, shaded pyrgeometer1(down_long_hemisp_shaded1)

• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer1)(inst_down_long_hemisp_shaded1_tp)
• inst_down_long_shaded1_dome_resist
• inst_down_long_shaded2_case_resist
• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer2)(inst_down_long_hemisp_shaded2_tp)
• inst_down_long_shaded1_case_resist
• inst_down_long_shaded2_dome_resist

NSA/SKYRAD/C2 - Reprocess: Calibration error

Due to confusion over ARM calibration policy, a revised calibration was installed and was 
in place for the duration of the time period indicated. When the error was noted, the 
original calibration was re-installed. Users may notice discontinuities in PIRd data at the 
time boundaries of this DQR.

Data will be reprocessed.

• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer1)(inst_down_long_hemisp_shaded_tp)

• inst_down_long_hemisp2_case_temp
• inst_down_long_hemisp2_tp
• down_long_hemisp2_min
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer2(down_long_hemisp2)
• down_long_hemisp2_std
• down_long_hemisp2_max
• inst_down_long_hemisp2_dome_temp

• down_long_hemisp_shaded2_min
• down_long_hemisp_shaded2_std
• Irradiance, longwave, downwelling, hemispheric, shaded pyrgeometer2(down_long_hemisp_shaded2)
• down_long_hemisp_shaded2_max

NSA/SKYRAD/C2 - reprocess: PIR identified as unshaded is really shaded

On 5/24/02 the Global PIR was moved from the unshaded 
position on the Skyrad stand to a shaded spot on the
tracker.  It is still using the same Logger channel as
it did as an unshaded PIR even though it is now shaded.

• inst_down_long_unshaded_dome_resist
• inst_down_long_unshaded_case_resist
• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer2)(inst_down_long_hemisp_unshaded_tp)

NSA/SKYRAD/C1 - reprocess: PIR identified as unshaded is really shaded

On 5/15/02 the Global PIR was moved from the unshaded
position on the Skyrad stand to a shaded spot on
the tracker.  It is still using the same Logger
channel as it did as an unshaded PIR even though it
is now shaded.

• inst_down_long_unshaded_case_resist
• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer2)(inst_down_long_hemisp_unshaded_tp)
• inst_down_long_unshaded_dome_resist

NSA/SKYRAD/C1 - Frosting and Condensation

The operators in both Barrow and Atqasuk reported significant ice buildup during nights 
for the period specified, with the ice melting during the days. This condition is reported 
in preventative maintenance reports as continuing until on or near 5/18/2004. However, 
review of data shows no discernable radiometer icing.

• Raw data stream - documentation not supported

• down_long_hemisp_shaded2_std
• down_long_hemisp_unshaded_std
• sky_ir_temp_min
• psps_mean
• sky_ir_temp_max
• psps_min
• down_long_hemisp_shaded2_max
• pirs_mean
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Minima(down_short_diffuse_hemisp_min)
• uvb_mean
• nip_min
• down_long_hemisp_shaded1_max
• pirs_min
• pir1_sd
• short_direct_normal_std
• pirs_max
• Downwelling Longwave Hemispheric Irrad., Shaded Ventilated Pyrgeometer, Minima(down_long_hemisp_shaded_min)
• psps_sd
• Downwelling Longwave Hemispheric Irradiance, Unshaded Pyrgeometer, Minima(down_long_hemisp_unshaded_min)
• Downwelling Longwave Hemispheric Irradiance, Unshaded Pyrgeometer, Maxima(down_long_hemisp_unshaded_max)
• psp1_min
• psp1_max
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Maxima(down_short_diffuse_hemisp_max)
• down_short_diffuse_hemisp_std
• pir1_mean
• nip_max
• psp1_mean
• sky_ir_temp_std
• Downwelling Ultra-Violet Irradiance, UV Biometer(down_uvb)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Maxima(short_direct_normal_max)
• irt1_mean
• uvb_min
• Radiation, shortwave, downwelling diffuse hemispheric irradiance, 1-min avg(down_short_diffuse_hemisp)
• down_uvb_std
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Maxima(down_short_hemisp_max)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Minima(down_short_hemisp_min)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Minima(short_direct_normal_min)
• nip_mean
• Downwelling Ultra-Violet Irradiance, UV Biometer, Maxima(down_uvb_max)
• uvb_sd
• down_short_hemisp_std
• Irradiance, longwave, downwelling, hemispheric, shaded pyrgeometer1(down_long_hemisp_shaded1)
• uvb_max
• pirs_sd
• irt1_min
• Irradiance, longwave, downwelling, hemispheric, shaded pyrgeometer2(down_long_hemisp_shaded2)
• IR Brightness Temperature(sky_ir_temp)
• psp1_sd
• irt1_max
• Radiation, shortwave, downwelling total hemispheric irradiance, 1-min avg(down_short_hemisp)
• Downwelling Longwave Hemispheric Irrad., Shaded Ventilated Pyrgeometer, Maxima(down_long_hemisp_shaded_max)
• down_long_hemisp_shaded2_min
• Downwelling Longwave Hemispheric Irradiance, Unshaded Pyrgeometer(down_long_hemisp_unshaded)
• nip_sd
• pir1_min
• Downwelling Ultra-Violet Irradiance, UV Biometer, Minima(down_uvb_min)
• Downwelling Longwave Hemispheric Irradiance, Shaded Ventilated Pyrgeometer(down_long_hemisp_shaded)
• down_long_hemisp_shaded_std
• psps_max
• irt1_sd
• Radiation, shortwave, direct normal irradiance, 1-min avg(short_direct_normal)
• pir1_max
• down_long_hemisp_shaded1_std
• down_long_hemisp_shaded1_min

• pir2_dome_therm
• inst_down_long_unshaded_case_resist
• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer1)(inst_down_long_hemisp_shaded_tp)
• Irradiance, ultraviolet, downwelling (UV Biometer)(inst_down_uvb_irradiance)
• inst_down_long_shaded_dome_resist
• pir2_uncorr_irradiance
• inst_down_uvb_temp
• inst_down_long_shaded2_dome_resist
• inst_down_long_shaded1_case_resist
• inst_down_long_shaded_case_resist
• uvb_temp
• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer2)(inst_down_long_hemisp_unshaded_tp)
• inst_down_long_shaded1_dome_resist
• uvb_uncorr_irradiance
• inst_down_long_shaded2_case_resist
• pir2_case_therm
• pir1_uncorr_irradiance
• pir1_case_therm
• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer2)(inst_down_long_hemisp_shaded2_tp)
• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer1)(inst_down_long_hemisp_shaded1_tp)
• pir1_dome_therm
• inst_down_long_unshaded_dome_resist

NSA/SKYRAD/C2 - Frosting and Condensation

The operators in both Barrow and Atqasuk reported significant ice buildup during nights 
for the period specified, with the ice melting during the days. This condition is reported 
in preventative maintenance reports as continuing until on or near 5/18/2004. However, 
review of data shows no discernable radiometer icing.

• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer1)(inst_down_long_hemisp_shaded1_tp)
• pir1_case_therm
• pir2_case_therm
• pir2_dome_therm
• inst_down_long_shaded2_case_resist
• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer2)(inst_down_long_hemisp_unshaded_tp)
• Irradiance, ultraviolet, downwelling (UV Biometer)(inst_down_uvb_irradiance)
• uvb_temp
• pir1_dome_therm
• pir1_uncorr_irradiance
• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer2)(inst_down_long_hemisp_shaded2_tp)
• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer1)(inst_down_long_hemisp_shaded_tp)
• inst_down_long_shaded1_dome_resist
• inst_down_long_unshaded_case_resist
• inst_down_long_shaded2_dome_resist
• inst_down_long_unshaded_dome_resist
• inst_down_long_shaded_case_resist
• inst_down_long_shaded_dome_resist
• uvb_uncorr_irradiance
• inst_down_long_shaded1_case_resist
• pir2_uncorr_irradiance
• inst_down_uvb_temp

• Raw data stream - documentation not supported

• down_long_hemisp_shaded2_std
• psp1_mean
• nip_max
• irt1_mean
• psp1_max
• pirs_mean
• pirs_max
• uvb_max
• irt1_max
• down_short_diffuse_hemisp_std
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Maxima(down_short_diffuse_hemisp_max)
• nip_mean
• uvb_sd
• psps_max
• psp1_sd
• Downwelling Longwave Hemispheric Irradiance, Shaded Ventilated Pyrgeometer(down_long_hemisp_shaded)
• IR Brightness Temperature(sky_ir_temp)
• uvb_mean
• down_long_hemisp_unshaded_std
• Radiation, shortwave, downwelling total hemispheric irradiance, 1-min avg(down_short_hemisp)
• down_short_hemisp_std
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Minima(down_short_hemisp_min)
• Downwelling Longwave Hemispheric Irradiance, Unshaded Pyrgeometer, Maxima(down_long_hemisp_unshaded_max)
• pirs_min
• Downwelling Ultra-Violet Irradiance, UV Biometer, Maxima(down_uvb_max)
• pirs_sd
• down_long_hemisp_shaded1_min
• sky_ir_temp_std
• down_long_hemisp_shaded1_std
• time_offset
• irt1_min
• Downwelling Ultra-Violet Irradiance, UV Biometer(down_uvb)
• Downwelling Ultra-Violet Irradiance, UV Biometer, Minima(down_uvb_min)
• pir1_sd
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Maxima(down_short_hemisp_max)
• down_long_hemisp_shaded_std
• sky_ir_temp_max
• sky_ir_temp_min
• Irradiance, longwave, downwelling, hemispheric, shaded pyrgeometer2(down_long_hemisp_shaded2)
• Irradiance, longwave, downwelling, hemispheric, shaded pyrgeometer1(down_long_hemisp_shaded1)
• nip_min
• Shortwave Direct Normal Irradiance, Pyrheliometer, Maxima(short_direct_normal_max)
• down_long_hemisp_shaded1_max
• psp1_min
• Downwelling Longwave Hemispheric Irradiance, Unshaded Pyrgeometer(down_long_hemisp_unshaded)
• psps_mean
• down_uvb_std
• Downwelling Longwave Hemispheric Irrad., Shaded Ventilated Pyrgeometer, Maxima(down_long_hemisp_shaded_max)
• down_long_hemisp_shaded2_min
• short_direct_normal_std
• uvb_min
• Downwelling Longwave Hemispheric Irrad., Shaded Ventilated Pyrgeometer, Minima(down_long_hemisp_shaded_min)
• nip_sd
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Minima(down_short_diffuse_hemisp_min)
• Radiation, shortwave, direct normal irradiance, 1-min avg(short_direct_normal)
• pir1_max
• pir1_min
• pir1_mean
• Downwelling Longwave Hemispheric Irradiance, Unshaded Pyrgeometer, Minima(down_long_hemisp_unshaded_min)
• Radiation, shortwave, downwelling diffuse hemispheric irradiance, 1-min avg(down_short_diffuse_hemisp)
• psps_sd
• psps_min
• Shortwave Direct Normal Irradiance, Pyrheliometer, Minima(short_direct_normal_min)
• down_long_hemisp_shaded2_max
• irt1_sd

TWP/SKYRAD/C1 - 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.

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

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

NSA/SKYRAD - Barrow SKYRAD PIRD Misconfiguration 12/9 - 12/12/98

The PIRD was incorrectly set from 12/9/98 to 12/12/98 that resulted in an 
error of approximately 3.7% (was set to 243902 instead of 235294).

• alt
• irt1_sd
• nip_mean
• time_offset
• pirs_min
• irt1_mean
• pirs_max
• psp1_mean
• uvb_min
• pir1_max
• pir1_min
• irt1_min
• base_time
• nip_min
• lat
• psp1_min
• psp1_max
• irt1_max
• pirs_mean
• external_voltage
• psps_sd
• nip_max
• uvb_mean
• nip_sd
• psp1_sd
• filename
• uvb_max
• bit_data
• psps_max
• lon
• uvb_sd
• pir1_sd
• pirs_sd
• internal_voltage
• pir1_mean
• logger_temp
• psps_mean
• psps_min

• pir2_dome_therm
• time_offset
• pir2_uncorr_irradiance
• base_time
• uvb_temp
• uvb_uncorr_irradiance
• lat
• pir2_case_therm
• pir1_uncorr_irradiance
• pir1_case_therm
• alt
• pir1_dome_therm
• lon
• filename

NSA/SKYRAD/C1 - Incorrect 20s dome thermistor data

The 30-second and 50-second PIR2 diffuse dome thermistor data
in all skyrad 20s data records taken to data is in fact case
thermistor data.  No other data are affected.  The 20 second
skyrad data cannot be used to recompute the diffuse PIR2 data.

Note: This data was named pir2_dome_therm at the beginning of
this time range andlater the variable was renamed to
inst_down_lng_shaded2_dome_resist.

• pir2_dome_therm
• inst_down_long_shaded2_dome_resist

TWP/SKYRAD/C1 - Incorrect 20s dome thermistor data

The 30-second and 50-second PIR2 diffuse dome thermistor data 
in all skyrad 20s data records taken to date is, in fact, case 
thermistor data.  No other data are affected.  The 20 second
skyrad data cannot be used to recompute the diffuse PIR2 data.

Note: This data was named pir2_dome_therm at the beginning of 
this time range and later the variable was renamed to
inst_down_long_shaded2_dome_resist.

• inst_down_long_shaded2_dome_resist
• pir2_dome_therm