SGP/IRT/E19 - Reprocess: Calibration error

The IRT was measuring ~20K higher sky temperatures than at other nearby extended facilies. 
The calibration of the instrument was incorrect. The problem was corrected by replacing 
the IRT.

The offset in the calibration will be determined and the data will be corrected.

• IR Brightness Temperature(sky_ir_temp)
• sky_ir_temp_max
• sky_ir_temp_min

• IR Brightness Temperature(sky_ir_temp)

SGP/IRT/E15 - Instrument noise problem

The data was much noisier than other nearby sites (a factor of 4-5 times more). The 
connections and communication and other settings were checked. The IRT was replaced on 
1/29/2008 at 17:37 but the response time was incorrectly set to 0.01 s. This problem was 
corrected when the setting was changed to 0.10 s.

• IR Brightness Temperature(sky_ir_temp)
• sky_ir_temp_min

• IR Brightness Temperature(sky_ir_temp)

• AVHRR satellite images for Darwin from BOM (RAW)(raw)

SGP/IRT/E13 - Reprocess: Sky temperature bias

Measurements of sky temperature, especially those <250K,, were positively biased compared 
with AERI because there was no compensation for the effect of the emissivity and 
temperature of the gold mirror. The problem was corrected by changing the IRT emissivity from 
1.000 to 0.987, adding an RTD and transmitter electronics to measure the temperature of the 
mirror, and changing the ambient temperature measurement for internal reference to 
external mirror temperature.

Use sky temperature measurements less than 230K with caution. Biases as large as 30K have 
been observed when the actual temperature, as measured by AERI, is less than 210 K.

• IR Brightness Temperature(sky_ir_temp)
• sky_ir_temp_max
• sky_ir_temp_min

• IR Brightness Temperature(sky_ir_temp)

SGP/IRT/E16 - reference temperature incorrect

The internal reference temperature was unrealistically high, ~360K (90C). The ambient 
temperature setting was checked. The problem was corrected by replacing the instrument. The 
sky temperature measurement appears to have been unaffected.

• ref_ir_temp_std
• ref_ir_temp

• ref_ir_temp

SGP/IRT/E6 - Response time

The time response of the temperature measurement was changed from 1.0 to 0.1 sec to 
accommodate the 5Hz sample rate. This produced a 370% decrease in the resolution (to 1.85C at a 
sky temperature of -50C) and a significant decrease in the signal-to-noise ratio.

• ref_ir_temp_std
• sky_ir_temp_std

• ref_ir_temp
• IR Brightness Temperature(sky_ir_temp)

SGP/IRT/E7 - Response time

The time response of the temperature measurement was changed from 1.0 to 0.1 sec to 
accommodate the 5Hz sample rate. This produced a 370% decrease in the resolution (to 1.85C at a 
sky temperature of -50C) and a significant decrease in the signal-to-noise ratio.

• ref_ir_temp_std
• sky_ir_temp_std

• ref_ir_temp
• IR Brightness Temperature(sky_ir_temp)

SGP/IRT/E8 - Response time

The time response of the temperature measurement was changed from 1.0 to 0.1 sec to 
accommodate the 5Hz sample rate. This produced a 370% decrease in the resolution (to 1.85C at a 
sky temperature of -50C) and a significant decrease in the signal-to-noise ratio.

• ref_ir_temp
• IR Brightness Temperature(sky_ir_temp)

• sky_ir_temp_std
• ref_ir_temp_std

SGP/IRT/E9 - Response time

The time response of the temperature measurement was changed from 1.0 to 0.1 sec to 
accommodate the 5Hz sample rate. This produced a 370% decrease in the resolution (to 1.85C at a 
sky temperature of -50C) and a significant decrease in the signal-to-noise ratio.

• IR Brightness Temperature(sky_ir_temp)
• ref_ir_temp

• sky_ir_temp_std
• ref_ir_temp_std

SGP/IRT/E11 - Response time

The time response of the temperature measurement was changed from 1.0 to 0.1 sec to 
accommodate the 5Hz sample rate. This caused a 370% decrease in the resolution (to 1.85C at a 
sky temperature of -50C) and a significant decrease in the signal-to-noise ratio.

• sky_ir_temp_std
• ref_ir_temp_std

• IR Brightness Temperature(sky_ir_temp)
• ref_ir_temp

SGP/IRT/E16 - Response time

The time response of the temperature measurement was changed from 1.0 to 0.1 sec to 
accommodate the 5Hz sample rate. This caused a 370% decrease in the resolution (to 1.85C at a 
sky temperature of -50C) and a significant decrease in the signal-to-noise ratio.

• ref_ir_temp_std
• sky_ir_temp_std

• IR Brightness Temperature(sky_ir_temp)
• ref_ir_temp

SGP/IRT/E19 - Response time

The time response of the temperature measurement was changed from 1.0 to 0.1 sec to 
accommodate the 5Hz sample rate. This caused a 370% decrease in the resolution (to 1.85C at a 
sky temperature of -50C) and a significant decrease in the signal-to-noise ratio.

• sky_ir_temp_std
• ref_ir_temp_std

• ref_ir_temp
• IR Brightness Temperature(sky_ir_temp)

SGP/IRT/E20 - Response time

The time response of the temperature measurement was changed from 1.0 to 0.1 sec to 
accommodate the 5Hz sample rate. This caused a 370% decrease in the resolution (to 1.85C at a 
sky temperature of -50C) and a significant decrease in the signal-to-noise ratio.

• ref_ir_temp_std
• sky_ir_temp_std

• ref_ir_temp
• IR Brightness Temperature(sky_ir_temp)

SGP/IRT/E13 - Response time

The time response of the temperature measurement was changed from 1.0 to 0.1 sec to 
accommodate the 5Hz sample rate. This caused a 370% decrease in the resolution (to 1.85C at a 
sky temperature of -50C) and a significant decrease in the signal-to-noise ratio.

• ref_ir_temp_std
• sky_ir_temp_std

• ref_ir_temp
• IR Brightness Temperature(sky_ir_temp)

SGP/IRT/E10 - Response time

The time response of the temperature measurement was changed from 1.0 to 0.1 sec to 
accommodate the 5Hz sample rate. This caused a 370% decrease in the resolution (to 1.85C at a 
sky temperature of -50C) and a significant decrease in the signal-to-noise ratio.

• IR Brightness Temperature(sky_ir_temp)
• ref_ir_temp

• sky_ir_temp_std
• ref_ir_temp_std

SGP/IRT/E5 - Response time

The time response of the temperature measurement was 1.0 sec instead of 0.1 sec (which it 
should have been to accommodate the 5Hz sample rate).

• ref_ir_temp
• IR Brightness Temperature(sky_ir_temp)

• ref_ir_temp_std
• sky_ir_temp_std

SGP/IRT/E12 - Reprocess: Calibration error

The measured sky temperature was lower than other SGP facilities because the original 
calibration, as set be the vendor, was wrong. The IRT was replaced and returned to the vendor.

• sky_ir_temp_min
• sky_ir_temp_max
• IR Brightness Temperature(sky_ir_temp)

SGP/IRT/E21 - Instrument failure

Instrument stopped recording data and was replaced on 2/23/2012 but the calibration was 
wrong, such that the sky temperatures were about 40 K less than at the other EFs. The 
problem was corrected when the IRT was replces again on 5/30/2012.

The data can be corrected if the calibration is determined.

• sky_ir_temp_max
• sky_ir_temp_min
• IR Brightness Temperature(sky_ir_temp)

NSA/IRT/C1 - Serial communication problem

Data acquisition was intermittent due to poor serial communication, causing many gaps in 
the datastream.

• lon
• time
• alt
• IR Brightness Temperature(sky_ir_temp)
• ref_ir_temp
• time_offset
• lat
• base_time

• sky_ir_temp_std
• base_time
• alt
• lat
• time_offset
• time
• logger_temp
• sky_ir_temp_max
• sky_ir_temp_min
• IR Brightness Temperature(sky_ir_temp)
• lon
• internal_voltage