HFE/MWR/M1 - Insufficient calibration stability

The noise diode temperature suddenly jumped to > 60 C after a power outage. Following 
additional power problems the noise diode injection temperature drifted fast and the 
radiometer was not able to calibrate properly.

Data during the indicated time periods are poorly calibrated and sometimes erratic. Users 
should be aware that the accuracy of the measurements is dramatically degraded. 

Users can use the microwave profiler (MWRP) data to supplement the MWR data.

• Sky brightness temperature at 31.4 GHz(tbsky31)
• Noise injection temp at nominal temperature at 31.4 GHz(tnd_nom31)
• Noise injection temp at 23.8 GHz adjusted to tkbb(tnd23)
• MWR column precipitable water vapor(vap)
• Temperature correction coefficient at 31.4 GHz(tc31)
• Temperature correction coefficient at 23.8 GHz(tc23)
• Noise injection temp at nominal temperature at 23.8 GHz(tnd_nom23)
• Averaged total liquid water along LOS path(liq)
• Mixer kinetic (physical) temperature(tkxc)
• (tknd)
• Sky brightness temperature at 23.8 GHz(tbsky23)
• Noise injection temp at 31.4 GHz adjusted to tkbb(tnd31)

• Noise injection temp at nominal temperature at 23.8 GHz(tnd_nom23)
• Noise injection temp at 31.4 GHz adjusted to tkbb(tnd31)
• Total water vapor along zenith path using tip-derived brightness temperatures(vaptip)
• Total liquid water along zenith path using tip-derived brightness temperatures(liqtip)
• Noise injection temp at 23.8 GHz derived from this tip(tnd23I)
• 23.8 GHz sky brightness temperature derived from tip curve(tbsky23tip)
• Temperature correction coefficient at 23.8 GHz(tc23)
• Mixer kinetic (physical) temperature(tkxc)
• Temperature correction coefficient at 31.4 GHz(tc31)
• 31.4 GHz sky brightness temperature derived from tip curve(tbsky31tip)
• Noise injection temp at 31.4 GHz derived from this tip(tnd31I)
• Noise injection temp at nominal temperature at 31.4 GHz(tnd_nom31)
• Noise injection temp at 23.8 GHz adjusted to tkbb(tnd23)
• (tknd)

HFE/MWRHF/M1 - 150-GHz data drop out

The sky brightness temperature at 150 GHz (tbsky150) dropped to zero at 12:29 GMT on 
20080804 and stayed flat lined until 23:40 GMT on 20081002.

• Sky brightness temperature (150 GHz)(tbsky150)

HFE/SKYRAD/M1 - IRT bias

The sky temperatures exhibited a positive bias compared to AERI, especially when < 230K. 
This is indicative of an incorrect emissivity setting (to compensate for the gold mirror) 
or a poor calibration. A similar problem with the same instrument occurred during the FKB 
deployment that was attributed to water vapor.

• Sky Infra Red Temperature Minima(sky_ir_temp_min)
• Sky Infra-Red Temperature(sky_ir_temp)
• Sky Infra Red Temperature Maxima(sky_ir_temp_max)

HFE/MWRHF/M1 - Frosting/Condensation

The heater module was installed on 6/4/2008. Before this time there is condensation on the 
window during night time and early morning. On 8/18 the heater appears to have failed 
and nighttime condensation re-occurred on the radome during conditions of high humidity.

Users can identify the segments affected by observing a smooth steady increase in the 
brightness temperature (BT). BT values can increase to more than 250 K and then smoothly 
decrease. The RH during these events is usually above 70%. Users should disregard data 
affected by condensation.

• Sky brightness temperature (150 GHz)(tbsky150)
• Sky brightness temperature (90 GHz)(tbsky90)

HFE/MWRHF/M1 - Calibration updates

The MWRHF calibration algorithm updates the calibration parameters every time a new 
successful tip curve is acquired. 

This results in small jumps (1-2 K) in the brightness temperatures each time calibration 
is updated. During times of frequent calibrations the data appear discontinuous with short 
data segments interrupted by small jumps.

• Sky brightness temperature (150 GHz)(tbsky150)
• Sky brightness temperature (90 GHz)(tbsky90)

HFE/MWRHF/M1 - Rain sensor failure

The rain sensor failed and the rain flag was always on.  When the rain flag is on the 
radiometer does not perform tip curves. The rain sensor was replaced 8/4.

• Rain flag(rain_flag)

HFE/MWRP/M1 - Reprocess: Bias in LWP retrievals

Since local radiosondes were not available, radiosondes from a different site were used to 
develop retrieval coefficients. LWP retrievals are biased in the summer months 
(June-September).  Data in May and December are not affected.

Additional analysis will be conducted to derive new retrieval coefficients and the data 
will be reprocessed.

• Retrieved liquid water path(liquidWaterPath)
• Retrieved liquid water path using only 23.835 and 30.0 GHz(liquidWaterPath2)