FKB/MWRP/M1 - LN2 Calibration-

Between 1100 and 1500 there were two calibration attempts.

• Dummy altitude for Zeb(alt)
• Surface absolute temperature at instrument(surfaceTemperature)
• Expected root-mean-square error in precipitable water retrieval(totalPrecipitableWaterRmsError)
• lon(lon)
• Surface water vapor density at instrument(surfaceWaterVaporDensity)
• Surface relative humidity at instrument(surfaceRelativeHumidity)
• Level of free convection pressure(levelFreeConvectionPres)
• Retrieved water vapor density(waterVaporDensity)
• Convective Available Potential Energy(cape)
• Equilibrium level(equilibriumLevel)
• air temperature (NGM250 predicted)(temperature)
• Derived virtual temperature(virtualTemperature)
• Frequency(frequency)
• Interpolated water vapor mixing ratio(waterVaporMixingRatio)
• Flag indicating moisture sensor status(wetWindowFlag)
• Retrieved liquid water path(liquidWaterPath)
• Lifting condensation level pressure(liftingCondensationLevelPres)
• Expected root-mean-square error in precipitable water retrieval using only
  23.835 and 30.0 GHz(totalPrecipitableWater2RmsError)
• elevation(elevation)
• Data quality flags(dataQualityFlags)
• Derived relative humidity(relativeHumidity)
• Expected root-mean-square error in liquid water content retrieval(liquidWaterContentRmsError)
• Total precipitable water vapor, from microwave radiometer(totalPrecipitableWater)
• lat(lat)
• Lifting condensation level(liftingCondensationLevel)
• Cloud base height(cloudBaseHeight)
• Internal blackbody reference temperature(blackbodyTemperature)
• Retrieved liquid water path using only 23.835 and 30.0 GHz(liquidWaterPath2)
• Retrieved total precipitable water vapor using only 23.835 and 30.0 GHz(totalPrecipitableWater2)
• Time offset of tweaks from base_time(time_offset)
• azimuth(azimuth)
• base time(base_time)
• time(time)
• Expected root-mean-square error in liquid water path retrieval(liquidWaterPathRmsError)
• Expected root-mean-square error in water vapor density retrieval(waterVaporDensityRmsError)
• Level of free convection(levelFreeConvection)
• Interpolated dewpoint temperature(dewpointTemperature)
• Expected root-mean-square error in liquid water path retrieval using only 23.835
  and 30.0 GHz(liquidWaterPath2RmsError)
• Microwave brightness temperature(brightnessTemperature)
• Retrieved cloud liquid water content(liquidWaterContent)
• Zenith-pointing infrared temperature at 10um(infraredTemperature)
• Surface pressure at instrument(surfacePressure)
• Equilibrium level pressure(equilibriumLevelPres)
• Array of heights for the range gates(height)
• Expected root-mean-square error in temperature retrieval(temperatureRmsError)
• atmospheric pressure at mean sea level and at tropopause (NGM250 predicted)(pressure)

FKB/MWRP/M1 - Reprocess: Updated 30-GHz calibration coefficient

On 9/17 the instrument was calibrated with liquid nitrogen. For the 30-GHz channel the 
results of calibration were not optimal and were causing a negative bias in the retrieved 
LWP.

On 10/9 the 30-GHz calibration parameters were updated with values derived from tip 
curves.

Data between 9/17 and 10/9 will be reprocessed to correct for the 30-GHz calibration.

• Retrieved liquid water path using only 23.835 and 30.0 GHz(liquidWaterPath2)
• Microwave brightness temperature(brightnessTemperature)
• Retrieved liquid water path(liquidWaterPath)

FKB/MWRP/M1 - Heavy rain and fog at the site

The months of November and December have been very rainy and wet at the AMF site. During 
rain events the radiometer does not work properly because of water accumulating on the 
window. In addition condensation and fog will affect the data causing very high brightness 
temperatures. Although the instrument is equipped with rain detection system to flag bad 
data, it is important that the user pays extra attention to the quality of the data during 
periods of continuous rain, drizzle or fog by applying the quality checks and screening 
for high brightness temperatures.

• Retrieved liquid water path using only 23.835 and 30.0 GHz(liquidWaterPath2)
• Derived relative humidity(relativeHumidity)
• Retrieved total precipitable water vapor using only 23.835 and 30.0 GHz(totalPrecipitableWater2)
• Interpolated water vapor mixing ratio(waterVaporMixingRatio)
• Total precipitable water vapor, from microwave radiometer(totalPrecipitableWater)
• Retrieved water vapor density(waterVaporDensity)
• Interpolated dewpoint temperature(dewpointTemperature)
• Microwave brightness temperature(brightnessTemperature)
• Retrieved cloud liquid water content(liquidWaterContent)
• Derived virtual temperature(virtualTemperature)
• Retrieved liquid water path(liquidWaterPath)
• air temperature (NGM250 predicted)(temperature)

FKB/MWRP/M1 - Possible slight drift of V-band calibration

During the month of November and December the bias between model computations and 
measurements for the 51.25 and 52.28 GHz channels has slightly increased to about 3 K. This might 
be due to a slight drift in the calibration of these channels.

The calibration error associated with these data is increased, to 2-3 K, for these two 
months. See this plot for a comparison of measurements (solid lines) and model (red 
dots) for the 51.25 (black), 52.28 (blue) and 53.85-GHz (green) channels.

• Microwave brightness temperature(brightnessTemperature)

FKB/MWRP/M1 - Periodic decrease in the 30-GHz brightness temperature

Starting around 12/19 until the end of December, the 30-GHz brightness temperature started 
to show a periodic oscillation between 9 and 11 AM GMT. The cause of this is probably 
thermal instability of the radiometer since it does correspond with some larger 
oscillations of the mixer temperature. During this time external temperatures displayed large 
variations going from -10 C at night to about +5 C during the day. The corresponding liquid 
water path retrievals are affected showing periodic negative values.

Liquid water path retrievals between 12/19 and 12/31 are the most affected variable since 
they are largely affected by the 30-GHz channel. A time series plot of the data will 
clearly show the periodic fluctuation of the LWP variable.

• Retrieved liquid water path using only 23.835 and 30.0 GHz(liquidWaterPath2)
• Microwave brightness temperature(brightnessTemperature)
• Retrieved cloud liquid water content(liquidWaterContent)
• Retrieved liquid water path(liquidWaterPath)