NIM/MWRP/M1 - Software problem

The MWRP computer failed and it was cloned with a new Gx620. Soon after, the MWRP program 
started to crash and was intermittent. Data were lost on March 3, 4, 5. 
On March 7 the program was forcefully ended and restarted. This appears to have cleared 
the problem. The instrument has been running since.

• Raw data stream - documentation not supported(raw)

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

• Raw data stream - documentation not supported(raw)

NIM/TSI/M1 - Reprocess: Data processing problem

Due to the high aerosol conditions at Niamey, the TSI appeared to be beyond the limits of 
processing the color JPEG image into cloud fraction values. Several attempts to adjust 
the sky filter values used to process the images did not yielded the desired results. The 
processed images indicate an opaque sky cover, even in the absence of clouds.

The problem was corrected by removing the neutral density filter from the lens and 
re-adjusting the sky filter values.

The data can be reprocessed.

• PNG data stream - documentation not supported(png)

• Pixel count: number total thin(count.thin)
• Pixel count: number thin in horizon area(region.horizon.count.thin)
• Pixel count: number total opaque(count.opaque)
• Pixel count: number opaque in horizon area(region.horizon.count.opaque)
• Pixel count: number opaque in zenith circle(region.zenith.count.opaque)
• Sunshine meter(sunny)
• Pixel count: number opaque in sun circle(region.sun.count.opaque)
• Pixel count: number thin in sun circle(region.sun.count.thin)
• Percent opaque cloud(percent.opaque)
• Percentage thin cloud(percent.thin)
• Pixel count: number thin in zenith circle(region.zenith.count.thin)

NIM/MWRP/M1 - Instrument noise problem

There are spikes and elevated noise in MWRP data. The origine of the spikes is RF 
interference from various sources.  All brightness temperatures are affected, but in particular 
the 5 K-band channels. LWP retrievals are noisy and affected by spikes as a result.

• Raw data stream - documentation not supported(raw)

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

• Raw data stream - documentation not supported(raw)

NIM/MWR/M1 - Instrument noise problem/RF interference

Data are affected by intermittent spikes that become more frequent starting in March 2006. 
Spikes affect data mostly around 9 AM and 18:00 PM. The origin of the spikes is probably 
RF interference.

• Averaged total liquid water along LOS path(liq)
• Sky brightness temperature at 23.8 GHz(tbsky23)
• MWR column precipitable water vapor(vap)
• 31.4 GHz sky signal(sky31)
• Sky brightness temperature at 31.4 GHz(tbsky31)
• 23.8 GHz sky signal(sky23)

• null(Raw data stream - documentation not supported)

• 31.4 GHz sky signal(tipsky31)
• 31.4 GHz sky brightness temperature derived from tip curve(tbsky31tip)
• 23.8 GHz sky brightness temperature derived from tip curve(tbsky23tip)
• Total water vapor along zenith path using tip-derived brightness temperatures(vaptip)
• 23.8 GHz sky signal(tipsky23)
• Total liquid water along zenith path using tip-derived brightness temperatures(liqtip)

NIM/MWRP/M1 - IRT Sensor Calibration

Discrepancies between the MWRP and Skyrad IRT were observed in January. The MWRP IRT 
readings were constantly higher than those of the skyrad IRT. Some changes were introduced to 
the MWRP IRT to address the problem (see DQR D060602.2). On May 3, the IRT mirror was 
replaced. After the change in the mirror, the MWRP IRT readings became about 5-8 C lower. On 
June 3 the agreement between MWRP and Skyrad IRT became satisfactory (2-5 degree C 
difference).

It is hard to numerically quantify the difference in the IRT readings caused by the change 
in the mirror. We can only warn the user that between January 1 and June 3 the MWRP 
readings are 8 to 15 degree higher than the skyrad IRT.

• Raw data stream - documentation not supported(raw)

• Zenith-pointing infrared temperature at 10um(infraredTemperature)

• Raw data stream - documentation not supported(raw)

NIM/MWRP/M1 - Reprocessed: IRT configuration setting error

The infrared thermometer settings (IRT) were not configured as specified by the 
manufacturer. The analog output was set to a range of -60 to +50 C (0-10V) instead of -50 to +50 C 
(0-10V). The settings were changed on April 20. The IR temperatures should be slightly 
smaller than reported.

The data have been reprocessed to correct the IRT calibrations.  Reprocessed data were 
archived in August 2006.

• Zenith-pointing infrared temperature at 10um(infraredTemperature)

NIM/MWRP/M1 - Reprocessed - New retrieval coefficients

Occasionally, the retrieved relative humidity was exceeding 120%. Upon reviewing the data 
it was noticed that the high values were appearing in the highest layers (above 8 km) and 
especially during spring season. Since retrievals at the highest levels are mainly 
affected by the climatology used to constrain the retrievals, we reviewed the statistical 
coefficients that were used to retrieve temperature and humidity. It was discovered that, in 
the training dataset (radiosonde), there were a few outliers (invalid radiosonde 
soundings) that had escaped the screening process and were affecting the computations of the 
retrieval coefficients.

We recomputed the retrieval coefficients with the newly screened set of radiosonde data 
and reprocessed all the previous data at Niamey.  The reprocessed data were archived in 
August 2006.

The new coefficients improve temperature and humidity profiles in two ways. The relative 
humidity will not exceed 120% in the upper layers and the temperature profiles will be in 
better agreement with the sonde in the first 4 km.

• Expected root-mean-square error in liquid water path retrieval(liquidWaterPathRmsError)
• Expected root-mean-square error in liquid water content retrieval(liquidWaterContentRmsError)
• Expected root-mean-square error in liquid water path retrieval using only 23.835
  and 30.0 GHz(liquidWaterPath2RmsError)
• Retrieved cloud liquid water content(liquidWaterContent)
• Derived relative humidity(relativeHumidity)
• Derived virtual temperature(virtualTemperature)
• Interpolated water vapor mixing ratio(waterVaporMixingRatio)
• Expected root-mean-square error in precipitable water retrieval(totalPrecipitableWaterRmsError)
• Expected root-mean-square error in water vapor density retrieval(waterVaporDensityRmsError)
• Retrieved liquid water path using only 23.835 and 30.0 GHz(liquidWaterPath2)
• air temperature (NGM250 predicted)(temperature)
• Retrieved water vapor density(waterVaporDensity)
• Interpolated dewpoint temperature(dewpointTemperature)
• Retrieved liquid water path(liquidWaterPath)
• Cloud base height(cloudBaseHeight)
• Retrieved total precipitable water vapor using only 23.835 and 30.0 GHz(totalPrecipitableWater2)
• Expected root-mean-square error in temperature retrieval(temperatureRmsError)
• Expected root-mean-square error in precipitable water retrieval using only
  23.835 and 30.0 GHz(totalPrecipitableWater2RmsError)
• Total precipitable water vapor, from microwave radiometer(totalPrecipitableWater)

NIM/MWRP/M1 - 51.25 GHz channel calibration drifted

After a power outage on May 5 the 51.25 GHz had a slight change in the calibration. The 
resulting LWP computed by using all 6 channels increased of about 0.025 mm (25 g/m2).

• Microwave brightness temperature(brightnessTemperature)

NIM/MWR/M1 - Reprocessed: Recalibration to correct for occasional overheating.

The radiometer was intermittently thermally unstable resulting in poor calibrations for 
four brief time periods.  These data have been reprocessed to apply corrected calibrations. 
 The affected time periods were:

20060302-20060303
20060423-20060425
20060512-20060515
20060531-20060603

• 23.8 GHz blackbody+noise injection signal(bbn23)
• Noise injection temp at 31.4 GHz adjusted to tkbb(tnd31)
• Mixer kinetic (physical) temperature(tkxc)
• MWR column precipitable water vapor(vap)
• Temperature correction coefficient at 23.8 GHz(tc23)
• 23.8 GHz Blackbody signal(bb23)
• (tknd)
• Noise injection temp at nominal temperature at 23.8 GHz(tnd_nom23)
• Noise injection temp at nominal temperature at 31.4 GHz(tnd_nom31)
• Sky brightness temperature at 31.4 GHz(tbsky31)
• Blackbody kinetic temperature(tkbb)
• 23.8 GHz sky signal(sky23)
• Averaged total liquid water along LOS path(liq)
• Sky brightness temperature at 23.8 GHz(tbsky23)
• Temperature correction coefficient at 31.4 GHz(tc31)
• 31.4 GHz blac2body+noise injection signal(bbn31)
• 31.4 GHz sky signal(sky31)
• Noise injection temp at 23.8 GHz adjusted to tkbb(tnd23)
• 31.4 GHz blackbody(bb31)

• 31.4 GHz blac2body+noise injection signal(bbn31)
• Mixer kinetic (physical) temperature(tkxc)
• Noise injection temp at 31.4 GHz adjusted to tkbb(tnd31)
• 31.4 GHz blackbody(bb31)
• Noise injection temp at 23.8 GHz adjusted to tkbb(tnd23)
• 31.4 GHz goodness-of-fit coefficient(r31)
• 31.4 GHz sky signal(tipsky31)
• 31.4 GHz sky brightness temperature derived from tip curve(tbsky31tip)
• 23.8 GHz goodness-of-fit coefficient(r23)
• 23.8 GHz blackbody+noise injection signal(bbn23)
• Total water vapor along zenith path using tip-derived brightness temperatures(vaptip)
• Noise injection temp at nominal temperature at 31.4 GHz(tnd_nom31)
• Temperature correction coefficient at 31.4 GHz(tc31)
• Noise injection temp at nominal temperature at 23.8 GHz(tnd_nom23)
• 23.8 GHz Blackbody signal(bb23)
• 23.8 GHz sky brightness temperature derived from tip curve(tbsky23tip)
• 23.8 GHz sky signal(tipsky23)
• Total liquid water along zenith path using tip-derived brightness temperatures(liqtip)
• Temperature correction coefficient at 23.8 GHz(tc23)
• Blackbody kinetic temperature(tkbb)
• (tknd)

NIM/MWR/M1 - Sun in field of view of radiometer

Around 12 pm every day between 8/1 and 8/31 there is an increase in the brightness 
temperature due to the sun being in the field of view of the radiometer.

• Averaged total liquid water along LOS path(liq)
• Sky brightness temperature at 23.8 GHz(tbsky23)
• MWR column precipitable water vapor(vap)
• Sky brightness temperature at 31.4 GHz(tbsky31)

NIM/MWRP/M1 - Sun in radiometer's field of view

Around noon local time every day there is a spike in the brightness temperature data. This 
is due to the sun being in the field of view of the radiometer. PWV and LWP are affected 
as a consequence

• Expected root-mean-square error in precipitable water retrieval(totalPrecipitableWaterRmsError)
• Expected root-mean-square error in liquid water path retrieval(liquidWaterPathRmsError)
• Retrieved liquid water path using only 23.835 and 30.0 GHz(liquidWaterPath2)
• Expected root-mean-square error in liquid water content retrieval(liquidWaterContentRmsError)
• Zenith-pointing infrared temperature at 10um(infraredTemperature)
• Retrieved liquid water path(liquidWaterPath)
• Expected root-mean-square error in liquid water path retrieval using only 23.835
  and 30.0 GHz(liquidWaterPath2RmsError)
• Retrieved total precipitable water vapor using only 23.835 and 30.0 GHz(totalPrecipitableWater2)
• Microwave brightness temperature(brightnessTemperature)
• Retrieved cloud liquid water content(liquidWaterContent)
• Expected root-mean-square error in precipitable water retrieval using only
  23.835 and 30.0 GHz(totalPrecipitableWater2RmsError)
• Total precipitable water vapor, from microwave radiometer(totalPrecipitableWater)

NIM/MWRP/M1 - IRTs do not agree with AERI

Since deployment at PYE, and then at NIM, the AMF SKYRAD IRT measured about 10K higher sky 
temperatures than the AERI and the MWRP IRT measured about 20K higher than the AERI.  
Several actions were taken to diagnose the problem including confirming the correct 
configuration of the IRTs and data logger, cleaning the mirror and lens, and replacing the mirror.

After several days of rain beginning 6/2/2006, the three instruments came into agreement. 
The cause of the discrepancy was probably dust accumulation on the lens of the instrument

• Zenith-pointing infrared temperature at 10um(infraredTemperature)

NIM/TSI/M1 - Shadowband glare

When the neutral density filter was removed from the lens, the reflection of the sun from 
the smooth shadowband strip became much brighter causing a glare in the image on clear 
days. To minimize this reflection, a rough surface (the "fuzzy" side of an adhesive velco 
strip) was placed along the length of the shadowband.

• Relative \'strength\' of direct sun(sun.strength)
• Pixel count: number total in sun circle(region.sun.count)
• Sunshine meter(sunny)

NIM/MWRP/M1 - Reprocessed: K-band calibration drift corrected

During October and November there was a drift in the K-Band calibration of the MWRP. This 
resulted in brightness temperatures that were too high.

New calibration coefficients were derived from the median value of the noise diode 
temperature for the months of October and November and the data were reprocessed to apply the 
corrected calibrations.  The reprocessed data were archived in January 2007.

• Retrieved liquid water path using only 23.835 and 30.0 GHz(liquidWaterPath2)
• Retrieved liquid water path(liquidWaterPath)
• Retrieved total precipitable water vapor using only 23.835 and 30.0 GHz(totalPrecipitableWater2)
• Microwave brightness temperature(brightnessTemperature)
• Retrieved cloud liquid water content(liquidWaterContent)
• Total precipitable water vapor, from microwave radiometer(totalPrecipitableWater)