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.

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

• Water vapor, total precipitable, derived from Tbright using stat. retrvl.(totalPrecipitableWater)
• Density, water vapor, prof. from sfc.-10 km, der. from Tbright stat. retrvl.(waterVaporDensity)
• Liquid water path, from Tbright at 23.835 and 30.0 GHz only, using stat. retrvl.(liquidWaterPath2)
• Microwave brightness temperature(brightnessTemperature)
• Retrieved dewpoint temperature(dewpointTemperature)
• Humidity, relative, prof. from sfc.-10km, from water vap. dens. and temp. prof.(relativeHumidity)
• Liquid water path, from brightness temperatures using statistical retrieval(liquidWaterPath)
• Liquid water content, cloud, vert. prof. sfc.-10km, from Tbright stat. retrvl.(liquidWaterContent)
• Temperature, virtual, vert. prof. sfc-10km, fr. wtr. vap. dens. and temp. prof.(virtualTemperature)
• Water vapor, tot. precipitable, from Tbright, 23.835 & 30.0 GHz, stat. retrvl.(totalPrecipitableWater2)
• Air temperature(temperature)
• Retrieved water vapor mixing ratio(waterVaporMixingRatio)

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

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.

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

• infraredTemperature

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

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.

• Water vapor, total precipitable, derived from Tbright using stat. retrvl.(totalPrecipitableWater)
• liquidWaterPathRmsError
• liquidWaterPath2RmsError
• waterVaporDensityRmsError
• totalPrecipitableWater2RmsError
• temperatureRmsError
• Density, water vapor, prof. from sfc.-10 km, der. from Tbright stat. retrvl.(waterVaporDensity)
• Liquid water path, from Tbright at 23.835 and 30.0 GHz only, using stat. retrvl.(liquidWaterPath2)
• liquidWaterContentRmsError
• Retrieved dewpoint temperature(dewpointTemperature)
• totalPrecipitableWaterRmsError
• Humidity, relative, prof. from sfc.-10km, from water vap. dens. and temp. prof.(relativeHumidity)
• Liquid water path, from brightness temperatures using statistical retrieval(liquidWaterPath)
• Liquid water content, cloud, vert. prof. sfc.-10km, from Tbright stat. retrvl.(liquidWaterContent)
• Temperature, virtual, vert. prof. sfc-10km, fr. wtr. vap. dens. and temp. prof.(virtualTemperature)
• Height, cloud base, height where IR temp. matches retrieved temp. profile(cloudBaseHeight)
• Water vapor, tot. precipitable, from Tbright, 23.835 & 30.0 GHz, stat. retrvl.(totalPrecipitableWater2)
• Air temperature(temperature)
• Retrieved water vapor mixing ratio(waterVaporMixingRatio)

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/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

• infraredTemperature