NSA/METTWR/C1 - CMH Data Not Representative

The intake of the CMH was blocked with hoar frost.  The temperatures measured by the 
chilled mirror and the temperature probe were not representative of the ambient conditions as 
a result.  The RH data calculated from these values is incorrect also.

• Chilled Mirror Calculated Vapor Pressure(VPCMH)
• Chilled Mirror Calculated Relative Humidity(CMHRH)
• Chilled Mirror Dew Point(CMHDP)
• Chilled Mirror Temperature(CMHTemp)
• Chilled Mirror Calculated Saturation Vapor Pressure(SatVPCMH)

NSA/METTWR/C1 - CMH Data missing

CMH dew point and temp data was missing. Since Dew Point and Temp data missing RH% value = 
100% during outage.  Corrosion on power plug was athe problem.

• Chilled Mirror Calculated Vapor Pressure(VPCMH)
• Chilled Mirror Calculated Relative Humidity(CMHRH)
• Chilled Mirror Dew Point(CMHDP)
• Chilled Mirror Temperature(CMHTemp)
• Chilled Mirror Calculated Saturation Vapor Pressure(SatVPCMH)

NSA/METTWR/C1 - Ultrasonic Wind Sensor Values Incorrect

The values collected from the ultrasonic wind sensor were intermittently incorrect.  Heavy 
wet snow during blizzard condition was interfering with the ultrasonic readings.

• Sonic Arithmetic Mean Wind Speed(SonicWS_S_WVT)
• Sonic Vector Averaged Wind Direction(SonicWD_DU_WVT)
• Average Y Component of Sonic Wind Speed(SonicY_AVG)
• Standard Deviation of Sonic Vector Averaged Wind Direction(SonicWD_SDU_WVT)
• Average Sonic Static Speed of Sound(SonicS_AVG)
• Sonic Vector Averaged Wind Speed(SonicWS_U_WVT)
• Average X Component of Sonic Wind Speed(SonicX_AVG)

NSA/METTWR/C1 - PWS data missing due to blizzard

PWS was offline and data was missing.  A blizzard consisting of heavy wet snow and strong 
winds caused snow impaction in the optics.  The PWS reported missing data as it was 
unable to measure anything meaningful.

• 15 minute Present Weather Code(PwCod15mi)
• 1 minute Average Visibility(AvgVis1mi)
• Instant Present Weather Code(InstPwCod)
• 1 hour Present Weather Code(PwCod1hr)
• Cumulative Snow Sum(CumSnow)
• 10 minute Average Visibility(AvgVis10m)
• Precipitation Rate(PcpRate)
• Present Weather Sensor Alarm(PWSAlarm)

NSA/METTWR/C1 - 2m Wind Speed Artificially Low

The 2m wind speed values were artificially low due to snow impaction during a heavy 
blizzard.  The cup anemometer heaters could not keep up with the rapid deposition of snow.

• 2m Vector Averaged Wind Speed(WS2M_U_WVT)
• 2m Arithmetic Mean Wind Speed(WS2M_S_WVT)

NSA/METTWR/C1 - CMH temp inaccurate

The CMH Temperature was consistently 4-7 degrees warmer than the 2M, 40M, 20M, and 10M 
temp. Intake fan failure; fan was replaced.

• Chilled Mirror Calculated Vapor Pressure(VPCMH)
• Chilled Mirror Calculated Relative Humidity(CMHRH)
• Chilled Mirror Dew Point(CMHDP)
• Chilled Mirror Temperature(CMHTemp)
• Chilled Mirror Calculated Saturation Vapor Pressure(SatVPCMH)

NSA/METTWR/C1 - 10m Wind Speed Low

The 10m wind speed values are too low due to ice accumulation on the cup anemometer.

• 10m Arithmetic Mean Wind Speed(WS10M_S_WVT)
• 10m Vector Averaged Wind Speed(WS10M_U_WVT)

NSA/METTWR/C1 - 10m Wind Speed Intermittently Low

The 10m wind speeds are intermittently too low due to ice accumulation on the cup 
anemometer.

• 10m Arithmetic Mean Wind Speed(WS10M_S_WVT)
• 10m Vector Averaged Wind Speed(WS10M_U_WVT)

NSA/METTWR/C1 - 40m Wind Speeds Intermittently Low

The 40m wind speed values were too low due to ice accumulation on the cup anemometer.

• 40m Vector Averaged Wind Speed(WS40M_U_WVT)
• 40m Arithmetic Mean Wind Speed(WS40M_S_WVT)

NSA/METTWR/C1 - 20m Wind Speeds Intermittently Low

The 20m wind speeds were artificially low due to ice accumulation on the cup anemometer.

• 20m Vector Averaged Wind Speed(WS20M_U_WVT)
• 20m Arithmetic Mean Wind Speed(WS20M_S_WVT)

NSA/METTWR/C1 - CMH Data Missing

CMH data was missing due to it being removed for maintenance.

• Chilled Mirror Calculated Vapor Pressure(VPCMH)
• Chilled Mirror Calculated Relative Humidity(CMHRH)
• Chilled Mirror Dew Point(CMHDP)
• Chilled Mirror Temperature(CMHTemp)
• Chilled Mirror Calculated Saturation Vapor Pressure(SatVPCMH)

NSA/METTWR/C1 - CMH Data Suspect

CMH data was suspect due to incorrect calibration caused by procedural errors.  The 
procedures were corrected and a new calibration completed.

• Chilled Mirror Calculated Vapor Pressure(VPCMH)
• Chilled Mirror Calculated Relative Humidity(CMHRH)
• Chilled Mirror Dew Point(CMHDP)
• Chilled Mirror Temperature(CMHTemp)
• Chilled Mirror Calculated Saturation Vapor Pressure(SatVPCMH)

NSA/METTWR/C1 - Wind direction measurements suspect

20m wind direction standard deviation was 0 degrees for extended periods of time.  This 
suggests the wind vane was icing up.

• 20m Vector Averaged Wind Direction(WD20M_DU_WVT)
• Standard Deviation of 20m Vector Averaged Wind Direction(WD20M_SDU_WVT)

NSA/MWR/C1 - TKAIR sensor failure

Between 7/14 and 7/28 the tkair variable is missing most of the time and sometimes has 
large negative spikes.  On 7/28, the sensor was cleaned of corrosion and the readings came 
back to normal.

• Ambient temperature(tkair)

NSA/SONDE/C1 - Noisy/Unstable RH and dew point data

The RH readings during the first 8 minutes of this sounding include three apparently 
incorrect oscillations to near-zero values.  After checking the absolutely raw data, it seems 
as though this period was excessively noisy, resulting in many missing values.  The noise 
abatted and the remaining sounding values are valid.

• Relative humidity inside the instrument enclosure(rh)
• Surface dew point temperature(dp)

NSA/SONDE/C1 - Bad surface RH and temperature values

This is a subtle problem that might escape notice.  For the identified sonde launches, the 
ground station lost its signal between the time it was removed from the ground check set 
and the time it was launched.  As a result, the software, which automatically determines 
the launch time and surface conditions at time of launch mistakenly used values of 
temperature and RH representative of the ground check set and the GW rather than of the 
ambient conditions before launch.  The bad values influenced only the first few samples and the 
remainder of the sounding values are correct.  

A procedural problem was identified and corrected.

• Relative humidity inside the instrument enclosure(rh)
• Dry bulb temperature(tdry)
• Surface dew point temperature(dp)

NSA/METTWR/C1 - Reprocess: Barometric Data Changed from hPa to kPa

Barometric pressure data was converted from hPa to kPa in order to standardize the 
measurement units among ARM sites and to conform to accepted standard units determined by the 
scientific community.

• Atmospheric Pressure(AtmPress)

NSA/METTWR/C1 - Present Weather Sensor data missing or incorrect due to calibration.

The Present Weather Sensor data was missing or incorrect due to calibration checks.

• 15 minute Present Weather Code(PwCod15mi)
• 1 minute Average Visibility(AvgVis1mi)
• Instant Present Weather Code(InstPwCod)
• 1 hour Present Weather Code(PwCod1hr)
• Cumulative Snow Sum(CumSnow)
• 10 minute Average Visibility(AvgVis10m)
• Precipitation Rate(PcpRate)
• Cumulative Water Sum(CumH2O)
• Present Weather Sensor Alarm(PWSAlarm)

NSA/SONDE/C1 - RH values offset due to error in ground check

Background: After installation of the latest software update , we began performing formal 
ground checks on RS92 radiosondes.  By comparing the radiosonde readings with reference 
values in a controlled environment, the ground check is intended to ensure that the 
radiosonde sensors are in calibration before launch.  The radisonde values during the ground 
check process are recorded automatically; the reference values are entered by the operator. 
 If the radiosonde readings vary from the reference values, the system 'corrects' the 
radiosonde values.  In the case of RH, the correction is applied as an offset (true RH = 
indicated RH + correction).

Problem: Some operators misunderstood the ground-check procedure and entered the 
radiosonde values of RH rather than the reference value (assumed 0%RH), thus, some soundings done 
during this period have RH values that are different from what they would be if the 
ground check procedure had been done correctly.

Consequence:  Because the RH corrections generally are small (averaging about 0.5% RH) and 
the precision of the reported RH data during this time period is 1% RH, some values will 
not be affected at all; others will be off by about 1% RH (still within the stated 
accuracy of the sensor).  Furthermore, because entering the radiosonde value as the reference 
value results in a near zero 'correction,' one may view these soundings as being done 
without the ground check correction.  Also note that the dew point value will be suspect as well.

I am attaching below a listing of the soundings that were affected during the indicated 
time period.  Users can see the magnitude of the problem and choose whether or not to apply 
an offset in RH.  Note that application of the offset to the processed RH data (in the 
netCDF file) will not have the same effect of applying the correction to the absolutely 
raw data (before processing), but the differences should be insignificant.  Also note that 
the corrections for each sounding are included in the netCDF header information.  These 
attributes are named 'humidity_correction' and 'humidity_correction_2'.  The values of RH 
indicated by the radiosonde while it is in the ground check set are in attributes 
'humidity_gc_sonde' and 'humidity_gc_sonde_2.'  There is an RH reading for each of the two RH 
sensors used in the RS92 radiosonde.

Here is the list - RH1 and RH2 are the radiosonde readings in the ground check set.  Ref 
is the reference value entered by the operator.  The correcte reference value should be 
0%.  To obtain an approximation to the RH value that would have been recorded if the ground 
check had been done properly, subtract the Ref value from the indicated RH.

 YYYYMMDD  HHMM  SerialNo     RH1     RH2     Ref
 20060713  0532  B1924431    0.30    0.20    0.30
 20060713  1751  B1854963    0.20    0.30    0.30
 20060714  0521  B1924425    0.40    0.40    0.40
 20060714  1739  B1854206    0.30    0.30    0.30
 20060715  0522  B1715127    1.20    1.20    1.20
 20060715  1737  B1854966    0.60    0.60    0.60
 20060716  0508  B1715126    0.40    0.40    0.40
 20060716  1732  B1844098    0.50    0.50    0.50
 20060717  0517  B1914170    0.40    0.40    0.40
 20060718  0516  B1914173    0.70    0.70    0.70
 20060720  0523  B1854149    0.40    0.40    0.40
 20060721  0517  B1914153    0.40    0.40    0.40
 20060722  0521  B1844097    1.00    1.10    1.10
 20060722  1730  B1914174    0.60    0.70    0.70
 20060723  0537  B1714439    0.40    0.40    0.40
 20060723  1734  B1734155    0.50    0.50    0.50
 20060724  0529  B1134336    0.50    0.50    0.50
 20060725  0525  B1754099    0.60    0.70    0.70
 20060726  0541  B1844108    1.80    1.80    1.80
 20060727  0520  B1714382    0.70    0.80    0.70
 20060728  0531  B1854116    0.80    0.80    0.80
 20060729  0527  B1724027    1.00    1.00    1.00
 20060729  1726  B1714392    0.70    0.80    0.80
 20060730  0522  B1854100    0.70    0.80    0.80
 20060730  1724  B1854764    0.90    1.00    1.00
 20060731  0515  B1664086    0.90    0.80    0.90
 20060801  0520  B1724758    1.50    1.50    1.50
 20060801  1729  B1754116    1.10    1.10    1.10
 20060802  0518  B1724516    0.80    0.80    0.80
 20060803  0523  B1674148    0.80    0.80    0.80
 20060804  0532  B1754092    0.90    0.90    0.90
 20060804  1727  B1844117    3.50    3.50    3.50
 20060805  0531  B1714741    0.30    0.30    0.30
 20060805  1728  B1754098    0.30    0.30    0.30
 20060806  0528  B1844115    0.40    0.40    0.40
 20060806  1728  B1914161    0.20    0.20    0.20
 20060807  0530  B1714549    0.30    0.30    0.30
 20060808  0517  B1844107    0.50    0.50    0.50
 20060808  1744  B1914166    0.20    0.20    0.20
 20060809  0527  B1914164    0.30    0.40    0.40
 20060809  1736  B1914163    0.30    0.30    0.30
 20060810  0521  B1914160    0.40    0.50    0.50
 20060810  1745  B1744671    0.40    0.40    0.40
 20060811  0525  B1854965    0.50    0.50    0.50
 20060811  1753  B1724131    0.10    0.10    0.10
 20060812  0527  B1754104    0.50    0.50    0.50
 20060812  1740  B1854256    0.30    0.40    0.40
 20060813  0522  B1854240    0.30    0.40    0.40
 20060814  0525  B1714106    0.20    0.20    0.20
 20060814  1742  B1854106    0.40    0.40    0.40
 20060815  0534  B1914169    0.50    0.60    0.60
 20060815  1734  B1854233    0.60    0.70    0.70
 20060816  0539  B1724791    0.20    0.20    0.20
 20060816  1732  B1914171    0.10    0.20    0.20
 20060817  0535  B1354283    0.10    0.10    0.10
 20060817  1740  B1354574    0.40    0.40    0.40
 20060818  0516  B1354633    0.50    0.40    0.50
 20060818  1744  B1364673    0.20    0.20    0.20
 20060819  0538  B1364126    0.20    0.30    0.30
 20060819  1745  B1354598    0.50    0.60    0.60
 20060820  0532  B1354290    1.10    1.10    1.10
 20060820  1729  B1354317    0.40    0.40    0.40
 20060821  0530  B1354545    0.60    0.70    0.70
 20060821  1728  B1354516    0.70    0.70    0.70
 20060822  0524  B1354619    0.50    0.60    0.60
 20060822  1728  B1364377    0.40    0.40    0.40
 20060823  0533  B1354309    0.30    0.30    0.30
 20060823  1730  B1354527    0.70    0.70    0.70
 20060824  0533  B1354230    0.60    0.60    0.60
 20060824  1812  B1354587    0.70    0.70    0.70
 20060825  0517  B1354614    0.70    0.70    0.70
 20060825  1730  B1354630    0.60    0.60    0.60
 20060826  0537  B1334114    0.90    0.90    0.90
 20060826  1734  B1354246    0.70    0.70    0.70
 20060827  0508  B1354534    0.70    0.70    0.70
 20060827  1729  B1354618    0.60    0.60    0.60
 20060828  0517  B1354115    0.40    0.40    0.40
 20060828  1738  B1354206    0.50    0.60    0.60
 20060829  0516  B1354617    0.50    0.60    0.60
 20060829  1717  B1354622    0.50    0.60    0.60
 20060830  0511  B1354314    0.40    0.50    0.50
 20060830  1732  B1354537    0.60    0.70    0.70
 20060831  1802  B1354239    0.60    0.80    0.80
 20060905  1724  B1354626    0.60    0.60    0.60
 20060906  0522  B1354525    0.60    0.80    0.80
 20060906  1734  B1354107    0.50    0.50    0.50
 20060907  0537  B1354543    0.70    0.70    0.70
 20060907  1803  B1354586    0.80    0.80    0.80
 20060908  0531  B1354519    0.60    0.60    0.60
 20060908  1728  B1354224    0.60    0.60    0.60
 20060909  0534  B1354532    0.70    0.80    0.80
 20060909  1732  B1354513    0.80    0.90    0.90
 20060910  0516  B1354125    0.60    0.70    0.60
 20060910  1727  B1354110    0.40    0.50    0.50
 20060911  0528  B1354235    0.90    0.90    0.90
 20060911  1849  B1354514    0.70    0.70    0.70
 20060912  0525  B1354124    0.60    0.70    0.70
 20060913  0534  B1344478    0.50    0.50    0.50
 20060914  0520  B1354226    0.70    0.70    0.70
 20060915  0529  B1344459    0.40    0.50    0.50
 20060916  0532  B1344469    0.50    0.40    0.50
 20060916  1732  B1354106    0.50    0.60    0.60
 20060917  0527  B1354210    0.70    0.70    0.70
 20060918  0533  B1354087    0.60    0.60    0.60
 20060919  0526  B1354097    0.70    0.50    0.60
 20060920  0516  B1344462    0.50    0.40    0.50
 20060920  1810  B1354536    0.70    0.70    0.70
 20060921  0534  B1354112    0.50    0.60    0.60
 20060921  1800  B1344502    0.40    0.40    0.40
 20060922  0525  B1354531    0.70    0.80    0.80
 20060922  1736  B1354541    0.70    0.70    0.70
 20060923  0519  B1354101    0.50    0.60    0.60
 20060923  1738  B1354576    0.70    0.50    0.70
 20060924  0536  B1354095    0.60    0.60    0.60
 20060925  0536  B1354098    0.60    0.60    0.60
 20060925  1755  B1354100    0.50    0.50    0.50
 20060926  0531  B1334691    0.70    0.70    0.70
 20060926  1742  B1354108    0.40    0.50    0.50

• Relative humidity inside the instrument enclosure(rh)
• Surface dew point temperature(dp)

NSA/SONDE/C1 - Increased precision for alt, dp, pres, rh, tdry

The output precision of the following variables was increased 20060929:

   alt	changed from 1m to 0.1m
   dp	changed from 0.1degC to 0.01degC
   pres changed from 0.1 hPa to 0.01 hPa
   RH	changed from 1%RH to 0.01%RH
   tdry changed from .1degC to 0.01degC

Note that the increase in precision does not necessarily imply an increase
in accuracy.  Users are cautioned to continue to use their best scientific
judgement when using these or any other data.

• Relative humidity inside the instrument enclosure(rh)
• Dry bulb temperature(tdry)
• Dummy altitude for Zeb(alt)
• Retrieved pressure profile(pres)
• Surface dew point temperature(dp)

NSA/METTWR/C1 - All data from 10m Level Missing

The winch that lowers the tower booms failed.  Manual testing of the motor and winch 
allowed the booms to be lowered briefly and then raised back into position.  A heavy freezing 
rain/icing event added extra weight to the booms.  This extra weight was suspected as the 
cause as to why the 10m boom became disconnected.  After a new motor was installed and 
all booms were lowered and re-raised the 10m level came back on line.

• 10m Average Calculated Dew Point(DP10M_AVG)
• 10m Average QLI Reference Temperature(RefT10m_AVG)
• Standard Deviation of 10m Calculated Vapor Pressure(VP10M_STD)
• 10m Average Relative Humidity(RH10M_AVG)
• 10m Vector Averaged Wind Speed(WS10M_U_WVT)
• 10m Average Calculated Vapor Pressure(VP10M_AVG)
• 10m Average QLI Input Voltage(Volt10M_AVG)
• Standard Deviation of 10m Vector Averaged Wind Direction(WD10M_SDU_WVT)
• 10m Average Temperature(T10M_AVG)
• Standard Deviation of 10m Relative Humidity(RH10M_STD)
• 10m Arithmetic Mean Wind Speed(WS10M_S_WVT)
• 10m Vector Averaged Wind Direction(WD10M_DU_WVT)
• Standard Deviation of 10m Calculated Dew Point(DP10M_STD)
• Standard Deviation of 10m Temperature(T10M_STD)

NSA/SONDE/C1 - Incorrect surface values of T and RH

The radiosonde was launched too quickly after being removed from the ground check set.  As 
a result, the system did not equilibrate with the local ground conditions and the 
automatically entered surface values are incorrect.

• Relative humidity inside the instrument enclosure(rh)
• Dry bulb temperature(tdry)
• Surface dew point temperature(dp)

NSA/METTWR/C1 - Missing CMH data

CMH data are missing.  Corrosion in the serial data line connections caused a loss of 
communication with the CMH.

• Chilled Mirror Calculated Vapor Pressure(VPCMH)
• Chilled Mirror Calculated Relative Humidity(CMHRH)
• Chilled Mirror Dew Point(CMHDP)
• Chilled Mirror Temperature(CMHTemp)
• Chilled Mirror Calculated Saturation Vapor Pressure(SatVPCMH)

NSA/METTWR/C1 - 10m level loss of power

The 10 meter instrument level lost power so all variables from this level are missing.

• 10m Average Calculated Dew Point(DP10M_AVG)
• 10m Average QLI Reference Temperature(RefT10m_AVG)
• Standard Deviation of 10m Calculated Vapor Pressure(VP10M_STD)
• 10m Average Relative Humidity(RH10M_AVG)
• 10m Vector Averaged Wind Speed(WS10M_U_WVT)
• 10m Average Calculated Vapor Pressure(VP10M_AVG)
• 10m Average QLI Input Voltage(Volt10M_AVG)
• Standard Deviation of 10m Vector Averaged Wind Direction(WD10M_SDU_WVT)
• 10m Average Temperature(T10M_AVG)
• Standard Deviation of 10m Relative Humidity(RH10M_STD)
• 10m Arithmetic Mean Wind Speed(WS10M_S_WVT)
• 10m Vector Averaged Wind Direction(WD10M_DU_WVT)
• Standard Deviation of 10m Calculated Dew Point(DP10M_STD)
• Standard Deviation of 10m Temperature(T10M_STD)

NSA/METTWR/C1 - 2m T/RH probe aspirator fan failed

The aspirator fan for the 2m level T/RH probe failed.  This caused higher than normal 
readings for temp and RH and artificially smoothed the data.

• 2m Average Calculated Vapor Pressure(VP2M_AVG)
• Standard Deviation of 2m Calculated Dew Point(DP2M_STD)
• Standard Deviation of 2m Relative Humidity(RH2M_STD)
• 2m Average Relative Humidity(RH2M_AVG)
• Standard Deviation of 2m Calculated Vapor Pressure(VP2M_STD)
• 2m Average Temperature(T2M_AVG)
• Standard Deviation of 2m Temperature(T2M_STD)
• 2m Average Calculated Dew Point(DP2M_AVG)

NSA/MWR/C1 - Rain sensor always on

The rain sensor was always on between 10/5 and 10/23 2006.
The user should be aware that not all data flagged as rainy are actually rainy. The 
problem was caused by a shift in the sensitivity of the rain sensor and was corrected by 
changing the sensor threshold in the configuration file.

• Water on Teflon window (1=WET, 0=DRY)(wet_window)

• Water on Teflon window (1=WET, 0=DRY)(wet_window)

NSA/SONDE/C1 - RH sensor failure

It appears that one of the two RH sensors on this radiosonde was affected by ice after 
emerging from a low cold cloud.  As a result the reported RH values oscillate by about 10 
percent until the alternate heating cycle stops.  I suspect the lower value is more close 
to correct, but can't be absolutely sure.

• Relative humidity inside the instrument enclosure(rh)
• Surface dew point temperature(dp)

NSA/METTWR/C1 - Wind direction sensor frozen

After a power outage the 40m wind direction sensor was frozen.  Data from this sensor was 
not representative of the true winds.

• 40m Vector Averaged Wind Direction(WD40M_DU_WVT)
• Standard Deviation of 40m Vector Averaged Wind Direction(WD40M_SDU_WVT)

NSA/METTWR/C1 - CMH Sensor Calibrated Incorrectly

The CMH temp and DP were higher than the co-located T/RH probe at the 2m level.  An 
incorrect calibration along with a failing thermistor caused the readings to be incorrect for 
both measured values Temp and Dew Point.

• Chilled Mirror Calculated Vapor Pressure(VPCMH)
• Chilled Mirror Calculated Relative Humidity(CMHRH)
• Chilled Mirror Dew Point(CMHDP)
• Chilled Mirror Temperature(CMHTemp)

NSA/METTWR/C1 - 40m wind sensor heater failure

The 40m wind direction became frozen at times.  The values from the sensor were flat-lined 
(stdev = 0) much of the time and did not match sensors from other levels.

• 40m Vector Averaged Wind Direction(WD40M_DU_WVT)
• Standard Deviation of 40m Vector Averaged Wind Direction(WD40M_SDU_WVT)

NSA/SONDE/C1 - Incorrect surface RH value

For an unknown reason the surface RH was reported a 0%.  Becuase these values are entered 
automatically by the system, this is NOT likely an operator error.  Examination of the 
raw data shows that the surface RH at launch time was approximately 81.2 %RH.

• Relative humidity inside the instrument enclosure(rh)
• Surface dew point temperature(dp)

NSA/METTWR/C1 - 40m Wind Direction Data Suspect

The 40m wind direction data was suspect due to icing on the vane or a failing shafter 
heater or a combination of both.  The affected data can be easily seen on comparison plots 
with other levels data or by checking the standard deviation of the 40m wind direction.  
Any standard deviation of less than 0.10 degrees for the 40m level suggest a sluggish/ice 
affected sensor.

• 40m Vector Averaged Wind Direction(WD40M_DU_WVT)
• Standard Deviation of 40m Vector Averaged Wind Direction(WD40M_SDU_WVT)

NSA/METTWR/C1 - 20m RH Data Questionable

The 20m RH data was questionable at times.  When the data appeared to be poor was when the 
2m and 20m agreed better than the 20m and the 40m and/or 10m.

• Standard Deviation of 20m Calculated Dew Point(DP20M_STD)
• Standard Deviation of 20m Calculated Vapor Pressure(VP20M_STD)
• Standard Deviation of 20m Relative Humidity(RH20M_STD)
• 20m Average Relative Humidity(RH20M_AVG)
• 20m Average Calculated Vapor Pressure(VP20M_AVG)
• 20m Average Calculated Dew Point(DP20M_AVG)