SGP/SMOS/E13 - 6-month Calibration Checks

During the time periods specified, the SMOS.E13 tower was
lowered for 6-month Calibration Checks.  During these times 
wind data are incorrect and temperature and humidity data 
may be incorrect.

Note, exact times when tower was down or maintenance was
being performed is sometimes unknown.  Users should use
the remaining data from these days with caution.

• Minimum Vapor Pressure(min_vap_pres)
• Minimum Relative Humidity(min_rh)
• Time of Maximum Temperature(time_max_temp)
• Maximum Relative Humidity(max_rh)
• Time of Minimum Vapor Pressure(time_min_vap_pres)
• Minimum Temperature(min_temp)
• Maximum Temperature(max_temp)
• Time of Minimum Temperature(time_min_temp)
• Minimum Barometric Pressure(min_bar_pres)
• Time of Maximum Vapor Pressure(time_max_vap_pres)
• Maximum Vapor Pressure(max_vap_pres)
• Time of Minimum Wind Speed(time_min_wspd)
• Time of Maximum Wind Speed(time_max_wspd)
• Maximum Barometric Pressure(max_bar_pres)
• Time of Maximum Relative Humidity(time_max_rh)
• maximum wind speed (gusts)(max_wspd)
• Time of Minimum Relative Humidity(time_min_rh)
• Minimum of Wind speed(min_wspd)
• Time of Minimum Barometric Pressure(time_min_bar_pres)
• Time of Maximum Barometric Pressure(time_max_bar_pres)

• Vapor Pressure (kiloPascals)(vap_pres)
• Wind Speed (vector averaged)(wspd_va)
• Beam 0 Temperature(temp)
• Unit Vector Wind Direction(wdir)
• barometric pressure(bar_pres)
• Mean Wind Speed(wspd)
• Relative humidity inside the instrument enclosure(rh)
• Standard Deviation of wind direction(sd_deg)

• Relative humidity inside the instrument enclosure(rh)
• Standard Deviation of Relative Humidity(sd_rh)
• Beam 0 Temperature(temp)
• Standard Deviation of Barometric Pressure(sd_bar_pres)
• Standard Deviation of Air Temperature(sd_temp)
• Mean Wind Speed(wspd)
• Standard Deviation of Vapor Pressure(sd_vap_pres)
• Wind Speed (vector averaged)(wspd_va)
• Standard Deviation of Wind Speed(sd_wspd)
• Standard Deviation of wind direction(sd_deg)
• Vapor Pressure (kiloPascals)(vap_pres)
• Unit Vector Wind Direction(wdir)
• barometric pressure(bar_pres)

• barometric pressure(bar_pres)
• Vapor Pressure (kiloPascals)(vap_pres)
• Standard Deviation of Vapor Pressure(sd_vap_pres)
• Standard Deviation of Barometric Pressure(sd_bar_pres)
• Standard Deviation of Relative Humidity(sd_rh)
• Standard Deviation of wind direction(sd_deg)
• Standard Deviation of Air Temperature(sd_temp)
• Standard Deviation of Wind Speed(sd_wspd)
• Relative humidity inside the instrument enclosure(rh)
• Unit Vector Wind Direction(wdir)
• Beam 0 Temperature(temp)
• Mean Wind Speed(wspd)
• Wind Speed (vector averaged)(wspd_va)

• Mean Wind Speed(wspd)
• barometric pressure(bar_pres)
• Standard Deviation of wind direction(sd_deg)
• Vapor Pressure (kiloPascals)(vap_pres)
• Wind Speed (vector averaged)(wspd_va)
• Beam 0 Temperature(temp)
• Unit Vector Wind Direction(wdir)
• Relative humidity inside the instrument enclosure(rh)

SGP/TSI/C1 - Metadata errors

The latitude, longitude and altitude of the Total Sky Imager 
(TSI) were incorrectly entered into the ARM database.  The 
correct location of the SGP.C1 TSI is:
   Lat: 36.606N
   Lon: 97.485W
   Alt:    316m

• Dummy altitude for Zeb(alt)
• lon(lon)
• lat(lat)

• lon(lon)
• Dummy altitude for Zeb(alt)
• lat(lat)

SGP/SIRS/C1 - SWFANAL Data description error

The long name attribute for the cloud effect fields incorrectly
defines the cloud effect to be the difference between the 
clearskyfit and measured values:

"Difference: ***fluxdn_clearskyfit - ***fluxdn_measured (***fcg)" ;

The cloud effects are correctly calculated by subtracting the 
irradiance calculated in the clear sky fit from the measured 
irradiance.

"Difference: ***fluxdn_measured - ***fluxdn_clearskyfit (***fcg)" ;

NOTE: this is just a documentation error.  The data are correctly
calculated.

• Difference: difswfluxdn_measured - difswfluxdn_clearskyfit (diffcg)(difswfluxdn_cloudeffect)
• Difference: sswfluxdn_measured - sswfluxdn_clearskyfit (sswfcg)(sswfluxdn_cloudeffect)
• Difference: gswfluxdn_measured - gswfluxdn_clearskyfit (gswfcg)(gswfluxdn_cloudeffect)

• Difference: gswfluxdn_measured - gswfluxdn_clearskyfit (gswfcg)(gswfluxdn_cloudeffect)
• Difference: sswfluxdn_measured - sswfluxdn_clearskyfit (sswfcg)(sswfluxdn_cloudeffect)
• Difference: difswfluxdn_measured - difswfluxdn_clearskyfit (diffcg)(difswfluxdn_cloudeffect)

SGP/BRS/C1 - SWFANAL Data description error

The long name attribute for the cloud effect fields incorrectly
defines the cloud effect to be the difference between the 
clearskyfit and measured values:
   
"Difference: ***fluxdn_clearskyfit - ***fluxdn_measured (***fcg)" ;
   
The cloud effects are correctly calculated by subtracting the
irradiance calculated in the clear sky fit from the measured 
irradiance.
   
"Difference: ***fluxdn_measured - ***fluxdn_clearskyfit (***fcg)" ;
   
NOTE: this is just a documentation error.  The data are correctly
calculated.

• Difference: sswfluxdn_measured - sswfluxdn_clearskyfit (sswfcg)(sswfluxdn_cloudeffect)
• Difference: difswfluxdn_measured - difswfluxdn_clearskyfit (diffcg)(difswfluxdn_cloudeffect)
• Difference: gswfluxdn_measured - gswfluxdn_clearskyfit (gswfcg)(gswfluxdn_cloudeffect)

• Difference: sswfluxdn_measured - sswfluxdn_clearskyfit (sswfcg)(sswfluxdn_cloudeffect)
• Difference: difswfluxdn_measured - difswfluxdn_clearskyfit (diffcg)(difswfluxdn_cloudeffect)
• Difference: gswfluxdn_measured - gswfluxdn_clearskyfit (gswfcg)(gswfluxdn_cloudeffect)

SGP/MWR/C1 - REPROCESS - Revised Retrieval Coefficients

IN THE BEGINNING (June 1992), the retrieval coefficients used to derive the precipitable 
water vapor (PWV) and liquid water path (LWP) from the MWR brightness temperatures were 
based on the Liebe and Layton (1987) water vapor and oxygen absorption model and the Grant 
(1957) liquid water absorption model.  

Following the SHEBA experience, revised retrievals based on the more recent Rosenkranz 
(1998) water vapor and oxygen absorption models and the Liebe (1991) liquid waer absorption 
model were developed.  The Rosenkranz water vapor absorption model resulted a 2 percent 
increase in PWV relative to the earlier Liebe and Layton model.  The Liebe liquid water 
absorption model decreased the LWP by 10% relative to the Grant model.  However, the 
increased oxygen absorption caused a 0.02-0.03 mm (20-30 g/m2) reduction in LWP, which was 
particularly significant for low LWP conditions (i.e. thin clouds encountered at SHEBA).

Recently, it has been shown (Liljegren, Boukabara, Cady-Pereira, and Clough, TGARS v. 43, 
pp 1102-1108, 2005) that the half-width of the 22 GHz water vapor line from the HITRAN 
compilation, which is 5 percent smaller than the Liebe and Dillon (1969) half-width used in 
Rosenkranz (1998), provided a better fit to the microwave brightness temperature 
measurements at 5 frequencies in the range 22-30 GHz, and yielded more accurate retrievals.  
Accordingly, revised MWR retrieval coefficients have been developed using MONORTM, which 
utilizes the HITRAN compilation for its spectroscopic parameters.  These new retrievals 
provide 3 percent less PWV and 2.6 percent greater LWP than the previous retrievals based on 
Rosenkranz (1998).

Although the MWR data will be reprocessed to apply the new monortm-based retrievals, for 
most purposes it will be sufficient to correct the data using the following factors:

PWV_MONORTM = 0.9695 * PWV_ROSENKRANZ
LWP_MONORTM = 1.026  * LWP_ROSENKRANZ

The Rosenkranz-based retrieval coefficients became active as follows (BCR 456):
SGP/C1 (Lamont)     4/16/2002, 2000
SGP/B1 (Hillsboro)  4/12/2002, 1600
SGP/B4 (Vici)       4/15/2002, 2300
SGP/B5 (Morris)     4/15/2002, 2300
SGP/B6 (Purcell)    4/16/2002, 2200
SGP/E14(Lamont)     4/16/2002, 0000
NSA/C1 (Barrow)     4/25/2002, 1900 
NSA/C2 (Atqasuk)    4/18/2002, 1700
TWP/C1 (Manus)      5/04/2002, 0200
TWP/C2 (Nauru)      4/27/2002, 0600
TWP/C3 (Darwin)     inception

The MONORTM-based retrieval coefficients became active as follows (BCR 984):

SGP/C1 (Lamont)     6/28/2005, 2300
SGP/B1 (Hillsboro)  6/24/2005, 2100
SGP/B4 (Vici)       6/24/2005, 2100
SGP/B5 (Morris)     6/24/2005, 2100
SGP/B6 (Purcell)    6/24/2005, 1942
SGP/E14(Lamont)     6/28/2005, 2300
NSA/C1 (Barrow)     6/29/2005, 0000 
NSA/C2 (Atqasuk)    6/29/2005, 0000
TWP/C1 (Manus)      6/30/2005, 2100
TWP/C2 (Nauru)      6/30/2005, 2100
TWP/C3 (Darwin)     6/30/2005, 2100
PYE/M1 (Pt. Reyes)  4/08/2005, 1900**

** At Pt. Reyes, the original retrieval coefficients implemented in March 2005 were based 
on a version of the Rosenkranz model that had been modified to use the HITRAN half-width 
at 22 GHz and to be consistent with the water vapor continuum in MONORTM.  These 
retrievals yield nearly identical results to the MONORTM retrievals.  Therefore the Pt. Reyes 
data prior to 4/08/2005 may not require reprocessing.

• Averaged total liquid water along LOS path(liq)
• MWR column precipitable water vapor(vap)

• Total liquid water along zenith path using tip-derived brightness temperatures(liqtip)
• Total water vapor along zenith path using tip-derived brightness temperatures(vaptip)

• Ensemble average for MWR liquid in window centered about balloon release(mean_liq_mwr)
• Ensemble average for MWR vapor in window centered about balloon release(mean_vap_mwr)

• MWR column precipitable water vapor(vap)
• Averaged total liquid water along LOS path(liq)

• MWR column precipitable water vapor(vap)
• Averaged total liquid water along LOS path(liq)

• MWR column precipitable water vapor(vap)
• Averaged total liquid water along LOS path(liq)