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					             An Analysis of the Results
               of Direct sun Dobson
                   Observations.
             20 March to 14 April 2006
8-11 Nov 06, Tenerife Spain   SAUNA Data Workshop   1
     R.D. Evans1, B. Haβler4, U. Köhler4, D.Quincy2
             S.J.Oltmans1, B.M. Walsh1,3
   1NOAA/ESRL                  Global Monitoring Division, 325 Broadway,
                              R/GMD-1, Boulder, CO 80305;
       2Cooperative        Institute for Research in Environmental
                                    Sciences,
                     University of Colorado, Boulder 80309
     3   Currently: York University, Toronto, Canada M3J 1P3
     4Deutscher         Wetterdienst - Meteorological Observatory
                      Hohenpeissenberg (DWD), Germany



8-11 Nov 06, Tenerife Spain           SAUNA Data Workshop              2
                 Operations at the FMI
• Operators were experienced and dedicated.
• Instruments were stored inside, and moved outside for use –
  experiencing large temperature changes.
• Instruments were operated at much lower temperatures than
  normal.
• Calibration and optical checks were made daily or every other day
  with reference lamps and mercury discharge lamps.
• D065 experienced some mechanical failures due to cold. After the
  campaign, the instruments were shipped to Hohenpeiβenberg.
  There, a loose retainer ring on the right side mirror was discovered
  when the wavelength (mercury) calibration tests were difficult to
  repeat. At FMI, no such problem existed, and there is no indication
  in the data that the ring was loose.




8-11 Nov 06, Tenerife Spain   SAUNA Data Workshop                        3
                              The Crew




8-11 Nov 06, Tenerife Spain    SAUNA Data Workshop   4
                                 Cold….




8-11 Nov 06, Tenerife Spain   SAUNA Data Workshop   5
•    The observations made during SAUNA were the type used for intercomparisons.
•    The first reading is with the wavelength selectors set for the C-wavelength, then
     for the D-wavelength, and then the A-wavelength.
•    The R-dial position is recorded for the C-wavelength at the first minute, the
     position for the D-wavelength at the next minute, and the position for the A-
     wavelength at the next minute after the D-wavelength.
•    This allows three wavelength measurements to be made in a short time period,
     and also to make coordinated measurements when desired.



Equations for
                                           ( NA         ND
Reduction of CDA
                                                    A     D )           p (mA  mD )
sequence observations.            X AD                          0.007 *
The results are                                      1.432                p0 ( A   D )
multiplied by 1000 to
convert to Dobson
                                               NC
                                                        ND
units.
                                           (
                                                    C     D )          p (mC  mD )
                                  X CD                          0.011*
                                                     0.459               p ( C   D )
                                                                            0


    8-11 Nov 06, Tenerife Spain      SAUNA Data Workshop                                 6
    Station Location Parameters Used
          for Dobson Calculations
•     Lat: 67.3600N Long: -026.6300E Dec. Deg
•     Ozone at 18000. meters (h).
•     Station Elevation (r) : 197.0 meters.
•     Mean Station Pressure (p) 1000.00 millibars.
•     Station Earth Radius (R) 6360116.0 meters.


                    
                                        R  h 
                              R  h  R  r  sin 2 (SZA)
                                     2          2




8-11 Nov 06, Tenerife Spain         SAUNA Data Workshop        7
8-11 Nov 06, Tenerife Spain   SAUNA Data Workshop   8
8-11 Nov 06, Tenerife Spain   SAUNA Data Workshop   9
8-11 Nov 06, Tenerife Spain   SAUNA Data Workshop   10
                         Other information
• The daily balloon flights give the ozone and
  temperature profiles. The correct ozone
  absorption coefficient can be found using the
  actual effective temperature of the ozone layer.
• New derivations of the Dobson ozone
  coefficients are consistently different from the
  official 1992 values. AD:1.428, CD:0.455
  (Germar Bernhard, Bass and Paur) Vs
  AD:1.432, CD:0.459
   With this information, the Dobson data can be
     reprocessed, and averages re-evaluated.

8-11 Nov 06, Tenerife Spain   SAUNA Data Workshop   11
8-11 Nov 06, Tenerife Spain   SAUNA Data Workshop   12
              Examining one long day in the
                  cold – 05 April 2006


8-11 Nov 06, Tenerife Spain   SAUNA Data Workshop   13
8-11 Nov 06, Tenerife Spain   SAUNA Data Workshop   14
  Now for the Dobson data, analyze by
  • applying the Germar derived absorption coefficients.
  • adjusting to the correct stratosphere temperature.

For the Brewer
data, recalculate
the total ozone,
considering the
correct height of the
ozone layer. The
Brewer data
reduction algorithm
uses 22KM for all
locations The
average height
during SAUNA was
18km.
 8-11 Nov 06, Tenerife Spain   SAUNA Data Workshop         15
8-11 Nov 06, Tenerife Spain   SAUNA Data Workshop   16
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            How representative is the
               SAUNA Data Set?
• If this data set is reported as part of the
  WOUDC archive, similar to other
  stations, how would it look?
• There are nearby stations with both
  Dobson and Brewer instruments.
• Vindeln, Sweden is reporting; Tromsø,
  Norway is not.


8-11 Nov 06, Tenerife Spain   SAUNA Data Workshop   19
           Near-By Ground Stations
            Tromsø,
            Dobson/Brewer,
            not reporting.




                                                Vindeln,
                                                Dobson/Brewer




8-11 Nov 06, Tenerife Spain   SAUNA Data Workshop               20
                                                                   The WOUDC data for FMI-ARC is a Daily
                                                                      average. During SAUNA, there is a
                                                                    “Reference Data Set” from DS Double
                                                                   Brewer measurements. Here, the value
                                                                     is the single value at local 12:00 Hrs




Vindeln is about 466 KM South (N64.25,
19.76E). The station operates a Brewer
(B006) and a Dobson (D030). Reports
only the “traditional” one value per day.
Compared to the OMI results (daily
average), the Brewer DS values are 0.4%
higher, and the ZS (zenith sky) values are
1.9% lower. The few Dobson values are
0.8% lower for DS and 0.1% higher for ZS.




    8-11 Nov 06, Tenerife Spain              SAUNA Data Workshop                                      21
         A day with 50 unit change in 8 hours




       Standard processing
8-11 Nov 06, Tenerife Spain   for both Dobson and Brewer instruments
                                SAUNA Data Workshop                    22
Spatial Considerations in Comparisons
                                             Composite of 29-30Mar06 Overpasses




                                                                        FMI



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 Some Conclusions and Questions
• Dobson Instruments operating on AD pairs and Single
  Brewers are limited to lower Slant Path Ozone values
  than expected.
• CD pair and Double Brewer have a higher range on
  Slant Path Ozone.
• Dobson data analysis can be improved by including
  more information about the real atmosphere.
• Question: Differences Between Single and Double
  Brewer?
• Question: AD/CD ratio at FMI is different than expected.
  The average CD results at the US Alaska sites, and the
  South Pole site are ~2-3% lower than AD results for
  calculated ozone.


8-11 Nov 06, Tenerife Spain   SAUNA Data Workshop            24

				
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