Evaluation of Ozone Measurements From a Tethered Balloon Sampling
Platform at South Pole Station in December, 2003
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Vertical boundary-layer ozone profiles were measured from a tethered balloon platform
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during the 2003 Antarctic Tropospheric Chemistry Investigation (ANTCI) at South Pole
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Station, Antarctica. Electrochemical concentration cell (ECC) ozonesondes were used in
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obtaining 128 ascent and descent profile measurements to about 500 m height during
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December 13-30, 2003. Various data checks and intercomparisons were done to confirm
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the accuracy of the ozonesondes. The ozonesondes compared well to a surface ozone
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ultra-violet (UV) absorption monitor located next to the tether balloon site. During the
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18-day period, ozonesonde measurement checks at the surface averaged 0.2 ± 1.0 ppbv
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higher than the continuous ozone measurements under ambient concentrations ranging
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from 18 to 51 ppbv. This agreement was also consistent when compared to the nearby
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NOAA UV monitor sampling at 17 meters above ground level during well mixed
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conditions near the surface. In addition to the single ECC sonde profiles, 5 dual ECC
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ozonesondes were run on the tether platform. Four release balloon-borne ozonesondes
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were also launched during the project. Under very sharp ozone gradient events, the
Bryan J. Johnsona, Detlev Helmigb, and Samuel J. Oltmansa
a
NOAA System Research Laboratory, Global Monitoring Division, 325 Broadway,
Boulder, Colorado 80305-3328 USA
b
Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO 803090450 USA.
Revised Manuscript for
Atmospheric Environment
March 6, 2007
Abstract
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release ozonesonde (with a rise rate of ~4-6 m/s) passed through the gradient layer too
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quickly to capture the detail as measured by the controlled tethersonde at ~ 0.3 m/s
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ascent/descent rate. Another method of ozone profiling was also done utilizing the UV
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monitor at the tether site and a 135 meter long Teflon sampling line with a sampling inlet
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mounted to and raised with the tethered balloon. The ECC ozonesonde averaged about
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0.7 ± 0.8 ppbv lower than the long line sampling method from 8 profiles.
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Key word index: ozonesonde, ozone measurements, tropospheric ozone, snow
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photochemistry,
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1. Introduction
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Tethered balloon measurements have been a valuable part of campaigns investigating
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boundary layer meteorology and chemical processes, especially in polar regions (Anlauf
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et al., 1994; Helmig et al., 2002). As part of the 2003 Antarctic Tropospheric Chemistry
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Investigation (ANTCI) campaign, vertical profiles of ozone, meteorological parameters,
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and nitric oxide (NO) were measured within the boundary layer at South Pole Station
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(Helmig et al., 2002, 2007 - this issue). The measurements were carried out on a tethered
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balloon platform capable of reaching an altitude in excess of 500 meters above the
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surface. The high resolution and high frequency of ozone measurements provided an
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important picture in the ozone production and destruction processes, which are a
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subsequent link to the active photochemical processes observed over the Antarctic
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plateau (Davis et al. 2001, 2004).
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Electrochemical concentration cell (ECC) ozonesondes were the primary ozone
measuring instrument used for several reasons: They are the most widely used instrument
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for long term ozone profiling networks; simple to prepare for flight; operate well in
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extreme environments such as the Antarctic; and have been used successfully in other
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tethersonde experiments (Knapp et al., 1998; De Muer et al., 1997). In addition, the slow,
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controlled ascent and descent of the tether balloon compensates for the relatively slow
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response time of the typical ECC ozonesonde, thereby allowing detailed profiles even
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when sharp ambient ozone concentration changes are present through the boundary layer.
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The ECC sensor response to a step change in ozone concentration is about 20-25 seconds
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to reach the 1/e (63%) level (Komhyr et al., 1995).
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The NOAA/ESRL Global Monitoring Division has a long record of measuring surface
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ozone, total column ozone, and vertical profiles from ozonesondes at South Pole station.
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Surface ozone has been measured with UV absorption instruments since 1975. A TEI
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(Thermo Electron Corporation Model 49C, Franklin, MA) monitor currently operates out
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of the Atmospheric Research Observatory (ARO) building. Weekly ECC balloon-borne
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ozonesonde measurements have been done since 1986. Ozone measurements during
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ANTCI, including one additional TEI ozone monitor operating next to the tether balloon
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facility, provided for numerous data calibration checks and intercomparisons with the
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tethersonde. One unique set of measurements included utilizing the TEI ozone monitor
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for several vertical profiles to nearly 120 m height by running a long sampling line (135
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m length) attached next to the ECC ozonesonde on the tether balloon platform. This
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communication summarizes the comparison results from the various combinations of
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ECC ozonesondes (tethered and release balloons), dual ozonesondes, and TEI ozone
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monitors during the ANTCI campaign.
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2. Experimental
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A total of 128 profiles (includes ascent and descent) of ozone were measured from
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December 13-30, 2003. The data summary and analysis, including the detailed
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descriptions of the tether balloon equipment and other meteorological measurements are
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described in detail by Helmig et al. (2007 - this issue).
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2.1. Electrochemical Ozonesondes
The ECC ozonesonde, developed by Komhyr (1986, 1995), uses an electrochemical
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cell sensor that consists of a cathode cell containing 3 ml of dilute KI solution, and an
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anode cell containing 1.5 ml of a saturated KI solution. A Teflon piston pump bubbles
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ambient air into the cathode cell solution. The ozone immediately oxidizes the iodide to
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iodine which generates a proportional electrical current from the cell and through an
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external circuit. The ozonesonde accuracy and precision has been investigated through
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intercomparison campaigns and by recent laboratory tests (Smit, et al., 2007 - in press).
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The EnSci 2Z ozonesondes used in this study (EnSci Corp., Boulder, CO), interfaced
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with a Vaisala RS-80 radiosonde, were prepared using the NOAA/ESRL Global
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Monitoring Division standard operating procedures. The ozonesondes used were each
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conditioned once for 30 minutes with high ozone (> 500 ppbv) 3 to 7 days prior to their
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first profile measurement. Only 4 ozonesonde instruments were used for all of the tether
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profile measurements, with one primary instrument used for 31 profiles. All of the
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ozonesondes showed no signs of degradation and remained consistent in performance
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checks done before each tether flight, except the flow rate of the primary instrument
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increased by about 2% after the first pre-flight preparation and remained fairly constant
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thereafter. The sonde pump flow rates were measured using a soap bubble flow meter. A
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3% correction (reduction in measured flow rate) was applied to account for evaporation
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of the soap solution from the dry air pumped through the sonde. Zero air was used to
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measure the sensor background current. The cathode sensing solution consisted of a 2%
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potassium iodide unbuffered solution, which is different than the EnSci manual
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recommendation of a 0.5% KI buffered solution. Previous surface tests (Johnson et al.,
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2002) have shown almost no difference in surface ozone readings using the two different
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solutions in lab and ambient air tests. Laboratory profile tests at JOSIE (Smit, et al., 2007
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- in press), however, showed about a 6 to 7% higher reading from the 0.5% KI solution.
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Different sensing solutions were compared on several dual ozonesonde packages run on
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the tethersonde during this field project to further investigate the comparability of these
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two different operational conditions.
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The ozonesonde was placed inside the standard Styrofoam box along with a 100 gram
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sealed water-can next to the pump frame, which kept the temperature stable under the
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cold conditions at South Pole. Batteries and sensor solutions were checked and changed,
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depending on how long the sonde was operating, before each profile run. Flow rates and
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backgrounds were usually checked at the end or beginning of the day.
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Prior to attaching to the tether platform, the ozonesonde package was run for several
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minutes (at about 1.5 meters) to compare to the TEI monitor at 2 or 4 m. The ECC
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ozonesonde was not calibrated or corrected to the UV absorption surface monitoring
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instruments.
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The ascent and descent rates of the tethered balloon were controlled at about 0.2 to 0.3
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m/sec with a hydraulic winch. Geopotential altitude was calculated from the pressure and
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temperature data and was adjusted accordingly so that the beginning ascent and final
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descent surface altitude would match whenever surface pressure changes occurred during
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the approximately 1 hour profile. On 4 occasions, a release ozonesonde was launched
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concurrently while a tether-borne ozonesonde was held at the apex of its flight for a fly-
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by comparison.
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2.2. Long sample line profiling technique
Finally, a new profiling technique outlined in detail by Helmig et al. (2007a,b – this
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issue), utilized the TEI surface ozone monitor at the tether site and a 135 m long
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conditioned PFA Teflon sampling line. The TEI instrument is tailored towards high
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accuracy and precision surface ozone measurements, with accuracy and precision
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typically better than 1 ppbv and 0.2 ppbv for 1-min data. The inlet was attached to the
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tether line next to the ECC ozonesonde. Profiles were measured to nearly 120 m by
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raising and lowering the line while the indoor surface ozone monitor pulled air through
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the long line. The sampled air residence time in the Teflon sampling line was 2.1 or 4.2
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min, depending on whether the NO instrument was sampling at the same time through the
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line. The 135 m- Teflon sampling line was conditioned for 2 days in the laboratory with
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250 ppbv ozone enriched air, prior to the field campaign. The mean ozone loss rate
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during sample transport through this tubing in the field was 1.9% in the long sampling
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line as determined by alternating between a 10 m sampling line and the 135 m line at the
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surface during a nine-day period at the campaign (Helmig et al., 2007b).
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3. Results
3.1. Surface ozone comparisons
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Figure 1 shows the daily surface ozone measurements from the two UV absorption
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instruments at the ARO building (17 m inlet height) and the tether balloon site which
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sampled at a 2 m inlet height during the year 2003 calendar days (CD) 348 – 350 and
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357.2 – 364. The inlet height was moved to ~ 4 m during CD 350 – 357.2. The ECC
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ozonesonde surface (sampling at 1.5 m height) comparison checks before and after
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balloon launches are shown as single blocks at the beginning and end of each tether
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profile. Overall, the ozonesondes and UV monitors compared well with the ECC
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ozonesondes measuring 0.2 ± 1.0 ppbv (0.8 ± 3.1%) higher than the TEI (2 m & 4 m).
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During a four-day period, after December 20 (Day 354), ozone increased sharply from 20
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ppbv to the 40 to 50 ppbv range at the surface. As discussed by Helmig et al. (2007a -
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this issue), this was a period of enhanced ozone under stable, sunny conditions with
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higher ozone near the surface extending up to 60 – 200 m. The ECC ozonesondes tended
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to read slightly lower than the TEI (4 m) during this time. Figure 1 also shows that during
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this period the ARO (17 m) was showing 3-4 ppbv lower ozone than the TEI at the tether
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site (4 m). This was due to the sharp decreasing gradient in ozone under these stable
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conditions and not related to instrumental differences (Helmig et al, 2007a - this issue).
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3.2. Dual and release ozonesondes
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Figures 2 and 3 compare various dual ECC ozonesonde tether profiles and release
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flights. The ozonesonde profiles in these examples all used 2Z Ensci ozonesondes with
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2% KI unbuffered sensor solutions unless noted in the charts as 0.5% KI buffered or 6A
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Science Pump ECC ozonesondes. The ozonesonde accuracy in the troposphere is
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generally considered to be ± 5%, which is related to uncertainties in the flow rate, the
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measured background, pump temperature, and the composition of the cathode sensing
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solution. In these dual experiments, the ozonesonde data from using 0.5% KI buffered
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solutions were about 3% higher than the 2% KI unbuffered profiles, except for the dual
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flight on December 23 (Fig. 3), which shows nearly identical agreement.
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An interesting observation is shown in Figures 2a-2c, comparing the release balloon-
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borne ozonesondes with the tethered ozonesonde profiles. The release ozonesondes were
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launched after the tether profile was at the apex and held fixed at that altitude for several
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minutes. The balloonborne ozonesonde rise rate is about 5 meters per second and would
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therefore travel from the surface to the ~ 500 meter apex height in just over 100 seconds.
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The response time of the ozonesonde is too slow to capture sharp ozone features which
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are observed as a slow delayed decrease or increase in ozone. For example, on December
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18 (Figure 2a) the tethered dual ozonesonde instruments recorded a fairly constant ozone
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mixing ratio of 30 ppbv up to 480 m height, then ozone dropped sharply to 25 ppbv
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within just a few meters. The gradient was the strongest during the controlled descent
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(dashed lines). The release ozonesonde was launched from the balloon facility located in
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the center of South Pole Station, about 400 meters from the temporary tether site. The
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ozonesonde profile was also relatively constant up to 450 m, with about a 1 ppbv offset
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from the tether profiles. The difference quickly increased though as the release sonde
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passed through the sudden ~5 ppbv drop in ozone. At the typical 5 m/s ascent rate, an
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ozone instrument would have to respond in just a few seconds to capture this feature.
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This particular ozonesonde showed a 1/e response time of 26 seconds during the preflight
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test. Therefore, at the given rise rate the release sonde would travel 300 m (vertically)
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until 90 % of this change would be recorded, assuming the ozone concentration remains
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constant after the step change. This behavior is clearly visible in Figure 2a, as the release
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sonde traveled an additional 260 m in height before it read the 24-25 ppbv mixing ratio
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that was measured by the tether instruments. De Muer and Malcorps (1984) developed a
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deconvolution technique for correcting the response time distortion for their Brewer-Mast
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electrochemical ozonesonde profiles. However, the correction can generate spurious
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peaks due to noise in the data (De Backer, 1999). We did not attempt to apply this
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correction to the release sonde data, rather we show this data to illustrate the necessity for
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slow, controlled ascent and descent rates of the tethered balloon. The other 3 release
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sondes (Figures 2b-2d) were launched next to the tether site and show a similar lag in
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response to the ozone features observed by the tethered ozonesonde. The surface
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measurements showed good agreement with the release sonde during the several minutes
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it was held at the surface before launch.
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3.3. Long line sample profiles and ECC ozonesonde comparison
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Figure 4 shows eight of the TEI long line and ECC ozonesonde profile comparisons.
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On average the ECC sonde was 0.7 ±0.8 ppbv lower (-1.7 ±2%) than the measurements
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by the TEI instrument. The TEI long line data includes a 1.9% line loss correction and an
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adjustment in altitude for the 2.1 to 4.2 minute residence time. The absolute differences
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in these two measurements are well within the stated uncertainty ranges of both
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measurements. Ascent and descent data were in good agreement in all eight profiles,
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regardless whether the ozone mixing ratio gradient was fairly flat or had a relatively steep
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gradient (Dec 24 profile).
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Conclusions
Electrochemical concentration cell ozonesondes provided high spatial and temporal
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resolution data of ozone mixing ratios within the boundary layer during an intensive
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profiling campaign at South Pole Station, Antarctica as part of the ANTCI experiment. A
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total of 128 ozone profiles, between the surface and approximately 500 meters, were
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measured from Dec 13-20, 2003. An assortment of intercomparisons and quality data
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checks were done to confirm the accuracy of the ECC ozonesondes. Overall the ECC
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ozonesondes used during ANTCI operated well within their limits of uncertainty and
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were shown to be well suited for boundary layer studies of ozone using a tethered balloon
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platform. In addition, the ozonesondes were shown to maintain good performance even
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after numerous profile runs. One particular sonde was used in 31 tether ascent/descent
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runs with no significant change observed in response tests or accuracy checks.
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During surface comparisons, ozone ranged from 18 to 51 ppbv. The ECC ozonesondes
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averaged 0.8 ± 3.1% higher than the UV absorption surface monitor operating out of the
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tether balloon building with the sampling inlet at 2 to 4 m above the surface. Another
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nearby (150 m away) UV monitor located in the ARO building was also used as a
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reference and showed good agreement. However, during strong ozone gradient episodes
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the higher 17 m sampling inlet at ARO showed 3-4 ppbv lower ozone compared to the
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surface tether site. Analysis of these episodes by Helmig, (2007a - this issue) showed
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that ozone, under certain stable conditions, is produced in a shallow layer above the snow
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surface and can build up and lead to ozone gradients as high as 5 ppbv between the
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surface and the 17 m inlet of the NOAA ozone monitor.
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A slow controlled ascent and descent of less than 0.3 m/s allows the ECC ozonesonde to
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capture the details of these ozone gradients. The high-resolution vertical ozone profiles
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proved to be highly valuable for evaluating the steep gradients in vertical concentrations
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and photochemistry in the shallow boundary layer at South Pole. The release
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ozonesondes, with a ~15-20-fold faster ascent rate tended to wash out the sharp features
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The UV ozone monitor at the tether balloon site was successfully used to measure
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ozone profiles from the surface to 120 m height by using a 135 m long Teflon sampling
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line. Eight of these profiles were compared to the ECC tether ozonesonde, which showed
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the ECC sonde reading an average of 1.7 ±2% lower than the UV monitor.
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References:
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Anlauf, K.G., Mickle, R.E., Trivett, N.B.A., 1994. Measurement of ozone during Polar
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Sunrise Experiment 1992, Journal of Geophysical Research, 99, 25345-25353.
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Davis D., Nowak J.B., Chen G., Buhr M., Arimoto R., Hogan A., Eisele F., Mauldin L.,
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Tanner D., Shetter R., Lefer B. and McMurry P., 2001. Unexpected high levels of NO
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observed at South Pole. Geophys. Res. Let. 28, 3625-3628.
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Davis D., Chen G., Buhr M., Crawford J., Lenshow D., Lefer B., Shetter R., Eisele F.,
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Mauldin L., and Hogan A.,2004. South Pole NOx chemistry: an assessment of factors
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controlling variability and absolute levels. Atmos. Environ. 38, 5375-5388.
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DeBacker, H. G., 1999. Homogenization of ozone vertical profile measurements at
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Uccle, edited by H. Malcorps, Sci. Publ. 007, l’Inst. R. Météorol. de Belgique, Brussels,
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1999.
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De Muer, D., and H. Malcorps, 1984. The frequency response of an electrochemical
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ozone sonde and its application to the deconvolution of ozone profiles, J. Geophys. Res.,
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89, 1361–1372.
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De Muer, D., Heylen, R., Van Loey, M. & De Sadelaer, D.G., 1997. Photochemical
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ozone production in the convective mixed layer, studied with a tethered balloon sounding
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system, Journal of Geophysical Research 102, 15933-15947.
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Helmig, D., Boulter, J., David, D., Birks, J.W., Cullen, N.J., Steffen, K., Johnson, B.J. &
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Oltmans, S.J., 2002. Ozone and meteorological boundary-layer conditions at Summit,
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Greenland, during 3-21 June 2000, Atmospheric Environment, 36, 2595-2608.
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Helmig, D. Johnson, B., Oltmans, S. J., Neff, W., Eisele, F., and Davis, D. D., 2007a.
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Elevated boundary-layer ozone at South Pole, Atmos. Environ., in press.
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Helmig, D., Johnson, B., Warshawsky, M., Morse, T., Neff, W., Eisele, F. and Davis,
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D.D. (2007b) Nitric oxide in the boundary-layer at South Pole during the Antarctic
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Tropospheric Chemistry Investigation (ANTCI). Atmos. Environ., submitted for
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publication.
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Johnson, B.J., Oltmans, S.J., Vömel, H., 2002. Electrochemical concentration cell (ECC)
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ozonesonde pump efficiency measurements and tests on the sensitivity to ozone of
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buffered and unbuffered ECC sensor cathode solutions, Journal of Geophysical Research,
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107, 4393.
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Komhyr, W.D., 1969. Electrochemical concentration cells for gas analysis, Ann.
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Geophysics 25, 203-210.
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Komhyr, W.D., R.A. Barnes, G.B. Brothers, J.A. Lathrop,, and D.P. Opperman, 1995.
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Electrochemical concentration cell ozonesonde performance evaluation during STOIC
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1989, Journal of Geophysical Research 100, 9231-9244.
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Knapp, K.G., Jensen, M.L., Balsley, B.B., Bognar, J.A., Oltmans, S.J., Smith, T.W. &
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Birks, J.W., 1998. Vertical profiling using a complementary kite and tethered balloon
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platform at Ferryland Downs, Newfoundland, Canada: observation of a dry, ozone-rich
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plume in the free troposphere, Journal of Geophysical Research 103, 13389-13397.
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Smit, H.G.J, Straeter W., Johnson, B.J., Oltmans, S.J., Davies, J., Hoegger, B., Stubi, R.,
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Schmidlin, F., Witte, J., Thompson, A., Boyd, I. Poisny, F., 2007. Assessment of the
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performance of ECC-ozone sondes under quasi-flight conditions in the environmental
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simulation chamber: Insights from the Jülich Ozone Sonde Intercomparison Experiment
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(JOSIE), Journal of Geophysical Research., submitted for publication.
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Acknowledgements
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This research was supported through the United States National Science Foundation
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(Office of Polar Programs, grant #0230046). A. Drexler, J. Seiffert and M. Warshawsky
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helped with the balloon experiment at SP and I. Brown and T. Morse assisted in the data
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analysis and preparation of some of the color figures. We thank Raytheon Polar Services
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and the U.S. 109th Air National Guard for providing excellent logistical support and the
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South Pole staff for an extraordinary effort in accommodating the tethered balloon
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experiment.
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FIGURE CAPTIONS
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Figure 1. Summary of surface ozone measurements from December 13 (day 347) to Dec
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30 (day 364) from the UV absorption TEI monitor operated at the ARO building (inlet at
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17 m above surface) and next to the tether balloon site (inlet at 2 and 4 m above surface).
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The ECC ozonesonde data are from ~ 5-min measurements at the beginning and end of
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each tether run at 1.5 meters. The relative differences (middle panel) and percent
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differences (lower panel) are also shown.
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Figure 2. Comparison of ECC ozonesonde profiles from tethered dual ozonesondes
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(ascent = asc, descent = des) with release balloon-borne ozonesondes. All of the
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ozonesondes were 2Z Ensci sondes using 2% KI unbuffered cathode unless designated
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differently on the chart. Data from the UV absorption TEI ozone monitors at 2/4 meters
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and 17 meters are also shown.
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Figure 3. Dual ECC ozonesonde tethered flights comparing the sensor solutions 2% KI
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unbuffered (both the same solutions in the left panel) and 0.5% KI unbuffered. Ascent
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data are illustrated by the solid lines and descent data by the dashed lines. The UV
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absorption TEI ozone monitors at 4 and 17 meters are also shown at the starting time of
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the tether profile.
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Figure 4. Comparison of ECC ozonesonde tether profiles (black lines) to the UV
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absorption TEI ozone (gray lines) using the long sampling line attached to the tether
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platform. Thick lines are ascent, thin lines are descent. The average surface ozone
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measurements from the ARO building (17 m) during the profile run are also shown.
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347
FIGURES
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17 meter TEI ARO
2/4 meter TEI
50
1.5 meter ECC sonde (start)
Ozone (ppbv)
45
1.5 meter ECC sonde (end)
40
35
30
25
20
Percent Difference
ppbv difference
15
4
3
2
1
0
-1
-2
-3
-4
2m
4m
2m
(sonde - 2/4 meter TEI) start
(sonde - 2/4 meter TEI) end
8
6
4
2
0
-2
-4
-6
-8
(sonde - 2/4 meter TEI) start
(sonde - 2/4 meter TEI) end
345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365
Calendar Day 2003
348
349
350
351
352
353
354
355
Figure 1. Summary of surface ozone measurements from December 13 (day 347) to Dec
30 (day 364) from the UV absorption TEI monitor operated at the ARO building (inlet at
17 m above surface) and next to the tether balloon site (inlet at 2 and 4 m above surface).
The ECC ozonesonde data are from ~ 5-min measurements at the beginning and end of
each tether run at 1.5 meters. The relative differences (middle panel) and percent
differences (lower panel) are also shown.
800
(a) Dec 18
(b) Dec 23
02:39
03:58
700
release sonde
release sonde 0.5%KI
tether asc
tether des
tether 0.5%KI asc
tether 0.5%KI des
17 meter TEI
4 meter TEI
Height (meters)
600
500
400
release sonde
tether asc
tether des
tether 0.5%KI asc
tether 0.5%KI des
17 meter TEI
4 meter TEI
300
200
100
0
24
26
28
30
32
24
28
Ozone (ppbv)
32
36
40
44
Ozone (ppbv)
800
(c)
700
Dec 29
03:26
release sonde
tether 2Z asc
tether des
tether 6A asc
tether 6A des
17 meter TEI
4 meter TEI
600
Height (meters)
(d)
Dec 26
03:04
500
400
300
tether asc
tether dsc
release sonde 6A
200
17 meter TEI
4 meter TEI
100
0
22
24
26
28
Ozone (ppbv)
356
357
358
359
360
361
362
363
30
32
20
22
24
26
28
30
32
Ozone (ppbv)
Figure 2. Comparison of ECC ozonesonde profiles from tethered dual ozonesondes
(ascent = asc, descent = des) with release balloon-borne ozonesondes. All of the
ozonesondes were 2Z Ensci sondes using 2% KI unbuffered cathode unless designated
differently on the chart. Data from the UV absorption TEI ozone monitors at 2/4 meters
and 17 meters are also shown.
600
Dec 21
09:09
Dec 23
09:00
Height (meters)
500
2% KI-u asc
2% KI-u des
0.5% KI-b asc
0.5% KI-b des
17 meter TEI
4 meter TEI
2% KI-u asc
2% KI-u des
2% KI-u asc
2% KI-u des
17 meter TEI
4 meter TEI
400
300
200
100
0
18
22
26
30
34
38
Ozone (ppbv)
364
365
366
367
368
369
370
371
372
42
46
20
24
28
32
36
40
44
Ozone (ppbv)
Figure 3. Dual ECC ozonesonde tethered flights comparing the sensor solutions 2% KI
unbuffered (both the same solutions in the left panel) and 0.5% KI unbuffered. Ascent
data are illustrated by the solid lines and descent data by the dashed lines. The UV
absorption TEI ozone monitors at 4 and 17 meters are also shown at the starting time of
the tether profile.
Height (meters)
100
ECC Sonde
TEI long line
ARO TEI 17 m
ECC Sonde
TEI long line
ARO TEI 17 m
Dec 17
02:39
Dec 19
04:14
ECC Sonde
TEI long line
ARO TEI 17 m
ECC SONDE
TEI Long Line
ARO TEI 17 m
Dec24
24
Dec
Dec 20
23:29
09:18
80
60
40
20
0
28 30 32 34 36
Ozone (ppbv)
34 36 38 40 42
Ozone (ppbv)
38 40 42 44 46
Ozone (ppbv)
ECC Sonde
TEI long line
ARO TEI 17 m
ECC Sonde
TEI long line
ARO TEI 17 m
ECC Sonde
TEI long line
ARO TEI 17 m
Height (meters)
Dec
Dec24
24
100
40 44 48 52
Ozone (ppbv)
ECC Sonde
TEI long line
ARO TEI 17 m
Dec 27
20:34
Dec 26
09:01
Dec 25
05:00
19:57
36
80
60
40
20
0
40 42 44 46 48 50
Ozone (ppbv)
373
374
375
376
377
378
42
44 46 48
Ozone (ppbv)
26
28
30
Ozone (ppbv)
32 26
28
30
Ozone (ppbv)
Figure 4. Comparison of ECC ozonesonde tether profiles (black lines) to the UV
absorption TEI ozone (gray lines) using the long sampling line attached to the tether
platform. Thick lines are ascent, thin lines are descent. The average surface ozone
measurements from the ARO building (17 m) during the profile run are also shown.
32