Methods to homogenize electrochemical concentration cell (ECC) ozonesonde measurements across changes in sensing solution concentration or ozonesonde manufacturer

摘要

pstrongAbstract./strong Ozone plays a significant role in the chemical and radiative state of the atmosphere. For this reason there are many instruments used to measure ozone from the ground, from space, and from balloons. Balloon-borne electrochemical cell ozonesondes provide some of the best measurements of the ozone profile up to the mid-stratosphere, providing high vertical resolution, high precision, and a wide geographic distribution. From the mid-1990s to the late 2000s the consistency of long-term records from balloon-borne ozonesondes has been compromised by differences in manufacturers, Science Pump (SP) and ENSCI (EN), and differences in recommended sensor solution concentrations, 1.0span class="thinspace"/span% potassium iodide (KI) and the one-half dilution 0.5span class="thinspace"/span%. To investigate these differences, a number of organizations have independently undertaken comparisons of the various ozonesonde types and solution concentrations, resulting in 197 ozonesonde comparison profiles. The goal of this study is to derive transfer functions to allow measurements outside of standard recommendations, for sensor composition and ozonesonde type, to be converted to a standard measurement and thus homogenize the data to the expected accuracy of 5span class="thinspace"/span% (10span class="thinspace"/span%) in the stratosphere (troposphere). Subsets of these data have been analyzed previously and intermediate transfer functions derived. Here all the comparison data are analyzed to compare (1)??differences in sensor solution composition for a single ozonesonde type, (2)??differences in ozonesonde type for a single sensor solution composition, and (3)??the World Meteorological Organization's (WMO) and manufacturers' recommendations of 1.0span class="thinspace"/span% KI solution for Science Pump and 0.5span class="thinspace"/span% KI for ENSCI. From the recommendations it is clear that ENSCI ozonesondes and 1.0span class="thinspace"/span% KI solution result in higher amounts of ozone sensed. The results indicate that differences in solution composition and in ozonesonde type display little pressure dependence at pressures a??a?￥a??span class="thinspace"/span30span class="thinspace"/spanhPa, and thus the transfer function can be characterized as a simple ratio of the less sensitive to the more sensitive method. This ratio is 0.96 for both solution concentration and ozonesonde type. The ratios differ at pressures &span class="thinspace"/span30span class="thinspace"/spanhPa such that OZsub0.a??5i%/i/sub/OZsub1.a??0a??i%/i/suba??=a??a??0.a??90a??+a??0.a??041a??a??a??logsub10/sub(ip/i) and OZsubSciencePump/sub/OZsubENSCI/suba??=a??a??0.a??764a??+a??0.a??133a??a??a??logsub10/sub(ip/i) for ip/i in units of hPa. For the manufacturer-recommended solution concentrations the dispersion of the ratio (SP-1.0span class="thinspace"/span/span class="thinspace"/spanEN-0.5span class="thinspace"/span%), while significant, is generally within 3span class="thinspace"/span% and centered near 1.0, such that no changes are recommended. For stations which have used multiple ozonesonde types with solution concentrations different from the WMO's and manufacturer's recommendations, this work suggests that a reasonably homogeneous data set can be created if the quantitative relationships specified above are applied to the non-standard measurements. This re