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<br />8. <br /> <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />contents versus JW values during the entire 1.5 hr flight of March 12. <br />Notice the very wide scatter of points, and that disagreements as high <br />asa factor of four were not uncommon. This Illustrates that no simple <br />calibration is possible. <br />There are two main reasons for the disagreement between the liquid <br />water content instruments. First, subsequent tests of the FSSPi n summer: <br />continental clouds and in wind tunnel tests suggested that it measured <br />liquid water content poorly. Summer intercomparison flights showed that <br />it normally overcounted the number concentration of drops (by factors up <br />to 50-100%}, and It may have also oversized the droplet diameters (of the <br />order of a few micrometers). Wind tunnel tests at the manufacturer <br />(Particle Measuring Systems) have subsequently confirmed that concentra- <br />tions Were being overcounted in.~at least the first channels of the instru- <br />ment. Both overcounting and oversizing would naturally cause the derived <br />liquid water content to be too high. Second, the JW.instrument would <br />sometimes underestimate the liquid water content. The sensitivity .of the <br />JW to droplets > ~ 30 ~m diameter, decreases whereas the spectra results <br />from the FSSP indicated that when there were significant amounts of liquid <br />water, droplets larger than this size were sometimes present. <br />Because of these considerations, the values of liquid water content <br />need to be treated cautiously. ,Consequently, the results from both <br />instruments are always Included In the analog plots which appear in this <br />report. <br />