A comparison of ice water content measurement techniques on the FAAM BAe-146 aircraft
Author:
Abel S. J.ORCID, Cotton R. J., Barrett P. A.ORCID, Vance A. K.
Abstract
Abstract. This paper presents a comparison of ice water content (qi) data from a variety of measurement techniques on the Facility for Airborne Atmospheric Measurements (FAAM) BAe-146 research aircraft. Data are presented from a range of cloud types measured during the PIKNMIX field experiment that include mixed phase stratocumulus, cumulus congestus and cirrus clouds. These measurements cover a broad range of conditions in which atmospheric ice particles are found in nature, such as the low ice water content environments typically found in mid-latitude cirrus and the much higher ice water content environments often observed in cold convective clouds. The techniques include bulk measurements from (i) a Nevzorov hot-wire probe (ii) the difference between the measured total water content (condensed plus vapour) and the water vapour content of the atmosphere and (iii) a Counterflow Virtual Impactor (CVI) (only for cirrus measurements). We also estimate the qi from integration of the measured particle size distribution (PSD) with assumptions on how the density of ice particles varies as a function of size. The results show that the only bulk ice water content technique capable of measuring high qi values (several g kg−1) was the total water content minus water vapour method. For low ice water contents we develop a new parametrization of the Nevzorov base-line drift that enables the probe to be sensitive to qi ± 0.002 g m−3. In cirrus clouds the agreement between the Nevzorov and other bulk measurements was typically better than a factor of two for the CVI (qi 0.01 g kg−1) and the total water content minus water vapour method (qi > 0.03 g kg−1). Good agreement with the bulk measurements for all cases could be obtained with the estimate from the PSD provided that appropriate a-priori assumptions on the mass–dimension relationship were made. This is problematic in the convective clouds sampled because pristine ice particles, heavily rimed particles and supercooled liquid drops were all present. In a cirrus case we show that using a temperature dependent mass–dimension relation was required to match the bulk measurement of qi.
Publisher
Copernicus GmbH
Reference29 articles.
1. Anderson, T. L., Charslon, R. J., and Covert, D. S.: Calibration of a counterflow virtual impactor at aerodynamic diameters from 1 to 15 \\mum, Aerosol Sci. Tech., 19, 317–329, 1993. 2. Baran, A. J., Bodas-Salcedo, A., Cotton, R. J., and Lee, C.: Simulating the equivalent radar reflectivity of cirrus at 94 GHz using an ensemble model of cirrus ice crystals: a test of the Met Office global numerical weather prediction model, Q. J. Roy. Meteorol. Soc., 137, 1547–1560, 2011. 3. Baumgardner, D., Brenguier, J. L., Bucholtz, A., Coe, H., DeMott, P., Garrett, T. J., Gayet, J. F., Hermann, M., Heymsfield, A., Korolev, A., Kramer, M., Petzold, A., Strapp, W., Pliewskiw, P., Taylor, J., Twohy, C., Wendisch, M., Bachalo, W., and Chuang, P.: Airborne instruments to measure atmospheric aerosol particels, clouds and radiation: a cook's tour of mature and emerging technology, Atmos. Res., 102, 10–29, 2011. 4. Brown, P. R. A.: Measurement of the ice water content in cirrus using an evaporative technique, J. Atmos. Ocean. Tech., 10, 579–590, 1993. 5. Brown, P. R. A. and Francis, P. N.: Improved measurement of the ice water content in cirrus using a total-water probe, J. Atmos. Ocean. Tech., 12, 410–414, 1995.
Cited by
1 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献
|
|