AMT Atmospheric Measurement Techniques AMT Atmos. Meas. Tech. 1867-8548 Copernicus Publications Göttingen, Germany 10.5194/amt-4-2777-2011 Comparisons of temperature, pressure and humidity measurements by balloon-borne radiosondes and frost point hygrometers during MOHAVE-2009 Hurst D. F. 1 2 Hall E. G. 1 2 Jordan A. F. 1 2 Miloshevich L. M. 3 Whiteman D. N. 4 Leblanc T. 5 Walsh D. 5 Vömel H. 6 Oltmans S. J. 2 Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado, USA NOAA Earth System Research Laboratory, Global Monitoring Division, Boulder, Colorado, USA Milo Scientific LLC, Lafayette, Colorado, USA NASA Goddard Space Flight Center, Greenbelt, Maryland, USA Jet Propulsion Laboratory, Table Mountain Facility, Wrightwood, California, USA Meteorologisches Observatorium Lindenberg, Deutscher Wetterdienst, Lindenberg, Germany 16 12 2011 4 12 2777 2793 Copyright: © 2011 D. F. Hurst et al. 2011 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://amt.copernicus.org/articles/4/2777/2011/amt-4-2777-2011.html The full text article is available as a PDF file from https://amt.copernicus.org/articles/4/2777/2011/amt-4-2777-2011.pdf

We compare coincident, in situ, balloon-borne measurements of temperature (<i>T</i>) and pressure (<i>P</i>) by two radiosondes (Vaisala RS92, Intermet iMet-1-RSB) and similar measurements of relative humidity (RH) by RS92 sondes and frost point hygrometers. Data from a total of 28 balloon flights with at least one pair of radiosondes are analyzed in 1-km altitude bins to quantify measurement differences between the sonde sensors and how they vary with altitude. Each comparison (<i>T</i>, <i>P</i>, RH) exposes several profiles of anomalously large measurement differences. Measurement difference statistics, calculated with and without the anomalous profiles, are compared to uncertainties quoted by the radiosonde manufacturers. Excluding seven anomalous profiles, <i>T</i> differences between 19 pairs of RS92 and iMet sondes exceed their measurement uncertainty limits (2 σ) 31% of the time and reveal a statistically significant, altitude-independent bias of 0.5 ± 0.2 °C. Similarly, RS92-iMet <i>P</i> differences in 22 non-anomalous profiles exceed their uncertainty limits 23% of the time, with a disproportionate 83% of the excessive <i>P</i> differences at altitudes >16 km. The RS92-iMet pressure differences increase smoothly from −0.6 hPa near the surface to 0.8 hPa above 25 km. Temperature and <i>P</i> differences between all 14 pairs of RS92 sondes exceed manufacturer-quoted, reproducibility limits (σ) 28% and 11% of the time, respectively. About 95% of the excessive <i>T</i> differences are eliminated when 5 anomalous RS92-RS92 profiles are excluded. Only 5% of RH measurement differences between 14 pairs of RS92 sondes exceed the manufacturer's measurement reproducibility limit (σ). RH measurements by RS92 sondes are also compared to RH values calculated from frost point hygrometer measurements and coincident <i>T</i> measurements by the radiosondes. The influences of RS92-iMet <i>T</i>and <i>P</i> differences on RH values and water vapor mixing ratios calculated from frost point hygrometer measurements are examined.

 References Brewer, A. W., Cwilong, B., and Dobson, G. M. B.: Measurements of absolute humidity in extremely dry air, Proc. Phys. Soc., 60, 52–70, 1948. Goff, J. A.: Saturation pressure of water on the new Kelvin temperature scale, Trans. Am. Soc. Heat. Ventilat. Eng., 63, 347–354, 1957. Hurst, D. F., Oltmans, S. J., Vömel, H., Rosenlof, K. H., Davis, S. M., Ray, E. A., Hall, E. G., and Jordan, A. F.: Stratospheric water vapor trends over Boulder, Colorado: Analysis of the 30 year Boulder record, J. Geophys. Res., 116, D02306, <a href="http://dx.doi.org/10.1029/2010JD015065">https://doi.org/10.1029/2010JD015065</a>, 2011. Immler, F. J., Dykema, J., Gardiner, T., Whiteman, D. N., Thorne, P. W., and Vömel, H.: Reference Quality Upper-Air Measurements: guidance for developing GRUAN data products, Atmos. Meas. Tech., 3, 1217–1231, <a href="http://dx.doi.org/10.5194/amt-3-1217-2010">https://doi.org/10.5194/amt-3-1217-2010</a>, 2010. Leblanc, T., Walsh, T. D., McDermid, I. S., Toon, G. C., Blavier, J.-F., Haines, B., Read, W. G., Herman, B., Fetzer, E., Sander, S., Pongetti, T., Whiteman, D. N., McGee, T. G., Twigg, L., Sumnicht, G., Venable, D., Calhoun, M., Dirisu, A., Hurst, D., Jordan, A., Hall, E., Miloshevich, L., Vömel, H., Straub, C., Kampfer, N., Nedoluha, G. E., Gomez, R. M., Holub, K., Gutman, S., Braun, J., Vanhove, T., Stiller, G., and Hauchecorne, A.: Measurements of Humidity in the Atmosphere and Validation Experiments (MOHAVE)-2009: overview of campaign operations and results, Atmos. Meas. Tech., 4, 2579–2605, <a href="http://dx.doi.org/10.5194/amt-4-2579-2011">https://doi.org/10.5194/amt-4-2579-2011</a>, 2011. Mastenbrook, H. J. and Oltmans, S. J.: Stratospheric water vapor variability for Washington, D.C./Boulder, CO; 1964–82, J. Atmos. Sci., 40, 2157–2165, 1983. Miloshevich, L. M., Paukkunen, A., Vömel, H., and Oltmans, S. J.: Development and validation of a time-lag correction for Vaisala radiosonde humidity measurements, J. Atmos. Ocean. Tech., 21, 1305–1327, 2004. Miloshevich, L. M., Vömel, H., Whiteman, D. N., and Leblanc, T.: Accuracy, assessment and correction of Vaisala RS92 radiosonde water vapor measurements, J. Geophys. Res., 114, D11305, <a href="http://dx.doi.org/10.1029/2008JD011565">https://doi.org/10.1029/2008JD011565</a>, 2009. Seidel, D. J., Angell, J. K., Christy, J., Free, M., Klein, S. A., Lanzante, J. R., Mears, C., Parker, D., Schabel, M., Spencer, R., Sterin, A., Thorne, P., and Wentz, F.: Uncertainty in signals of large-scale climate variations in radiosonde and satellite upper-air temperature datasets, J. Climate, 17, 2225–2240, <a href="http://dx.doi.org/10.1175/1520-0442(2004)017<2225:UISOLC>2.0.CO;2">https://doi.org/10.1175/1520-0442(2004)017<2225:UISOLC>2.0.CO;2</a>, 2004. Thorne, P. W., Parker, D. E., Christy, J. R., and Mears, C. A.: Uncertainties in climate trends: Lessons from upper-air temperature records, B. Am. Meteorol. Soc., 86, 1437–1442, <a href="http://dx.doi.org/10.1175/BAMS-86-10-1437">https://doi.org/10.1175/BAMS-86-10-1437</a>, 2005. Titchner, H. A., Thorne, P. W., McCarthy, M. P., Tett, S. F. B., Haimberger, L., and Parker, D. E.: Critically reassessing tropospheric temperature trends from radiosondes using realistic validation experiments, J. Climate, 22, 465–485, 2009. Vömel, H., David, D. E., and Smith, K.: Accuracy of tropospheric and stratospheric water vapor measurements by the cryogenic frost point hygrometer: Instrumental details and observations, J. Geophys. Res., 112, D08305, <a href="http://dx.doi.org/10.1029/2006JD007224">https://doi.org/10.1029/2006JD007224</a>, 2007a. Vömel, H., Selkirk, H., Miloshevich, L., Valverde-Canossa, J., Valdes, J., Kyro, E., Kivi, R., Stolz, W., Peng, G., and Diaz, J. A.: Radiation dry bias of the Vaisala RS92 humidity sensor, J. Atmos. Ocean. Tech., 24, 953–963, <a href="http://dx.doi.org/10.1175/JTECH2019.1">https://doi.org/10.1175/JTECH2019.1</a>, 2007b.