Advances in Continuously Profiling the Thermodynamic State of the Boundary Layer: Integration of Measurements and Methods

Ulrich Löhnert Institute for Meteorology and Geophysics, University of Cologne, Cologne, Germany

Search for other papers by Ulrich Löhnert in
Current site
Google Scholar
PubMed
Close
,
S. Crewell Institute for Meteorology and Geophysics, University of Cologne, Cologne, Germany

Search for other papers by S. Crewell in
Current site
Google Scholar
PubMed
Close
,
O. Krasnov Delft University of Technology, Delft, Netherlands

Search for other papers by O. Krasnov in
Current site
Google Scholar
PubMed
Close
,
E. O’Connor University of Reading, Reading, United Kingdom

Search for other papers by E. O’Connor in
Current site
Google Scholar
PubMed
Close
, and
H. Russchenberg Delft University of Technology, Delft, Netherlands

Search for other papers by H. Russchenberg in
Current site
Google Scholar
PubMed
Close
Restricted access

Abstract

This paper describes advances in ground-based thermodynamic profiling of the lower troposphere through sensor synergy. The well-documented integrated profiling technique (IPT), which uses a microwave profiler, a cloud radar, and a ceilometer to simultaneously retrieve vertical profiles of temperature, humidity, and liquid water content (LWC) of nonprecipitating clouds, is further developed toward an enhanced performance in the boundary layer and lower troposphere. For a more accurate temperature profile, this is accomplished by including an elevation scanning measurement modus of the microwave profiler. Height-dependent RMS accuracies of temperature (humidity) ranging from ∼0.3 to 0.9 K (0.5–0.8 g m−3) in the boundary layer are derived from retrieval simulations and confirmed experimentally with measurements at distinct heights taken during the 2005 International Lindenberg Campaign for Assessment of Humidity and Cloud Profiling Systems and its Impact on High-Resolution Modeling (LAUNCH) of the German Weather Service. Temperature inversions, especially of the lower boundary layer, are captured in a very satisfactory way by using the elevation scanning mode. To improve the quality of liquid water content measurements in clouds the authors incorporate a sophisticated target classification scheme developed within the European cloud observing network CloudNet. It allows the detailed discrimination between different types of backscatterers detected by cloud radar and ceilometer. Finally, to allow IPT application also to drizzling cases, an LWC profiling method is integrated. This technique classifies the detected hydrometeors into three different size classes using certain thresholds determined by radar reflectivity and/or ceilometer extinction profiles. By inclusion into IPT, the retrieved profiles are made consistent with the measurements of the microwave profiler and an LWC a priori profile. Results of IPT application to 13 days of the LAUNCH campaign are analyzed, and the importance of integrated profiling for model evaluation is underlined.

Corresponding author address: Dr. Ulrich Löhnert, Institute for Meteorology and Geophysics, Zülpicher Straße 49a, 50674 Cologne, Germany. Email: loehnert@meteo.uni-koeln.de

This article included in the Fifth International Symposium on Tropospheric Profiling (ISTP) special collection.

Abstract

This paper describes advances in ground-based thermodynamic profiling of the lower troposphere through sensor synergy. The well-documented integrated profiling technique (IPT), which uses a microwave profiler, a cloud radar, and a ceilometer to simultaneously retrieve vertical profiles of temperature, humidity, and liquid water content (LWC) of nonprecipitating clouds, is further developed toward an enhanced performance in the boundary layer and lower troposphere. For a more accurate temperature profile, this is accomplished by including an elevation scanning measurement modus of the microwave profiler. Height-dependent RMS accuracies of temperature (humidity) ranging from ∼0.3 to 0.9 K (0.5–0.8 g m−3) in the boundary layer are derived from retrieval simulations and confirmed experimentally with measurements at distinct heights taken during the 2005 International Lindenberg Campaign for Assessment of Humidity and Cloud Profiling Systems and its Impact on High-Resolution Modeling (LAUNCH) of the German Weather Service. Temperature inversions, especially of the lower boundary layer, are captured in a very satisfactory way by using the elevation scanning mode. To improve the quality of liquid water content measurements in clouds the authors incorporate a sophisticated target classification scheme developed within the European cloud observing network CloudNet. It allows the detailed discrimination between different types of backscatterers detected by cloud radar and ceilometer. Finally, to allow IPT application also to drizzling cases, an LWC profiling method is integrated. This technique classifies the detected hydrometeors into three different size classes using certain thresholds determined by radar reflectivity and/or ceilometer extinction profiles. By inclusion into IPT, the retrieved profiles are made consistent with the measurements of the microwave profiler and an LWC a priori profile. Results of IPT application to 13 days of the LAUNCH campaign are analyzed, and the importance of integrated profiling for model evaluation is underlined.

Corresponding author address: Dr. Ulrich Löhnert, Institute for Meteorology and Geophysics, Zülpicher Straße 49a, 50674 Cologne, Germany. Email: loehnert@meteo.uni-koeln.de

This article included in the Fifth International Symposium on Tropospheric Profiling (ISTP) special collection.

Save
  • Baedi, R. J. P., de Wit J. J. M. , Russchenberg H. W. J. , Erkelens J. S. , and Poiares Baptista J. P. V. , 2000: Estimating effective radius and liquid water content from radar and lidar based on the CLARE’98 data-set. Phys. Chem. Earth, 25 , 10571062.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Boukabara, S., Clough S. A. , Moncet J-L. , Krupnov A. F. , Tretyakov M. Y. , and Parshin V. V. , 2005: Uncertainties in the temperature dependence of the line-coupling parameters of the microwave oxygen band: Impact study. IEEE Trans. Geosci. Remote Sens., 43 , 11091114.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Crewell, S., and Löhnert U. , 2007: Accuracy of boundary layer temperature profiles retrieved with multifrequency multiangle microwave radiometry. IEEE Trans. Geosci. Remote Sens., 45 , 21952201.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Czekala, H., and Simmer C. , 2002: On precipitation induced polarization of microwave radiation measured from space. Meteor. Z., 11 , 4960.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Fox, N. I., and Illingworth A. , 1997: The potential of a spaceborne cloud radar for the detection of stratocumulus. J. Appl. Meteor., 36 , 676687.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Hogan, R. J., and O’Connor E. J. , 2004: Facilitating cloud radar and lidar algorithms: The Cloudnet Instrument Synergy/Target Categorization product. Cloudnet documentation, 14 pp. [Available online at http://www.cloud-net.org/data/products/categorize.html].

  • Hogan, R. J., Illingworth A. J. , O’Connor E. J. , and Poiares Baptista J. P. V. , 2003: Characteristics of mixed-phase clouds: Part II: A climatology from ground-based lidar. Quart. J. Roy. Meteor. Soc., 129 , 21172134.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Illingworth, A. J., and Coauthors, 2007: CLOUDNET: Continuous evaluation of cloud profiles in seven operational models using ground-based observations. Bull. Amer. Meteor. Soc., 88 , 883898.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Kadygrov, E. N., and Pick D. R. , 1998: The potential performance of an angular-scanning single-channel microwave radiometer and some comparisons with in situ observations. Meteor. Appl., 5 , 393404.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Karstens, U., Simmer C. , and Ruprecht E. , 1994: Remote sensing of cloud liquid water. Meteor. Atmos. Phys., 54 , 157171.

  • Klett, J. D., 1981: Stable analytical inversion solution for processing lidar returns. Appl. Opt., 17 , 211220.

  • Krasnov, O. A., and Russchenberg H. W. J. , 2002: The relation between the radar to lidar ratio and the effective radius of droplets in water clouds: An analysis of statistical models and observed drop size distributions. Preprints, 11th Conf. on Cloud Physics, Ogden, Utah, Amer. Meteor. Soc., P1.7.

  • Krasnov, O. A., and Russchenberg H. W. J. , 2006: A synergetic radar-lidar technique for the LWC retrieval in water clouds. Preprints, Seventh Int. Symp. on Tropospheric Profiling: Needs and Techniques, Boulder, CO.

  • Liebe, H. J., Hufford G. A. , and Manabe T. , 1991: A model for the complex permittivity of water at frequencies below 1th3. Int. J. Infrared Millimeter Waves, 12 , 659675.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Löhnert, U., and Crewell S. , 2003: Accuracy of cloud liquid water path from ground-based microwave radiometry. Part I: Dependency on cloud model statistics. Radio Sci., 38 .8041, doi:10.1029/2002RS002654.

    • Search Google Scholar
    • Export Citation
  • Löhnert, U., Crewell S. , and Simmer C. , 2004: An integrated approach toward retrieving physically consistent profiles of temperature, humidity, and cloud liquid water. J. Appl. Meteor., 43 , 12951307.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Löhnert, U., van Meijgaard E. , Baltink H. K. , Groß S. , and Boers R. , 2007: Accuracy assessment of an integrated profiling technique for operationally deriving profiles of temperature, humidity, and cloud liquid water. J. Geophys. Res., 112 .D04205, doi:10.1029/2006JD007379.

    • Search Google Scholar
    • Export Citation
  • Neisser, J., and Steinhagen H. , 2005: Die Historie des Meteorologischen Observatoriums Lindenberg 1905–2005. Promet, 31 , 82114. [Available online at http://www.dmg-ev.de/gesellschaft/publikationen/promet_archiv.htm.].

    • Search Google Scholar
    • Export Citation
  • Rocadenbosch, F., and Comeron A. , 1999: Error analysis for the lidar backward inversion algorithm. Appl. Opt., 38 , 44614474.

  • Rodgers, C. D., 2000: Inverse Methods for Atmospheric Sounding: Theory and Practice. World Scientific, 238 pp.

  • Rogers, R. R., and Yau M. K. , 1989: A Short Course in Cloud Physics. 3rd ed. Butterworth-Heinemann, 304 pp.

  • Rogers, R. R., Lamoureux M-F. , Bissonnette L. R. , and Peters R. M. , 1997: Quantitative interpretation of laser ceilometer intensity profiles. J. Atmos. Oceanic Technol., 14 , 396411.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Rose, T., Crewell S. , Löhnert U. , and Simmer C. , 2005: A network suitable microwave radiometer for operational monitoring of the cloudy atmosphere. Atmos. Res., 75 , 183200.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Rosenkranz, P. W., 1998: Water vapor microwave continuum absorption: A comparison of measurements and models. Radio Sci., 33 , 919928.

  • Warner, J., 1955: The water content of cumuliform clouds. Tellus, 7 , 449457.

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 894 504 50
PDF Downloads 252 110 16