Co-Chairs: Ulla Wandinger, Adolfo Comeron, Dimitrios Balis, Albert Ansmann, Vassilis Amiridis, Eduardo Landulfo, Chris Hostetler, Igor Veselovskii S3O-01 - Invited Talk
AEROSOL-CLOUD INTERACTION, A NOTORIOUS SOURCE OF UNCERTAINTIES IN CLIMATE RESEARCH: ROLE OF LIDAR IN LIQUID-WATER AND MIXED-PHASE CLOUD
STUDIES
Albert Ansmann, Patric Seifert, Johannes Bühl, Thomas Kanitz, Ronny Engelmann, and Dietrich Althausen
Leibniz Institute for Tropospheric Research, Permoserstrasse 15, 04318 Leipzig, Germany
The potential of ground–based lidar to contribute to research of layered clouds in the lower and middle troposphere is discussed. Emphasis is put on the important process of heterogeneous ice formation. Lidar–
based statistics of liquid and mixed–phase clouds observed at clean southern and polluted northern mid-latitudes, and the tropics are compared and discussed. Simultaneous observations of polarization lidar and Doppler lidar (vertical wind observations) offer the opportunity to better separate meteorological aspects and aerosol effects in cloud evolution and ice formation. Recent activities in this field of lidar observations are discussed in addition.
S3O-02
WATER CLOUD MEASUREMENT USING RAMAN LIDAR TECHNIQUE: CURRENT UNDERSTANDING AND FUTURE WORK
Tetsu Sakai1, Felicita Russo2, David N. Whiteman3, David Turner4, Igor Veselovskii5, S. Harvey Melfi3, Raymond Hoff6 and Tomohiro Nagai1
1Meteorological Research Institute, 1-1 Nagamine, Tsukuba, Ibaraki 305-0052, Japan
2ISAC / Italian National Research Council, Via Gobetti, 101, 40129 Bologna, Italy
3NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
4 NOAA National Severe Storms Laboratory, 120 David L Boren Blvd, Norman, OK 73072, USA
5Physics Instrumentation Center, General Physics Institute, Troitsk, Moscow Region 142190, Russia
6University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore MD 21250, USA
This paper describes the current state of our research into the Raman liquid water cloud measurement technique. We describe the results of spectroscopic measurements acquired at National Aeronautics and Space Administration (NASA) Goddard Space Flight Center (GSFC) and analysis of data from the Atmospheric Radiation Measurement (ARM) Program Southern Great Plains (SGP) site of the U. S.
Department of Energy. The range resolved spectral measurements indicate that the backscattering spectra measured in and below low clouds at NASA GSFC on November 15, 2011, agree well with theoretical spectra for vapor and liquid water. A small enhancement may be observed due to aerosol fluorescence.
The calibration coefficients of the liquid water measurement for the Raman lidar at the ARMSGP site were determined by comparisons with the liquid water path (LWP) obtained with Atmospheric Emitted Radiance Interferometer (AERI) and the liquid water content (LWC) obtained with the millimeter wavelength cloud radar and water vapor radiometer (MMCR-WVR). Areas requiring further research in this technique include study of the influence of aerosol fluorescence on the Raman measurements and linearity of the lidar signals during the rapid decay as clouds are penetrated.
CORRELATED MEASUREMENTS OF HUMIDITY AND EXTINCTION IN CIRRUS CLOUDS BY AIRBORNE LIDAR
Martin Wirth, Silke Groß, Andreas Fix, Ehret Gerhard
\Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Physik der Atmosphäre, Münchner Str. 20, 82234 Wessling, Germany
During the first mission of the new German research aircraft HALO, the combined aerosol and water vapor LIDAR WALES made extensive combined measurements of humidity and cloud optical thickness in the vicinity and, for the first time, within fully developed cirrus clouds. A comparison with joint in-situ measurements carried out on synchronous flights with DLR’s Falcon F20 aircraft showed that the main variability in relative humidity over ice was caused by fluctuations of water vapor concentration and not by temperature fluctuations. This validated the use of numerical weather prediction temperature data to convert the absolute humidity, as measured by the LIDAR, to relative humidity. In this way high resolution joint distributions of relative humidity over ice and cloud optical thickness within cirrus could be established for the first time. For this task the extended vertical range of HALO was indispensable as it enabled the LIDAR system to keep its minimum distance to the cloud tops which reached up to 13 km during this mission.
S3O-04
LIDAR BACKSCATTERING BY QUASI-HORIZONTALLY ORIENTED HEXAGONAL ICE PLATES
Anatoli Borovoi1, Alexander Konoshonkin1, Natalia Kustova1, Hajime Okamoto2
1V.E. Zuev Institute of Atmospheric Optics, Rus. Acad. Sci., 1, Academician Zuev Sq., Tomsk 634021, Russia
2Kyushu University, Research Institute for Applied Mechanics, 6-1 Kasuga-koen Kasuga-city, Fukuoka 816-8580, Japan
Three values measured by the spaceborne lidar CALIPSO, i.e. backscattering coefficient, color ratio and depolarization ratio, have been calculated within the framework of physical optics for quasi-horizontally oriented hexagonal ice plates. The dependence of these values on the effective deviation of crystal orientations is obtained for the case of normal incidence of light and axially symmetric distribution of crystal orientations. Such results are applicable for the data obtained by CALIPSO at the initial tilt of its axis at 0.3° from nadir.
S3O-05
MID-LATITUDE CIRRUS ANALYSIS WITH LIDARS: CLUSTERING AND MATCH APPROACH
Davide Dionisi1,2, Philippe Keckhut2, Christophe Hoareau2, Nadège Montoux3, Fernando Congeduti1
1Institute of Atmospheric Sciences and Climate-CNR, Via del Fosso del Cavaliere 100, 00133 Roma, Italy
2Laboratoire ATmosphères, Milieux, Observations Spatiales, Versailles St-Quentin University, CNRS/INSU, UMR8190, 11, boulevard d'Alembert, 78280 Guyancourt, France
3Laboratoire de Météorologie Physique, Blaise Pascal University /CNRS /OPGC -UMR 6016, les Cezeaux, 24 Avenue des Landais, 63177 Aubiere, France
A review of the recent and on going works about the characterization of mid-latitude cirrus through two advanced multi-channel lidar systems, located in the Mediterranean area, is presented. These systems, at the Observatory of Haute Provence (OHP, 43.9° N, 5.7° E) in France and at Rome Tor Vergata (RTV, 41.8° N, 12.6° E) in Italy, observe cirrus in operational or semi-operational mode. A statistical approach has been used to derive cirrus classification (and climatology) over the period 1996-2007 for OHP lidar measurements. Similarly, a preliminary cirrus classification has been performed on RTV lidar data for three years period and compared to the French one. Finally a study to assess the feasibility of a future observing strategy that couples lidar measurements to a Match approach has been conducted to characterize cirrus optical properties using both the French and the Italian site. A case of upper tropospheric thin cirrus advection has been identified and studied through this approach.
S3O-06
RAMAN BACKSCATTER-COEFFICIENT SPECTRA OF CIRRUS ICE Jens Reichardt
Richard-Aßmann-Observatorium, Deutscher Wetterdienst, Am Observatorium 12, 15848 Lindenberg, Germany For simultaneous measurements of water in its gaseous and condensed phases, a spectrometer has been added to RAMSES, the Raman lidar for moisture sensing of the German Meteorological Service. The spectrometer is coupled to the far-range receiver with a fiber bundle, and consists of a Czerny-Turner spectrograph (500 mm focal length) and a 32-channel single photon-counting detection system based on a multi-anode photomultiplier. During a typical measurement (with a transmitter wavelength of 355 nm), the spectrum between 385 and 410 nm is recorded with a spectral resolution of 0.8 nm; the spatial resolution is 15 m, the height range 15 km. In this contribution, the techniques are outlined that are applied to calibrate the spectrum measurement and to ensure that fluorescence does not contribute as a source of error. Also, vibrational Raman spectra of cirrus particles are reported for the first time. Spectrum-integrated ice backscatter coefficients of up to 2.8 Em_1sr_1 have been measured. The ice data obtained so far do not suggest a simple relation between ice backscatter coefficient and cirrus optical properties such as the extinction coefficient.
DETERMINATION OF CLOUD MICROPHYSICAL PROPERTIES WITH DUAL-FIELD-OF-VIEW RAMAN LIDAR MEASUREMENTS Jörg Schmidt1, UllaWandinger1, Aleksey V. Malinka2, Johannes Bühl1
1Leibniz Institute for Tropospheric Research, Permoserstrasse 15, 04318 Leipzig, Germany,
2BI Stepanov Institute of Physics, National Academy of Science of Belarus, Pr. Nezavisimosti 68, Minsk 220072, Belarus
Dual-field-of-view Raman lidar measurements are performed with the lidar MARTHA (Multiwavelength Atmospheric Raman Lidar for Temperature, Humidity and Aerosol Profiling) at the Leibniz Institute for Tropospheric Research (IfT) in Leipzig, Germany. Light that is scattered in forward direction by cloud droplets and inelastically backscattered by N2 molecules is simultaneously detected with two different fields of view (FOVs). An inversion algorithm is used to derive profiles of the effective droplet radius, extinction coefficient, and liquid-water content (LWC) of the investigated clouds. Case studies are presented illustrating the effect of aerosol properties as well as vertical wind speed on cloud microphysical properties. Furthermore, a case study comparing the retrieved liquid-water path (LWP) with corresponding measurements of a microwave radiometer (MWR) is presented, which constitutes a verification of the retrieved cloud properties.