AIRBORNE LIDAR OBSERVATIONS SUPPORTING THE ADM-AEOLUS MISSION FOR GLOBAL WIND PROFILING
Oliver Reitebuch, Christian Lemmerz, Uwe Marksteiner, Stephan Rahm, Benjamin Witschas 1Deutsches Zentrum für Luft- und Raumfahrt DLR, Institut für Physik der Atmosphäre, Oberpfaffenhofen, 82234
Wessling, Germany
The Atmospheric Dynamics Mission ADM-Aeolus of ESA will be the first lidar mission to sense the global wind field from space. The instrument is based on a direct-detection Doppler lidar operating at 354.9 nm with two spectrometers for aerosol/cloud and molecular backscatter. In order to assess the performance of the Doppler lidar ALADIN on ADM-Aeolus and to optimize the retrieval algorithms with atmospheric signals, an airborne prototype – the ALADIN Airborne Demonstrator A2D - was developed.
The A2D was the first airborne direct-detection Doppler lidar with its maiden flight on the DLR Falcon aircraft in 2005. Three airborne campaigns with a coherent-detection 2-µm wind lidar and the direct-detection wind lidar A2D were performed for pre-launch validation of Aeolus from 2007-2009.
Furthermore, a unique experiment for resolving the Rayleigh-Brillouin spectral line shape in the atmosphere was accomplished in 2009 with the A2D from a mountain observatory at an altitude of 2650 m. Results of this experiment and the latest airborne campaign in the vicinity of Greenland and Iceland will be discussed.
S5O-02
CROSS-WIND LIDAR PROTOTYPE
Geary K. Schwemmer, Matthew Banta1, Alex Achey, Sangwoo Lee, Jie Lei1, Mikhail Yakshin, Jumani Blango
1 Science & Engineering Services, Inc. (SESI),6992 Columbia Gateway Drive, Columbia, MD, 21046, USA A prototype Cross (X) -Wind Lidar system was designed and developed with the objective of measuring 2-D wind vector profiles with 200 m and 2 s resolution along a single line of sight as a substitute for an array of conventional cup and vane anemometers. Innovative aspects of the system design include a 1030 nm Yb:YAG laser transmitter, and twin fiber-coupled transceivers with photon counting detectors and automatic irises to limit background light. The system was tested by comparing winds aloft as measured with the lidar to Aircraft Communications Addressing and Reporting System (ACARS) wind data taken by commercial aircraft at the same altitudes and times at nearby locations. To validate the lidar measurements, a controlled experiment was performed, in which a small engine driven propeller was used to generate a quasi-steady state stream of aerosol laden air. The lidar was positioned to observe the prop-wash from the engine and the resulting wind data was compared to sonic anemometer measurements from within the prop’s air stream. The air stream was seeded with smoke to ensure the lidar signal measurements were heavily weighted to the range of the plume so as not to be averaging ambient air motions into the wind measurements.
2D-DECONVOLUTION METHOD TO REMOVE THE EFFECTS OF A CHIRPED LASER PULSE FROM COHERENT WIND LIDAR DATASETS
Johannes Bόhl, Ronny Engelmann, Albert Ansmann
Leibniz Institute for Tropospheric Research, Permoserstrasse 15, 04318 Leipzig, Germany
A chirped laser pulse can introduce artifacts into coherent Doppler lidar datasets. At close vicinity of strong signal gradients artificial velocities can occur. In regions with continuous signal strength the measured velocities can be shifted by a constant factor. We show how to remove these artifacts and how to retrieve accurate velocity estimations from clouds, virgae and the planetary boundary layer. A two-dimensional deconvolution technique is applied to the averaged Doppler spectra in order to correct the chirp effect in the range-frequency space. The chirp correction for a two-hour vertical velocity measurement of a mid-level cloud is presented. The deconvolution method is applied to the averaged Doppler spectra. No access to the raw heterodyne signal is necessary. The complexity of the data acquisition software and the amount of data to be stored is significantly reduced. The method also increases the signal resolution in the range-and frequency dimension and should thus be applied even if there is no chirp.
S5O-04
COMPARATIVE ANALYSIS OF DIFFERENT THEORETICAL MODELS OF THE DOPPLER FREQUENCY ESTIMATION
Evgeniya A. Shelekhova, Alexander P. Shelekhov
Institute of Monitoring of Climatic and Ecological Systems Siberian Branch of RAS, Tomsk, 10/3, Academichesky Ave., 634055, Russian Federation
In this paper we compare the local, non-local, Gaussian, and non-Gaussian models of the Doppler shift estimation. It shows that the non-Gaussian model agrees to the local model if conditional Gaussian fluctuations of the Doppler shift estimation are zero and size of scattering volume is small. The behavior of the Doppler shift estimation of non-Gaussian random signal agrees to results obtained by the non-local model if conditional Gaussian fluctuations are zero. Results of the Gaussian and non-Gaussian models are the same in the case of large size of scattering volume.
S5O-05
ALL-FIBER COHERENT DOPPLER LIDAR DEVELOPMENT FOR CHARACTERIZATION OF PLANETARY BOUNDARY LAYER DYNAMICS AND COMPARISON TO OTHER
VERTICAL PROFILERS
Mark F. Arend, Sameh Abdelazim, David Santoro, Fred Moshary, Barry Gross, Yonghua Wu, Sam A. Ahmed
Optical Remote Sensing Lab, City College of New York, NY, NY 10031, USA
The development, operation and utility of a fiber based Doppler Wind Lidar is presented. The ongoing development strategy exploits standard telecommunicating technologies and is inspired by robust system design goals that incorporate advancements in high data rate data acquisition with Field Programmable Gate Array programming techniques. The system has been operated in scanning mode, providing horizontal and vertical wind vector information as well as in a purely vertical mode, allowing for uninterruptable characterization of updraft and downdraft. By simultaneously incorporating observations from an aerosol backscatter direct detection atmospheric lidar at 1064nm as well as a hyperspectral microwave radiometer, cross validation of the vertical profiles can be performed and a more complete understanding of the planetary boundary layer (PBL) can be obtained. Some examples of the operation are presented, pointing out the usefulness of the wind lidar observables alongside observations from the other profilers for characterization of the growth (e.g. mixing height) of the PBL layer.
S5O-06
EARLY RESULTS OF COMPACT COHERENT DOPPLER WIND LIDAR AT IITM, PUNE, INDIA
Panuganti C.S. Devara, Yeddu Jaya Rao, Sunil M. Sonbawne, M.G. Manoj, Kundan K. Dani Indian Institute of Tropical Meteorology, Dr. Homi Bhabha Road, Pashan, Pune 411 008, India
A coherent Doppler wind lidar (Leosphere Model WindCube70TM) has been operated, for the first time, at the Indian Institute of Tropical Meteorology (IITM), Pune, India (18o43’N, 73o51’E, 559 m amsl.) for mapping of 3-dimensional wind fields up to about 2 km amsl. under different meteorological situations, during July 2009. This lidar operates with an eye-safety laser radiation at 1.54 µm at pulse energy of 10 µJ. These specifications facilitate the entire system highly portable so that it can be operated easily at different locations associated with varied environmental conditions. One of the unique features of the system is that, unlike the conventional lidars, this mini-lidar is equipped with a wiper assembly which allows the system to operate during rain etc. The high performance of the above system prompted us to install next generation (extended) wind lidar (WindCube200TM) with higher pulse power (100 μJ) in July 2010 to probe the winds in clear-air (aerosol particles as tracers) as well as in cloud-air (cloud particles as tracers) up to about 12 km amsl. In this communication, we present a brief description of the low-power lidar together with some salient results, including comparison with co-located AWS, related to winds and waves. Sample data obtained with extended lidar and its calibration with colocated, GP Radiosonde (Vaisala-DigiCORA-MW31) is also presented.