NASA Contractor Report 3960 Analysis of Airborne Doppler oppler Radar, and Tall Tower Measurements eric Flows in uiescent and Stormy Weather H. B. Bluestein R. Rabin University of OkZaboma National Severe Storms Laboratory Norman, OkZaboma Norman, OkZahoma R. J. Doviak and M. D. Eilts A. Sundara-Rajan NationaZ Severe Storms Laboratory Cooperative Institute for Norman, OkZaboma M esoscaZe MeteoroZogicaZ Studies Norman, OkZahoma E. W. McCaul University of OkZaboma D. S. Zrnic’ Norman, OkZaboma NationaZ Severe Storms Laboratory Norman, OkZahoma Prepared for George C. Marshall Space Flight Center under Contract NAS8-34749 National Aeronautics and Space Administration Scientific and Technical Information Branch 1986 J PREFACE AND ACKNOWLEDGMENTS The first experiment to combine airborne Doppler lidar and ground based dual Doppler-radar measurements of wind to detail the lower tropospheric flows in quiescent and stormy weather was conducted in Central Oklahoma during four days of June-July 1981. Data from these unique remote sensing instruments, coupled with those from conventional and novel in-situ facilities such as a 500 m tall meteorologically instrumented tower, rawinsonde, and a dense network of surface based sensors, have been analyzed to enhance the under- standing of wind, waves, and turbulence. The data collected for this study and the analyses presented in this report had the multifaceted purposes of (1) comparing winds mapped by ground-based dual Doppl er radars, by anemometers on a tall tower, and by NASA's innovative airborne Doppler lidar, (2) comparing measured atmospheric boundary layer flow with flows predicted by theoretical models; (3) investigating the kinematic structure of air mass boundaries that precede the development of severe storms and, (4) studying the kinematic structure of thunderstorm phenomena (e.g. downdrafts, gust fronts, etc,) that produce wind shear and turbulence hazardous to aircraft but are difficult to observe with conventional instrumentation. The results of experiments reported herein show that it is feasible to have detailed but remotely acquired measurements of the cloudless atmospheric motion in many provocative weather situations, whereas such observations were previously 1imited to scaled-down laboratory experiments, We have carried out these detailed measurements in nature's own laboratory so we can improve fore- casts using data that may become avai 1ab1 e to operational meteorologists. Meeting the challenge of improving weather forecasts and storm hazard warnings demands an integrated and well -conceived experimental design that bui Ids upon a base of theoretical and experimental results and uses the technological expertise, leadership, and cooperation of several research groups, bound together with strong and enduring commitments. NASA's Marshal 1 Space Flight Center (MSFC), NOAA's National Severe Storms Laboratory (NSSL), and the Uni - versity of Oklahoma's Department of Meteorology and Cooperative Institute for Mesoscale Meteorological Studies (CIMMS) have this commitment. This report is the first one showing the results of the combined efforts from this group dedicated to improve our understanding of weather. ii The report is divided into 3 parts. Part I, "Intercomparison of Wind Data From Ai rborne Lidar , Ground-Based Radars and Instrumented 444 m Tower, gives results of the first intercomparison of atmospheric boundary layer wind measured by dual Doppler radars and airborne Doppler lidar. The second part, "The Structure of the Convective Atmospheric Boundary Layer as Revealed by Lidar and Doppler Radars" re1ates remotely sensed properties of homogeneous turbulent flow in the atmospheric boundary layer to those properties predicted by theories. Part I 11, "Doppler Lidar Observations in Thunderstorm Envi ron- ments," gives an analysis of the first observations with an airborne Doppler lidar of thunderstorm outflows and flow of environmental air into a complex of cumulus clouds. Appendix A describes the Doppler lidar instrumentation, its operation, and methods used to deduce the Doppler velocity component of hori- zontal wind. These first results are due to the dedicated efforts of many and the authors are indebted to NASA for its support, under the management of Drs. James Dodge and William Vaughan, and to both the NSSL and NASA staffs for their fine engineering support for this large data collection effort. Jim Bilbro and Ed Weaver of NASA, Chuck DiMarzio of Raytheon, and Bob Lee of Lassen Research, helped us to better understand the airborne lidar system, its unique features and the errors that it is vulnerable to. Dr. Dan Fitzjarrald, NASA, is to be especially thanked for presenting us with the lidar data in an easily usable form, and for constructive discussions Drs. Doug1 as Li1 ly and Claude E. Duchon of the University of Oklahoma gave beneficial comments and suggestions during the course of this study. Encouragement and support from Dr. E. Kessler and staff at NSSL were critical to the quality of the work. Joan Kimpel of CIMMS and Robert Goldsmith of NSSL provided graphic services, and Michelle Foster of NSSL typed the manuscript. The work reported herein has already led to the publication of nine papers and to two others in preparation. The article "The structure of the convective atmospheric boundary layer as revealed by 1 idar and Doppler radars" has appeared in a recent issue of the international journal: Boundary-Layer Meteorology and another article "Estimation of the average surface heat flux over an inhomogeneous terrain" has been accepted for publication in that jour- nal. The paper "Comparison of winds, waves, turbulence as observed by ai r- borne lidar, ground based radars, and instrumented tower" has appeared in the iii American Geophysical Union's journal : Radio Science. The research on "An observational study of a mesoscale area of convection under weak synoptic- scale forcing" has been pub1 ished by the American Meteorological Society's Monthly Weather Review. Papers to Applied Optics and The Journal of Atmospheric and Oceanic Technology are in preparation. This work has also supported two Master Is Theses. Editor. Richard J. Doviak National Severe Storms Laboratory 1313 Halley Circle Norman, OK 73069 April 1985 iv TABLE OF CONTENTS Part Page Preface and Acknowledgments ............................................. ii I . Intercomparison of Wind Data From Airborne Lidar. Ground-Based Radars and Instrumented 444 m Tower ................................... 1 Abstract ............................................................... 2 1.1 Introduction .................................................... 3 1.2 The Experiment .................................................. 3 1.3 Synthesis of Wind Fields ....................................... 6 1.4.1 Mean Wind ...................................................... 7 1.4.2 Wind Profiles ................................................... 8 1.4 3 Intensity of Turbulence ......................................... 9 1.4.4 Spectra of Horizontal Velocity F1 uctuations ..................... 13 1.5 Explanation of Differences Between Lidar and Radar Measured Winds ............................................. 14 1.6 Comparison of Data Collected on July 2. 1981 ................ 18 1.7 Conclusions .................................................... 25 I1 . The Structure of the Convective Atmospheric Boundary Layer as Revealed by Lidar and Doppler Radars ................................. 27 Abstract .................................................... 28 2.1 Introduction ................................................... 29 2.2 Data Collection ................................................ 29 2.3 Data Analysis ................................................... 29 2.3.1 Construction of the Wind Profile .............................. 30 2.3.2 Calculation of Velocity Spectra ........................... 31 2.3.3 Determination of Micrometeorological Parameters ............... 31 2.3.4 Estimation of Momentum Flux Profiles .......................... 35 2.4 Results ..................................................... 36 2.4.1 Vertically Averaged Winds .................................. 36 2.4.2 Momentum Flux and Geostrophic Wind Profiles ..................... 38 2.4.3 Spectra of Horizontal Wind ...................................... 41 2.5 Concluding Remarks .............................................. 41 I11 . Doppler Lidar Observations in Thunderstorm Environments ............. 43 Abstract .............................................................. 44 3.1 Introduction ................................................... 45 3.2 Meteorological Setting for the Experiment ....................... 47 3.3 Data Collection ................................................. 49 3.4 Data Analysis ................................................... 55 3.4.1 Navigation Data Review and Editing .............................. 56 3.4.2 Doppler Spectral Moment Data Review and Editing ................ 58 3.4.3 Velocity Errors Due to Beam Pointing Errors ..................... 59 3.4.4 Preparation of Meteorological Data Fields ...................... 61 3.5 Meteorological Interpretation ................................... 64 3.5.1 Interpretation of Thunderstorm Outflow Data .................... 64 3.5.2 Interpretation of Data at the Edge of an Isolated Cumulus Congestus ............................................... 80 V 1 TABLE OF CONTENTS (Concluded) Part 3.6 Conclusions and Recommendations ................................. Appendix