GWOLF and VALIDAR Comparisons M. Kavaya & G. Koch NASA/LaRC D. Emmitt & S. Wood SWA Lidar Working Group Meeting Sedona, AZ January 2004 Outline NASA/LaRCs Lidar Intercomparison Facility VALIDAR GWOLF VALIDAR intercomparisons Hard target experiments Cloud returns Vertical motion Lidar Intercomparison Facility (LIF) at NASA Langley Research Center Lidar Intercomparison Facility Features: Inside NASA grounds Paved parking lot for up to 4 lidar systems Row of surveyed marks on parking lot with 32-foot spacing Row of 4 target lights on tall structure with 32-foot spacing Surveyed positions of lidars and targets allows for parallel alignment among the lidars Target lights at 677-m range, and 6 elevation angle Target lights atop poles allowing atmospheric data collection while aimed at lights Utilities available including telephone, intercom, internet, and electrical power VALIDAR & GWOLF at the Lidar Intercomparison Facility Location Of Target Lights Bldg 1297 R-B-Y-G View Of Lidars From The Target Lights Location Location Of Lidars Bldg 1159 Lidar Intercomparison Facility Possible Enhancements: Lidar aim compensation for differing beam departure heights Calibrated flat targets mounted on flat structure or at ground level for horizontal path Calibrated velocity moving targets (> ? m/s) Detectors near the target lights to confirm lidar aiming Ancillary in situ and/or lidar sensors Validar Objectives: Demonstrate advanced 2- m lidar components in a complete lidar system. High-energy lasers, receiver optics, detectors, and electronics are being developed at LaRC from a variety of funding sources. Validar serves as a testbed for this development. Make field measurements as required for validation. FY 04 Specifications are - laser pulse energy = 100 mJ (78 mJ) - pulse repetition rate = 5 Hz (10 Hz) - pulse width = 150 ns - wavelength = nm Lidar Specifications FY 02 FY 03 FY 04 (water cooled) (cond. cooled) (cond. cooled) pulse energy 30 mJ 83 mJ (65 mJ) 100 mJ (78 mJ) pulse rep. freq. 5 Hz 5 Hz (10 Hz) 5 Hz (10 Hz) wavelength nm nm nm pulse length 180 ns 150 ns 150 ns spectrum single freq. single freq. single freq. VALIDAR Trailer Lidar System Data Analysis & Visitors Rooms Validation Lidar Facility Validation Lidar (VALIDAR) Facility: Well-instrumented 48 ft long Trailer Hemispherical Scanner with 20 cm effective aperture Elaborate Video System consisting of 2 sets of cameras, monitors, and recorders Weather Station GPS Receiver Powerful state-of-the-art Coherent Doppler Lidar mJ, 5-10 Hz, Diode-pumped Transmitters 10 cm COTS and 25 cm SPARCLE Telescopes Real-time data processor and display Validation Lidar Facility GWOLF (Groundbased Wind Observing Lidar Facility) Funded by IPO as part of NPOESS development of cal/val program for space based wind observing systems such as QuikScat, WindSat, CMV, WVMV and future DWLs Currently the TODWL system mounted in a trailer; plan to replace TODWL scanner with a roof mounted hemispherical scanner. Validar/GWOLF Comparisons Performed at LaRCs LIF Horizontal and vertical stares 200m resolution for Validar 1 minute averaging GWOLF hard target and threading Performed at LaRCs LIF Using corrugated metal enclosed elevator shaft at 677 meters from lidar as hard target 100 meter range gates 5 peak threading Cloud returns Performed at LaRCs LIF Objective is to understand how to process and interpret GWOLF returns from cloud boundaries (large ~ dB backscatter gradients) Vertical velocity from VADs Performed at LaRCs LIF Question is How accurate and reliable is the estimate of the vertical velocity using the offset in the sine fit of a partial VAD Interweaved a 25 second vertical stare into a 7 point partial VAD. Summary The LaRCs Lidar Intercomparison Facility enables long term, iterative evaluation of specific lidar performance issues. Cloud boundary returns, hard target (ground surrogate) returns, instrument stability and low SNR signal processing investigations Plan is to bring direct detection systems to LaRC for detailed investigations of both individual as well as hybrid wind sensing issues. Clouds Backscatter values based upon backscatter data at wavelengths other than 2 microns Modeled to 2 microns (rather wavelength independent) Cirrus (0 to -37 C): 7.0 E-5 m -1 sr -1 Warm, opaque: 1.8 E-5 m -1 sr -1 Per hard target calibration Per current theory TODWL 03 Cirrus at 5800 m agl Lidar Design