Search NASA⌕ Search

SEARCH · Search NASA

Results for “WIND MEASUREMENT”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1987

Comparison of moored wind measurements from a spar and toroidal buoy in the eastern equatorial Pacific during February-March 1981

Wind measurements at 3.8 m from a surface-following toroid and at 4.0 m from a vertically stable spar were compared to estimate the influence of mooring motion. Buoys were separated by 9 km. Data were obtained at 15-min intervals for 41 days in the equatorial Pacific, where the maximum 15-min averaged wind speed was 9.0 m/s and wind speeds averaged 4.5 m/s. Toroid wind speeds were 3.5 percent greater than the spar data, and the correlation coefficient between 15-min toroid and spar data was 0.92. The frequency of the 50-percent noise level was 0.125 cph, and the correlation coefficient between 8-hour averaged toroid and spar data was 0.98. Toroid 8-hour averaged wind speeds referenced to 10-m height were 2 percent larger thancorresponding spar data.

Halpern, David↗
NASA NTRS1992

Vertical wind estimation from horizontal wind measurements

This presentation begins with a brief description of the downdraft measurement problem for airborne Doppler based systems and the importance of the downdraft in assessing the hazard posed by a microburst wind shear. This is followed by a review of research on the feasibility of using simple microburst models to compute the downdraft from horizontal wind measurements. The current methodologies for computing the vertical wind are then discussed. A summary of the results and the plan for future research are also presented.

Vicroy, Dan D.↗
NASA NTRS1984

D1 LF Wind Measurements in the 90 to 100 Km Height Range

A short historical review of the development and use of D1 low frequency (LF) techniques for wind measurement is presented and the measuring and evaluation procedures are described. The advantages and disadvantages of D1 LF measurements are examined. Finally, the results of measurements over Central Europe acquired by the Collm Geophysical Observatory are discussed.

Schminder, R.↗
NASA NTRS1985

Influence of coherent mesoscale structures on satellite-based Doppler lidar wind measurements

Efforts to develop display routines for overlaying gridded and nongridded data sets are discussed. The primary objective is to have the capability to review global patterns of winds and lidar samples; to zoom in on particular wind features or global areas; and to display contours of wind components and derived fields (e.g., divergence, vorticity, deformation, etc.). Current considerations in support of a polar orbiting shuttle lidar mission are discussed. Ground truth for a shuttle lidar experiment may be limited to fortuitous alignment of lidar wind profiles and scheduled rawinsonde profiles. Any improvement on this would require special rawinsonde launches and/or optimization of the shuttle orbit with global wind measurement networks.

Emmitt, G. D.↗
NASA NTRS1985

NASA scatterometer oceanic wind measurement system

Satellite scatterometers are active microwave radars designed to yield measurements of near surface horizontal wind velocity over the ocean. Scatterometers are unique in that they are the only existing microwave remote sensing instruments that allow measurements of both wind speed and wind direction. NASA will fly a scatterometer, NSCAT, aboard the Navy Ocean Remote Sensing System (N-ROSS) mission starting in late 1990. N-ROSS is a spaceborne ocean remote sensing system with a planned mission life of three years. In addition to the NSCAT, N-ROSS will have three other microwave instruments mounted on a single satellite flying in a near polar orbit: an altimeter; a special sensor microwave/imager (SSM/I); and a low frequency microwave radiometer. The NSCAT to be flown on N-ROSS is described.

Freilich, M.↗
NASA NTRS1994

Performance of a 2-micrometer coherent Doppler lidar for wind measurements

Measurements of boundary layer winds are presented using a 2-micrometer coherent Doppler lidar and the optimal performance of the maximum likelihood estimator. The systematic error for single-shot estimates was estimated as 3.6 cm/s using measurements from a stationary hard target. The estimation error for measurements of the radial component of the wind field was determined, as well as the fraction of the estimates that are randomly distributed over the velocity search space, when the signal power is low and speckle fading is important. The results from actual data are compared with the results from ideal simulations. The first direct estimation of the spatial structure function of the radial wind field and of the energy dissipation rate is presented for both horizontal and vertical directions of propagation. The rms estimation error of the velocity estimates is found to be within 30% of ideal performance based on simulation.

Frehlich, Rod↗
NASA NTRS1982

Wind measurements by parachute

Tests used the 8 cm Lotta grenade as well as 12 cm M/70 and 10.5 m/62 grenades, released at altitudes between 2000 and 6400 meters. The parachutes were tracked by AP and RFK. In later experiments wind data were also obtained for comparison by tracking hydrogen filled balloons in part with the CORA system, in part with radar. Generally radar picked up the objects without visual assistance. Wind measurements from parachutes correlated well with those obtained by balloon. Even when the radar locked on to a part of a grenade, descending faster than the parachute, some of the measurements obtained were good. Bodies with a greater rate of descent than parachutes, with less or no tendency toward drift and with sufficient, surface for radar tracking, ought to provide reliable results. The existence of vertically well defined winds of jet stream type at low altitudes was established.

Nordstroem, S.↗
NASA NTRS1987

Results from 1984 airborne Doppler lidar wind measurement program. Flight 6: Analysis of line-of-sight elevation angle errors and apparent Doppler velocities

During the summer of 1984 the Marshall Space Flight Center's Airborne Doppler Lidar System (ADLS) made a series of wind measurements in the California Central Valley. This study quantifies the lidar beam angle errors and velocity errors through analysis of ground return signals. Line-of-sight elevation (LOSE) angle errors are under 1 deg. Apparent Doppler ground velocities, as large as 2m/s, are considerably less than in a previous flight experiment in 1981. No evidence was found of a Schuler resonance phenomenon common to inertial navigation systems (INS), however the aperiodic nature of the apparent velocities implies an error in the INS-derived ground speeds. Certain features and subtleties in the ground returns are explained in terms of atmospheric structure and characteristics of the ADLS hardware and software. Finally, least squares and low-pass filtering techniques are suggested for eliminating errors during post-processing.

Rothermel, Jeffry↗
NASA NTRS2019

Analyzing Error in Balloon-Based Wind Measurements Due to Spatial Separation Using the North American Regional Reanalysis

Weather balloons have been a longstanding asset to NASA and Aerospace meteorology. Balloons are used from launch vehicle design to day-of-launch operations. One of the most valuable assets from these balloons is wind data from the surface up to 30 kilometers. Due to aloft winds, the balloons may drift downrange of the launch site and vehicle flight path. A 2017 study found balloons at Kennedy Space Center (KSC) can drift as far as 200 kilometers from the launch site (Decker 2017). To obtain robust launch vehicle wind assessments, it is highly desirable to characterize the wind environment along the flight path. This study looks into the errors associated with spatial separation of wind measurements using the North American Regional Reanalysis (NARR).

Curtis, Nathan↗
NASA NTRS1989

Wind measurements by electromagnetic probes

The operation and performance characteristics of the Marshall Space Flight Center's Radar Wind Profiler, designed to provide measurement of the wind in the troposphere, are discussed. The Radar Wind Profiler uses a technology similar to that used in conventional Doppler radar systems, except the frequency is generally lower, antenna is larger, and dwell time is much longer. Its primary function is to monitor the vertical wind profile prior to launch of the Space Shuttle at more frequency intervals and nearer to launch time than is presently possible with the conventional balloon systems. A new wind profile will be obtained on the order of every 15 min based on an average of five wind profiles measured every 3 min at a height interval of 150 m to 20 km. The most significant features of the Radar Wind Profiler are the continuity in time and reliability.

Susko, Michael↗
NASA NTRSDate not supplied

Lidar and UAS Measurements of Winds for the NASA Advanced Air Mobility Mission

The envisioned future of Advanced Air Mobility involves low-altitude operation of a new class of air vehicles. The low altitudes of the flight paths would have these vehicles spending most of their operation in conditions where unpredictable wind and turbulence effects may occur. Wind measurements will hence be critical to ensure safe and efficient operations for AAM. Such wind measurement could be used as a monitoring system for warning of hazardous wind events, as data input to forecasting models, or as a research tool to understand wind effects in complex environments. To meet this need NASA is evaluating wind sensing technologies with a capability to probe the atmospheric boundary layer. Doppler lidar is a leading candidate ground-based sensor, as shown by the decades-long history of being an effective tool for many wind studies. However, there is a need to re-assess the Doppler wind lidars for the AAM application which involves evaluating wind effects as vehicles operate in and out of vertiports, notably regarding spatial resolution. Meeting the needs for spatial resolution may involve the use of dual-Doppler techniques, rather than just single Doppler lidar. The study was furthermore motivated by looking toward the future of AAM, in which the air vehicles involved can also provide wind measurements. Airborne wind measurements, obtained directly from vehicle-mounted anemometers or indirectly from vehicle navigation data, offer a means to compare remotely sensed wind lidar with in-situ measurements. The following sections report on results of wind measurements obtained using lidar and the small uninhabited aircraft systems (sUAS’s) operating in the same volume of air.

Adam Medina↗
NASA NTRS1990

Temperature and wind measurements and model atmospheres of the 1989 Airborne Arctic Stratospheric Expedition

The ER-2 Meteorological Measurement System provides accurate in situ measurements of atmospheric state variables. During the Airborne Arctic Stratospheric Expedition (AASE) the ER-2 flew over the polar region on 14 occasions in January and February, 1989. Vertical temperature profiles, during aircraft takeoff at about 60 deg N and during midflight descent and ascent at high latitudes, are presented. Latitudinal variations of the horizontal wind measurement are illustrated and discussed. Based on observation data, model atmospheres at 60 deg and 75 deg N, representative of the environment of the AASE campaign, are developed.

Chan, K. R.↗
NASA NTRS1992

Design of a near-IR coherent lidar for high spatial and velocity resolution wind measurement

A coherent Doppler lidar based on a CW diode-pumped, injection seeded, Th:YAG laser operating at approx. 2.02 microns is currently under development. This system is optimized for measurements of boundary layer winds with high spatial, temporal, and velocity resolution. Initially, the system will run alongside a new high repetition rate (5-10 kHz) CO2 mini-Master Oscillator Power Amplifier (mini-MOPA) Doppler lidar, which will provide simultaneous range-resolved Differential Absorption Lidar (DIAL) water vapor measurements. Water vapor DIAL operation of the 2 micron system is being considered as a future option. The anticipated specifications and the preliminary design are discussed.

Grund, Christian J.↗