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At least 181 records · Page 10

Implementation and evaluation of the new wind algorithm in NASA's 50 MHz doppler radar wind profiler

The purpose of this report is to document the Applied Meteorology Unit's implementation and evaluation of the wind algorithm developed by Marshall Space Flight Center (MSFC) on the data analysis processor (DAP) of NASA's 50 MHz doppler radar wind profiler (DRWP). The report also includes a summary of the 50 MHz DRWP characteristics and performance and a proposed concept of operations for the DRWP.

Taylor, Gregory E.

Observing system simulation experiments related to space-borne Lidar wind profiling. Part 1: Forecast impacts of highly idealized observing systems

Simulation experiments comparing the relative importance of an idealized LIDAR wind profiling system with idealized temperature and pressure sounding systems on 12 h forecasts are studied for three "nature' fields representing the true evolving atmospheric states. The three fields are obtained respectively from: (1) a long integration of the GLAS 4th Order Model (4 deg lat x 5 deg lon x 9 levels), (2) a continuous sequence of NMC operational analysis and, (3) a long integration of the ECMWF high resolution (1.875 deg 1 lat x 1.875 deg lon x 15 layers) operational forecast model. These fields are interpolated to the grid of the GLAS model and used for simulating the observed global analysed fields of winds, temperature, moisture and surface pressure. The same interpolated fields are also used for verification of forecast impact. The effects of clouds, aerosol concentrations, and instrument accuracies on the simulated observation will be discussed.

Halem, M.

Comparison Analysis of the Eastern Range False Cape 915-MHz Doppler Radar Wind Profiler

The United States Space Force (USSF) is responsible for space vehicle launches at its Eastern Range (ER), which includes the Cape Canaveral Space Force Station (CCSFS). Multiple systems are used to measure the atmosphere at the ER, including suites of Doppler Radar Wind Profilers (DRWPs) operating at 915MHz that measure winds within the lowest few kilometers of the atmosphere. Observations of boundary layer winds can be used for multiple applications, including serving as input to toxic dispersion models and characterizing winds for low-level aborts. In fall 2020 the USSF requested NASA’s Marshall Space Flight Center (MSFC) Natural Environments Branch (NE) to evaluate wind output from the False Cape(FC) DRWP system (MSFC NE 2021). In that analysis, it was found that data availability was low in the lowest few hundred meters of a profile, shown in Figure 1. To increase the available data, the USSF modified the quality control (QC) algorithm for the FCDRWP, which collected data from October 2020 to January 2021. In Fall 2021, the USSF requested NASA’s MSFC NE to evaluate the modified QC algorithm by comparing the data processed by the modified method (referred to as beam data) to data processed with the original QC method (referred to as original data). This report describes the system and the analyses that MSFC NE conducted to compare the availability and quality of data from the two QC methods

Maggire Fielder

Tropospheric and stratospheric wind profiling with a direct detection Doppler lidar

The Space Physics Research Laboratory at the University of Michigan has been operating a direct detection, high resolution Doppler Lidar (HRDL) to measure winds in the boundary layer, free troposphere and lower stratosphere. A direct detection Doppler lidar measures the Doppler shift of the aerosol or Rayleigh backscattered signal, from which the wind velocity vector can be retrieved (Benedetti-Michelangeli et al, 1972, 1974; Chanin et al., 1989; Abreu et al., 1992). The system components are shown. The transmitting system is a Continuum NY-60 Nd:YAG laser frequency doubled to a wavelength of 532 nm. The laser is injection seeded for single line mode operation yielding a linewidth of 0.0045 cm(exp -1) (135 MHz) with excellent shot-to-shot frequency stability. The laser produces 60 mJ pulses and operates at a 50 Hz repetition rate for an effective output power of 3.0 W. A description of the University of Michigan's Doppler lidar is given with examples of wind profiles for the boundary layer, free troposphere, and for the lower stratosphere. The system provides a reliable method of remotely measuring the wind. The wind error is smallest in regions of high aerosols. The system also produces aerosol extinction profiles versus altitude which can be determined by the shape of the spectra. The system has been installed in a trailor so that measurements can be made for field campaigns. Winds and aerosol data are available immediately at the site for use in forecasting.

Abreu, Vincent J.

Wind profile estimation from point to point laser distortion data

The author's results on the problem of using laser distortion data to estimate the wind profile along the path of the beam are presented. A new model for the dynamics of the index of refraction in a non-constant wind is developed. The model agrees qualitatively with theoretical predictions for the index of refraction statistics in linear wind shear, and is approximated by the predictions of Taylor's hypothesis in constant wind. A framework for a potential in-flight experiment is presented, and the estimation problem is discussed in a maximum likelihood context.

Leland, Robert

Expected Characteristics of Global Wind Profile Measurements with a Scanning, Hybrid, Doppler Lidar System

Over 20 years of investigation by NASA and NOAA scientists and Doppler lidar technologists into a global wind profiling mission from earth orbit have led to the current favored concept of an instrument with both coherent- and direct-detection pulsed Doppler lidars (i.e., a hybrid Doppler lidar) and a stepstare beam scanning approach covering several azimuth angles with a fixed nadir angle. The nominal lidar wavelengths are 2 microns for coherent detection, and 0.355 microns for direct detection. The two agencies have also generated two sets of sophisticated wind measurement requirements for a space mission: science demonstration requirements and operational requirements. The requirements contain the necessary details to permit mission design and optimization by lidar technologists. Simulations have been developed that connect the science requirements to the wind measurement requirements, and that connect the wind measurement requirements to the Doppler lidar parameters. The simulations also permit trade studies within the multi-parameter space. These tools, combined with knowledge of the state of the Doppler lidar technology, have been used to conduct space instrument and mission design activities to validate the feasibility of the chosen mission and lidar parameters. Recently, the NRC Earth Science Decadal Survey recommended the wind mission to NASA as one of 15 recommended missions. A full description of the wind measurement product from these notional missions and the possible trades available are presented in this paper.

Kavaya, Michael J.

A Comparison of Boundary Layer Wind Profilers for Use with Space Launch Vehicles

The United States Air Force (USAF) operates two space launch ranges, the Eastern Range (ER) and the Western Range (WR). The ER is primarily located at the Cape Canaveral Air Force Station (CCAFS) and the WR is located at the Vandenberg Air Force Base (VAFB). Multiple systems are used to measure the atmosphere at both ranges, including a suite of 915-Mhz (megahertz) Doppler Radar Wind Profilers (DRWP). The 915-MHz DRWPs are used to measure winds in the lowest few kilometers of the atmosphere, primarily in the boundary layer. Boundary layer winds are important during launch, and observations of such can be used as input to toxic dispersion and low-level abort trajectory models. However, these 915-MHz systems are nearing the end of their service life and need to be replaced by systems with similar, or greater, capabilities. The USAF funded evaluations of two systems: a 449-MHz DRWP and a Lidar. Both systems were stationed at each range for separate periods of approximately three months from November 2017 through May 2018. The USAF also funded NASA’s Marshall Space Flight Center (MSFC) Natural Environments Branch (NE) to evaluate wind output from the two systems. MSFC NE conducted analysis to demonstrate the system’s wind accuracy relative to measurements from the Automated Meteorological Profiling System (AMPS) (Divers et al., 2000), data availability, and Effective Vertical Resolution (EVR).

Orcutt, John M.

The influence of velocity variability on the determination of wind profiles

High sensitivity radars allow the determination of velocity estimates at time resolutions down to one minute or better. Because of the variability introduced to the mean wind due to turbulence and waves, the high resolution profiles may not be too useful for forecasting applications, although they yield the most realistic estimate of the instantaneous wind profile. Profiles of wind speed and direction, vertical velocity and echo power, which were deduced in real-time on 23 August 1981 with the spaced antenna drift mode of the SOUSY-VHF-Radar are shown. Whereas these profiles were measured within 1 minute, the operating routine allowed the selection of variable (longer) measuring periods, and one has to search for the optimum duration of the data averaging period. A high time resolution wind vector diagram is given which gives an idea of the temporal variability. The data were obtained with the spaced antenna technique, which allows a good estimate of the horizontal wind without having to correct for the vertical velocity component. The wind vectors specifically indicate a quasi-periodic variation in direction. This is assumed to be due to gravity waves since the vertical velocity also shows periodical variations with the same period. The consistency of these spaced-antenna VHF radar results along with the radiosonde data convinced researchers that the method is quite suitable for wind profiling applications.

Rottger, J.

Airborne Wind Profiling With the Data Acquisition and Processing System for a Pulsed 2-Micron Coherent Doppler Lidar System

A pulsed 2-micron coherent Doppler lidar system at NASA Langley Research Center in Virginia flew on the NASA's DC-8 aircraft during the NASA Genesis and Rapid Intensification Processes (GRIP) during the summer of 2010. The participation was part of the project Doppler Aerosol Wind Lidar (DAWN) Air. Selected results of airborne wind profiling are presented and compared with the dropsonde data for verification purposes. Panoramic presentations of different wind parameters over a nominal observation time span are also presented for selected GRIP data sets. The realtime data acquisition and analysis software that was employed during the GRIP campaign is introduced with its unique features.

Beyon, Jeffrey Y.

Constraints on resolving meso-alpha and meso-beta phenomena using a space-based Doppler lidar wind profiler

Lidar shot management and wind computation algorithms are used to determine the constraints on resolving mesoscale (alpha and beta) wind fields. Examples of simulated Doppler lidar performance in resolving wind gradient features are presented using currently proposed scan and signal processing parameters, and GCM model outputs are used as input wind fields. Results indicate that with the present constraints on lidar lifetime, scan rates, and orbit altitudes, the limits of mesoscale wind feature resolution are close to wavelengths of 100 km.

Emmitt, G. D.

Determining the power-law wind-profile exponent under near-neutral stability conditions at sea

On the basis of 30 samples from near-simultaneous overwater measurements by pairs of anemometers located at different heights in the Gulf of Mexico and off the Chesapeake Bay, Virginia, the mean and standard deviation for the exponent of the power-law wind profile over the ocean under near-neutral atmospheric stability conditions were determined to be 0.11 +/- 0.03. Because this mean value is obtained from both deep and shallow water environments, it is recommended for use at sea to adjust the wind speed measurements at different heights to the standard height of 10 m above the mean sea surface. An example to apply this P value to estimate the momentum flux or wind stress is provided.

Hsu, S. A.

The Use of MERRA-2 Near Surface Meteorology to Understand the Behavior of Planetary Boundary Layer Heights Derived from Wind Profiler Data over the US Great Plains

The atmospheric general circulation model (GCM) that underlies the MERRA-2 reanalysis includes a suite of physical parameterizations that describe the processes that occur in the planetary boundary layer (PBL). The data assimilation system assures that the atmospheric state variables used as input to these parameterizations are constrained to the best fit to all of the available observations. Many studies, however, have shown that the GCM-based estimates of MERRA-2 PBL heights are biased high, and so are not reliable for boundary layer studies.A 20-year record of PBL heights was derived from Wind Profiler (WP) backscatter data measured at a wide network of stations throughout the US Great Plains and has been validated against independent estimates. The behavior of these PBL heights shows geographical and temporal variations that are difficult to attribute to particular physical processes without additional information that are not part of the observational record.In the present study, we use information on physical processes from MERRA-2 to understand the behavior of the WP derived PBL heights. The behavior of the annual cycle of both MERRA-2 and WP PBL heights shows four classes of behavior: (i) canonical, characterized by a monthly progression in PBL height that follows the solar insolation, (ii) double peak, characterized by canonical behavior that is interrupted by a minimum in July, (iii) late peak, characterized by a suppressed heights in May and June, and return to canonical in July and August, and (iv) early peak where the PBL height rises with solar insolation but is suppressed later in the summer. The explanation for these behaviors and the relationship to local precipitation, temperature, sensible and latent heat fluxes, net radiation and aerosol load is articulated using information from MERRA-2.

Salmun, Haydee

The Use of MERRA-2 Near Surface Meteorology to Understand the Behavior of Planetary Boundary Layer Heights Derived from Wind Profiler Data over the US Great Plains

The atmospheric general circulation model (GCM) that underlies the MERRA-2 reanalysis includes a suite of physical parameterizations that describe the processes that occur in the planetary boundary layer (PBL). The data assimilation system assures that the atmospheric state variables used as input to these parameterizations are constrained to the best fit to all of the available observations. Many studies, however, have shown that the GCM-based estimates of MERRA-2 PBL heights are biased high, and so are not reliable for application related to constituent transport or the carbon cycle. A new 20-year record of PBL heights was derived from Wind Profiler (WP) backscatter data measured at a wide network of stations throughout the US Great Plains and has been validated against independent estimates. The behavior of these PBL heights shows geographical and temporal variations that are difficult to attribute to particular physical processes without additional information that are not part of the observational record. In the present study, we use information on physical processes from MERRA-2 to understand the behavior of the WP derived PBL heights. The behavior of the annual cycle of both MERRA-2 and WP PBL heights shows three classes of behavior: (i) canonical, where the annual cycle follows the annual cycle of the sun, (ii) delayed, where the PBL height reaches its annual maximum after the annual maximum of the solar insolation, and (iii) double maxima, where the PBL height begins to rise with the solar insolation but falls sometimes during the summer and then rises again. Although the magnitude of these types of variations is described by the WP PBL record, the explanation for these behaviors and the relationship to local precipitation, temperature, hydrology and sensible and latent heat fluxes is articulated using information from MERRA-2.

MERRA

WINDPROF: Merged Best-Estimate Wind Profile Data – Site A1 (AWAKEN Campaign)

WINDPROF provides 10-minute wind and turbulence profiles, integrating Doppler lidars and anemometers during the AWAKEN campaign. Key data include wind speed, direction, vertical velocity, and turbulence parameters, with standardized quality control (e.g., instrument-specific thresholds and inter-instrument validation). Profiles are interpolated to a height grid (20 m spacing below 100 m; 30 m above) and include uncertainty estimates, offering reproducible methods for atmospheric research, model validation, and wind energy studies.

17 WIND ENERGY

WINDPROF: Merged Best-Estimate Wind Profile Data – Site A2 (AWAKEN Campaign)

WINDPROF provides 10-minute wind and turbulence profiles, integrating Doppler lidars and anemometers during the AWAKEN campaign. Key data include wind speed, direction, vertical velocity, and turbulence parameters, with standardized quality control (e.g., instrument-specific thresholds and inter-instrument validation). Profiles are interpolated to a height grid (20 m spacing below 100 m; 30 m above) and include uncertainty estimates, offering reproducible methods for atmospheric research, model validation, and wind energy studies.

17 WIND ENERGY

WINDPROF: Merged Best-Estimate Wind Profile Data – Site H (AWAKEN Campaign)

WINDPROF provides 10-minute wind and turbulence profiles, integrating Doppler lidars and anemometers during the AWAKEN campaign. Key data include wind speed, direction, vertical velocity, and turbulence parameters, with standardized quality control (e.g., instrument-specific thresholds and inter-instrument validation). Profiles are interpolated to a height grid (20 m spacing below 100 m; 30 m above) and include uncertainty estimates, offering reproducible methods for atmospheric research, model validation, and wind energy studies.

17 WIND ENERGY

Methods for verifying the accuracy of wind profiles

Comparisons of radar-measured winds have been made with several types of measurements not only to verify radar data but also to seek a satisfactory comparison method. Three of the comparisons that have been made with Colorado Profiler radars are summarized. Radar measurements were compared with radiosonde measurements. Infrared lidar and 915 MHz radar were compared with radiosondes. A brief radar/radar comparison was made using the 50-MHz radar and a 3-cm wavelength meteorological Doppler radar during precipitation.

Strauch, R. C.