Abstract:

This dataset contains Light Detection and Ranging (LiDAR) and sonic anemometer measurements of wind speed and aerosol variability within the atmospheric boundary layer on Galveston Island, Texas. The data includes daily measurements over five months from 2018-11-17 to 2019-04-28 from two instruments, Halo Streamline XR Doppler Wind LiDAR and 3D CSAT Sonic anemometer, deployed at approximately 100 m from the shore of Galveston, Texas. The LiDAR measures 1D wind velocity [m/s] and doppler backscatter [/m/str] at a spatial resolution of 18 m within a typical range of ~1500 m from the position. The LiDAR dataset is of .hpl format, where each .hpl file consists following information about a particular scan: Range gate length, Pulses/ray (Sampling frequency), Start time and Doppler resolution [m/s]. The sonic anemometer data is simply collocated in .dat format with different columns for timestamps (year, day of the year, hours in decimal, seconds), three velocity components Ux, Uy, Uz [m/s] and atmospheric temperature [deg. Celsius].

Suggested Citation:

Pandya Y., and G.V. Iungo. 2021. LiDAR and sonic anemometer measurements of wind speed and aerosol variability within the atmospheric boundary layer on Galveston Island, Texas from 2018-11-17 to 2019-04-28. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/n7-byg4-d338

Purpose:

The Doppler LiDAR measures velocity and aerosol backscatter at the same spatio-temporal coordinate, which makes it an important instrument to learn the effects of marine-oil aerosol. This data was primarily acquired via various types of scans across the Marine Atmospheric Boundary Layer (MABL) to investigate the marine aerosol effects and dynamics in the same. The sonic data were used to characterize the atmospheric stability (Obukhov length) and turbulent fluxes simultaneously.

Data Parameters and Units:

Main parameters: ID number; Date [Year; Day in that year; eg. Day=40 would correspond to Feb 9th of that year; Hours and minutes in the 24 hr time format; eg. 1535 corresponds to 15:35 time; Seconds]; Ux [X component of velocity (m/s)]; Uy [Y component of velocity (m/s)]; Uz [Z component of velocity (m/s)]; Temperature [air temperature (degree celsius)]; LL [Obukohv length (meters)]; utau [Friction velocity (m/s)]; TS [Respective UTC timestamp of each measurement]. Latitude and longitude of the LiDAR: 29◦11’26.5"N 94◦57’29.8"W; Latitude and longitude of the Sonic anemometer: 29°11'26.5"N 94°57'29.9"W. The LiDAR dataset is of .hpl format, where each .hpl file consists following information about a particular scan: Range gate length, Pulses/ray (Sampling frequency), Start time and Doppler resolution [m/s]. Each scan consists of a set of rays at a particular sampling frequency; each ray has unique data about the position of the scanner - azimuth and elevation [deg.], pitch and roll of the LiDAR system [deg.], ray timestamp, and three columns of wind velocity [m/s], intensity and beta - backscatter coefficient [/m/str] at every range gate. This can be used to generate data of wind velocity and backscatter at a set of spatial locations from the radial range and azimuth-elevation of the scanner, at specific timestamps from a particular .hpl file. Each subfolder consists of all .hpl files generated on that day of the year. All timestamps are in UTC. The CSAT3 Sonic anemometer data is shared in the .dat format in every folder named after each date when it was collected. Some folders may also contain a collocated data of that day in the form of a .m file. Each file contains data for approximately 30 minutes. This data is collected for 20 Hz sampling rate. The .dat files can be opened with any text editor including Notepad. The sonic was aligned pointing towards the Azimuth=270 degrees relative to the LiDAR's coordinate system, or along the shore direction. The coordinate axis for velocity components are aligned such that the positive X along the shore, in the south-east direction anticlockwise from the geographic north and the positive Z points vertically upwards. The Y-axis is thus towards the sea from the shore. The numerical sign of the velocity components is according to this coordinate system. The dataset also includes a ReadMe file with details on file organization and column descriptions.

Methods:

The LiDAR data was generated by the data acquisition computer embedded inside the LiDAR system. The sonic data was collected with the help of a datalogger with an in-house developed code to store .dat files at prescribed scheduling.

Instruments:

LiDAR: Halo Streamline XR Doppler Wind LiDAR Sonic: Campbell Scientific 3D CSAT Sonic anemometer

Individual Files: