Skip Navigation Links 
NOAA logo-Select to go to the NOAA homepage NDBC Title GraphicClick to go to NDBC home page   Select to go to the NWS homepage
Home News Organization
    Station List

    Mobile Access
    Interactive Map
    Classic Maps
    Obs Search
    Ship Obs Report
    BuoyCAMs Image indicating link to BuoyCAMs page
    HF Radar
    RSS Feeds Image indicating link to RSS feed access page
    Obs Web Widget
    Email Access
    Web Data Guide

 Station Status
    NDBC Maintenance
    NDBC Platforms

 Program Info
    Facebook Logo
    NDBC on Facebook
    About NDBC
          Moored Buoy
    IOOS® Program

    NDBC Draft PEA
    NDBC DQC Handbook
    Hurricane Data Plots

 Science Education

 Media Inquiries
 Contact Us
 Visitor Information is the U.S. government's official web portal to all federal, state and local government web resources and services.

What averaging procedures are performed on the wind measurements?

Two wind averaging methods are used to calculate average wind speed and direction.

  1. The first wind averaging technique applies to those measurements reported by all DACT, VEEP, and ARES payloads. The average wind speed is the simple scalar average of the wind speed observations. A "unit-vector" average is used to calculate the average wind direction. In this technique, unity serves as the length of the vector, and the wind direction observations serve as the orientation of the vector. The u and v components are then calculated for each observation. Next, the average u and v components are computed and the average wind direction is derived from "arctan(u/v)." Note that this technique will produce greater wind speeds than if a true vector average was used.
  2. The second method, used to calculate average speed and direction reported by NDBC's older GSBP payloads, is a true vector average. In this scheme, the magnitude of the vector is represented by the wind speed observation and the direction observations are used for the orientation. The vectors are then broken down into their u and v components. All u and v components are then averaged separately. The resulting average speed and direction are calculated from the Pythagorean Theorem and "arctan(u/v)," respectively.
For a comparison of vector and scalar averaging of winds, see:

Gilhousen, D.B., 1987: A field evaluation of NDBC moored buoy winds. Journal of Atmospheric and Oceanic Technology,4, 94-104.