Wind Roses
Product Description

Wind Roses for stations can be created with many different options across a station’s period of record. 

Traditional versus Inverted Wind Rose

A traditonal wind rose shows the direction the wind blows from. An inverted wind rose shows the direction that the wind blows towards.

Sub-Interval Windows

Changing the Start and End Date windows will create a wind rose for only the date range selected.  For example, a wind rose for just spring dates would have start and end dates of March 1 and May 31 respectively. 
Changing the hour window will create a wind rose between the hours selected.  For example, a wind rose for times between 8:00 AM and 4:00 PM would have start and end hours of 8 and 16 respectively.

Output Types

Three unit types are available: miles per hour, meters per second and knots.  Table outputs available are either the percent of wind in each category or the total count of observations in each category. Wind speed divisions default to the Beaufort scale, but can also be chosen for every 1, 2, 3 or 5 units.  The calm threshold is for the units that are selected, and can be changed.  The default of 1.3 mph is the calm threshold for the Beaufort scale.   Wind roses can be done either on a 16-point (directional) or 36-point compass. 
USE OF 16-POINT COMPASS DISCLAIMER
Since wind direction in modern times is measured every 10 degrees, some bias to the cardinal directions of north, south, east and west are present in the 16 point compass.  No bias correction has been applied to the 16-point compass wind rose, and should be used with caution.  Read about three methods to apply wind rose bias correction in Applequist 2011.

Element Filtering

Wind rose output can also be filtered by other observed variables, such as air temperature and precipitation.  The filter can be applied for both an upper and lower bound if desired.  Examples include:

1. Precipitation greater than 0.00 inches
2. Average Air Temperature between 80°F and 90°F
3. Visibility less than 1 mile

Output

Both a Highcharts wind rose and a table of values are available on the output page.  Wind speed ranges can be toggled on and off in the wind rose, and values can be found by hovering over each category on the rose.  The wind rose can also be downloaded from the menu in the top right of the rose. 
A CSV version of the wind rose output table is forthcoming from the left side of the main menu.

 

About Hourly Data within MRCC's cli-MATE Portal

The MRCC uses the Applied Climate Information System (ACIS) hourly data feed for cli-MATE's hourly data products. Developed by NOAA’s Regional Climate Centers (RCCs), ACIS simplifies climate data management, offering historical weather data from sources such as the National Weather Service, Automated Surface Observing System (ASOS), the Community Collaborative Rain Hail & Snow (CoCoRaHS) network, and various gridded datasets.

While using the MRCC’s hourly data products, there are a few important caveats to consider:

Top-of-the-hour observations only: Hourly products are based solely on top-of-the-hour readings and exclude sub-hourly observations, special observations, and 24-hour summary observations.

Limited to first-order (ASOS) stations: Only data from first-order U.S. ASOS stations, which are mainly located at medium to large airports, are provided. These stations measure standard weather variables, including temperature, humidity, wind speed and direction, visibility, precipitation, and atmospheric pressure.

Non-quality-controlled data: Hourly data are based on raw decoded METAR observations, which have not been fully quality-controlled.

Enhancements are underway within the ACIS system to expand access to sub-hourly observations, offer more station locations, and integrate with quality-controlled data from the Global Historical Climatology Network (GHCN) hourly dataset.