Ocean, Atmosphere and Biorssource

What is a Wind Rose?

A wind rose shows the frequency of wind coming from various directions, often combined with speed categories. It helps identify dominant wind directions and their associated speeds.

2. Elements of a Wind Rose

• Sectors: Represent wind directions (e.g., N, NE, E, etc., usually divided into 16 or 32 sectors).

• Bars: Indicate the frequency of winds from each direction, scaled as percentages of total measurements.

• Colors: Represent wind speed ranges (e.g., 0–2 m/s, 2–4 m/s, etc.).

• Inner Circle: Represents calm conditions, often shown as a percentage.

What is Wind Shear?

Wind shear is the rate of change of wind speed (and sometimes direction) with height, often expressed mathematically as: u(z)=[u_*/k] x [ln(z/z_0)]
Where:

• u(z): Wind speed at height z.

• u_*​: Friction velocity.

• k: von Kármán constant (≈0.4\approx 0.4≈0.4).

• z_0​: Surface roughness length.

wind shear plays a significant role in explaining the stress at the atmosphere-ocean interface. The interaction between atmospheric winds and the ocean surface generates wind stress, which is critical for driving ocean currents, waves, and mixing processes.