Wind Plugin for wind along both x and y axes

I am trying to use the wind plugin. I have added the following lines of code to the world file.

`<!-- Wind Plugin -->
<plugin name='wind_plugin' filename='libgazebo_wind_plugin.so'>
  <frameId>base_link</frameId>
  <robotNamespace/>
  <windVelocityMean>6.0</windVelocityMean>
  <windVelocityMax>12.0</windVelocityMax>
  <windVelocityVariance>0</windVelocityVariance>
  <windDirectionMean>1 0 0</windDirectionMean>
  <windDirectionVariance>0</windDirectionVariance>
  <windGustStart>0</windGustStart>
  <windGustDuration>0</windGustDuration>
  <windGustVelocityMean>0.0</windGustVelocityMean>
  <windGustVelocityMax>0.0</windGustVelocityMax>
  <windGustVelocityVariance>0</windGustVelocityVariance>
  <windGustDirectionMean>1 0 0</windGustDirectionMean>
  <windGustDirectionVariance>0</windGustDirectionVariance>
  <windPubTopic>world_wind</windPubTopic>
</plugin>`

I wanted to simulate wind with velocity 3 m/s along x-axis and 4 m/s along y-axis.
How should I modify the code of the wind plugin to achieve this. Also I wanted to ask whether the wind velocities are in m/s?