The cover photo shows the seasonal average surface wind speed within five years from 2007 to 2011 through the study into "Evaluation of resource spatial-temporal variation, dataset validity, infrastructures and zones for Vietnam offshore wind energy".

The seasonal variation of wind speed and direction over the period 2007 to 2011 can be evaluated from the figure, where the study considers four seasons: winter being December - January - February (DJF), spring including March - April - May (MAM), summer including June - July - August (JJA), and autumn including September - October - November (SON). In the winter months, the north-eastern monsoon is stronger than the winds during the other seasons in Vietnam. The south-western monsoon is quite strong in the summer months June - July - August (JJA).  

To get more understanding about the topic, please see the full article "Evaluation of resource spatial-temporal variation, dataset validity, infrastructures and zones for Vietnam offshore wind energy" in pages 03-16 of this issue.