During the long winter, the harsh restrictions provoked anger and outrage in the public. What is the best way to describe this clause?

In the sentence:

During the long winter, the harsh restrictions provoked anger and outrage in the public.

The clause is ‘During the long winter’, which is a adverbial clause.

Adverb are words used in shifting or adding meaning of a verb, clause, adjective, or another adverb. These words can be used if: firstly, a sentence contains a subject and a predicate. Secondly, when a subordinate conjunction is used and thirdly, if it answer the ‘adverbial questions’ - when, why, when and how. It is also further categorized to time, place, manner, degree, condition, concession and reason