aubade vs early morning

aubade

noun
  • A poem or song evoking or greeting the dawn or early morning. 

  • A concert held at dawn or in the morning, especially outdoors. 

  • A morning love song, or a song of lovers parting in the morning. 

early morning

noun
  • the time between midnight and sunrise 

How often have the words aubade and early morning occurred in a corpus of books? (source: Google Ngram Viewer )