He lived in Paris (and Munich) in the first decade of the 20th century. In Paris, he continued his course of self-education by devoting his time to studying works in the museums and galleries. His paintings thereafter took on aspects of 19th-century French genre and landscape painting, a style suited to Jonnevold's representational approach to landscape. He was primarily a painter of the California landscape, with special emphasis on marine subjects (waves breaking on a rocky shore) and mountain vistas.
Sources: AskArt; Artists in California 1786 - 1940, Edan Milton Hughes, 3d ed.