This is an interesting question. On one hand, they sure look like streetlights to me. After all, if it stands like a streetlight, and shines like a streetlight...1
However, I perused some dictionaries, to shed some light on this. Can a streetlamp be used to light anything besides a street? In the dictionary, I found the qualifier "used to light a street or road" surprisingly, stubbornly prevalent in the definitions!
- a light mounted on a high pole, used to illuminate a street or road (YD)
- a light, usually supported by a lamppost, for illuminating a street or road (d.com)
- a light usually mounted on a pole and constituting one of a series spaced at intervals along a public street or highway (M-W)
- a light, usually on a tall post, that lights a road at night (Cambridge)
- A light supported on a lamppost; for illuminating a street (Ultralingua)
- a light illuminating a street or road, typically mounted on a tall post (OED)
When I visited Wordnik, however, I did manage to find a meaning that allows a more general usage of the word (from Wiktionary):
Concerning a compound word like streetlight, is that a word that gets coined because the first such contraptions were used to light streets? Or is the word meant to purposefully differentiate streetlights from, say nightlights, porch lights, and rinklights? If I carry my backpack like a briefcase, is it no longer a backpack? If I use a screwdriver to open a paint can, is it no longer a screwdriver? And if I use a streetlamp to light an outdoor rink, is it no longer a streetlamp?
Strictly speaking, the dictionaries would caution you against using the word streetlight to describe a light for a rink, but, if I was your editor, I might let it slide. It all depends on the image you want to convey: if the lamp was made by a company that manufactures streetlights (and the ones in your picture seem to be just that, because of the "arm" that distances the bulb from the pole), then I think streetlight is fine. But if they are specially-designed lights used to light up a field or rink, then floodlights would be much more appropriate.
1A reference to the "duck test."