What is the Japanese word (noun) that means “the bittersweetness of a brief, fading moment of transcendent beauty.”?

The article written by Emily Anthes, appearing in the New Yorker, May 12 issue under the title, “The Glossary of Happiness” wraps up with the following paragraph:

Lomas (a lecturer in applied positive psychology at the University of East London) returned to the University of East London and launched the Positive Lexicography Project, an online glossary of untranslatable words. “If you just put them out there and people are aware of them, then—almost like linguistic natural selection—people will find ones that appeal to them, and they might start using them,” Lomas said. If he succeeds, we may stroll through these waning days of spring more aware of aware—the Japanese noun for “the bittersweetness of a brief, fading moment of transcendent beauty.”

I can’t think up a Japanese word (noun) equivalent to the notion, “the bittersweetness of a brief, fading moment of transcendent beauty” in English. Would you suggest me any Japanese counterpart that comes up to your mind?