CREATE TABLE table_name_37 (purpose VARCHAR, yield VARCHAR, location VARCHAR, elevation_ VARCHAR, _height VARCHAR)
Which Purpose has an Elevation + Height of 0 + metres (ft), a Location of bikini, namu (charlie), and a Yield of 220 kt?
SELECT purpose FROM table_name_37 WHERE elevation_ + _height = "0 + metres (ft)" AND location = "bikini, namu (charlie)" AND yield = "220 kt"