A permit that allows US amateurs to operate in certain countries of the Americas✓Bonne réponse
The internal amateur radio practices policy of the FCC
An indication of increased antenna reflected power
A forecast of intermittent aurora radio propagation
Explication
An IARP is the International Amateur Radio Permit issued under the Inter-American Convention, which supports operation in signatory countries of the Americas. The other expansions of the acronym do not exist in the rules.