Ticosonde is a NASA-supported collaboration between the United States and Costa Rica, now in in its 13th year, that makes regular balloonsonde measurements of ozone and water vapor from the surface to the middle stratosphere over Costa Rica. At a latitude of 10N, Ticosonde is the only long-term balloonsonde program measuring stratospheric water vapor in the deep tropics. In addition to water vapor and ozone, since 2012 Ticosonde has been profiling sulfur dioxide plumes emitted from Turrialba, an active volcano close to San Jose.