What we have learned from the ALMA Long Baseline Campaigns

I present mm/submm phase characteristics measured at the ALMA long baseline campaigns, and suggestions to a large aperture submillimeter telescope. All the measured spatial structure function (SSF) show that the phase fluctuation increases as a function of baseline length, with a power-law slope of ~0.6 up to around 1 km. In many cases, the slope becomes shallower (average of ~0.2-0.3) at baseline lengths longer than around 1 km, namely showing a turn-over in SSF, but in some rare cases, the slope keep the same from short baselines to long baselines. This characteristics affects the site selection of the single-dish telescopes that may correlate with ALMA. Furthermore, for a large aperture submillimeter telescope, short baseline phase characteristics affect its pointing, known as the anomalous refraction. I will also mention about this effect based on the ALMA Long Baseline Campaign data.