Through an idealized modeling study with a depth level coordinate general ocean circulationmodel (GFDL/MOM), the sensitivity of tracer injection into the oceans onthe horizontal resolution in thermally driven circulations is investigated. As the resolutionbecomes higher, convective mixing in high latitudes becomes weaker, and boththe strength of the overturning and the concentration of the tracer, which is injectedfrom the surface into the ocean interior, weaken. The rate of decrease is greater withthe tracer. When the resolution was increased from two degrees to quarter degree, thetracer concentration was decreased by 50 %, but the overturning weakens only by20 % or so. This suggests that in a coarse resolution model, even though the overalloverturning is reasonable, tracer injection could be overestimated due to excessiveconvective mixing in high latitudes.