Passive microwave measurements of seasonal snow in South America

In the Northern Hemisphere, the land masses are situated much closer to the poles than they are in the Southern Hemisphere. The land not only acts as a source area for cold air, but because of its lower thermal inertia compared to water, it does not modify the cold temperatures nearly as much as does water, even cold Antarctic waters. Thus the middle latitudes are much cooler during winter in the Northern Hemisphere than in the Southern Hemisphere, and snowfall occurs more frequently. Associated with this is the fact that high pressure systems or anticyclones occur less often in the Southern Hemisphere than in the Northern Hemisphere. Because there is less land in the mid latitudes of the Southern Hemisphere, the southern westerlies are stronger than their northern counterpart, and large nearly stationary "high" systems such as the "Siberian High" have a more difficult time becoming established. These large "highs" are important in refrigerating surface air and influencing the strength and tracks of storm systems. Despite these drawbacks, however, snow does occur in the middle latitudes of the southern Hemisphere and occasionally even in the sub-tropics. In this paper SMMR and SSM/I microwave observations made in 1994, 1995 and 1996 are reported