chapter - Atmospheric and Oceanic Science

2.2.2. Annual and seasonal averages
La Plata basin climatology
At great scale, two well defined precipitation regimes are observed (e.g.,
Berbery and Barros 2002): the first one toward the North of the basin and the second
over the central portion (Fig. 2.2a). The transition between both regimes is
clearly illustrated in figure 2.2b, which represents the annual cycle of precipitation
averaged in bands of longitude between 60 and 50 W, as a function of latitude. The
regime of Summer precipitation, associated to the South American monsoon system,
can be observed up to the 20ºS (Fig. 2.3b), while more to the South, the central
portion of the basin can reach its maximum at different times of the year, what
suggests that there is more than one acting mechanism, not only the monsoon forcing.
Therefore, precipitation in the central and southern strips of the basin tends to
be more evenly distributed during the whole year (Fig. 2.3 a, d). Thus, during the
Fig. 2.3. Seasonal precipitation of the basin in mm/day.
21