SAMOA

Trends

The NOAA/CMDL monitoring facility in Samoa, located at Cape Matatula on the island of Tutuila, was chosen as a representative tropical Southern Hemisphere baseline location. Despite characteristic wet and dry seasons and considerable cloudiness, a fairly continuous AOD anomaly record has been obtained at this site from 1977 to the present; only 1-2 monthly values are reported as missing for a typical year. The most obvious features of the record are the high-frequency background variability, attributable to fluctuations in boundary layer sea salt, and the increases in AOD associated with the explosive volcanic eruptions of El Chichón (Mexico, 1982) and Pinatubo (Philippines, 1991). For the El Chichón event, the maximum AOD anomaly at Samoa was only 0.08 (during September 1983), which was comparable to the maximum reached at the NOAA/CMDL South Pole site but much smaller than that at either of the two Northern Hemisphere baseline stations. Conversely, the Pinatubo eruption resulted in a large increase in AOD at this site: the maximum anomaly value of 0.25 occurred in August 1991. AOD anomalies have remained well above background levels through the end of the current record.

When the intrinsic variability of the data and the impact of the volcanic events are removed, the AOD record from Samoa shows no long-term trend.

Samoa (Cape Matalula)
U.S. Territory
South Pacific Ocean
Rocky promontory
14° 15' S, 170° 34' W
42 m above MSL

Samoa Optical Depth Graph

• Monthly aerosol optical depth anomalies at Samoa