Monthly averaged aerosol optical depth anomalies at Barrow for March and April

Monthly averaged aerosol optical depth anomalies at Barrow (Alaska) for March and April. The anomalies are relative to a base of non-volcanic years. Data from 1992 and 1993 were removed due to stratospheric aerosol influx from the Pinatubo eruption in 1991. Vertical lines represent 1 standard deviation of the monthly mean