Fig. 2: Dust optical depth proxies and sulfate aerosol asymmetry.
From: Natural and anthropogenic contributions to the hurricane drought of the 1970s–1980s
a Barbados summer dust measurements rescaled by satellite measurements of main development region dust optical depth during the 1980s (black), main development region dust optical depth reconstruction based on the Sahel precipitation index (SPI) proxy (dark blue) and 95% confidence interval on the SPI proxy (pale blue). Dotted lines are not filtered, and full lines are low-pass filtered. b Low-pass filtered anthropogenic and volcanic sulfate aerosol optical depth asymmetry (black), and SPI (blue). The y-axis for the precipitation index is reversed so that peaks indicate dry years. Dotted lines are not filtered, and full lines are low-pass filtered.
