Figure 1. Geographical distribution of soluble iodine speciation observations (measurements of I-, IO3- and SOI). Stations: triangles; Cruises: dots (see legend). For clarity, campaigns where only the TSI/TI fraction was measured are not included in the map.
Figure 1 shows the geographical distributions of the observations of iodine speciation in aerosol. Unfortunately, the speciation data is rather sparse, with an uneven spatial coverage, especially in the longitudinal coordinate. Most measurements were performed in the East and Central Atlantic and in the Eastern Indian-Western Pacific region. Still, the campaigns sampled the complete range of latitudes, which enables a spatial analysis of the data. In contrast to total iodine measurements, long-term series of iodine speciation do not exist. Moreover, the published data are relatively recent, between 1983 and 2018, and most soluble speciation measurements were carried out between 2002 and 2014. This precludes a long-term trend analysis of the speciation data.
Field observations of TI, TSI, iodine enrichment in aerosol and soluble iodine speciation in aerosol in bulk, fine (PM1 or PM2.5) and coarse aerosol are compiled in the Supplementary Dataset S1. Field observations of major aerosol ions in fine (PM1) and coarse aerosol are available in the Supplementary Dataset S2.
In order to investigate relationships between sea surface variables and the iodine speciation in aerosol, sea surface salinity (SSS), chromophoric dissolved organic mater (CDOM), detritus absorption at 443 nm and phytoplankton absorption at 443 nm composites have been obtained from the NASA online eard data open acces resounces. The SSS composite (25/08/2011 to 07/06/2015) was contructed with data from the Aquarius sattellite mission, while the Chl-a, CDOM, and 443 nm detritus and phytoplankton absorption composites (04/07/2002 to 20/05/2021) were constructed using MODIS-A satellite data.