There seems to be little seasonality with slightly higher deposits in Spring and a general decrease towards Fall (see Cassar et al., 2007).

Cassar N., Bender M.L., Barnett B.A., Fan S., Moxim W.J., Levy H. II, Tilbrook B., 2007. The Southern Ocean Biological Response to Aeolian Iron Deposition. Science, 317 (5841), 1067-1070.

Cassar N., Bender M.L., Barnett B.A., Fan S., Moxim W.J., Levy H. II, Tilbrook B., 2008. Response to Comment on "The Southern Ocean Biological Response to Aeolian Iron Deposition". Science, 319 (5860), 159b.

Dawei:

Have a look at this link for insights:

http://www.ldeo.columbia.edu/~winckler/Publications_files/Lamy_Gersonde_Winckler_et_alScience2014.pdf

Best

Syed

Thanks Bernard and Syed Abbas.