A Climatology of Atmospheric Iron Inputs to the Atlantic Ocean

Desert dust can be picked up by strong winds and transported great distances, sometimes thousands of kilometres, through the atmosphere. This process has some interesting effects on the climate of our planet. Iron makes up a small portion of the dust and this element is often in short supply for the plants (phytoplankton) that live in the ocean. Wind-blown dust can be an important source of iron to these organisms in some ocean regions and so dust supply can be linked to phytoplankton growth and the uptake of carbon from the atmosphere that this causes. While in the atmosphere, dust also alters the way that radiation is absorbed or reflect by the planet. It is therefore important to include dust transport in models of the Earth's climate system, but our current understanding of this transport is rather poor. One particular difficulty is the lack of measurements available to help constrain and develop such models. Some long-term monitoring sites provide information on changes in dust transport over time, but they are too few and too widely spaced to give adequate information on spatial variability. The UEA group has recently carried out 10 long-transect crossings of the Atlantic Ocean, sampling the atmosphere for the iron content of aerosol and rain. This is a unique dataset and will allow us to assess the atmospheric input of iron to the Atlantic directly, based on field data, for the first time. The results of our study will be shared directly with modellers at the Hadley Centre and the QUEST Earth System Science programme, so that we can ensure that the benefit of this extra information is passed directly to the modelling community.