Spatial and Temporal Variations in Icelandic Dust Emissions: a decade of insights from MODIS

Abstract:

A detailed picture of global dust emissions at low latitudes has been achieved through the use of remote sensing. However most surveys have been restricted to latitudes between 50°N and S and have not considered dust from high latitude regions. Field studies have shown that dust emissions, particularly from glacierised areas, at high latitudes can be extremely intense and extensive, but the potential for exploring this at larger spatial scales and longer temporal scales using remote sensing remains unrealised.

Accepted and reliable remote sensing methodologies for quantifying low latitude dust have provided information on the geomorphological characteristics of dust sources and insights into spatial and temporal patterns of dust release. However, these methodologies have not been widely tested at high latitudes; possible limitations to their use are that most remote sensing retrievals are optimised for low latitudes and cloud cover in high latitudes tends to be persistent and extensive.

This research examines whether approaches to the remote sensing of dust that have been successful at low latitudes can be applied at high latitudes and adopts a scale of enquiry appropriate to identify patterns and trends in Icelandic dust emissions from 2003-2014. In particular, we evaluate the utility of broad-scale aerosol products (Aerosol Optical Depth retrievals from MODIS at 10x10 km and 1 degree) for obtaining information on the dynamics of dust source regions and transport pathways associated with southern Iceland. Daily data make it difficult to establish spatial and temporal trends because they are incomplete due to cloud cover. To increase data retrievals we used 8-day averages of AOD for each cell and this made it possible to identify a clear seasonal pattern in the AOD during the decade with highest values occurring April and May. Examination of AOD over land indicates that the frequency and intensity of dust emissions varies spatially, with the glacial outwash plains of Skeiđarásandur identified as a particularly persistent dust source which is in accordance with other research. Results suggest that the MODIS AOD retrievals can be used to identify spatial and temporal patterns in high latitude dust emissions provided appropriate scales of enquiry are used.