New paper on trend changes of African airmass intrusions
A new paper entitled “Trend changes of African Airmass intrusions in the marine boundary layer over the subtropical Eastern North Atlantic region in winter”, by Alonso-Pérez et al., has been accepted for publication in Tellus (Series B: Chemical and Physical Meteorology; Impact Index: 4.278).
This study shows the trend change of the frequency and intensity of African dust intrusions in the marine boundary layer of the subtropical Eastern North Atlantic region in winter, which have been found to occur after 1979. It also quantifies the impact of circulation changes (Azores High position, shape and strength) on this trend change.
Winter dust concentrations simulated by the BSC-DREAM model for the Mediterranean Basin and Northern Africa were used for the period 1958-2006.
The trend change of the particle concentration series coincides with the trend change of the Madrid Tenerife Index (MTI). This is a new teleconnection index first introduced in this paper that accounts better than the NAO index for the shape and the eastward shift of the Azores High. This index was calculated from both in-situ measurements and reanalysis data from NCEP/NCAR and ECMWF. These trend changes also coincide with that calculated for the African Index (AFI) series, which accounts for the frequency of African airmass intrusions over the subtropical North Atlantic Ocean.
The results show that after 1980, in winter, the Azores High intensified and presented a more eastwards elongated shape, favouring an increase of easterlies over Western Sahara and North Mauritania. Surface dust concentration series simulated by the BSC-DREAM model for the period 1961-2006 show an increase of dust over the Western Sahara and North Mauritania after 1980. However no significant changes in dust concentration and surface winds over the rest of the Northern Africa are found. The increase in wind velocity over the dust source (observed in NCEP reanalysis) might result in an increase of dust mobilization, which is consistent with higher dust concentrations observed with BSC-DREAM model over these dust sources in the 1981-2006 period.
Winter mean dust concentrations in the study region for the period 1981-2006 are approximately twice those of the period 1958-1980.
Full reference: S. Alonso-Pérez, E. Cuevas, C. Pérez, X. Querol, J.M. Baldasano, R. Draxler and J.J. de Bustos, Trend changes of African Airmass intrusions in the marine boundary layer over the subtropical Eastern North Atlantic region in winter. Tellus B, doi: 10.111/j.1600-0889.2010.00524.x Accepted 27-dec-2010.
Abstract and paper (pdf), here.