Potential Impacts of Sahara Dust Aerosol on Rainfall Vertical Structure over the Atlantic Ocean as Identified from EOF Analysis (dataset.rar)

The current study investigates the potential impacts of Sahara dust on
rainfall vertical structure over the Atlantic Ocean by employing multi-sensor
satellite observations. The variabilities in rainfall vertical structure are
decomposed by empirical orthogonal function (EOF) analysis. For a given near
surface rain rate, the mean storm height of stratiform rain under dust-laden
condition is significantly higher than that under the dust-free condition. The
stratiform rain rate at the layers well above the freezing level is substantially
enhanced under dust-laden condition. Those changes may result from dynamic and thermodynamic
effect of Sahara Air Layer effect and/or the effect that dust aerosol acting as
additional ice nuclei. For convective rain, there is no significant
difference in the leading three normalized EOF modes between the dust-laden and
dust-free sectors, implying that dust effect, if exists, is not strong enough
to cause evident changes in convective rainfall profiles. For stratiform rain,
the EOF1 shows no signals of dust effect either. However, significant
difference are found in the EOF2 and EOF3 modes between dust-laden and
dust-free conditions. The normalized EOF2 and EOF3 under dust-laden condition
both represent enhanced rain rate at upper layer well above the freezing level,
where heterogeneous ice nucleation prevails. The statistical study shows consistent results
with case study, except that the aerosol-related changes in stratiform rainfall
vertical structure is isolated in the EOF3 only. This study suggests EOF
analysis a promising way for isolating the potential and relatively weak
aerosol effects on precipitation from the strong dynamic effects.<br>