Fig 1.
Locations of data collection at the field site near Egmond aan Zee and the KNMI weather station at IJmuiden.
The red stars indicate the location of the field site (local wind measurements) and the KNMI weather station at IJmuiden (regional wind measurements). Reprinted from Esri Netherlands & Community Maps providers under a CC BY license, with permission from Esri Netherlands, original copyright 2019.
Fig 2.
Morphological conditions at the beach near Egmond aan Zee.
A: cross-shore profile of the field site in 2015 (red) and 2017 (black) and B: photo of the beach with the vegetated embryonic dunes (0.8—1.0 m height), south of the cross-shore measurement array of the field campaign in 2017.
Fig 3.
Wind rose at the IJmuiden weather station based on 10-minute data from January 1, 2007 up to and including December 31, 2016.
Fig 4.
Wind conditions (speed and direction) measured at IJmuiden during all field experiments.
Wind speed is plotted in black and wind direction in blue. The cross-shore and alongshore orientations are indicated with a black-continuous and a black-dotted line, respectively. The red dots indicate the moments when the cross-shore array of ultrasonic anemometers was deployed.
Fig 5.
Classification of the data based on the wind direction measured in IJmuiden.
Table 1.
Linear regressions of the comparison of regional and local wind velocities based on the regional wind approach angle.
Fig 6.
Comparison of the (regional) wind speed at IJmuiden estimated at 0.9 m height and the measured (local) wind speed at all locations at the beach near Egmond aan Zee for each 20° bin (based on the wind direction measured in IJmuiden).
The colors indicate all data points in a certain 20° bin from perpendicular (manganese) towards almost alongshore (black) approaching winds relative to the dune normal. The black dotted line indicates equality of the regional and local wind speeds and the colored thick lines are the regression lines corresponding to the same-colored data points. For regression information see Table 1.
Fig 7.
Local wind speed on the beach relative to that at the dune foot as a function of the downwind distance to the dune foot.
Note that A and B show data from the two field campaigns in 2015 and 2017, respectively, and are separated due to morphological differences. The embryo dunes in front of the foredune are higher (0.8–1.0 m) in the situation of B compared to the situation of A (embryo dunes of ∼0.5 m).
Fig 8.
Wind steering over the beach during onshore winds.
Wind direction measured at the weather station in IJmuiden is compared with the wind direction at the intertidal beach (A), dry beach (B) and dune foot (Ci) in Egmond aan Zee. Directions are relative to the dune-normal, with negative values for southerly winds and the positive values indicate northerly approaching winds. Panel Cii shows the absolute steering at the dune foot.
Table 2.
Five scenarios to compute the effect of the use of local, instead of regional, wind conditions in aeolian sand transport models.
Fig 9.
Potential transport magnitudes, based on Eq 13, in 20°-wide directional bins for 5 scenarios.
The 5 scenarios are explained in Table 2.