Atmosphere 2022, 13, 1634 
10 of 21 
Negative storm surges in Cuxhaven (271 events) 
70 
60 
„50 
J 
4 40; 
339. 
‚DJF: 169 
MAM: 74 
JA: 0 
‚SON: 28 
20 
9 
D- 
aan) 
A} 
mM 
er 
ge fl np a 2 
Mm DD MM © OA OO A N 
A 
Month 
Figure 6. Monthly distribution of all 271 ELWSs at the tide gauge Cuxhaven from 1950-2019. 
3.4. Mean Conditions before Negative Storm Tides 
In the following, we analyse the climatology of the 271 ELWs that have been recorded 
between 1950 and 2019 at Cuxhaven. The aim is to identify typical situations, initiating the 
onset and/or prevailing during ELW events. 
3.4.1. Pressure Field before Negative Storm Tide 
A first overview regarding the meteorological conditions right before the 271 ELWs 
is provided by the SLP composite anomaly: Figure 7 shows the mean anomaly of the 
nean pressure fields 24 h before all 271 events, based on the climatology of 1971-2000. 
This composite is marked by a dipolar pattern separated along the north-west to south- 
cast axis, with a positive pressure anomaly over Scandinavia and a negative pressure 
anomaly over the north Atlantic and the Iberian Peninsula. This pattern is very similar 
to the pattern for anomalies for all days classified as LWT SE (independent of the 
occurrence of an ELW; see Figure 8) but shows stronger anomalies. It also matches 
the situation seen in the case study of 2018 (see Section 3.2) and corresponds well 
with the effective wind direction of 142° (see Section 2.2.4) that was derived for ELWs 
at Cuxhaven. 
65° N 
60° N 
55° N 
50° N 
45° N 
10° WWV 
AS 
10° FE 
20° 
C 
a, 
„ Ü 
10° W 0° 10°E 20°E 
65° N 
50° N 
55° N 
50° N 
45° N 
20 
10 "To 
a 
L s 
0 = 
E 
10 < 
-—20 
Figure 7. Mean sea level pressure anomaly field during a 24-h period before the respective 271 ELWs 
derived from 1950-2019 ERA5 reanalysis data, compared to the climatology of 1971-2000.