(a) Summer maximum

(b) Winter minimum

Δ20 s

Δ50 s

Δ80 s

Δ20 s

Δ50 s

Δ80 s

WK

1.2

2.5

3.7

1.9

3.8

5.4

SP

1.3

2.6

3.8

1.7

4.1

5.5

MM

1.1

2.3

3.3

2.1

3.5

5.0

TH

1.4

2.6

4.0

1.9

3.2

4.7