Since monsoon winds prevail in South China Sea (SCS), SCS is
unique for investigating wave characteristics during a typhoon’s
passage in conjunction with steady monsoon wind forcing. This
study investigated SCS wave characteristics using Wave Watch III,
the third-generation wave model with winter typhoon forcing. The
model was forced by a high resolution wind field from NASA’s Cross
Calibrated Multi Platform (CCMP) ocean surface winds combined
with the tropical cyclone wind model. The Wave Watch III model
was evaluated using Jason-2 altimetry observations during the
period of Typhoon Durian (2006). The effects of typhoon and
winter monsoon on the wave characteristics in SCS were analyzed
with two situations:
a) Realistic winds
b) Ideal typhoon winds. The typhoon effect was simulated
using ideal typhoon winds (Situation-2). The winter monsoon
effect was simulated using the difference between Situation-1
and Situation-2 (Figures 1-5).
Figure 1: The global harvest of marine and fresh water aquatic plants from 1950 to 2009.
Figure 2: Daily evolution of Hs in SCS during the passage of Typhoon Durian (2006).
Figure 3: Six hour evolution of directional wave spectra on point_1 (13.8°N, 114.0°E) from 0600UTC on December 1 to 1800UTC
on December 4, 2006. Typhoon Durian was at this location at 0000UTC on December 3. Arrow presents the wind speed and
Figure 4: Horizontal distributions during passage of Typhoon Durian (2006): maximum forcing wind speeds (left), and maximum
Hs calculated using Wave Watch III (right).
Figure 5: Differences between two situations (with monsoon winds minus without monsoon winds) in: maximum wind speed
(left), and maximum Hs (right).
Along Typhoon Durian’s translation track, the core of the
maximum significant wave height (Hs) was asymmetric with higher
Hs and wider core in the right side than the left side. At a single
position, the maximum Hs were always in the right-front quadrant
of the typhoon center. Directional wave spectra at the forward
and rightward points show the generation of low frequency wave
of swell due to resonant effects. The wave spectra at the leftward
and backward points have more complicated structures. The
steady winter monsoon winds generate high waves. Monsoon
winds weakly affect the Hs field near the typhoon’s track and
strongly away from the track, especially in the deep water area of
the north SCS. Before the typhoon arrival, the monsoon- generated
swell dominated; after the typhoon departure, the monsoon swell
remained dominant (non-decaying) and the typhoon-introduced
waves decayed gradually. These results reveal the unique features
of SCS wave characteristics.