Numerical Experiment Research of a Marine Fog Event in the Pearl River Estuary Region

A marine fog event that occurred near the Pearl River Estuary region on 26March 2002 was investigated with the fifth-generation Pennsylvania State University/National Centerfor Atmospheric Research Mesoscale Model (MM5). The results of numerical experiment are veryconsistent with the surface observations, especially in the processes of marine fog formation andevolution. Besides, a series of sensitivity numerical experiments were performed by varying thedistribution of landuse type and the turbulence exchange process. It is shown that the marine fogforms along the coastal line. Tests have indicated that when the distribution of landuse type ismodified, the regions where the marine fog can intrude into are obviously different. The turbulenceprocess in the model is important for fog formation and evolution. If the influence of turbulenceprocess is ignored in numerical simulation experiment, the simulated maximum of the cloud liquidwater content and the height of fog top will be decreased greatly.

Tidal energy budget in the Zhujiang(Pearl River) Estuary

Tidal energy budget in the Zhujiang（Pearl River） Estuary（ZE） is evaluated by employing high-resolution baroclinic regional ocean modeling system（ROMS）. The results obtained via applying the least square method on the model elevations are compared against the tidal harmonic constants at 18 tide stations along the ZE and its adjacent coast. The mean absolute errors between the simulation and the observation of M_2, S_2, K_1 and O_1 are 4.6, 2.8, 3.2 and 2.8 cm in amplitudes and 9.8°, 15.0°, 4.6° and 4.6° in phase-lags, respectively. The comparisons between the simulated and observed sea level heights at 11 tide gauge stations also suggest good model performance. The total tidal energy flux incoming the ZE is estimated to be 343.49 MW in the dry season and larger than 336.18 MW in the wet season, which should due to higher mean sea level height and heavier density in the dry season. M_2, K_1, S_2, O_1 and N_2, the top five barotropic tidal energy flux contributors for the ZE,import 242.23（236.79）, 52.97（52.08）, 24.49（23.96）, 16.22（15.91） and 7.10（6.97） MW energy flux into the ZE in dry（wet） season, successively and respectively. The enhanced turbulent mixing induced by eddies around isolated islands and sharp headlands dominated by bottom friction, interaction between tidal currents and sill topography or constricted narrow waterways together account for the five energy dissipation hotspots, which add up to about 38% of the total energy dissipation inside the ZE.