Evaluation of the simulation capability of the Wavewatch Ⅲ model for Pacific Ocean wave

Wave climate analysis and other applications for the Pacific Ocean require a reliable wave hindcast. Five source and sink term packages in the Wavewatch III model （v3.14 and v4.18） are compared and assessed in this study through comprehensive observations, including altimeter significant wave height, advanced synthetic aperture radar swell, and buoy wave parameters and spectrum. In addition to the evaluation of typically used integral parameters, the spectra partitioning method contributes to the detailed wave system and wave maturity validation. The modified performance evaluation method （PS） effectively reduces attribute numbers and facilitates the overall assessment. To avoid possible misleading results in the root mean square error-based validations, another indicator called HH （indicating the two authors） is also calculated to guarantee the consistency of the results. The widely used Tolman and Chalikov （TC） package is still generally efficient in determining the integral properties of wave spectra but is physically deficient in explaining the dissipation processes. The ST4 package performs well in overall wave parameters and significantly improves the accuracy of wave systems in the open ocean. Meanwhile, the newly published ST6 package is slightly better in determining swell energy variations. The two packages （ACC350 and BIA） obtained from Wavewatch III v3.14 exhibit large scatters at different sea states. The three most ideal packages are further examined in terms of reproducing wave- induced momentum flux from the perspective of transport. Stokes transport analysis indicates that ST4 is the closest to the NDBC-buoy-spectrum-based transport values, and TC and ST6 tend to overestimate and underestimate the transport magnitude, respectively, in swell mixed areas. This difference must be considered, particularly in air-wave-current coupling research and upper ocean analysis. The assessment results provide guidance for the selection of ST4 for use in a background Pacific Ocean hindcast for high wave climate research and China Sea swell type analysis.

PARAMETERIZATION OF MOBILIZATION AND TRANSPORT OF SAND-DUST DURING BLACK STORM AND MESOSCALE NUMERICAL EXPERIMENTS

The typical black storms or sand-dust storms in the northwestern China are generated and developed through an interaction between the specific large scale circulation pattern and mesoseale systems.The passing by/over a huge sand-abundant desert of a strong cold front with intensive frontal zone at mid and lower levels is a necessary condition for the formation and development of a black storm or a severe sand-dust storm.In order to investigate the mechanism of the sand-dust mobilization,transport and sedimentation during the black or sand-dust storms,a parameterization scheme of sand-dust source-sink terms and an equation of transport for the sand-dust were proposed and incorporated into the MM4 mesoscale model.The modified MM4 model was applied to the“May 1993”black storm case and succeeded in reproducing the evolution of the weather systems associated with the black-storm,the sand-dust concentration at surface layer and its vertical distribution,and the sand-dust sedimentation and transport.Our results show that the numerical simulating method by using a mesoscale model,with inclusion of an equation of the sand-dust transport and a parameterization scheme of the sand-dust source-sink terms,is a promising approach to study the mechanism for sand-dust mobilization,transport and sedimentation during a sand-dust storm event.