Application of Satellite-Derived Ocean Surface Winds to the Detection of Weather Systems and the Prediction of Near-Ocean Surface Winds around Hawaii

The Hawaiian Island chain is surrounded by the open ocean and is an ideal place to conduct the application of QuikSCAT satellite-derived ocean surface winds to the detection of weather systems. With the help of QuikSCAT winds, the associated circulation of the weather systems over the open ocean around Hawaii can be identified. In this study, the obvious cyclonic circulation associated with a Kona storm, the significant wind shift and wind confluence related to the surface cold front, and the anticyclonic circulation related to high-pressure systems for both a strong-wind event and a trade-wind condition are revealed over the open ocean through QuikSCAT winds. The propagation of a cold frontal boundary, defined by the wind shift and wind confluence, also can be clearly detected using the reanalyzed ocean-surface winds

Incorporating Additional Sounding Observations in Weather Analysis and Rainfall Prediction During the Intensive Observing Period of 2006 TWP-ICE

Using additional sounding observations during the Intensive Observing Period (IOP) of the Tropical Warm Pool-International Cloud Experiment (TWP-ICE) in 2006, the characteristics of weather systems and associated environmental conditions are further analyzed during four temporal regimes (active wet monsoon, suppressed dry monsoon, clear day, and monsoon break). Monsoon low-pressure systems are predominant during the active wet monsoon and monsoon break periods. During the active monsoon period, heavy rainfall (> 100 mm day-1) is produced over the nearby tropical ocean of north Australia and the maritime continent centered on the Tiwi Islands, where the apparent southerly-to-southwesterly winds dominate at low levels over the ocean under the influence of the monsoon low in contrast to the westerly winds during a typical active north Australia summer monsoon regime. In the monsoon break, limited scattered rainfall is distributed over coastal regions of northern Australia and inland

Prediction of a Mei-yu Frontal Cyclone and the Associated Torrential Rainfall over Southern Taiwan During 2008 Mei-yu Season

A torrential rain episode (≥ 200 mm day-1) was observed over coastal regions of southern Taiwan (south of 23.0°N) on 5 June 2008 under the influence of a meso-scale frontal cyclone (MFC) formed along the western flank of a Mei-yu frontal zone. Through the incorporation of additional observations over the ocean collected during Southwest Monsoon Experiment (SoWMEX)/Terrain-influenced Monsoon Rainfall Experiment (TiMREX), the location of a Mei-yu frontal boundary, defined by the wind shift, is better identified over the open ocean by the data assimilation of dropsonde observations. Meanwhile, the low-level cyclonic vorticity and horizontal convergence are increased along the Mei-yu frontal zone, and an increment maximum center of cyclonic vorticity locates over the north of South China Sea (SCS), where the MFC subsequently forms

Respective roles of shallow convection and stratiform rainfall on the simulation of Madden-Julian Oscillation.

Respective Roles of Shallow Convection and Stratiform Rainfall on the Simulation of Madden Julian Oscillation Joshua Xiouhua Fu IPRC, SOEST, University of Hawaii The IPRC/UH Hybrid-coupled GCM (HcGCM), which combined ECHAM-4 AGCM with UH intermediate ocean model, produces robust Tropical Intra-Seasonal Oscillations including the boreal-winter MJO and boreal-summer Monsoon Intra-Seasonal Oscillation. In this study, two sets of sensitivity experiments (i.e., short-term retrospective forecast of one MJO event observed during TOGA COARE and long-term free integrations) have been carried out to understand the respective roles of shallow-convection and stratiform rainfall on the simulations and predictions of the MJO. Major findings are summarized as following: Shallow-convection ahead of MJO deep convection moistens the lower-troposphere and preconditions the movement of the MJO. Present study shows that this process is very important to the eastward propagating speed of the MJO. A significant fraction of stratiform rainfall (~30%; stratiform part vs. total rainfall) is needed for ECHAM-4 to have a robust MJO. The above findings suggest that in addition to deep convection, shallow convection and stratiform rainfall needs to be well represented in conventional GCMs to ensure a robust model MJO