| dc.description.abstract | The shortwave radiation heating is the main factor of the diurnal temperature deviation, which is critical for local circulation, such as land-sea breeze and mountain-valley flow. In the interaction between shortwave radiation and topography, the tilting slope and terrain blocking effect both play important roles of altering the spatial energy distribution. The phenomenon had been demonstrated and evaluated by using numerical parameterization method (Lai, 2010), but haven’t been implied in atmospheric model simulation. This study uses WRFV3.5.1 model with revised new Goddard shortwave radiation scheme with parameterization of topographic effect to make the comparison with the original WRFV3.5.1 model first simulate an idealized model to see how the shortwave radiation parameterization method affects model simulation.
With three different local time of the comparison between the modified model and the original model, the modified model shows different range and strength on local circulation from the original model nearby slope area.
Due to the diverse geographic elevation of Taiwan, there are two weak synoptic condition case study in northern Taiwan, one with rainy system generate (2016/7/18 00 UTC to 2016/7/19 18 UTC) and the other without (2016/8/21 00 UTC to 2016/8/22 18 UTC), for the two model to simulate.
By the cross-section result, the phenomena we saw in the idealized model simulation still can be seen in real case, and the modified model simulation result also improved the temperature, wind speed and the reflectivity around the complicated geographic area with slope, but in the flat plain area the improvement is insignificant.
As a result, the parameterization method can make a different simulation depends on how diverse geographic elevation of the area, and owing to its more realistic energy distribution, the method will be promising if it is used for long term weather simulation. | en_US |