This RADAR reflectivity shows one of the most common raining type in winter Taiwan.
(1) Local precipitation due to winter monsoon(north-easterly) and topography (raining region is concentrated in 宜蘭 and 基隆). The cloud of this type precipitation is relative shallow(stratus cloud) and the maximum diabatic heating level is around 850hPa
(2)The convergence zone between land-sea breeze and winter monsoon , its raining region is near the east coast of Taiwan. This type of raining is getting stronger in the midnight when the land breeze is the strongest. It's heating profile is close to deep convection but more stationary (it can last over 3 days)
(3)"Overrunning". the warm-moisture air from south China sea is tilting by northeasterly, and when the free troposphere is stable(with strong stratification), the feature of gravity wave becomes more obvious. Its raining region can go across from south to north Taiwan.
The speed of gravity wave we saw on the RADAR is around 70km/hr=19.45m/s. It's easy to say this is 3or 4th internal mode from a simplification wave speed diagnostic equation. The maximum heating level is around
800hPa~700hPa.
External Mode~300m/s
1st internal mode~60m/s
2st internal mode~(60/2)=30 m/s
3st internal mode~(60/3)=20 m/s
4st internal mode~(60/4)=15m/s
...
nth. internal mode~(60/n)=... (m/s)
..
and the maximum heating profile is also easy to find on the following picture.
