1. On the Definition of Precipitation Efficiency
Speaker: Liou
Date:2007/03/08

2. Introduction
Generally speaking, the range of PE might be less 100% and greater 0%.
LSPE cloud be negative and might be greater then 100%.
CMPE might be greater then 100%.

3. Model setting The cloud-resolving model.
The horizontal boundary is periodic.
The horizontal domain is 768km and the grid resolution is 1.5km.
The vertical grid size is 200m to 1000m.
The time step is 12s.
Hourly 96km-mean simulation data.

4. Cloud-microphysics precipitation efficiency (CMPE)
(Sui et al. 2005)

5. The CMPE1 does not include all source terms for eventual formation of surface precipitation. And get new CMPE2 is :
PS較大….表示左項小於零=>來源向不明

6. CMPE1 vs. CMPE2
Using hourly 96-km average data during 21-day integration.

7. CMPE1 vs. Ps
CMPE2 vs. Ps
For strong rainfall (PS>5mm h-1), 50%< CMPE1＆CMPE2<100%
For weak rainfall (PS>5mm h-1), 0%< CMPE1<350%
0%< CMPE2<100%

8. Large-scale precipitation efficiency (LSPE)
(water vapor budget)
(Gao et al. 2005)
is the local vapor change =
is the vapor convergence =
is the surface evaporation rate

9. LSPE1 vs. LSPE2
-500%< LSPE1<500%
0%< LSPE2<100%

10. LSPE1 vs. Ps
LSPE2 vs. Ps
LSPE2 tends increase with increasing Ps.
LSPE1 has a much wider range of variability then LSPE2.
The negative values of LSPE1 are often occurred in light rain. (Ps<5mm h-1).

11. LSPE2(QCM=0) vs. LSPE2
LSPE2(QCM=0) is larger then LSPE2
LSPE2(QCM=0) cloud be larger 100%
The effect of QCM in the larger LSPE2 is more important.

12. CMPE2 vs. LSPE2 hourly mean 48km average data
對長時間的平均而言，雲微物理項變小了(被平均)LSPE和CMPE較不敏感對空間尺度分析而言
The hourly 96-km average data
Daily mean 96km average data
hourly mean 24km average data

13. linear correlation coefficient
RMS
(vs. CMPE)
linear correlation coefficient
LSPE(96km hourly)
18.5%
0.85
LSPE(96km 6-hourly)
22.3%
0.79
LSPE(96km daily)
23.4%
0.70
LSPE(48km hourly)
17.9%
LSPE(24km hourly)
17.8%
0.84

14. Conclusion LSPE2 and CMPE2 range form 0 to 100%.
CMPE2 is only including microphysical process and LSPE2 is including both hydrometer species and water vapor.
When light rain occurs, the LSPE1 and CMPE1 are more likely then 100%.
Unanswer:
1.CMPE裡面為什麼PS增加時會區近為一定直？
對於其他個案降水效率維和
CMPE2和LSPE2可以用在其他3為地形上嗎