1. High-Resolution Simulation of Hurricane Bonnie (1998)
High-Resolution Simulation of Hurricane Bonnie (1998). Part II: Water Budget
演講人:陳登舜
Braun, S. A., 2006: High-Resolution Simulation of Hurricane
Bonnie (1998). Part II: Water Budget. J. Atmos. Sci., 63,
43-64.

2. Key words
Water Budget, The requirement that the change in the amount of water stored in the atmosphere moving across a region should equal the difference between precipitation input to and evaporation loss from the underlying surface. (AMS ,glossary)
CFADs,Contoured Frequency by Altitude Diagrams (CFADs)

3. Outline Introduction Simulation and analysis description
a.Simulation description
b.Simulated structure and validation
Budget formulation
Budget results
a.Water vapor budget
b.Condesed water budget
c.Volume–integrated budget
d.The artificial water source
Conclusions

4. Introduction I The water vapor budget
a. The condensation in the eyewall occurs convective hot towers
b. Evaporation from the surface was approximately 20% and 25% of the condensation and total advection, respectively .(Kurihara’s 1975)
c. Ocean source of water vapor was typically only about 6% - 13% of horizontal transport ( Hawkins and Imbembo 1976)
d. in the eyewall the horizontal advection contribution was small compared to vertical advection. (Zhang et al. 2002)

5. Introduction II The condensation water budget
a. Marks (1985) estimated that 60% of inner core-region rainfall of Hurricane Allen (1980) fell within stratiform rain areas and the water vapor convergence into this areas was more than twice the rainfall .
b. the eyewall and stratifrom region ,analogous to tropical squall lines in which 30%-50% of precipitation falls out as outer region.( Marks and Houze 1987)
c. it suggested that this localized outflow from the eyewall thus contributed significant amounts of ice for development of the stratiform precipitation.

6. Introduction III
Horizontal advection tended to transport drier air into the core in the boundary layer and moist air from the eye to the eyewall within the low-level outflow above the boundary layer (Zhang et al. 2002).
Outside of the eyewall the condensation occurs in weaker updrafts, indicative of a larger role of stratiform precipitation processes.
In this study, we compute budgets of both water vapor and total condensed water (cloud condensate, and precipitation) from a high-resolution simulation of Hurricane Bonnie (1998).

7. Simulation and analysis description
a. Simulation description
Coarse-resolution:
Started at 1200 UTC 22/08/1998 (36 hrs)
36 km: 91× km: 160×160
High-resolution:
Started at 1800 UTC 22/08/1998 (30 hrs)
6 km: 225×225
2 km: 226×226
Vertical: 27 levels

8. 1800 UTC 22 Aug. TRMM 1050 UTC 24 Aug. TRMM 1200 UTC 23 Aug MM5
Too much rainwater mass occurs in the simulation

9. Radar Reflectivity CFAD
Contoured Frequency by Altitude Diagrams (CFADs)
1800 UTC 22 Aug.
TRMM
1200 UTC 23 Aug.
MM5

10. 40 m 2.7km Vr’ (contour) W (contour) 1-h Time Average (24-25 h) 6.8km
C ) this shift occurs because of changes in the storm-relative environmental flow with height .
D) This asymmetry is caused by the storm-relative flow associated with the environmental wind shear.

11. 1-h Time Average
(24-25 h)
dBZ + w
(qcl+qci) + w
dBZ + Vr

12. tangential velocity radial velocity vertical velocity qv -0.3 g/kg
56ms-1 @750m
vertical velocity
qv -0.3 g/kg
qrain, qsnow, qgr
qcl + qci
0 oC

13. Budget Formulation local change horizontal flux divergence
vertical flux divergence
Divergence
qv is mixing ratio of water vapor; qc is the mixing ratio of cloud liquid water and ice; qp is the mixing ratio of rain, snow and graupel;
V’ is the storm-relative horizontal air motion; w is the vertical air motion; VT is the hydrometeor motion; + is source; - is sink; C is the condensation and deposition; E is the evaporation and sublimation; B is the contribution from the planetary boundary
layer; D is the turbulent diffusion term; Z is the artificial source term associated with setting
negative mixing ratios to zero.
zero term
surface precipitation flux
Qc+ ,Qc- ,Qp+ ,and Qp-
are the cloud and precipitation source and sink term

14. Budget Formulation(con’t)
Zx is artificial source terms associated with setting negative mixing ratios (caused by errors associated with the finite differencing of the advective terms) to zero, that is, mass is added to eliminate negative mixing ratios.
Dale R. Durran,2003

15. Budget Formulation(con’t)
the temporal and azimuthal mean:
(kg·m-3·h-1 )
the time-averaged and vertically integrated amount:
(kg·m-2·h-1 )
the time-averaged, volumetrically integrated amount:
(kg·h-1 )
the azimuthally averaged horizontal advective flux is simply that associated with radial transport

16. Budget results a. Water vapor budget 1-h Average (24-25 h)
condensation
horizontal flux divergence,
Melting layer
evaporation
vertical flux divergence,
Cond + Evap
HF + VF divergence
divergence term
boundary layer source term
DRY

17. much of the eyewall condensation is associated with hot towers.
eyewall region (30-70 km)
outer region ( km)
The percentage of the area The percentage of condensation occurring in updraft
Updrafts greater than 2 m/s occupy somewhat less than 10% of the eyewall area at low to mid level, and produce 75% of the total condensation
Updrafts greater than 4 m/s generally occupy less than 5% of the eyewall area, and account for almost half of the condensation.
much of the eyewall condensation is associated with hot towers.
The smaller contribution of stronger updrafts is indicative of the larger role of stratiform precipitation processes outside of the eyewall.

18. cloud budget b. Condensed water budget cloud sink
horizontal flux divergence
Evaporation;
Autoconversion;
Collection;
net source
condensation (total source of cloud)
vertical flux divergence
added water mass to offset negative mixing ratios
boundary layer source
Cloud liquid water
Unlike in the water vapor , the flux divergence term is much smaller than the source/sink term

19. precipitation budget Source sink Warm-rain proc. Evaporation rain
Melting layer
graupel
Melting
snow
Have a evaporation though the downdraft processes.

20. precipitation budget net microphysical source
horizontal flux divergence
precipitation fallout and vertical flux divergence
cloud sink
added water mass to offset
negative mixing ratios

21. Horizontal distribution
condensation
evaporation
downdraft
precipitation fallout qv
Only have slightly (a few tens of kilometers at most ) downwind of the condensation peak .

22. Displacement of the precipitation
total rain source
warm rain source
Rain source +
graupel sink
cold rain source
graupel source
Graupel sink
The two factors of displacement of the precipitation have only slightly downwind peak.
The first factor is that much of the rainwater production in the eyewall occurs in association with warm rain processes.
The second factors is that upward motion at upper levels is located on the western side of the storm

23. c.Volume–integrated budget
Ocean source term of vapor which is only 4% of the low level radial import of moisture .
The moisture convergence into the eyewall was more than twice the volumetric rainfall.
Not all of the moisture converged into the eyewall is carried outward in the form of condensation .
Almost 45% of total condensation is evaporated .
The PBL source of vapor term is 8% of the low-level moisture import ,but 27% of the transport into the eyewall.

24. d. The artificial water source
Cloud content
Precipitation content
cloud liquid water
cloud ice
rain
snow
graupel

25. cloud water
rain
graupel

26. Conclusion
The simulation generally reproduces the track, intensity, and structure of the storm, but overpredicts the precipitation as inferred from comparison of model and TRMM radar reflectivities.
The water vapor budget confirms that the ocean source of vapor in the eyewall region is very small relative to the condensation and inward transport of vapor, with the ocean vapor source in the eyewall (0.7) being approximately 4% of the inward vapor transport into the eyewall (16.8) region.

27. Conclusion
In the eyewall, most of the condensation occurs within convective towers while in the outer regions condensation results from a mix of convective and stratiform precipitation processes.
Precipitation processes acting outside of the eyewall region are not very dependent on the condensate mass produced within and transported outward from the eyewall.
The artificial water mass source contribute an amount of water that is equivalent to 15%–20% of the total surface precipitation.

28. Typhoon Nari (2001)
Water budget

29. Condensation Condensation Interval 2 g/m^3 h Bonnie 1998
Nari
2001

30. Evaporation Evaporation Interval 0.5 g/m^3 h Bonnie 1998
Nari
2001

31. Net Condensation Bonnie 1998 Net Condensation Interval 2 g/m^3 h
Nari
2001

32. Horizontal Flux Divergence
Bonnie 1998
Horizontal Flux Divergence Interval 20 g/m^3 h
Horizontal Flux Divergence Interval 10 g/m^3 h
Nari
2001

33. Vertical Flux Divergence
Horizontal Flux Divergence
Interval 20 g/m^3 h
Bonnie 1998
Vertical Flux Divergence
Interval 10 g/m^3 h
Nari
2001

34. Total Flux Divergence Total Flux Divergence Interval 2 g/m^3 h
Bonnie 1998
Total Flux Divergence Interval 1 g/m^3 h
Nari
2001

35. Divergence Divergence Interval 0.5 g/m^3 h Bonnie 1998
Nari
2001

36. PBL Bonnie 1998 PBL Interval 0.5 g/m^3 h PBL Interval 0.5 g/m^3 h Nari
2001

37. Water Vapor Budget
Bonnie 1998
Nari
2001

38. Liquid/Ice Water Budget
Bonnie 1998
Nari
2001
Zero term =?? ??

39. Future Works
納莉與Bonnie在海上的water budget 大致上有一致的結果，但eyewall 區域降水偏少，目前還在檢查程式，待解決降水偏少的問題就可以計算出artificial zero term 的大小。
未來還要針對在陸地上做納莉颱風的water budget，我們預期會相較於海上還要造成更多的降水。
藉此我們就可以充分暸解在，颱風與地形的交互作用下，各項降水粒子的分佈。

40. Model Setup Model Domain Levels Microphysics PBL Radiation IC BC
MM5, version 3.4; Dudhia1933; Grell et al. 1995
Domain
D1 : 36 km (91 x 97) ; D2 : 12 km (160 x 160) two-way
Levels
27 half sigma levels, model top is 50 hPa
Microphysics
Goddard (Tao and Simpson 1993; McCumber et al. 1991)
PBL
Blackadar PBL (Blackadar 1979; Zhang and Anthes 1982)
Radiation
Rapid Radiative Transfer Model (RRTM) long wave (Mlawer et al ) and Dudhia short wave scheme (Dudhia 1989) IC
12-hourly global analyses from the ECMWF archived BC

41. dBZ (shading)
W (contour)
Qc+Qi (shading)
W (contour)
dBZ (shading)
Vr’ (contour)
1-h Time Average
(24-25 h)

42. In the outer region the PBL source of vapor term is about 8% of the low-level moisture import ,but 27% of the transport into the eyewall.
About 70% of the condensate falls to the surface as precipitation.
The outward transport of condensate aloft is about 9% of eyewall condensation
The precipitation efficiency is about 65% ,and artificial term is about 13% of condensation in both region.