1. A statistical approach to the life cycle analysis of cumulus clouds selected in a virtual reality environment Harm Jonker Harry Van den Akker Eric Griffith Frits Post Michal Koutek J. Geophys. Res. 2009 Thijs Heus (thijs.heus@zmaw.de)

2. Life cycle of cumulus clouds Life cycle effects are often a bias in statistics Not that much observational time-dependent data present; how can we be even sure that the definition of non-decaying clouds in airplane observations is correct? LES should be perfect tool with complete datasets: Select a large number of clouds to analyze in time, e.g. conditional sampling over life stage. 2

3. Evolution in Time 3 Initial Phase

4. Evolution in Time 4 Mature Phase

5. Evolution in Time 5 Decay Phase

6. Evolution in Time 6 Decay Phase

7. Evolution in Time 7 Decay Phase

8. Pulsating growth 8 Observed in reality and/or models by Malkus(1952), Grinnel(1996), French(1999), Blyth(2005), Zhao & Austin (2005),… All are studies on limited amount of clouds Why does this pulsating growth happen anyway?

9. Cloud Selection 9 Create 4D, high-res data sets in DALES Visualize in Virtual Reality (thanks to Eric Griffith et. al.) 35 exemplary clouds from BOMEX, plus quite some from other cases selected => Possibility of statistics

10. Mean cloud statistics 10

11. Cloud properties in height and time 11 t p = 408s

12. W versus t/z 12 Inside the cloudAround the cloud

13. Shell in z/t 13

14. Total massflux 14

15. Cloud lifecycle means 15

16. The composite pulse 16 The pulse is the building block of the cloud A pulse is defined here as the distance between 2 minima in liquid water at 800m The average lifetime of a pulse t p =408s Composition over 140 pulses

17. Pulse Properties 17

18. First and subsequent pulses 18

19. No Pulsating signal from the sub cloud 19

20. 20 The buoyancy precedes the massflux, that precedes the horizontal divergence Mass flux and Lateral entrainment

21. Heus et al., JAS 2008 21 Ye Olde Cloud top/lateral mixing controversy

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25. Conclusions 25 Pulse based statistics capture much more of the cloud dynamics than cloud based statistics Pulses are independent of subcloud and mesoscale, but due to massive entrainment below the ascending pulse top The APT creates a detrainment/entrainment pattern that may resemble cloud top entrainment for the first pulse, but is effectively lateral mixing after this initial phase

26. Puzzles Why does the mass flux regime changes so suddenly? What is the role of the subcloud thermal, and how to get a grip on it? 26