# source:palm/trunk/TUTORIAL/SOURCE/exercise_cumulus.tex@1649

Last change on this file since 1649 was 1649, checked in by knoop, 9 years ago

Latex lecture update for PALM seminar in Hong Kong

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1% $Id: exercise_cbl.tex 1515 2015-01-02 11:35:51Z boeske$
4
5%\usepackage[utf8]{inputenc}
6\usepackage[T1]{fontenc}
7\usepackage{ngerman}
8\usepackage{pgf}
9\usepackage{subfigure}
10\usepackage{units}
11\usepackage{multimedia}
12\usepackage{hyperref}
13\newcommand{\event}[1]{\newcommand{\eventname}{#1}}
14\usepackage{xmpmulti}
15\usepackage{tikz}
16\usetikzlibrary{shapes,arrows,positioning}
17\usetikzlibrary{calc}                             %neues paket
18\usetikzlibrary{decorations.markings}             %neues paket
19\usetikzlibrary{decorations.pathreplacing}        %neues paket
20\def\Tiny{\fontsize{4pt}{4pt}\selectfont}
21\usepackage{amsmath}
22\usepackage{amssymb}
23\usepackage{multicol}
24\usepackage{pdfcomment}
25\usepackage{graphicx}
26\usepackage{listings}
27\lstset{showspaces=false,language=fortran,basicstyle=
28        \ttfamily,showstringspaces=false,captionpos=b}
29
30\institute{Institute of Meteorology and Climatology, Leibniz Universit{\"a}t Hannover}
31\selectlanguage{english}
32\date{last update: \today}
33\event{PALM Seminar}
35
36\setbeamertemplate{footline}
37  {
38    \begin{beamercolorbox}[rightskip=-0.1cm]&
39     {\includegraphics[height=0.65cm]{imuk_logo.pdf}\hfill \includegraphics[height=0.65cm]{luh_logo.pdf}}
40    \end{beamercolorbox}
41    \begin{beamercolorbox}[ht=2.5ex,dp=1.125ex,
44    \end{beamercolorbox}
45    \begin{beamercolorbox}[colsep=1.5pt]{lower separation line foot}
46    \end{beamercolorbox}
47  }
48%\logo{\includegraphics[width=0.3\textwidth]{luhimuk_logo.pdf}}
49
50
51\title[Exercise 10: Cumulus Cloud]{Exercise 10: \\Cumulus Cloud With Bulk Cloud Physics}
52\author{PALM group}
53
54\begin{document}
55
56% Folie 1
57\begin{frame}
58\titlepage
59\end{frame}
60
61\section{Exercise}
62\subsection{Exercise}
63
64% Folie 2
65\begin{frame}
66   \frametitle{Exercise 10: Cumulus Cloud With Bulk Cloud Physics}
67
68   Simulate a cumulus cloud:
69   \begin{itemize}
70%      \scriptsize
71           \item<2-> Initialize the simulation with a marine, cumulus-topped, trade-wind region boundary layer.
72           \item<3-> Trigger the cloud by a bubble of rising warm air.
73           \item<4-> Parameterize condensation using a simple bulk cloud physics scheme.
74           \item<5-> Learn how to carry out conditional averages.
75   \end{itemize}
76 \end{frame}
77
78% Folie 3
79\section{Hints}
80\subsection{Hints}
81\begin{frame}
82   \frametitle{Hints I}
83
84   The setup of this exercise is based on the LES-intercomparison BOMEX (Siebesma et al., 2003, J. Atmos. Sci.):
85%   \only<2>{\begin{center}
86%      \includegraphics[width=0.7\textwidth]{exercise_cumulus_figures/ptq.pdf}
87%   \end{center}}
88%   \only<2->{
89   \begin{itemize}
90      \scriptsize
91
92      \item<2-> In order to prescribe vertical profiles of temperature and humidity, set:\\
93                         \texttt{initializing\_actions = 'set\_constant\_profiles',}
94            \item<3-> \texttt{pt\_surface = 297.9,}
95
97
99            \item<4-> \texttt{q\_surface = 0.016,}
100
101            \texttt{q\_vertical\_gradient = -2.97297E-4, -4.5238095E-4, -8.108108E-5,}
102
103            \texttt{q\_vertical\_gradient\_level = 0.0, 740.0, 3260.0,}
104
105            \item<5-> \texttt{surface\_pressure = 1015.4,}
106
107            \item<6-> Note that contrary to BOMEX, no geostrophic wind, no surface fluxes, and no subsidence is prescribed in this setup.
108
109              \item<7-> domain size: about $\unit[1000 \times 3600 \times 3000]{m^3}$ ($x$/$y$/$z$)
110           \item<8-> grid size: $\unit[50]{m}$ equidistant
111           \item<9-> simulated time:    $\unit[1800]{s}$
112   \end{itemize}
113%   }
114\end{frame}
115
116
117% Folie 4
118\begin{frame}
119   \frametitle{Hints II}
120
121   How to initialize a bubble of warm air?
122   \begin{itemize}
123      \scriptsize
124      \item<2-> In the subroutine \texttt{user\_init}, initialize the bubble of warm air by a temperature excess at the first time step (\texttt{current\_timestep\_number == 0})
125      \item<3-> The temperature excess can be added directly to the three-dimensional field of liquid water potential temperature:
126
127      \texttt{pt(k,j,i) = pt(k,j,i) + EXP( -0.5 * ( y / bubble\_sigma\_y )**2 ) * \&}
128
129      \texttt{\hphantom{pt(k,j,i) = pt(k,j,i) + }EXP( -0.5 * ( z / bubble\_sigma\_z )**2 ) * \&}
130
131      \texttt{\hphantom{pt(k,j,i) = pt(k,j,i) + }initial\_temperature\_difference}
132
133
134      with the locations:
135
136      \texttt{y = j * dy - bubble\_center\_y}
137
138      \texttt{z = zu(k) - bubble\_center\_z}
139
140      \item<4-> Initialize the bubble by the following parameters:
141
142      \texttt{bubble\_center\_y = 1800.0, bubble\_center\_z = 170.0,}
143
144      \texttt{bubble\_sigma\_y = 300.0, bubble\_sigma\_z = 150.0,}
145
146      \texttt{initial\_temperature\_difference = 0.4}
147      \item<5-> Think parallel: Mind that the domain of each PE extends only from \texttt{nxlg} to \texttt{nxrg} and \texttt{nysg} to \texttt{nyng}! (Note that the just mentioned dimensions include ghost points)
148    \end{itemize}
149\end{frame}
150
151% Folie 5
152\begin{frame}
153   \frametitle{Hints III}
154   Bulk cloud physics in PALM:
155   \begin{itemize}
156      \scriptsize
157            \item<2-> PALM offers two bulk cloud physics schemes: A very simple, one-moment scheme by Kessler (1969, Meteor. Monogr.) and a state-of-the-art two-moment scheme by Seifert and Beheng (2006, Meteor. Atmos. Phys.).
158
159            \item<3-> You will use the saturation adjustment scheme, as applied in the Kessler-scheme, for parameterizing condensation. (Note that this kind of scheme is used in the vast majority of today's bulk cloud physics parameterizations.)
160
161            \item<4-> The liquid water is diagnosed by $q_\text{l} = \max(0, q_\text{t} - q_\text{s})$: If the total water content $q_\text{t}$ exceeds the saturation water content $q_\text{s}$, all supersaturations condensate immediately to liquid water. On the other hand, no liquid water is present in subsaturated conditions.
162
163   \end{itemize}
164
165    \onslide<4-> Turn on simple cloud microphysics in your parameter file (\texttt{inipar} namelist):
166
167   \begin{itemize}
168      \scriptsize
169            \item<5-> \texttt{humidity = .TRUE., cloud\_physics = .TRUE.,}
170
171            \item<6-> \texttt{cloud\_scheme = 'kessler', precipitation = .FALSE.}
172   \end{itemize}
173 \end{frame}
174
175
176% Folie 6
177\begin{frame}
178   \frametitle{Hints IV}
179
180   What is conditional averaging?
181   \begin{itemize}
182      \scriptsize
183      \item<2-> A horizontal average (e.\,g., for retrieving vertical profiles) might be inappropriate for the analysis of a heterogeneous phenomenon (e.\,g., cumulus clouds).
184      \item<3-> A conditional average can restrict the analysis to the regions of interest (e.\,g., cloudy and non-cloudy regions).
185    \end{itemize}
186   \onslide<4->What kind of conditional average are you going to derive?
187   \begin{itemize}
188      \scriptsize
189      \item<5-> You will derive vertical profiles of \textbf{cloud cover} and \textbf{cloud core cover}. These profiles are the basis for more complex profiles (e.\,g., the cloud core vertical velocity).
190      \item<6-> Cloudy grid cells are defined as grid cells with a non-zero liquid water content ($q_\text{l}>0$, \texttt{ql(k,j,i) > 0.0}). Cloud core grid cells are defined as cloudy grid cells, which are also positively buoyant with respect to the slab average ($\theta_\text{v}>\langle \theta_\text{v} \rangle$, \texttt{vpt(k,j,i) > hom(k,1,44,sr)}).
191      \end{itemize}
192\end{frame}
193
194% Folie 7
195\begin{frame}
196   \frametitle{Hints V}
197
198    PALM offers a convenient way to compute and output user-profiles:
199     \begin{itemize}
200      \scriptsize
201      \item<2-> In the subroutine \texttt{user\_statistics}, you can compute the cloud cover profile by counting all cloudy grid cells at a certain grid level \texttt{k}:
202
203      \texttt{IF ( ql(k,j,i) > 0.0 )  THEN}
204
205      \texttt{\hphantom{aaa}sums\_l(k,pr\_palm+1,tn) = sums\_l(k,pr\_palm+1,tn) + 1.0}
206
207      \texttt{ENDIF}
208
209      \item<3-> The computation of the cloud core cover profile is up to you!
210
211
212       \item<4-> PALM automatically cares for the summation across the PE's boundaries and the normalization of the profiles (i.\,e., dividing it by the total amount of grid cells in horizontal directions).
213
214      \item<5-> Do not forget to adapt \texttt{user\_check\_data\_output\_pr} (for defining your user-profiles) and your parameter file (\texttt{userpar} namelist) for the output (with the parameter \texttt{data\_output\_pr\_user = 'your\_profile'})!
215      \item<6-> Check the online documentation of PALM for more detailed information on the implementation of user profiles:\\
216      \texttt{\hphantom{aaa}http://palm.muk.uni-hannover.de/trac/wiki/doc/app/userint/output\#part\_1}\\
217      Further examples are also provided within the subroutines \texttt{user\_statistics} and \texttt{user\_check\_data\_output\_pr}.
218
219      \end{itemize}
220\end{frame}
221
224% Folie 8
225\begin{frame}
227
228   \begin{itemize}
229    \item<1-> Output instantaneous yz-cross sections of \texttt{ql} and \texttt{w} at \texttt{section\_yz = 0}. (\texttt{pt}, \texttt{q} and \texttt{vpt} are also interesting!) An output interval of $60\,\text{s}$ is adequate.
230   \item<2-> Output instantaneous vertical profiles of cloud cover and cloud core cover! Again, an output interval of $60\,\text{s}$ is adequate.
231   \item<3-> Answer the following questions:
232   \begin{itemize}
233   \item How does the cloud develop?
234   \item Can you identify the \textit{actively growing} and the \textit{decaying stage} of the cloud's life cycle by comparing the profiles of cloud and cloud core cover profiles? (Mind the profiles' definitions and physical implications!)
235   \end{itemize}
236   \item<4-> If you are really fast: What changes during the cloud's development turning on precipitation (\texttt{precipitation = .TRUE.})?
237   \end{itemize}
238
239\end{frame}
240
241% Folie 9
242\section{Results}
243\subsection{Results}
244
245\begin{frame}
246   \frametitle{$yz$-cross sections at $t \approx \unit[500]{s}$}
247%   The bubble of warm air rises, but has not reached its condensation level.
248   \vspace{-5mm}
249   \begin{center}
250      \includegraphics[angle=90,width=1.0\textwidth]{exercise_cumulus_figures/500.pdf}
251   \end{center}
252\end{frame}
253
254% Folie 8
255\begin{frame}
256   \frametitle{$yz$-cross sections at $t \approx \unit[800]{s}$}
257%   Condensation starts, and the cloud appears as the the visible top of the rising bubble.
258   \vspace{-5mm}
259   \begin{center}
260      \includegraphics[angle=90,width=1.0\textwidth]{exercise_cumulus_figures/800.pdf}
261   \end{center}
262\end{frame}
263
264% Folie 9
265\begin{frame}
266   \frametitle{$yz$-cross sections at $t \approx \unit[1200]{s}$}
267%   The cloud is vigorously growing.
268   \vspace{-5mm}
269   \begin{center}
270      \includegraphics[angle=90,width=1.0\textwidth]{exercise_cumulus_figures/1200.pdf}
271   \end{center}
272\end{frame}
273
274% Folie 9
275\begin{frame}
276   \frametitle{$yz$-cross sections at $t \approx \unit[1500]{s}$}
277%   The cloud dilutes and dissipates due to turbulent entrainment of environmental air.
278   \vspace{-5mm}
279   \begin{center}
280      \includegraphics[angle=90,width=1.0\textwidth]{exercise_cumulus_figures/1500.pdf}
281   \end{center}
282\end{frame}
283
284% Folie 10
285\begin{frame}
286   \frametitle{Cloud cover (clcov) and cloud core cover (cocov) profiles}
287   \begin{center}
288      \includegraphics[width=1.0\textwidth]{exercise_cumulus_figures/prof.pdf}
289   \end{center}
290\end{frame}
291
294% Folie 13
295\begin{frame}
297   {\footnotesize }
298   How does the cloud develop?
299   {\footnotesize }
300   \begin{itemize}
301   \item See frames 9 -- 12: The clouds develops from a rising bubble of warm air ($t \approx \unit[500]{s}$). Reaching the condensation level ($t \approx \unit[800]{s}$), the cloud appears as the bubble's visible top. Afterwards, the cloud starts to grow more vigorously by the release of latent heat ($t \approx \unit[1200]{s}$). In the end of the cloud's life-cycle, the cloud dissipates by turbulent entrainment of environmental air and the subsequent evaporation of the cloud ($t \approx \unit[1500]{s}$).
302   \end{itemize}
303\end{frame}
304
305\begin{frame}
307   {\footnotesize }
308Can you identify the (i) actively growing and (ii) decaying stage of the cloud's life cycle by comparing the profiles of cloud and cloud core cover profiles?
309   {\footnotesize }
310      \begin{itemize}
311   \item See Frame 13: As long as the cloud core is present, i.\,e., a positively buoyant region producing upward motion, the cloud grows actively (until $1400\,\text{s}$). From $1500\,\text{s}$ on, no cloud core is visible. As a result, the cloud's upward motion decelerates and the rate of condensation decreases. Thus, the cloud's dilution by the entrainment of environmental air can not be counterbalanced anymore. As a consequence, the cloud decays and finally dissipates.
312   \end{itemize}
313\end{frame}
314
315\begin{frame}