source: palm/trunk/TUTORIAL/SOURCE/exercise_cumulus.tex @ 1532

Last change on this file since 1532 was 1532, checked in by hoffmann, 10 years ago

updated tutorial (ncl, particle model), new exercise (bulk cloud physics)

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1% $Id: exercise_cbl.tex 1515 2015-01-02 11:35:51Z boeske $
2\input{header_tmp.tex}
3%\input{header_lectures.tex}
4
5\usepackage[utf8]{inputenc}
6\usepackage{ngerman}
7\usepackage{pgf}
8\usepackage{subfigure}
9\usepackage{units}
10\usepackage{multimedia}
11\usepackage{hyperref}
12\newcommand{\event}[1]{\newcommand{\eventname}{#1}}
13\usepackage{xmpmulti}
14\usepackage{tikz}
15\usetikzlibrary{shapes,arrows,positioning}
16\usetikzlibrary{calc}                             %neues paket
17\usetikzlibrary{decorations.markings}             %neues paket
18\usetikzlibrary{decorations.pathreplacing}        %neues paket
19\def\Tiny{\fontsize{4pt}{4pt}\selectfont}
20\usepackage{amsmath}
21\usepackage{amssymb}
22\usepackage{multicol}
23\usepackage{pdfcomment}
24\usepackage{graphicx}
25\usepackage{listings}
26\lstset{showspaces=false,language=fortran,basicstyle=
27        \ttfamily,showstringspaces=false,captionpos=b}
28
29\institute{Institute of Meteorology and Climatology, Leibniz Universit{\"a}t Hannover}
30\selectlanguage{english}
31\date{last update: \today}
32\event{PALM Seminar}
33\setbeamertemplate{navigation symbols}{}
34
35\setbeamertemplate{footline}
36  {
37    \begin{beamercolorbox}[rightskip=-0.1cm]&
38     {\includegraphics[height=0.65cm]{imuk_logo.pdf}\hfill \includegraphics[height=0.65cm]{luh_logo.pdf}}
39    \end{beamercolorbox}
40    \begin{beamercolorbox}[ht=2.5ex,dp=1.125ex,
41      leftskip=.3cm,rightskip=0.3cm plus1fil]{title in head/foot}
42      {\leavevmode{\usebeamerfont{author in head/foot}\insertshortauthor} \hfill \eventname \hfill \insertframenumber \; / \inserttotalframenumber}
43    \end{beamercolorbox}
44    \begin{beamercolorbox}[colsep=1.5pt]{lower separation line foot}
45    \end{beamercolorbox}
46  }
47%\logo{\includegraphics[width=0.3\textwidth]{luhimuk_logo.pdf}}
48
49
50\title[Exercise 11: Cumulus Cloud]{Exercise 11: \\Cumulus Cloud With Bulk Cloud Physics}
51\author{PALM group}
52
53\begin{document}
54
55% Folie 1
56\begin{frame}
57\titlepage
58\end{frame}
59
60\section{Exercise}
61\subsection{Exercise}
62
63% Folie 2
64\begin{frame}
65   \frametitle{Exercise 11: Cumulus Cloud With Cloud Physics}
66   
67   Simulate a cumulus cloud:
68   \begin{itemize}
69%      \scriptsize
70           \item<2-> Initialize the simulation with a marine, cumulus-topped, trade-wind region boundary layer.
71           \item<3-> Trigger the cloud by a bubble of rising warm air.
72           \item<4-> Parameterize condensation using a simple bulk cloud physics scheme.
73           \item<5-> Learn how to carry out conditional averages.
74   \end{itemize}   
75 \end{frame}
76
77% Folie 3
78\section{Hints}
79\subsection{Hints}
80\begin{frame}
81   \frametitle{Hints I}
82
83   The setup of this exercise is based on the LES-intercomparison BOMEX (Siebesma et al., 2003, JAS):
84%   \only<2>{\begin{center}
85%      \includegraphics[width=0.7\textwidth]{exercise_cumulus_figures/ptq.pdf}
86%   \end{center}}
87   \only<2->{
88   \begin{itemize}
89      \scriptsize
90     
91      \item<2-> In order to prescribe vertical profiles of temperature and humidity, set:\\
92                         \texttt{initializing\_actions = 'set\_constant\_profiles',}
93            \item<3-> \texttt{pt\_surface = 297.9,}
94           
95            \texttt{pt\_vertical\_gradient = 0.0, 0.58588957,}
96           
97            \texttt{pt\_vertical\_gradient\_level = 0.0, 740.0,}
98            \item<4-> \texttt{q\_surface = 0.016,}
99           
100            \texttt{q\_vertical\_gradient = -2.97297E-4, -4.5238095E-4, -8.108108E-5,}
101           
102            \texttt{q\_vertical\_gradient\_level = 0.0, 740.0, 3260.0,}
103           
104            \item<5-> \texttt{surface\_pressure = 1015.4,}
105           
106            \item<6-> Note that contrary to BOMEX, no geostrophic wind, no surface fluxes, and no subsidence is prescribed in this setup.
107           
108              \item<7-> domain size: about $\unit[1000 \times 3600 \times 3000]{m^3}$ ($x$/$y$/$z$)
109           \item<8-> grid size: $\unit[50]{m}$ equidistant
110           \item<9-> simulated time:    $\unit[1800]{s}$
111   \end{itemize} 
112   }
113\end{frame}
114
115
116% Folie 4
117\begin{frame}
118   \frametitle{Hints II}
119   
120   How to initialize a bubble of warm air?
121   \begin{itemize}
122      \scriptsize
123      \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})
124      \item<3-> The temperature excess can be added directly to the three-dimensional field of liquid water potential temperature:
125     
126      \texttt{pt(k,j,i) = pt(k,j,i) + EXP( -0.5 * ( y / bubble\_sigma\_y )**2 ) * \&}
127     
128      \texttt{\hphantom{pt(k,j,i) = pt(k,j,i) + }EXP( -0.5 * ( z / bubble\_sigma\_z )**2 ) * \&}
129     
130      \texttt{\hphantom{pt(k,j,i) = pt(k,j,i) + }initial\_temperature\_difference}
131     
132     
133      with the locations:
134     
135      \texttt{y = j * dy - bubble\_center\_y}
136     
137      \texttt{z = zu(k) - bubble\_center\_z}
138     
139      \item<4-> Initialize the bubble by the following parameters:
140     
141      \texttt{bubble\_center\_y = 1800.0, bubble\_center\_z = 170.0,}
142     
143      \texttt{bubble\_sigma\_y = 300.0, bubble\_sigma\_z = 150.0,}
144     
145      \texttt{initial\_temperature\_difference = 0.4}
146      \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}!
147    \end{itemize}
148\end{frame}
149
150% Folie 5
151\begin{frame}
152   \frametitle{Hints III}
153   Bulk cloud physics in PALM:
154   \begin{itemize}
155      \scriptsize
156            \item<2-> PALM offers two bulk cloud physics schemes: A very simple, one-moment scheme by Kessler (1969, MM) and a state-of-the-art two-moment scheme by Seifert and Beheng (2006, MAP).
157           
158            \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.)
159           
160            \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. 
161           
162   \end{itemize} 
163   
164    \onslide<4-> Turn on simple cloud microphysics in your parameter file (\texttt{inipar} namelist):
165   
166   \begin{itemize}
167      \scriptsize
168            \item<5-> \texttt{humidity = .TRUE., cloud\_physics = .TRUE.,}
169           
170            \item<6-> \texttt{cloud\_scheme = 'kessler', precipitation = .FALSE.}
171   \end{itemize} 
172 \end{frame}
173   
174   
175% Folie 6
176\begin{frame}
177   \frametitle{Hints IV}
178   
179   What is conditional averaging?
180   \begin{itemize}
181      \scriptsize
182      \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).
183      \item<3-> A conditional average can restrict the analysis to the regions of interest (e.\,g., cloudy and non-cloudy regions).
184    \end{itemize}
185   \onslide<4->What kind of conditional average are you going to derive?
186   \begin{itemize}
187      \scriptsize
188      \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).
189      \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)}).
190      \end{itemize}
191\end{frame}
192
193% Folie 7
194\begin{frame}
195   \frametitle{Hints V}
196
197    PALM offers a convenient to compute and output user-profiles:
198     \begin{itemize}
199      \scriptsize
200      \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}:
201     
202      \texttt{IF ( ql(k,j,i) > 0.0 )  THEN}
203     
204      \texttt{\hphantom{aaa}sums\_l(k,pr\_palm+1,tn) = sums\_l(k,pr\_palm+1,tn) + 1.0}
205     
206      \texttt{ENDIF}
207     
208      \item<3-> The computation of the cloud core cover profile is up to you!
209
210     
211       \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).
212     
213      \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'})!
214      \item<6-> \textbf{Check also the examples provided in \texttt{user\_statistics} and \texttt{user\_check\_data\_output\_pr} for the implementation of user profiles!}
215     
216     
217
218
219      \end{itemize}
220\end{frame}
221
222\section{Tasks}
223\subsection{Tasks}
224% Folie 8
225\begin{frame}
226   \frametitle{Tasks to be done:}
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   \begin{center}
249      \includegraphics[width=1.0\textwidth]{exercise_cumulus_figures/500.pdf}
250   \end{center}
251\end{frame}
252
253% Folie 8
254\begin{frame}
255   \frametitle{$yz$-cross sections at $t \approx \unit[800]{s}$}
256%   Condensation starts, and the cloud appears as the the visible top of the rising bubble.
257   \begin{center}
258      \includegraphics[width=1.0\textwidth]{exercise_cumulus_figures/800.pdf}
259   \end{center}
260\end{frame}
261
262% Folie 9
263\begin{frame}
264   \frametitle{$yz$-cross sections at $t \approx \unit[1200]{s}$}
265%   The cloud is vigorously growing.
266   \begin{center}
267      \includegraphics[width=1.0\textwidth]{exercise_cumulus_figures/1200.pdf}
268   \end{center}
269\end{frame}
270
271% Folie 9
272\begin{frame}
273   \frametitle{$yz$-cross sections at $t \approx \unit[1500]{s}$}
274%   The cloud dilutes and dissipates due to turbulent entrainment of environmental air.
275   \begin{center}
276      \includegraphics[width=1.0\textwidth]{exercise_cumulus_figures/1500.pdf}
277   \end{center}
278\end{frame}
279
280% Folie 10
281\begin{frame}
282   \frametitle{Cloud cover (clcov) and cloud core cover (cocov) profiles}
283   \begin{center}
284      \includegraphics[width=1.0\textwidth]{exercise_cumulus_figures/prof.pdf}
285   \end{center}
286\end{frame}
287
288%\section{Answers}
289\subsection*{Answers}
290% Folie 13
291\begin{frame}
292   \frametitle{Answers to questions I}
293   {\footnotesize }
294   How does the cloud develop?
295   {\footnotesize }
296   \begin{itemize}
297   \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 bubbles 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 ($t \approx \unit[1500]{s}$).
298   \end{itemize}
299\end{frame}
300
301\begin{frame}
302   \frametitle{Answers to questions II}
303   {\footnotesize }
304Can 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?
305   {\footnotesize }
306      \begin{itemize}
307   \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.
308   \end{itemize}
309\end{frame}
310
311\begin{frame}
312   \frametitle{Answers to questions III}
313   {\footnotesize }
314What changes during the cloud's development turning on precipitation (\texttt{precipitation = .TRUE.})?
315      {\footnotesize }
316      \begin{itemize}
317   \item Almost nothing. The simulated cloud is very shallow, therefore no significant masses of rain are produced that might alter the cloud.
318   \end{itemize}
319\end{frame}
320
321\end{document}
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