Projektübung Klimamodellierung André Paul

Projektübung Klimamodellierung (05-3034) – A. Paul Vorbesprechung Projektübung Klimamodellierung (05-3034) – A. Paul

Veranstaltungsdaten Veranstaltungskennziffer: 05-3034 ECTS-Punkte: 2.5 2 SWS, Mi von 13:00-15:00, GEO 1480/90

Website http://www.palmod.uni-bremen.de/~apau/projektuebung/Material_zur_LV.html

Inhalt Einführung in die wissenschaftliche Programmierung anhand einfacher Beispielprogramme und ihrer schrittweisen Veränderung Beschreibung des Klimasystems mit Hilfe von Erhaltungsgleichungen Zeitliche und räumliche Diskretisierung von Erhaltungsgleichungen Numerische Lösung diskretisierter Erhaltungsgleichungen auf einem Computer Numerische Experimente mit physikalischen Ozean- und Atmosphärenmodellen

Ziel Einführung in die Methoden der Klimamodellierung und deren praktische Anwendung (weg vom Klimamodell als "black box")

Bewertung Anforderungen: selbstständige Lösung von Übungsaufgaben auf dem Computer (während der Übung/im Computerraum) Referat

Literatur Stocker, T (2005) Skript zur Vorlesung „Einführung in die Klimamodellierung“, 141 Seiten, PDF (16 MB), korrigierte Version 15.2.2005 http://www.climate.unibe.ch/~stocker/papers/skript0405.pdf

Einführung in die wissenschaftliche Programmierung mit Fortran 90 Verwendung von MATLAB o. ä. freigestellt Schleifen, Lesen und Schreiben von Dateien, usw.

Reading The following notes are based on Ellis, T.M.R., Phillips, Ivor R., and Lahey, Thomas M.: Fortran 90 Programming, Addison-Wesley Publishing Company.

Telling a Computer What To Do To get a computer to perform a specific task it must be given a sequence of unambiguous instructions or a program. Generating a program: Text file with instructions (Source Code; Fortran 90) Translation into computer-compatible form (Compiler) Executable Program

The Linux look and feel Cygwin is a Linux-like environment for Windows that consists of two parts: A DLL (“Dynamic Link Library”, cygwin1.dll) A collection of tools, which provide Linux look and feel Link: http://www.cygwin.com

A few useful Linux commands pwd – print name of current/working directory ls – list directory contents cd – change directory mkdir – make directories rm – remove files or diretories man – format and display the on-line manual pages (e.g. man pwd)

How to start cygwin Open cygwin window by double-clicking on the start_cygwin DOS batchfile provided with this exercise If this does not work ...

Creating and Running a Program Invoke the editor from the Start menu, or type notepad hello.f90 & into the cygwin window to create a file called hello.f90.

Creating and Running a Program Type the following source code: Compile by typing g95 hello.f90 (in the cygwin window) Run the program by typing ./a.exe (g95 by default creates an executable called a.exe) PROGRAM firsttry PRINT *,“hello“ END PROGRAM firsttry

Basic Fortran 90 concepts All words which have a special meaning in Fortran are known as keywords. Every main program unit must start with a PROGRAM statement which consists of the word PROGRAM followed by the name of the program as given by the programmer.

Avoid implicit declaration The special IMPLICIT NONE statement should always be placed immediately after the PROGRAM statement. It instructs the compiler that all variables must be declared before use.

Basic building blocks A main program unit: PROGRAM hydrostatic_balance IMPLICIT NONE ! Parameter declarations ! Variable declarations ! Executable statements END PROGRAM hydrostatic_balance

REAL and INTEGER variables Use the INTEGER :: name statement to declare a whole-number variable Use the REAL :: name statement to declare a floating-point variable ! Variable declarations ! k = loop variable ! p = pressure (Pa) ! dp = pressure change (Pa) INTEGER :: k REAL :: p,dp

Repeating parts of your program ! Loop over vertical levels DO k=1,101 ! Block of statements p = p + dp END DO

Using files to preserve data Connecting external files to your program Connect a file to a unit by OPEN(UNIT=unit_number,FILE=file_name), where unit_number is an integer number, variable or parameter and file_name is a character expression.

Using files to preserve data Write a record to a file by WRITE (UNIT=unit_number,FMT=*) Disconnect a file from a unit by means of a CLOSE (UNIT=unit_number) statement