ENSC 408: Lab 8 Numerical Weather Prediction November 5 th , 2019 - - PowerPoint PPT Presentation

ENSC 408: Lab 8

Numerical Weather Prediction November 5th, 2019

Lab 6 Marks

Great Job! No overall comments..

Weather Forecasting Results

Average Score: 5 / 10 Low Temp. (C) High Temp. (C) Precipitation (no/yes/type) Observed

• 10

4 Forecasted

• 6

4 Class Average

• 7

2 Class

• 10

3

• 8

2

• 5

5

• 6

5

• 7

2

• 5

5 2

• 7
• 4
• 5

Objective:

• learn some of the fundamentals of

NWP).

• Specifically to learn about finite

differencing, and the importance of

• rder and grid resolution on

solution accuracy.

Materials:

• a FORTRAN program
• Additional resources on

programming in FORTRAN can be found online

• An R script file for plotting the
• utput

Numerical Weather Prediction (NWP)

Weather forecasts are made by solving the primitive equations for the atmosphere. Since they are non-linear partial differential equations they must be solved approximately using numerical methods Higher order of estimation == greater degree of accuracy (but also require more information and computational time..) the first order methods just require knowledge of u at the current point and one other, the second order method required knowledge of u at two other points, and the fourth order method requires knowledge of u at four other points.

Finite Differences

Taylor Series expansion around point x First Order (forwards) First Order (backwards) Second Order (centered) Fourth Order Truncated estimations of first – fourth order derivatives

Provided code to preform the second and fourth order estimations 1. Save the FORTRAN program to your H: (network) drive. 2. Use the ssh program to login to ugrad 3. cd to the “wfs” folder 4. compile the program g77 -o nwp nwp.f 5. run the program ./nwp Two output files will be created: 1. finite.dat with the results of the finite difference schemes 2. errors.dat the errors computed for each scheme

FORTRAN Code

You will be editing this parameter… ngr=9, ngr=13, ngr=17

Assignment

This lab assignment is due at the start of next week’s lab (November 12th at 8:30 am) It is worth 5% of the final course grade There are several plots to make as well as discussion questions to answer based primarily on the FORTRAN code results