lecture 4 weather maps and models chapters 3 and 4

Lecture 4

Weather Maps and Models

Chapters 3 and 4

Homework

• Due Friday, September 22, 2006 (add to previous homework)

• Ch 4 TYU 2,6,9,12,14,17,18,23,25 TYPSS #2

Meteograms

• Display state variables graphically over a period of time.

• AOS rooftop site:

http://rig.ssec.wisc.edu/

Surface Station Model

Surface Station Model

Weather Symbols

Surface Maps

Station Plots Dew point analysis

MSLP analysis (mean sea level pressure)

Temperature analysis

Upper Air Station Plot

Upper air charts

http://www.aos.wisc.edu/weatherdata

Upper Air chart(Constant pressure surface)

Upper air charts

http://www.aos.wisc.edu/weatherdata

Forecasting Weather

Weather Models

• Mathematical equations describe how:– Air accelerates or decelerates based on Newton’s

Laws– Mass of air and its properties move from one position

to another while conserving properties of mass and energy

– Mass of water vapor is moved and transformed to rain and snow

– Air is heated or cooling by condensation, radiation • These differential equations are integrated

forward in time by solving them numerically on a grid

Two Basic types of Models

• Finite Difference Model– Solved on a grid– Taylor series approximations to continuous equations

• Spectral Model– Analysis of variables on a grid in real space is

transformed to a grid in wave space grid using a Fourier transform

– Equations moved forward in wave space analytically– Variables transformed back to real space

Examples of Horizontal Grids

Vertical Grid

Vertical grid may be :

•Height coordinate

•Pressure coordinate

•Sigma or terrain following coordinate

Map Projection

Various map projections are used to take into account the curved Earth surface. For instance:

1. Mercator projection

2. Polar Stereographic Grid

3. Lambert Conformal

4. Spherical Grid

Topography Representation

Ensemble Prediction

Look at AOS Web Page

• Real Time analysis and Prediction available on the Web:

Weather Maps (Current and Forecast Maps):

http://www.aos.wisc.edu/weather/index.htm (Maps drawn by UW AOS Department)http://cup.aos.wisc.edu (Tripoli’s NMS Model output)http://www.nws.noaa.gov/outlook_tab.php (National Weather Service Maps)http://weather.unisys.com/ (Unisys (Purdue) Maps….traditional leader in Internet map technology)http://www.meteo.psu.edu/%7Egadomski/ewall.html (Penn State Electronic Maps)http://www.atmos.albany.edu/weather/difax.html (NWS difax maps from SUNY Albany)http://www.rap.ucar.edu/weather/ (National Center for Atmospheric Research Weather)http://hdrweather.com/f2p2/default.htm (Colorado weather by Henz)