1. Definition of Mesoscale Meteorology Term was coined by Lidga (51) in the compendium of meteorology (AMS) Lidga was a radar meteorologist Used the term to classify phenomena observed by radars that were not observed by conventional observations. Since then, a number of classification schemes have been proposed: From Orlanski (75, BAMS)

2. Definition of Mesoscale Meteorology Fujita (81, JAS)

3. The Challenge of Mesoscale Meteorology Check out the spectral analysis of observations from a weather station below: Notice the following peaks: –Minutes: turbulence –1 day: diurnal oscillation –A few days: synoptic-scale motions –Months: planetary scale waves Notice the LACK of energy in the mesocale!! – there is a “spectral gap” in the mesoscale spatial and time scales In other words, they were not being resolved! Is this true today?

4. What is “spectral analysis”? Blue curve: diurnal variation of wind speed Magenta curve: synoptic variation of wind speed Yellow: sum of diurnal and synoptic: what you observe Take the observed yellow curve and decompose it into the blue and magenta curves. Then plot the amount of energy in each “wave” versus period of all waves observed

5. OK, let’s check out this “Definition of the Mesoscale” module to finish our introduction: http://www.meted.ucar.edu/mesoprim/mesodefn/index.htm (pgs 1 - 12)http://www.meted.ucar.edu/mesoprim/mesodefn/index.htm NOTES: