Definition of Mesoscale Meteorology Term was coined by

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)

Definition of Mesoscale Meteorology • Fujita (81, JAS)

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?

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

• 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) • NOTES: