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W ATER C YCLE A ND W EATHER S CALES. What is weather scale?. Meteorologists classify weather phenomena into four classes or scales. The four scales are: microscale, mesoscale, synoptic scale, and global scale. Each scale has its own phenomena. Global scale. Global scale
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What is weather scale? • Meteorologists classify weather phenomena into four classes or scales. The four scales are: microscale, mesoscale, synoptic scale, and global scale. • Each scale has its own phenomena.
Global scale • Global scale • These patterns are covering tens of thousands of miles and affecting large parts of the world.
Analyse water cycle over the global • To assess water resource (change) • To assess soil erosion (change) • To assess …… (change) Vaporout Vapor in temperature, precipitation radiation , …… large spatial scale (planetary scale) long time scale (year) imprecise result (trend, change)
dry heating Plateau (moist/dry) moist precipitation gulf Mississippi plain Synoptic Scale • The synoptic scale is the level just below the global scale. gulf of Mexico Mexican plateau medium spatial scale ("weather map" scale ) medium time scale Medium-range weather forecast - flood control, combat drought
Mesoscale Land surfaces absorb and emit radiation more efficiently than water surfaces. Therefore, a thermally driven circulation will form. Sea breeze may bring significant precipitation. • Mesoscale phenomena have an approximate size between 1km and 100 km and a time span between a few minutes to a day. cold warm cold
Relation between different scales--Nested Grid • A model may have a low grid resolution for a large area . Then, it has the ability to take a higher resolution grid and nest it over a region of importance. • Initial conditions: • Observed data • or • data from larger scale model
May it be “from above to below”? imprecise model The SST of the Atlantic Ocean will affect the precipitation at Tokyo.
Land surface model • Although land(30%) is smaller than ocean(70%), over land, variations in soil moisture can lead to as large differences in BL θe as several degrees in SST.
2 1 3 1 The World’s Water Cycle