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 –These patterns are covering tens of thousands of miles and affecting large parts of the world.

Analyse water cycle over the global Vapor in Vapor out To assess water resource (change) To assess soil erosion (change) To assess …… (change) temperature, precipitation radiation, …… large spatial scale (planetary scale) long time scale (year) imprecise result (trend, change)

Synoptic Scale The synoptic scale is the level just below the global scale. gulf of Mexico Mexican plateau Plateau (moist/dry) gulf Mississippi plain moist dry heating medium spatial scale ("weather map" scale ) medium time scale Medium-range weather forecast - flood control, combat drought precipitation

Mesoscale Mesoscale phenomena have an approximate size between 1km and 100 km and a time span between a few minutes to a day. Land surfaces absorb and emit radiation more efficiently than water surfaces. Therefore, a thermally driven circulation will form. Sea breeze may bring significant precipitation. 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: 1.Observed data or 2.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 θ e as several degrees in SST. LandOcean Depend on soil moistureSurface is saturated No observedObserved SST

The World’s Water Cycle