WATER CYCLE AND WEATHER SCALES What is weather

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WATER CYCLE AND WEATHER SCALES

WATER CYCLE AND WEATHER SCALES

What is weather scale? • Meteorologists classify weather phenomena into four classes or scales.

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

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 Vapor out Vapor in temperature, precipitation radiation ,

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

Synoptic Scale heating Plateau (moist/dry) dry moist precipitation gulf Mississippi plain gulf of Mexico

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

Mesoscale cold warm cold Land surfaces absorb and emit radiation more efficiently than water

Mesoscale cold warm cold 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 1 km and 100 km and a time span between a few minutes to a day.

Relation between different scales --Nested Grid Initial conditions: 1. Observed data or 2. data

Relation between different scales --Nested Grid Initial conditions: 1. Observed data or 2. data from larger scale model • 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.

May it be “from above to below”? imprecise model The SST of the Atlantic

May it be “from above to below”? imprecise model The SST of the Atlantic Ocean will affect the precipitation at Tokyo.

Land surface model Land Ocean Depend on soil moisture Surface is saturated No observed

Land surface model Land Ocean Depend on soil moisture Surface is saturated No observed Observed SST • 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.

The World’s Water Cycle 2 1 3 1

The World’s Water Cycle 2 1 3 1