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GLOBAL PATTERNS OF THE CLIMATIC ELEMENTS: (1) SOLAR ENERGY (Linked to solar insolation & R, net radiation)
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Global patterns of the climatic elements

Mar 22, 2017

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Akshay Jasani
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Page 1: Global patterns of the climatic elements

GLOBAL PATTERNS OF THE

CLIMATIC ELEMENTS:

(1) SOLAR ENERGY

(Linked to solar insolation

& R, net radiation)

Page 2: Global patterns of the climatic elements

CONTROLS OF SOLAR INSOLATION

1) Sun angle (intensity) -- changes with latitude,

time of day, time of year

2) Duration (day length) -- changes with latitude,

time of year

3) Cloud cover

(and general reflectivity of atmosphere)

4) Surface albedo

(water, soil, snow, ice, vegetation, land use)

In general, land areas (with lower atmospheric moisture) receive more insolation than adjacent water areas and thehighest values occur over subtropical deserts.

Page 3: Global patterns of the climatic elements

REVIEW OF

INSOLATION

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Page 8: Global patterns of the climatic elements

DURATION

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INTENSITY

Page 12: Global patterns of the climatic elements

RADIATION /

ENERGY BALANCE

Q* = ( K↓ - K↑ ) + ( L↓ - L↑ )where K↓ = direct + diffuse shortwave

solar radiation

Page 13: Global patterns of the climatic elements
Page 14: Global patterns of the climatic elements

Kiehl and Trenberth (1997) BAMS

Page 15: Global patterns of the climatic elements

Trenberth et al. (2009) BAMS

Page 16: Global patterns of the climatic elements

Radiative Components

Net short-wave radiation =

short-wave down - short-wave up

Net long-wave radiation =

long-wave down - long-wave up

Net radiation (R net) =

net short-wave radiation + net long-wave radiation

Positive values represent energy moving towards the

surface, negative values represent energy moving

away from the surface.

Page 17: Global patterns of the climatic elements

Net short-wave radiation =

Positive values represent

energy moving towards the

surface, negative values

represent energy moving

away from the surface.

Page 18: Global patterns of the climatic elements

SW absorbed =

Function of

INTENSITY &

DURATION & sun

angle / albedo

Page 19: Global patterns of the climatic elements

Net long-wave radiation =

Positive values represent

energy moving towards the

surface, negative values

represent energy moving

away from the surface.

Page 20: Global patterns of the climatic elements
Page 21: Global patterns of the climatic elements

Net Surplus

Page 22: Global patterns of the climatic elements

Annual mean absorbed solar radiation,

emitted longwave radiation (OLR) and

net radiation by latitude

Page 23: Global patterns of the climatic elements

S = Solar radiation T = Terrestrial

radiation

Page 24: Global patterns of the climatic elements

Net Radiation =

Positive values represent

energy moving towards the

surface, negative values

represent energy moving

away from the surface.

Page 25: Global patterns of the climatic elements
Page 26: Global patterns of the climatic elements

Non-Radiative Components

Sensible heat flux (H) = direct heating, a

function of surface and air temperature

Latent heat flux (LE) = energy that is stored

in water vapor as it evaporates, a function of

surface wetness and relative humidity

Positive values for sensible and latent heat flux

represent energy moving towards the atmosphere,

negative values represent energy moving away from

the atmosphere.

Page 27: Global patterns of the climatic elements

Non-Radiative Components

Change in heat storage (G) =

net radiation - latent heat flux - sensible heat flux

G = R net - LE - H

Positive values for change in heat storage

represent energy moving out of storage,

negative values represent energy moving into

storage.

Page 28: Global patterns of the climatic elements

Sensible Heat Flux = H

Positive values for sensible and

latent heat flux represent energy

moving towards the atmosphere,

negative values represent energy

moving away from the atmosphere.

Page 29: Global patterns of the climatic elements

Latent Heat Flux = LE

Positive values for sensible and

latent heat flux represent energy

moving towards the atmosphere,

negative values represent energy

moving away from the atmosphere.

Page 30: Global patterns of the climatic elements
Page 31: Global patterns of the climatic elements

Humid

Tropical /

Equatorial

rainforest

Tropical

desert

R net

LE

H

R net

LE

H

Page 32: Global patterns of the climatic elements

Tropical wet-dry climate

Grassland /steppe climate

Tropical wet climate

Tropical desert

climate

Page 33: Global patterns of the climatic elements

Change in Heat Storage = G

Positive values for change in heat

storage represent energy moving

out of storage, negative values

represent energy moving into

storage.

Page 34: Global patterns of the climatic elements
Page 35: Global patterns of the climatic elements

Air Temperature (at the surface) = T (C)Seasonal temperature variations can be explained in terms

of the latitudinal & seasonal variations in the surface energy balance.

The pattern of temperatures are a function

of net short-wave radiation, net long-wave

radiation, sensible heat flux, latent heat

flux and change in heat storage.

Page 36: Global patterns of the climatic elements

GLOBAL PATTERNS OF

THE CLIMATIC

ELEMENTS:

(2) TEMPERATURE

Page 37: Global patterns of the climatic elements

CONTROLS OF HORIZONTAL

TEMPERATURE PATTERNS

1. Sun angle & Duration

2. Land vs. water thermal contrasts

3. Warm & Cold surface ocean

currents

4. Elevation

5. Ice/Snow albedo effects

6. Prevailing atmospheric

circulation

Page 38: Global patterns of the climatic elements

1. Sun Angle & Duration

Sun angle (influences intensity of solar insolation &

albedo)

Duration (based on day length)

- both change with latitude and time of year

Leads to: zonal (east-west) distribution of isotherms,

hot in low latitudes; cold in high latitudes

Page 39: Global patterns of the climatic elements

Given the same intensity of insolation, the surface of any

extensive deep body of water heats more slowly and cools more

slowly than the surface of a large body of land.

4 Reasons:

1) water has a higher specific heat and heat capacity than land

2) transmission of sunlight into transparent water

3) mixing is possible in water, but not soil

4) evaporation cools air over water during hot season (less evap

during winter)

Leads to:

• annual and diurnal temperature ranges will be less in

coastal/marine locations

• the lag time from maximum insolation to time of maximum

temperature may be slightly longer in coastal/marine locations

2. Land vs. water thermal contrasts

Page 40: Global patterns of the climatic elements

3. Warm and Cold Ocean Currents

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4. Elevation

Page 42: Global patterns of the climatic elements

5. Ice /Snow Albedo & Other Effects

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6. Prevailing atmospheric circulation

Temperatures are affected by the

temperature "upwind" -- i.e. where the

prevailing winds and air masses originate

Page 44: Global patterns of the climatic elements

MAPPING HORIZONTAL

TEMPERATURE PATTERNS

•Isotherms = lines connecting points of equal temperature

•Isotherms will be almost parallel, extending east-west if

Control #1 (sun angle) is the primary control.

•If any of the other controls are operating, isotherms on a

map will have an EQUATORWARD shift over COLD surfaces

and a POLEWARD shift over WARM surfaces

•The TEMPERATURE GRADIENT will be greatest where

there is a rapid change of temperature from one place to

another (closely spaced isotherms).

Continental surfaces in winter tend to have the

steepest temperature gradients.

Temperature gradients are much smaller over oceans,

no matter what the season.

Page 45: Global patterns of the climatic elements

JANUARY JULYNorthern Hemisphere

Southern Hemisphere

Page 46: Global patterns of the climatic elements

Southern Hemisphere

Northern Hemisphere

JANUARY JULY

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http://geography.uoregon.edu/envchange/clim_animations/

Constructed by:

Jacqueline J. Shinker, “JJ”

Univ of Oregon Climate Lab

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The NCEP / NCAR

REANALYSIS PROJECT

DATASET

http://www.cdc.noaa.gov/cdc/data.ncep.reanalysis.html

Page 52: Global patterns of the climatic elements

The assimilated data are:

-- computed by the reanalysis

model at individual gridpoints

-- to make gridded fields

extending horizontally over the

whole globe

-- at 28 different levels in the

atmosphere.

(Some of these levels correspond to

the "mandatory" pressure height

level at which soundings are taken,

e.g., 1000, 850, 700, 500, 250 mb,

etc.)

Page 53: Global patterns of the climatic elements

The horizontal resolution of the gridpoints is based on the T62

model resolution (T62 = "Triangular 62-waves truncation") which is

a grid of 192 x 94 points, equivalent to an average horizontal

resolution of a gridpoint every 210 km.

The pressure level data are saved on a 2.5 latitude-longitude grid.

Note that the gridpoints for computed model output are more numerous and much closer together in the mid and high latitudes, and fewer and farther apart over the low latitudes.

Page 54: Global patterns of the climatic elements

Map of locations of Raobs soundings for the globe:

Raobs = rawindsonde balloon soundings

Page 55: Global patterns of the climatic elements

Reanalysis Output Fields

The gridded output fields computed for different

variables have been classified into four classes (

A, B, C, and D) depending on the relative

influence (on the gridded variable) of:

(1) the observational data

(2) the model

IMPORTANT: "the user should exercise caution in interpreting results of the reanalysis, especially for variables classified in categories B and C." (p 448)

Page 56: Global patterns of the climatic elements

Class A = the most reliable class of variables;

"analysis variable is strongly influenced by observed

data"

value is closest to a real observation

Class A variables:

mean sea level pressure,

geopotential height (i.e. height of 500 mb surface,

700 mb surface, etc.),

air temperature,

wind (expressed as two vectors dimensions: zonal

= u wind (west-east ) and meridional = v wind

(north-south),

vorticity (a measure of rotation)

Page 57: Global patterns of the climatic elements

Class B = the next most reliable class of variables

"although some observational data directly affect

the value of the variable, the model also has a very

strong influence on the output values."

Class B variables:

surface pressure,

surface temperature (and near-surface 2-m

temperature) ,

max and min temperature,

vertical velocity,

near-surface wind (u & v wind at 10 m),

relative humidity, mean relative humidity,

precipitable water content, and snow cover

Page 58: Global patterns of the climatic elements

Class C = the least reliable class of variables

-- NO observations directly affect the variable and it is

derived solely from the model computations

-- forced by the model's data assimilation process, not

by any real data.

Class C variables:

precipitation,

snow depth,

soil wetness and soil temperature,

surface runoff,

cloud fraction (% high, middle, low),

cloud forcing, skin temperature, surface wind

stress, gravity wind drag,

and latent and sensible heat fluxes from surface or top

of the atmosphere.