Title: GLOBAL PATTERNS OF THE CLIMATIC ELEMENTS: (1) SOLAR ENERGY
1GLOBAL PATTERNS OF THE CLIMATIC ELEMENTS (1)
SOLAR ENERGY (Linked to solar insolation R,
net radiation)
2CONTROLS 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 the highest values occur over subtropical
deserts.
3REVIEW OF INSOLATION
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8DURATION
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11INTENSITY
12RADIATION / ENERGY BALANCE
Q ( K? - K? ) ( L? - L? ) where K? direct
diffuse shortwave solar radiation
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14Kiehl and Trenberth (1997) BAMS
15Trenberth et al. (2009) BAMS
16Radiative 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.
17Net short-wave radiation
Positive values represent energy moving towards
the surface, negative values represent energy
moving away from the surface.
18SW absorbed Function of INTENSITY DURATION
sun angle / albedo
19Net long-wave radiation
Positive values represent energy moving towards
the surface, negative values represent energy
moving away from the surface.
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22Annual mean absorbed solar radiation, emitted
longwave radiation (OLR) and net radiation by
latitude
23S Solar radiation T Terrestrial radiation
24Net Radiation
Positive values represent energy moving towards
the surface, negative values represent energy
moving away from the surface.
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26Non-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.Â
27Non-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.
28Sensible 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.Â
29Latent 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.Â
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31Humid Tropical / Equatorial rainforest
Tropical desert
32Tropical wet climate
Tropical wet-dry climate
Tropical desert climate
Grassland /steppe climate
33Change in Heat Storage G
Positive values for change in heat storage
represent energy moving out of storage, negative
values represent energy moving into storage.
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35Air Temperature (at the surface) T (?C)
Seasonal temperature variations can be explained
in terms of the latitudinal seasonal
variations in the surface energy balance.Â
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.Â
36GLOBAL PATTERNS OF THE CLIMATIC ELEMENTS (2)
TEMPERATURE
37CONTROLS OF HORIZONTAL TEMPERATURE PATTERNS
- Sun angle Duration
- Land vs. water thermal contrasts
- Warm Cold surface ocean currents
- Elevation
- Ice/Snow albedo effects
- Prevailing atmospheric circulation
381. 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
392. Land vs. water thermal contrasts
- Â 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
403. Warm and Cold Ocean Currents
414. Elevation
425. Ice /Snow Albedo Other Effects
436. Prevailing atmospheric circulation
Temperatures are affected by the temperature
"upwind" -- i.e. where the prevailing winds and
air masses originate
44MAPPING 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.
45JANUARY
JULY
Northern Hemisphere
Southern Hemisphere
46JANUARY
JULY
Northern Hemisphere
Southern Hemisphere
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50http//geography.uoregon.edu/envchange/clim_animat
ions/
Constructed by Jacqueline J. Shinker, JJ Univ
of Oregon Climate Lab
51The NCEP / NCAR REANALYSIS PROJECT DATASET
http//www.cdc.noaa.gov/cdc/data.ncep.reanalysis.h
tml
52The 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.)
53The 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.
54Map of locations of Raobs soundings for the
globe
Raobs rawindsonde balloon soundings
55- 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 - the observational data
- 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)
56Class 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)
57Class 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
58Class 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.