Geoscience Reference
In-Depth Information
- in the atmosphere, radiative and convective losses are equal to 350-324-165-
30+78+24=-67 W/m
2
, which is balancing exactly the 67 W/m
2
fraction of solar
energy absorbed by the atmosphere,
- at the surface, the solar contribution (168 W/m
2
) is counterbalanced by the
sum of infrared radiative losses (390-324=66 W/m
2
) and by sensible and latent heat
fluxes (24+78=102 W/m
2
).
Figure. 4.2.
Average global radiation budget of the Earth's system. Source: “Climate change
2001 working group I: the scientific basis”, IPCC Third Assessment Report
This energy exchange occurring between the Earth's surface and the atmosphere
maintains a global average temperature of 14°C on the Earth's surface. If there were
no greenhouse gases present in the atmosphere, this average temperature would fall
down to -19°C, a temperature corresponding to an infrared emission of the climate
system, as seen from space, of 235 W/m
2
.
The general circulation of the atmosphere and of the ocean, and consequently
climate variables fields, are strongly constrained by the variability of the radiative
fluxes (its diurnal and annual cycle, latitudinal variations, influence of cloud cover,
GHG concentration).
Other relevant factors include altitude, type and properties of the underlying
surface (especially radiative properties in terms of e.g. albedo), irrespective of
whether the surface is land or ocean.
Geographical information, which provides boundary information used in weather
and climate modeling is essential.
Meteorological phenomena cover a wide range of spatial and temporal scales,
ranging from the micro-scale to planetary scale (Figure 4.3). They can be modeled
