Climate, Climate Variability and Impacts in the Mediterranean Area: An Overview
41
sea level increased while around Sicily a strong and in most parts of the western
Mediterranean Sea a much smaller decrease is observed. The SST is rising
everywhere at a pace of at least 0.1 cC/year but in its north-eastern parts according
to the ATSR measurements regionally up to 0.3C per year. In the AVHRR data,
and only here, a small increase of the SST is observed south of Sicily which would
not explain the depression in the sea level. This indicates that the sea level changes
in the Mediterranean must have dynamical reasons.
In the average these measurements suggest that the Mediterranean SST increases
in the order of 0.15 C/year, which is much more than any land surface temperature.
To assess the impact of SST changes on the water cycle one has to take into account
that evaporation not only depends on the temperature of the evaporating surface but
on the gradient of the vapour pressure above the surface and the wind speed as well.
The latent heat flux is computed according to the formula (Korres et aI. 2000a):
0.622
E = PaCe IWI[ew1 (T,) - r"e,at eTa ) ] - -
(1)
Pa
where
Po air density (average value l.27 kg m- 3 at sea level)
Ce turbulent exchange coefficient (estimated to be 1100)
W monthly mean 1000 hPa wind vector
elm
saturation water pressure (17 hPa at ISC, 25 hPa at 21C, 41 hPa at 30C,
74 hPa at 40~C)
T,
SST
To monthly mean atmospheric temperature
rh
monthly mean relative humidity at 1000 hPa
p"
surface air pressure (1013 hPa).
This give an impression of the complexity of the task to assess magnitude and
causes of climate variability throughout the Mediterranean basin. It needs accurate
information about the humidity and wind velocity fields on top of the sea surface and
it must be questioned whether the computations results in the same monthly latent
heat flux average if monthly mean values are used in the equation or if, say, half
hourly instantaneous values are averaged.
5 What Does the Mediterranean Basin Contribute to the
Global Carbon Budget and Atmospheric Pollution?
5.1 Fluxes of Biogene Volatile Organic Compounds
Land-surface processes are linked to the global climate system through the exchange
with the atmosphere of energy, momentum and matter. Of overriding importance for
vegetation growth and its sustainable development is the water cycle which will be
dealt with in the next section. Of equal importance for the global system are the
41
sea level increased while around Sicily a strong and in most parts of the western
Mediterranean Sea a much smaller decrease is observed. The SST is rising
everywhere at a pace of at least 0.1 cC/year but in its north-eastern parts according
to the ATSR measurements regionally up to 0.3C per year. In the AVHRR data,
and only here, a small increase of the SST is observed south of Sicily which would
not explain the depression in the sea level. This indicates that the sea level changes
in the Mediterranean must have dynamical reasons.
In the average these measurements suggest that the Mediterranean SST increases
in the order of 0.15 C/year, which is much more than any land surface temperature.
To assess the impact of SST changes on the water cycle one has to take into account
that evaporation not only depends on the temperature of the evaporating surface but
on the gradient of the vapour pressure above the surface and the wind speed as well.
The latent heat flux is computed according to the formula (Korres et aI. 2000a):
0.622
E = PaCe IWI[ew1 (T,) - r"e,at eTa ) ] - -
(1)
Pa
where
Po air density (average value l.27 kg m- 3 at sea level)
Ce turbulent exchange coefficient (estimated to be 1100)
W monthly mean 1000 hPa wind vector
elm
saturation water pressure (17 hPa at ISC, 25 hPa at 21C, 41 hPa at 30C,
74 hPa at 40~C)
T,
SST
To monthly mean atmospheric temperature
rh
monthly mean relative humidity at 1000 hPa
p"
surface air pressure (1013 hPa).
This give an impression of the complexity of the task to assess magnitude and
causes of climate variability throughout the Mediterranean basin. It needs accurate
information about the humidity and wind velocity fields on top of the sea surface and
it must be questioned whether the computations results in the same monthly latent
heat flux average if monthly mean values are used in the equation or if, say, half
hourly instantaneous values are averaged.
5 What Does the Mediterranean Basin Contribute to the
Global Carbon Budget and Atmospheric Pollution?
5.1 Fluxes of Biogene Volatile Organic Compounds
Land-surface processes are linked to the global climate system through the exchange
with the atmosphere of energy, momentum and matter. Of overriding importance for
vegetation growth and its sustainable development is the water cycle which will be
dealt with in the next section. Of equal importance for the global system are the