6
I
terrestrial atmosphere
4.5
TlON
0
RAIN
EVAPORA
AN
TRANSPI
71
RATION
1D7
land
ice and snow 43i'OO
surface water 360
underground
water
15,300
biota
~
S9,OOO
I
ADVECTION 36 (
marine atmosphere
J
\
11
EVAPORATION I
RAIN
of34
39B
oceans
mi"ed lafer sopoo
thermocilne 46IJIlOO
RIVERS 36
abyssal
..82!l!IIlIl
1~
c:::)
-
Reservoirs in 10'5 kg Fluxes in 10'5 kg yr-'
E. Raschke
J
Figure 1.1: Estimates of the global water reservoirs in the atmosphere, on the continents and
within the oceans and of the transports between them (from Chahine, 1992).
heat capacities of the continental ice shelfs and the major (deeper) ocean layers. It modulates
all longterm transient processes.
Water in such large amounts is still available on our planet, due to the high mass of our earth
and the moderate temperatures caused by the distance of the Sun. Its availability during
almost the whole life of the Earth is responsible for many geochemical processes which led
to the present state of our climate system. Further details have recently been discussed by
Webster (1994), and can also be found in many textbooks on planetary sciences. Fig. 1.2 shows
the estimated phase transition curves for water and hypothetical climate trajectories for Mars,
Earth and Venus.
In the following sections 1.3 and 1.4 more details are provided on the abundance of water
in its gaseous and liquid and solid phases in the atmosphere and on their possible retrievals
with passive and active remote sensing techniques. Section 1.5 reports on the radiation budget
components, while the remaining chapters describe the precipitation, evaporation and runoff.
1.3 Atmospheric water vapor
(see also contributions by Simmer, Weitkamp)
Water vapor is the major greenhouse gas, contributing dominantly to the major radiative
warming in the lower troposphere, and some cooling in the upper layers. This is illustrated in
Fig. 1.3 from Manabe and Moller (1961), where also the contributions of other greenhouse gases
(C02 and 0 3 ) are shown for some annual and global average. Its abundance in at least the
lower layers of the troposphere is closely but not completely related to the mean air temperature
(e.g.: Gaffen et al., 1992, Stephens et aI., 1990), thus the water vapor concentration will exert
a positive greenhouse effect. When the surface temperatures will increase, then also the mixing
ratio of the water vapor will increase, and more absorption of radiative energy can occur.
I
terrestrial atmosphere
4.5
TlON
0
RAIN
EVAPORA
AN
TRANSPI
71
RATION
1D7
land
ice and snow 43i'OO
surface water 360
underground
water
15,300
biota
~
S9,OOO
I
ADVECTION 36 (
marine atmosphere
J
\
11
EVAPORATION I
RAIN
of34
39B
oceans
mi"ed lafer sopoo
thermocilne 46IJIlOO
RIVERS 36
abyssal
..82!l!IIlIl
1~
c:::)
-
Reservoirs in 10'5 kg Fluxes in 10'5 kg yr-'
E. Raschke
J
Figure 1.1: Estimates of the global water reservoirs in the atmosphere, on the continents and
within the oceans and of the transports between them (from Chahine, 1992).
heat capacities of the continental ice shelfs and the major (deeper) ocean layers. It modulates
all longterm transient processes.
Water in such large amounts is still available on our planet, due to the high mass of our earth
and the moderate temperatures caused by the distance of the Sun. Its availability during
almost the whole life of the Earth is responsible for many geochemical processes which led
to the present state of our climate system. Further details have recently been discussed by
Webster (1994), and can also be found in many textbooks on planetary sciences. Fig. 1.2 shows
the estimated phase transition curves for water and hypothetical climate trajectories for Mars,
Earth and Venus.
In the following sections 1.3 and 1.4 more details are provided on the abundance of water
in its gaseous and liquid and solid phases in the atmosphere and on their possible retrievals
with passive and active remote sensing techniques. Section 1.5 reports on the radiation budget
components, while the remaining chapters describe the precipitation, evaporation and runoff.
1.3 Atmospheric water vapor
(see also contributions by Simmer, Weitkamp)
Water vapor is the major greenhouse gas, contributing dominantly to the major radiative
warming in the lower troposphere, and some cooling in the upper layers. This is illustrated in
Fig. 1.3 from Manabe and Moller (1961), where also the contributions of other greenhouse gases
(C02 and 0 3 ) are shown for some annual and global average. Its abundance in at least the
lower layers of the troposphere is closely but not completely related to the mean air temperature
(e.g.: Gaffen et al., 1992, Stephens et aI., 1990), thus the water vapor concentration will exert
a positive greenhouse effect. When the surface temperatures will increase, then also the mixing
ratio of the water vapor will increase, and more absorption of radiative energy can occur.