F3986

The mean annual hemispherical and global average values over the 14-year period from 1984 to 1997, for the incoming, outgoing, net incoming (i.e. absorbed) SW radiation at TO A, and planetary albedo, are given in Table 8.8 and compared against ERBE data and other published values. In Table 8.9 are given the incoming and outgoing SW radiation, and the net incoming and planetary albedo for the hemispheres and the globe. On a 14-year basis (1984-1997), the Earth is found to reflect back-to-space 101.2 W m~2 from the global mean received 341.5 W m~2, resulting in a long-term planetary albedo equal to 29.6%. The interhemispherical differences are equal to 0.34 W m~2 for ISR, 0.1 W m~2 for OSR, 1.43 W m~2 for the net incoming SW radiation at TOA, and 0.35% for Rp, implying slightly larger Northern than Southern Hemispherical values.

Table 8.8 Model mean annual hemispherical and global averages of outgoing shortwave radiation at the top-of-atmosphere (OSR) and planetary albedo. NH is Northern Hemisphere, SH is Southern Hemisphere. The radiative fluxes are expressed in W mT2, while the planetary albedo is in per cent. NCEP/NCAR, ECMWF and NASA results are from reanalysis, model results are from Hatzianastassiou et. al. (2004b).

Table 8.8 Model mean annual hemispherical and global averages of outgoing shortwave radiation at the top-of-atmosphere (OSR) and planetary albedo. NH is Northern Hemisphere, SH is Southern Hemisphere. The radiative fluxes are expressed in W mT2, while the planetary albedo is in per cent. NCEP/NCAR, ECMWF and NASA results are from reanalysis, model results are from Hatzianastassiou et. al. (2004b).

Study

OSR

Planetary Albedo

NH

SH

Globe

NH

SH

Globe

Model (1984-1997)

100.63

101.72

101.17

29.45

29.80

29.62

Model (1985-1989)

101.30

102.36

101.83

29.65

29.99

29.82

ERBE (1985-1989)

101.04

100.76

100.90

30.10

29.10

29.6

NCEP/NCAR (1982-1994)

115.75

33.87

ECMWF (1985-1993)

103.75

30.36

NASA (1981-1992)

94.75

27.72

Yang et al. (1999)

115.3

Wild et al. (1998 - ECHAM4)

105.0

30.7

Chen and Roeckner (1996)

106.4

31.0

Rossow and Zhang (1995)

111.55

32.6

8.4.7 Time series of planetary albedo

The time series of monthly average planetary albedo (in %), for the 14-year (1984-1997) period for the globe is shown in Fig. 8.15. The mean global planetary

Table 8.9 Model mean annual hemispherical (NH is Northern Hemisphere, SH is Southern Hemisphere) and global average: incoming shortwave radiation (Fy), outgoing shortwave radiation (Fj) and net incoming shortwave radiation (Fnet,{) at the top-of-atmosphere, and planetary albedo (Rp), for the 14-year (1984-1997) period. The radiative fluxes are expressed in W m-2, while the planetary albedo in %.

Fj Ft FneU Rp

NH 341.67 100.63 241.04 29.45

SH 341.33 101.72 239.61 29.80

Globe 341.50 101.17 240.32 29.62

0,34-

0,33-

T3

0,32-

<L>

Bj

0,31-

11)

0,30-

g

PH

0,29- 1

0,28-

0,27-

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