14
NET AIR-SEA HEAT FLUX AND MERIDIONAL HEAT TRANSPORT
100
o
- 100
-35
o
35
70
Figure 17: Zonal mean of net air-sea heat exchange. Shaded area gives errors using the
estimates from Isemer & Hasse (1987), which yields relative errors of 7.8 % for shortwave
radiation, 14.7 %for longwave radiation, 12.6 %for latent heatfiux and 31.3 %for sensible
heatfiux.
For better comparison we repeated their calculations with COADS reports by applying their
parameterisations of the four heat flux components and integrated the results to obtain the
meridional heat transport.
Because the integration is started at the northern edge of the Atlantic, differences between the three studies increase southward. At least at 30 0 S it becomes obvious that the
parameterisations of ISEMER & HASSE and HASTENRATH & LAMB provide too weak
(0.17 PW) and too strong (0.92 PW) heat transports, respectively. Our calculation yields a
transport of 0.47 PW across 30 o S, in good agreement with the oceanographic estimate by
HOLFORT (1994). His result is confirmed by other investigations. An overview is given by
MACDONALD (1993), who compiled the results of several oceanic heat transport studies.
For the Atlantic between 28°S and 32°S he listed eight values from different authors with an
average of 0.51 PW.
I&H constrained their parameterisations such, that the MHT at 25°N became equal to 1
PW. Our simulation using exactly the same formulae but another data set (COADS) yields
a transport of only 0.87 PW across this latitude. There are three possible reasons for this
difference:
The first is of course the use of a different data set, secondly, only mean results of the individually computed fluxes were available for I&H. Thus, crude assumptions were necessary
to change the wind speed scale from WMO to KAUFELD scale. Thirdly, the Mediterranean
Sea is included in our evaluations, while in the original I&H study the heat transport through
NET AIR-SEA HEAT FLUX AND MERIDIONAL HEAT TRANSPORT
100
o
- 100
-35
o
35
70
Figure 17: Zonal mean of net air-sea heat exchange. Shaded area gives errors using the
estimates from Isemer & Hasse (1987), which yields relative errors of 7.8 % for shortwave
radiation, 14.7 %for longwave radiation, 12.6 %for latent heatfiux and 31.3 %for sensible
heatfiux.
For better comparison we repeated their calculations with COADS reports by applying their
parameterisations of the four heat flux components and integrated the results to obtain the
meridional heat transport.
Because the integration is started at the northern edge of the Atlantic, differences between the three studies increase southward. At least at 30 0 S it becomes obvious that the
parameterisations of ISEMER & HASSE and HASTENRATH & LAMB provide too weak
(0.17 PW) and too strong (0.92 PW) heat transports, respectively. Our calculation yields a
transport of 0.47 PW across 30 o S, in good agreement with the oceanographic estimate by
HOLFORT (1994). His result is confirmed by other investigations. An overview is given by
MACDONALD (1993), who compiled the results of several oceanic heat transport studies.
For the Atlantic between 28°S and 32°S he listed eight values from different authors with an
average of 0.51 PW.
I&H constrained their parameterisations such, that the MHT at 25°N became equal to 1
PW. Our simulation using exactly the same formulae but another data set (COADS) yields
a transport of only 0.87 PW across this latitude. There are three possible reasons for this
difference:
The first is of course the use of a different data set, secondly, only mean results of the individually computed fluxes were available for I&H. Thus, crude assumptions were necessary
to change the wind speed scale from WMO to KAUFELD scale. Thirdly, the Mediterranean
Sea is included in our evaluations, while in the original I&H study the heat transport through