Earth's
Energy Flows
by
Miklos Zagoni
miklos.zagoni@earthenergyflows.com
Are you
familiar with this energy balance diagram?
(Stephens
et al.2012)
Let's
focus on the longwave part:
Clear-sky
emission to space (266.4) and all-sky outgoing longwave radiation
(239.7)
differ, by definition, by one longwave cloud radiative effect,
LWCRE (26.7, each in Wm-2).
But the fact that their
absolute value is an integer multiple of LWCRE, with a
difference of 0.6
Wm-2, which is the TOA imbalance, is a surprise!
Also for the upward and the downward emissions at the surface, with a
difference of 1.5 Wm-2
!
And that the surface emission itself can be expressed as an integer
multiple of
LWCRE, which is the greatest surprise! Surface longwave upward
emission, as a
definite multiple integer
of the TOA LW cloud effect?
That sounds crazy, or at least implausible—but history taught science
is not
about plausibility but validity, and this, at least on this diagram,
seems
valid!
Taking the values from the diagram: If LWCRE = 1 unit
(shown in red
bold typeface) = 26.7 Wm-2, then OLR(all-sky
= 9 units,
OLR(clear-sky) = 10 units (difference = 0.6 Wm-2;
same as
the TOA imbalance), DLR(clear-sky) = 12 units, and
DLR(all-sky)
= 13 units (difference is 1.5 Wm-2),
and surface upward
emission is 1 units, with a difference of only 2.5 Wm-2,
contrary to the far larger uncertainties noted on the diagram.
Really
interesting!
Next year, the IPCC (2013) report showed the following diagram; let's
first
deal with the shortwave irradiances:
Using the same unit flux of 1 = LWCRE = 26.7
Wm-2,
incoming solar radiation is 51 units (= 1361.7 Wm-2)
on
the intercepting cross-section disk to incoming solar radiation (that
is,
before division by four for spherical weighting, see Fig. 2.2 from
Hartmann:
Global Physical Climatology, 1994)
and 51/4
units = 340.4 Wm-2 on the
sphere. From this, 15/4
units = 100.1 Wm-2 is reflected
and 36/4 units =
240.3 Wm-2 is emitted as outgoing longwave
radiation.
Furter, 3 units = 80.1 Wm-2
is absorbed in the
atmosphere and 6 units = 160.2 Wm-2
is absorbed in
the surface. These shortwave integer positions are extremely close,
within 1
Wm-2 to the shown values given by the IPCC AR5 (2013) report (based on
Wild et
al. 2013).
***
Next
year, Norman Loeb published this estimate, based on more than a decade
of CERES
data:
Here
the novelty is that with this very slightly refined unit flux of 26.67
Wm-2,
at the TOA each of the difference is zero! Atmospheric longwave cooling
differs
only by 0.3 Wm-2, and that all the components
are within their noted
range of uncertainty, even the components of the convective flux,
separately.
Below I show a recent publication (Wild 2020, Clim Dyn)
comparing clear-sky and all-sky data from four different
sources: CMIP6
model mean (in red), CMIP5 model mean (pink), Martin Wild's own
estimate, and
Seiji Kato's CERES data from a previous data product (EBAF Edition 4.0,
2018).
Clear-sky: Incoming solar: 340; reflected solar:
53, outgoing longwave:
267; solar absorbed atmosphere: 73, solar down surface: 247, solar
absorbed
surface: 214, thermal up surface: 398, thermal down surface: 314-318.
***
All-sky: Incoming solar: 340; reflected solar: 100,
outgoing longwave:
239; solar absorbed atmosphere: 80, solar down surface: 187, solar
absorbed
surface: 160, thermal up surface: 398, thermal down surface: 344
***
I will
show that these energy flow components in the annual global mean
clear-sky and
all-sky diagrams may be derived from simple geometric considerations,
without
referring to the atmospheric gaseous composition or reflective
properties.
The
starting point of the deduction is the simplest greenhouse model,
consisting og a surface
and a solar-transparent, infrared-opaque
atmospheric layer — as for example is shown in Hartmann (1994), Global
Physical
Climatology, Fig. 2.3:
PART
TWO
Further
details:
Zagoni,
M.: Trenberth’s (2022) Greenhouse Geometry, EGU General Assembly 2024,
Vienna,
Austria, 14–19 Apr 2024, EGU24-7
https://doi.org/10.5194/egusphere-egu24-7
Supplementary
Material (video) (2:20:35):
https://www.earthenergyflows.com/Zagoni-EGU2024-Trenberths-Greenhouse-Geometry_Full-v03-480.mp4