Radiative and temperature effects of the observed ozone and greenhouse gas atmospheric content changes in 1980 - 1990 are evaluated using the two-dimensional energy balance radiative-convective model of the zonally and annually averaged troposphere and stratosphere. Calculated radiative flux changes for standard conditions quantitatively agree with their estimates in WMO/UNEP 1991 review. Model estimates indicate rather small influence of ozone depletion in the lower stratosphere on the greenhouse tropospheric warming rate, being more significant in the non-tropical Southern Hemisphere. The calculated cooling of the lower stratosphere is close to the observed temperature trends there in the last decade

Frolkis, Victor A.

Karol, Igor L.

English

NASA Technical Reports Server

N95- 10671
MODEL EVALUATION OF THE RADIATIVE AND TEMPERATURE EFFECTS OF THE OZONE
CONTENT CHANGES IN THE GLOBAL ATMOSPHERE OF 1980-IES
Igor L. Karo], Victor A. FroJkJs
Main Geophysical Observatory
Karbyshev Str., 7, St.-Petersburg, 194018, Russia
ABSTRACT
Radiative and temperature effects of the
observed ozone and greenhouse gas atmospheric
content changes in 1980 - 1990 are evaluated using
the two-dimensional energy balance radiative-conve-
ctive model of the zonally and annually averaged
troposphere and stratosphere. Calculated radiative
flux changes for standard conditions quantitatively
agree with their estimates in WMO/UNEP, 1991
review. Model estimates indicate rather small
influence of ozone depletion in the lower strato-
sphere on the greenhouse tropospheric warming rate,
being more significant in the non tropical Southern
Hemisphere. The calculated cooling of the lower
stratosphere is close to the observed temperature
trends there in the last decade.
1. INTRODUCTION
Significant ozone content changes in the
lower stratosphere and troposphere as observed in
1980-ies with enhanced intensity during the recent
years [WMO/UNEP, 1991] result in variations of
radiative and temperature climate of the global
atmosphere. The preliminary estimates of these
variations have been used for important conclusions
about their influence on the rate of greenhouse
warming of the global llxoposphere [WMO/UNEP, 1991;
Ramaswamy etal., 1992]. In these publications the
meridlonal distributions of radiative flux vari-
ations at the tropopause level are evaluated, as
caused by the observed changes of ozone and green-
house gas content at various latitudes and levels
of the global atmosphere in 1980-1990.
As the tropospheric temperature changes only
to some extent are determined by the above
radiative flux variations, more precise evaluation
of the climatic radiative and temperature effects
by tile comprehensive climatic models is necessary
[Ramaswamy et al., 1992]. However, the relative
small amplitude of ozone changes makes difficult to
reveal tile effect "signal" over the considerable
"noise" level in such models [IPCC, 1990].
In this paper the mean annual, zonally
averaged solar and thermal radiation fluxes and
temperature variat imps at various levels of tile
global atmosphere ave estimated using the two
dimensional Energy Balance Radiative Convective
Model (EBRCM), described in [Karol and Frolkls,
1984]. As indicated in this paper and in [Karol et
al., 1986] the radiative and temperature changes
caused by the increase of CO_ concentration in the
atmosphere and estimated by E_RCN are very close to
those obtained in the three-dimensional compre-
hensive atmospheric climate models.
In the first part of the paper after the
short description of the model, the radiative
forcing caused by ozone and greenhouse gases (GG)
content changes in conditions used in [WMO/UNEP,
1991; Ramaswamy etal., 1992] are calculated and
compared with results in these publications, maklng
in a such way the comparison of the radiative
schemes codes and models. Then the annually aver-
aged pean zonal radiative flux and temperature
changey_Arre estimated [IPCC, 1990] as caused by the
observed 6G and ozone content changes for the time
period 1980-1990. Some observed evidences of these
changes are discussed in the conclusion of the
paper.
2. SHORT DESCRIPTION OF THE MODEL
The model is presented in details in [Karol
and Frolkis, 1984]. Annually and zonally averaged
radiation fluxes and temperature distributions in
the global atmosphere up to fl=0.64 hPa (50 km)
level with prescribed radiatively-active atmos-
pheric constituent concentrations and other parame-
ters are determined by successive approximation up
to equilibrium state. At each step the vertical
temperature profiles are determined from eight
Radiative-Convectlve Models (RCH) at 80 O, 600 , 400 ,
150 N and S with 15 horizontal layers, and with
surface air temperature T 0, taken from the previous
approximation step. These profiles and other
information are used for computation of solar and
thermal radiation fluxes S H and F H at the conside-
red upper atmospheric boundary. T O distributions
are the solutions of the energy balance equation
d "(X)'(1-X 2) dT°(x) -Fu(X) -Sn(X)J dx "
where 9 is tile latitude; x=sin 9; j(x) = jn.K(x);
j_ = c .p_ /gRe2' K(x) is the effective horizontal
U p U " 'heat transport coefficient. "Heat walls" at the
poles are the boundary conditions for this equation
solution, which is used for eight RCM at the next
338
https://ntrs.nasa.gov/search.jsp?R=19950004259 2020-06-16T11:26:06+00:00Z
step of successive approximation. Besides the
coarse grld of elg_t zonal belts the flne grld of
36 belts wlth Ag=5v Is used in computations.
Solar radiation flux calculations are based
on the two-stream delta-Eddlngton scheme. The UV
band (197.5-312.5 nm) Is divided into 11 spectral
intervals, where Op O_ NO 2 and aerosol effects
are accounted. Visible band contains two spectral
intervals with Incluslon of 03 , NO 2, molecular,
aerosol and cloud scattering and reflectance. NIR
band (750-4000 nm) is divided Into 12 spectral
intervals, in which the selective H_, COp 03, N_
and CH 4 absorption Is accounted approximated by the
Goody transmission function for the statistical
model of the absorption band. An original approach
is used for the approximate calculation of selec-
tive gas absorption and scattering of photons by
aerosol and clouds with multiple reflection from
the cloud layer boundaries.
The thermal radiation fluxes are calculated
for 17 spectral intervals in the 4.4-1000 microme-
ters band. The transmission functions for the same
gas selective absorption are approximated as in NIR
with the atmospheric vertical density layering
accounted by Curtls-Godson approximation. Weak
absorption approach is used for CFCs. H_ continuum
absorption and diffusivlty approximation are
included, but the cloud and aerosol transmission
functions are non-selective. The ground surface and
clouds are considered as black bodies.
The external data and conditions, used in the
calcuiatlons of the radiation flux variations,
caused by the GG and ozone changes are presented in
Tables I and 2. These data are taken from the
sources and are the closest to those used in
[Ramaswamy et al., 1992], for model comparison. In
Table 2 the daily averaged cosine of the solar
zenith angle 9*, the clear day relative duration t,
and surface albedo A s for selected cases used in
our calculations are also presented, being not
indicated in {W_O/UNEP, 1991; Ch.7 and Ramaswamy et
al., 1992]. For comparison purposes the clear sky
Mode A with fixed temperature profiles Model I
radiative forcing values are used from the above
publication.
Gas ]CO 2 CH_
Units ppmv
1980 337 1.57
1980-1990 17 0.15
Table 1. Globally and annually averaged GG tropo-
spheric mixing ratios in 1980 and their
increases to 1990 [IPCC, 1990; W_O/UNEP,
1991].
t CFCN _ 11 12 113 22
ppbv
302.610.158 0.27 0.015 0.05
8.0 JO 111 0.17 0.050 0.07
3. RESULTS OF CALCULATIONS,
The radiative forcing (the net total long +
short wave radiative flux variations at the
tropopause level) is compared in Table 3 for the
above conditions as calculated by EBRCM and by Mode
A, _odei 1 in IWMO, UNEP. 1991]. The radiative
forcing caused by ozone, CFC and other GG content
chan_e ix shown separately. The a_reement between
the two model results are good, not only at t_e
tropopause, but at the ground surface also. being
the worst for CFC, as in EBRCM only the radiative
forcing of CFC-11 and 12 are included.
Table 2. Cases selected for radiative forcing
calculations due to ozone depletion in
the lower stratosphere &(Oj) for stan-
dard temperature profiles: tropical-T;
mldlatltude summer-MLS and wlnter-MLW;
subarctic wlnter-SAW [IOIO/UNEP, 1991].
Daily averaged solar zenith angle 9,,
clear day relative duration t,and surface
albedo A S, whlch are used In calculations.
No. Lati-
tude
1 0 u
2 450N
3 450N
4 450S
5 45_s
6 700N
7 750S
Month
July
July
Feb.
Jan.
Aug.
Mar.
Oct.
Temp. A(O_) cosg, t, A s
Pro- (_
file
T -0.5 0.586 0.500 0.076
MLS -2.0 0.570 0.640 0.123
MLW -8.0 0.301 0.399 0.271
MLS -6.0 0.570 0.639 0.067
MLW -5.0 0.296 0.396 0.098
SAW -17.0 0.134 0.372 0.641
SAW -32.0 0.205 0.588 0.799
r. 0.7
? 0.6
E
0.5
'" 0.4-
z< 0,3
T
o 0.2
_ 0.1
.--0.0
_-0.1
 o-0.2
-0.3
Fig. I. Total net
level (for
to only 0 3
O 3) and to
. "_5._LZl2t GG-Oa. JAN _xj_x_ GG--Oa, JUL
O_(Str), JAN O_(Str'_', JUL
CFC. JAN e.44e4 CFC. JLIL
sd-gc-:;d-td6 '2'0'4'06'0'8
LATITUDE
flux changes at the tropopause
Mode A) for January and July due
(O_(Str)), to non-ozone GG (GG-
CF_ (CFC) content variations.
Figure 1 demonstrates the merldional distri-
bution of solar and thermal net radiation flux
changes at the tropopause level for January and
July, calculated by EBRCM for ozone and non-ozone
GG content variations, indicated in Tables 1 and 2.
for Mode A and clear sky conditions.
Ozone depletion leads to increasing of the
solar radiation flux coming to the surface-troposp-
here system at all latitudes throughout the year.
The long wave cooling of this system by ozone
depletion in Mode A is exceeding its solar warming
only in the polar winter. The influence of the
atmospheric temperature changes on the radiation
339
flux variations may be assessed from Table 4 with
the merldlonal variations of annually and zonally
averaged changes of solar end thermal radiation
fluxes at the tropopause level for Mode C, for the
cloudy atmosphere, for GG content increase In Table
I and for annually averaged ozone depletion esti-
mates In Table 5. The Mode C difference from the
Node B in [WMO/UNEP, 1991; Ramaswamy et al., 1992]
is that in Mode C the radiation variations induced
by the temperature changes are calculated by EBRCM
with account of clouds. In the Mode B the
tropospheric temperature and humidity remain
unchanged, while the stratospheric temperature is
In the radiative equilibrium under the assumption
of a so-called Fixed Dynamical Heating concept
[I@40/UNEP, 1991].
Table 3. Net radiation flux changes at the tropo-
pause and at the surface levels due to GG
and ozone content variations and for the
cases and conditions indicated in Table 1
and 2, as evaluated in [WMO/UNEP, 1991,
Ch.7]-Node A and in this work-F.
C
a
s Tropo-
e pause
S
1 .54
2 .51
3 .41
4 .51
5 .41
6
.34
7
.34
CO2÷CH4+ CFC OzoneCOo+CH4+
+N_÷CFC
Surface
F A F
,520 .14 .154
.460 .20 .231
.400 .35 .369
.457
.400
A F e
.16 .096
.13 .074
.08 .053
.13 .071
.08 .053
A F
.01 .006
.08 .024
.03 •026
.06 .064
.05 .025
-.17 -.041
-.41 -.066
.347 .28 b .284 b
.342 .37 c .377 c
.05 .034
.05 .033
e/ _ For CFC-II plus CFC-12 only.
b/ . For SAS temperatureprofile.
c/ _ For SAW temperatureprofile.
Figure 2 demonstrates the calculated zonally
and annually averaged surface alr temperature
changes, induced by the radiative forcing due to 6G
and ozone content changes in Tables 1 and 5,
calculated for Mode C conditions and for cloudy
atmosphere assumed not to be changing during the
period under consideration. The meridional
distribution of caiculated air cooling in the lower
stratosphere, due to ozone depletion being maximal
at the 60 mb level is also presented at Fig.2.
3, reveal the good agreement of calculation results
for all cases, bearing in mind the possible devi-
ations in surface short wave albedo, which is not
Indicated in [WMO/UNEP, 1991, Ch.7]. The agreement
of CFC radiative forcing estimates in Table 3 will
be improved substantially by increasing our esti-
mates by about 40-60_ for account of radiative
effects of CFC content increase, other than
CFC-11,12.
0.2
O.q
oo
-
CFC
--°'---Sc;--{sO--_d--_d-_"- (b " 2"o " 4:0 " 6'0
L.ATIT tJ DE
Flg.2. The calculated AT o obtained for all 06
without 03 (G0-03) , for CFC only (CFC), for
lower stratospheric O3only (O3(Str)) and AT
at 80 mb level divided by 10 (O3(80mb)) all
for Mode C.
Table 4. The net fluxes of solar AS and total AR
radiation changes (Wm "2) at the tropopause
level for modes A and C due to gas content
variations, indicated in Tables I and 5.
Gas Flux Sout,hernLatitudes Nort,harnLatitudes
300 000 400 150 150 400 600 000
Node A
03b
03b
O3 IS
03 AR
CFOs i R
GGa & R
GGa & S
&s
iR
.12 ,24 .125 .014
-.074 .090 ,074 .010
.022 .034 .040 .050
.31 .37 .435 .AT
.004 -.012 -,025 -.016
.I0 .21 ,I12 .012
-.004 .073 .051 .oog
Mode C
.013 .12 .17 .14
.019 .18 .13 -.050
.058 .048 ,03T .028
A0 A4 .38 .3A
-.010 -.024-.014 -.004
.012 .I0 ,14 .11
.008 .09 .I0 -.051
03 AS .012 .25 .13 .015
03 iR -0.:4 -.i_ -.01 .040
CFCs iR -.003 -,004 9E-4 .003
GGa AR -.0033 .00_2.013 -2E-4
_'_ 030 .00g -.Tg.v,v ,
002 _ O0_ - 00_
-6E-4 .017 .0012 -.033
a, . The sum ;f greenhousegases, omitting the o:one ,ariations•
b/ . Ozone content changes only in the lowerstratosphere.
4. DISCUSSION OF RESULTS.
The comparison of the net radiation flux
variations for the seven standard cases, indicated
in the Table 2 and evaluated in [WNO/UNEP,
1991.Ch.7] and in this work as presented in Table
The meridional profiles of radiation flux
changes in FJg.l and in Table 4 are close to
relevant curves in Figs. 7.3 and 7.4 in IWMO/UNEP,
1991, Ch.7] for Mode A with fixed atmospheric
temperatures. Flux changes are somewhat greater in
340
the cloudless atmosphere (Node A) as compared to
those in the cloudy atmosphere (Node C). Therefore
our radiation flux calculation schemes and Node A
(fixed temperature) result_ are close to those In
[WMO/UNEP, 1991; Ramaswamy et al., 1992]. The
radiative cooling of the lower stratosphere by the
ozone depletion effects enhances the negative mean
annual total radiation change in the Southern
Hemisphere outside of tropics and in the northern
polar zone. This ozone caused negative change
outweighs by several times the positive (thermal)
radiation forcing, caused by the CFC in north polar
and south non-tropical latitudes, as it has been
found In [_O/UNEP, 1991], but not In the north
temperate latitudes. (The account of other CFCs
increases the forclng by 30-504 only [IPCC, 1990]
and will not change the above conclusion qualitat-
Ively.) Due to above explained differences In
temperature change evaluation, the radiation flux
variations in the affected temperature fields in
EBRCM and in [Ramaswamy et al., 1992] are incompar-
able in principle and GG and ozone content vari-
ation effects assessed by EBRCM may be estimated
better by the temperature change analysis.
Table 5. Annually and zonally averaged ozone
content changes (4) during 1980-1990 at
Indicated latitudes and layers, as
estimated in [WNO/UNEP, 1991] and used in
calculations.
Layer
(k=)
N, Latitudes
800 600 400
Troposph. 0 8 8
h [r-h Tr÷7
37 - 45
-20 -10 -8
-I0 -5 -3
20_- S, Latitudes
-2o% 40o60o 800
2 0 0 O
-1.6 -10 -20 -30
-0.8 -5 -10 -i7
The ATo-surface air annually averaged
"radiative" temperature profiles at Fig.2
demonstrate, that the negative AT 0 produced by th'e
observed ozone depletion in the lower stratosphere,
surpasses the positive CFC AT (underestimated, as
pointed out above) only in the polar zones. Maximal
ozone produced AT 0 around the South Pole attains
of about 70_ of GG warming in this area, but in the
Northern ffemisphere the ozone produded reduction of
GG warming does not exceed 254, being maximal in
the North Pole area. This small reduction of the
greenhouse warming rate in the lower atmosphere
due to observed ozone depletion may be even less in
reality wlth account of the known oceanic thermal
inertia effect [IPCC, 1990, Ch.6]. According to
several estimates the time delay of the surface air
greenhouse warming due to this effect is. about
10-20 years [IPCC, 1990; Karoi and Jagovkina, 1992]
and therefore the actual T O increase in 1980-ies is
reflecting the greenhouse radiative forcing in
previous decades, when ozone depletion forcing was
nonsignificant.
The globally averaged AT0._O.129K from Fig.2
and ARe=0.44 Wm -2 from Table 4 _or all GG increase
except ozone in 1980-1990 is in good agreement
with AT0a=O.139K and ARe=0.54 Wm -2 estimated in
[IPCC, 1990]. The negative ATso in the lower
stratosehere at FI£.2, when _Ioba_ly averaged is
ATe = -0.58 K and It is close to the globally
averaged observed temperature negative trend of 0.4
K/decade In the layer between I00 and 50 hPa
[WNO/UNEP, 1991, Ch.2].
The observed ozone concentration changes
outside the lower stratosphere are much less
influencing the radiation and temperature regime in
the lower troposphere, as revealed by Table 4,
where the solar and net radiation flux changes are
compared as caused by all the ozone variations,
indicated in Table 4, and by its variations in the
lower stratosphere only.
The consequences of "ozone compensation" of
the greenhouse warming in the southern polar zone
In 1980-Ies may result In different changes in the
total areas of snow and of ice in the Antarctic and
in the Arctic [Cloersen and Campbell, 1991]. While
this area decreases in the Arctic, it does not
undergo any changes in the Antarctic.
An express Builetln [GECR, 1992] announced
recently that UARS satellite measured 104 lower
ozone concentration in 100 S - 200 N zone in
January 1992 as a possible result of Mt. Plnatubo
volcano aerosol plume effects. Ten percent ozone
reduction in the 7 km layer over the tropopause of
the 200 S - 200 N zone leads to calculated AS= 0.13
Wm "2 and &R= 0.15 Wm -2 of solar and total flux
changes for Mode A, thus offsetting the tropical
minimum of ozone induced change In the flux
meridional profile (see Fig. 1 and Table 4). Due to
short period radiative forcing, caused by volcano
plumes, and its transient effect on the air
temperature, the stationary EBRCM is not suited for
evaluation of such effects.
REFERENCES
GECR, 1992: Global Environmental Change Report,
v. IV, N3, 2.
Gloersen P., Campbell W.J., 1991: Recent variations
In Arctic and Antarctic sea-ice covers, Nat__at_p__ure
352, 33-36.
IPCC, 1990: Climate Change. The IPCC Scientific
Assessment WNO/UNEP_ Cambridge Only. Press,
365p.
Karol I.L., Frolkis V.A., 1984: Energy balance
radiative-convective model of the global
climate, Meteoroi. i Gidrol., 8, 59-68 (in
Russian).
Karol et al., 1986: Radiative-photochemical models
of the atmosphere [p.p. 51-70),
Gidrometeoizdat, Leningrad (in Russian).
Karol I.L., Frolkis V.A., 1992: Estimation of
radiative and temperature consequences of ozone
content changes in tlle global atmosphere in
1980-1990, Doklady of Russian Academy of
Sciences, 323, 66-69 (in Russian).
Karol I.L., Jagovkina S.V. 1992:The estimations of
the ocean thermal inertia contribution to the
greenhouse warming potentials of the freons,
Meteorol. i Gidrol.j 7, 45-53 (in Russian).
Ramaswamy V., Schwarzkopf M.D., Shine K.P., 1992:
Radiative forcing of climate from halocarbon
induced global stratospheric ozoue lnss,
Nature_355, 810-812.
WNO/UNEP, 1991: Scientific Assessment of Ozone
Depletion 1991, WMO Global Ozone Res. and
Monitnring Prnject_ Rep. N25, Washington I).C.
341


Model evaluation of the radiative and temperature effects of the ozone content changes in the global atmosphere of 1980's

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server