WCP 86, A preliminary cloudless standard atmosphere for radiation computation

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- 37 -

The first evaluation of LIMS measurements (Russell

et al., 1983) resulted in higher concentration at 52°N for

the winter months

197

8/7

with a tendency towards reduced

concentrations as the year progresses. The values for January

and February converted to height by means of the Mid-Latitude

Winter Atmosphere are given in the following Table, 3.4.

Table 3.4: Vertical Profiles of the Volume Fraction of

HN0

as obtained from the LIMS experiment at 52°N

latitude.

Height (Km) 15 16 17 18 19 20 21 22 23 24

Volune fraction 5 6 7 8 9 10 11 11.5 12 12.5 1

(ppbv)

Height (km) 26 27 28 29 30 35 40 45

Volume fraction 11 10.5 9.5 8.5 7.5 3.5 2 2.5

(ppbv)

In the light of these new results it can be stated that the

volume fractions given in Table 3.3 are probably conservative.

3.8 Halocarbons

Monofluorotrichloromethane (CFC1

) and Difluorodichloro-

methane (CF

) are continuously monitored at the ground

(Mendonca, 1979; Herbert, 1980; Bodhaine and Harries, 1982;

DeLuisi,

1982).

Five groups contribute to vertical profile

measurements by means of balloons and aircraft (Goldan et

al.,

1930 and 1981; Heidt et al., 1975; Ehhalt et al., 1978;

and Volz et al.,1981; Inn et al., 1979; and Vedder et al.,

1931;

Farmer et al., 1980, Schmidt et al.,

1981).

The profiles

show considerable latitudinal variability. In the tropics

stratospheric volume fractions tend to be higher than in mid

latitudes,

especially if winter is considered. Current data

show the following spread of the volume fraction (Table 3.5).

- 38 -

Table 3.5: Variability of Halogenated Methane Volume

Fractions (in pptv)

Altitude CFC1

^^г ^З

(km) Tropics Mid-Lat. Tropics Mid-Lat.

180

140

250

500

120

100 250

450

20 80

250 240

300

25 35 2

190

150

100

100 130

60 50

- -

10 20

— — —

In this Table alse Methylchloride is listed.

Average profiles for CFCI3 and CFC1

extrapolated to 1985/86

are given in Table 3.3 (after Section 3.3).

3.9 Nitrogen Dioxide (N0

)

All information about stratospheric N0

has come from

remote sensing techniques, most of them at rising and setting

sun. N0

shows a diurnal as well as seasonal and latitudinal

variation. Concentrations measured at a specific time, e.g.

sunrise or sunset, need therefore not to be representative

for an average profile. A "first guess" average profile accor-

ding to WMO (1981) is given in Table 3.6 (see also e.g.

Niple and Mankin,

1980).

Table 3.6: Stratospheric Volume Fraction of Nitrogen Dioxide

Height (km) 15 17 20 25 30 35 40

Volume fraction (ppbv) 0.3 0.5 1 3 6 7 7

- *9 -

In the unpolluted lower troposphere the values are

between 0.5 and 4 ppbv.

From January to May 1979, during and after a strato-

spheric warming event, the following data have been deduced

from LIMS observations for 52°N (Russell,

1983):

Table 3.7: Stratospheric volume fraction of Nitrogen

Dioxide during and after stratospheric warming

after Russell et al., 1983.

Height (km) 16 20 25 30 32 35 40 45 50

Volume fraction (ppbv) 2 2.5 4.5 7.5 9 8.5 7 5.5 5

Ghazi (1984) reports strong diurnal variation with

higher nighttime values of 3 (day) - 9 (night) ppb. Naudet et

al.

(1984) obtain nighttime volume fractions of about 12

ppbv at 35 km.

The new measurements made from the Solar Mesosphere

Explorer by limb-scanning (Mount et al., 1983) are consistent

with measurements made by Ackerman et al.

(1972,

1976) and Kerr

and McElroy (1976) around 33 km.altitude (log number density

= 9.3).

3.10 Nitric Oxide (NO)

The NO vertical profile is not well established and

variable.

Based upon data presented in WMO (1981) the following

mean distribution can be adopted (z in km) (see also Ridley

et al.,

1976):

10 < z £ 17 km: ф =0.3 ppbv

17 ^ z < 32 km: ф(г) = exp(0.22 z - 4.96) ppbv

z ^ 32 km: ф(г) = 8.0 ppbv

The suggested maximum and minimum values are presented in

Table 3.8.

Table 3.8: Maximum and Minimum Stratospheric Volume Fraction

of Nitric Oxide

Height (km) 12.5 15 20 25 30 35 40 45 50

Volume fraction (10~ °)

maximum 5 6 11 28 120 210 290 300 310

minimum 1.3 1.7 3 7 19 43 60 44 33

In the unpolluted lower troposphere values of 0.5 - 2.7 ppbv have

been reported. Above 60 km the NO concentration increases rapidly,

Ghazi (1984) reports a value of 42 ppb at 50 km.

- 40 -

3.11 Other trace gases

The abundance of a number of other gases has been

determined at the surface or in the atmosphere. Though these

gases do not normally contribute accountably to the radiative

transfer in the atmosphere these mostly rough numbers will be

presented here for the sake of completeness. Some measurements

have been made of hydrogen chloride (Farmer et al., 1976,

1930;

Girard et

al.

1978/79).

These indicate a strong

lati-

tudinal dependence with a minimum at the equator. The data

presented in Table 3.9 refer to 30°N.

C10 shows a very high variability (Weinstock et al.,

1981;

Anderson et al., 1980) at latitudes between 24 and 55

degree.

The range of most of the measurements is from

1x10*

to бхЮ"

at 25 km altitude and from

6x10~

-9

1.5x10

at 40 km altitude with one exceptionally high

measurement (41°N) of

5x10~

(25 km) to

9x10""

(40 km).

Few measurements are available about the vertical

dis-

tribution of SO2. Over Europe its variability is rather large,

between about 10 and 200 pptv in the free troposphere and up

to more than 1000 pptv at 1-2 km. Average concentrations in

the free troposphere and lower stratosphere are around 60

pptv (Meixner, 1982; Maroulis et al.,

1980b).

SO2 concentrations

are sometimes given in densities. Note that 1 pg m"

is equiva-

lent to 342 pptv.

11 -

Table

3.9:

Tentative Fraction Vertical Distributions

for

some Minor Atmospheric Constituents

Specie Source

Volume

Fraction

Height

in km

15 20

Remarks

0.2

0.5

1.0

0.7

1.5

0.9

1.5

30°N

0.5

1.0 1.5

1.9

4.5

HC1

WMO, 1981;

Farmer

et al.,

1976,

198C

Ghazi,

1984

ppbv

Farmer

al.,

1980

Weinstock

et al.,

1981

Ghazi,

1984

pptv

ppbv

ClO

Anderson

et al.,

1980

pptv

Maroulis

et al.,

1980b; Inn et al.,

Inn et al., 1981

Brticken,

Georgii,

1971;

Georgii, 1978

Gandrud,

Lazrus,

1981

pptv

СС1„

Borchers

et al.,

1983

pptv

CCI

Borchers

et al.,

1983

pptv

100 10C ЮО 83

Ю0

-10

O.I 0.2 0.25 0.6 0.1

ЗО 150 300 800

4 0.2 0.001

speculativ

140 120 100 90 40

150 140 115 90 28

CDAC,

1984

Troposphere

Rudolph

al.,

1981

ppbv

Rudolph

etal., 1981

ppbv

0.3

Rudolph

al.,

1981

ppbv

0.2

Ramanathan,

Coakley,

1978

ppbv

0.2

WMO, 1981

ppbv

0.65

СС1.

Penkett

alJ,

1979

Singh

et al., 1979

ppbv

0.15

Georgii,

MUller,

1974

ppbv

0.3-4

COS

Torres

et al., 1980

Maroulis

al.,1977

Gandrund,

Lazrus,

1981

Inn et al., 1981

ppbv

0.5

0.1 (14 km)

ppbv

О.ОЗ

- 42 -

INTERPOLATION TECHNIQUE

It is an important point both for interpolation and

for integration, that anyone using these models will use the

same number of molecules or aerosols between successive levels

where densities or mixing ratios are given. The following scheme

is recommended for interpolation and integration.

a) Pressure/ and all gas densities which can be

represented by the formula (4.1) should be

interpolated exponentially with height.

b) Temperature, aerosol and all other gas densities

and gas volume fractions should be interpolated

linearly with height.

The following is provided as an example for the inter-

polation and integration of gas, the density of which can be

expressed according to fromula

(4.1).

A mean effective scale

height can be defined from two altitudes including level z

as given in equation

(4.2).

Finally the mass per unit area

between two levels z' and z" can be calculated according equa-

tion

(4.3).

p , P

have units of pressure respectively density at

levels n and n+1.

-(z-z )н

(4.1) p (z) =p^e

# z < z < z _

n n n +1

(4.2) H -

z . - z

<>n/>n

(4.3) /p(z)dz = H {p(z») - p(z")}, Az = z" - z'

z 4 z' < z" £ z __,

n n+1

The procedure for linear interpolation and integration

is shown in equations (4.4) and (4.5) respectively.

(4.4) p(z) = P + —— — (z - z )

„

(4.5) /p(z) =

p(2,)

Р(2И)

Lz *

- 43 -

For example, if we consider two levels with air densities

of 2

3 at 2 km and of

0.3194

kg m"

at 4 km, the scale height

is H =

9.7013

and the mass between the levels per m

according to

(4.3):

1.820 kg m~

and according to

(4.5):

1.826 kg m~

Note that the volume fractions (mixing ratios) provided

in section 3 must be converted into densities or pressures be-

fore applying equations (4.1) -

(4.5).

It might be desirable to

calculate mean volume fractions in order to use them directly

in radiative transfer calculations or to convert them into

densities or partial pressures. In this case the linear

interpolation is appropriate.

The conversion from volume fractions to densities or

pressures is accomplished by the formulas (4.6) respectively

(4.7):

(4.6) p. = W.p

i i a

(4.7)

- W. ^ p

where

(4.8)

and

M. V M.

i - FT v—: *i

- ф

a m, i a

л.

density of trace consitituents

air density

mass fraction of gas i relative to air (= p./p )

molar volume of air

molar volume of gas i

molar mass of air

molar mass of gas i

According to D'Ans and Lax (1949) M

and V

have the

following values at 1013 hPa and 273 K:

- 44 -

kg mol"

3 .-1

m mol

air (dry)

0.02896

0.02240

°3

0.0480

0.0216

0.06406

0.02189

0.044016 0.02225

0.030008

0.02239

0.02801 0.02240

0.04401 0.02226

сн

0.01604

0.02236

0.03007

0.02216

0.02604

0.02222

0.12092

0.2195

5. OUTLOOK

The vertical distributions of many of the trace con-

stituents described in this report are not constant in space

and time. This becomes more and more evident with the advent

of the results of trace constituent measurements by means of

space techniques. First two dimensional cross sections of

HNO3,

N20, NO2f CH

, and H

0 have recently become available

(e.g.

Jones and Pyle, 1984; Gille and Russell, 1984; Russell III

et al., 1984a and b; Mount et al.,

1984),

the distribution of

aerosols in the stratosphere has been observed for many

years (e.g. Kent and McCormick,

1984),

and a large number of

papers has been published on the ozone distribution (see

recent survey by Zerefos and Ghazi, 1985, as well as for

specific new techniques; McCormick et al., 1984; Peters

et al., 1984; Nagatani and Miller,

1984).

Also more

and more measurements from balloons or aircraft are made

at different locations and different times (e.g. Ridley

et al., 1984; Girard and Louisnard, 1984) so that a

more complete picture of trace constituent distributions

is emerging. It would therefore seem natural if this report

is the first one in a series presenting in the future more

and more refined distributions as required for advanced

climate and environmental studies.

- 45 ~

REFERENCES

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dioxide from infrared absorption spectra. Nature, 240,

300.

Ackerman, M., et al., 1976: Stratospheric HCl from infrared

spectra. Geoph. Res. Let.

_3, 81-83.

Anderson, J.G., J. Grassl, R.E. Shetter and J.J. Margitan,

1980:

Stratospheric free chlorine measured by balloon-

borne in situ resonance fluorescence. J. Geoph.

Res.

85,

2869-2887.

Barth,

C.A. et al., 1983: Solar Mesosphere Explorer: Scien-

tific objectives and results. Geoph. Res. Let., 10,

207-240.

Bischof, W., P. Fabian and R. Borchers, 1980: Decrease of C0

Observed in the stratosphere. Submitted to Science.

Bodhaine,

B.A., and J.M. Harries, Eds., 1982: Geophysical

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Bor'chers,

and P.. Fabian, 1983: First measurements of the

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and CH

CC1

in the strato-

sphere.

Naturwissenschaften, 70, 514-516.

Briicken, M.

and H. Georgii, 1971: Ein Beitrag zum atmosphari-

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Cadle,

R.D., 1973: Report of Task Group V intended for in-

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Changing Climate;

National Acad. Press, 1963.

Chedin,

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des-

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1980.

Chedin,

A., and N.A. Scott, 1980b: Quantitative analysis of

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DeLuisi,

J.J., Ed., 1981: Geophysical monitoring for climate

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Driscoll.,

W.G., and W. Vaughan, Eds., 1978: Handbook of

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Ehhalt,

D.H., 1974: The atmospheric cycle of methane. Tellus 26,

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- 46 -

Ehhalt, D.H., L.E. Heidt, R.H. Lueb, and E.A. Martell

1975:

Concentrations of CH

, CO,

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0 in the upper

stratosphere. J. Atm. Scie., 32:, 163-169.

Elterman,

R.B. Tooline, and J.D. Essex, 1973: Stratospheric

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Opt., Г2, 330-337

Fabian, P., R. Borchers, K.H. Weiler, U. Schmidt, A. Volz,

D.H.

Ehhalt, W. Seiler, and F. Mttller, 1979: Simultaneously

measured vertical profiles of H

, CH

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0, CFC1

and

in the mid-latitude stratosphere and troposphere.

J. Geoph. Res., 34, 3149-3154.

Fabian, R., R. Borchers, G. Flentje, W.A. Matthens, W. Seller,

U. Schmidt, and A. Volz, 1980: The vertical distribution of

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0, H

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HF at northern and southern mid-latitudes. J. Geoph. Res.,

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1621-1632.

Fischer, K., 1973: Mass absorption coefficient of natural aero-

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Gandrud, B.W., and A.L. Lazrus, 1981: Filter measurements of

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Mt. St. Helens. Science, 211, 826-827.

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