Atmospheric chemistry of cis-CF3CH=CHCl (HCFO-1233zd(Z)): Kinetics of the gas-phase reactions with Cl atoms, OH radicals, and O3

Article abstract of DOI:10.1016/j.cplett.2015.09.008

FTIR smog chamber techniques were used to measure the rate coefficients k(Cl + cis-CF₃CH=CHCl) = (6.26 ± 0.84) × 10^-11, k(OH + cis-CF₃CH=CHCl) = (8.45 ± 1.52) × 10^-13, and k(O₃ + cis-CF₃CH=CHCl) = (1.53 ± 0.12) × 10^-21 cm³ molecule^-1 s^-1. The atmospheric lifetime of cis-CF₃CH=CHCl is determined by reaction with OH radicals and is estimated to be 14 days. The infrared spectrum of cis-CF₃CH=CHCl was recorded and the integrated absorption over the range 600-2000 cm^-1 was measured to be (1.48 ± 0.07) × 10^-16 cm molecule^-1. Accounting for non-uniform horizontal and vertical mixing leads to a GWP₁₀₀ value of essentially zero. Correction to account for unwanted Cl atom chemistry in our previous relative rate study of the kinetics of the reaction of OH with trans-CF₃CH=CHCl gives k(OH + trans-CF₃CH=CHCl) = (3.61 ± 0.37) × 10^-13 cm³ molecule^-1 s^-1.

Full text of DOI:10.1016/j.cplett.2015.09.008

Chemical Physics Letters 639 (2015) 289–293
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Chemical Physics Letters
journal homepage: www.elsevier.com/locate/cplett
Atmospheric chemistry of cis-CF3CH CHCl (HCFO-1233zd(Z)):
Kinetics of the gas-phase reactions with Cl atoms, OH radicals, and O3
Lene Løffler Andersena,∗, Freja From Østerstrøma, Mads P. Sulbaek Andersena,b
,
Ole John Nielsena, Timothy J. Wallingtonc
a Copenhagen Center for Atmospheric Research, Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
b Department of Chemistry and Biochemistry, California State University Northridge, 18111 Nordhoff St., Northridge, CA 91330-8262, USA
c System Analytics and Environmental Sciences Department, Ford Motor Company, Mail Drop RIC-2122, Dearborn, MI 48121-2053, USA
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 17 June 2015
In final form 3 September 2015
Available online 25 September 2015
FTIR smog chamber techniques were used to measure the rate coefficients k(Cl + cis-CF3CH CHCl) =
(6.26 0.84) × 10–11
,
k(OH + cis-CF3CH CHCl) = (8.45 1.52) × 10–13
,
and k(O3 + cis-CF3CH CHCl) =
(1.53 0.12) × 10–21 cm3 molecule–1 s–1. The atmospheric lifetime of cis-CF3CH CHCl is determined by
reaction with OH radicals and is estimated to be 14 days. The infrared spectrum of cis-CF3CH CHCl
was recorded and the integrated absorption over the range 600–2000 cm−1 was measured to be
(1.48 0.07) × 10–16 cm molecule−1. Accounting for non-uniform horizontal and vertical mixing leads
to a GWP100 value of essentially zero. Correction to account for unwanted Cl atom chemistry in
our previous relative rate study of the kinetics of the reaction of OH with trans-CF3CH CHCl gives
k(OH + trans-CF3CH CHCl) = (3.61 0.37) × 10–13 cm3 molecule–1 s–1
.
© 2015 Elsevier B.V. All rights reserved.
1. Introduction
if the atmospheric lifetime of cis-CF3CH CHCl is sufficiently low,
the compound will not reach the stratosphere, and thus not par-
ticipate in the catalytic destruction of the ozone layer. Prior to
large-scale industrial use an assessment of the atmospheric chem-
istry and environmental impact of cis-CF3CH CHCl is needed. To
fulfill this need we have conducted an experimental investiga-
tion of the atmospheric chemistry of cis-CF3CH CHCl. Experiments
were conducted in the smog chamber at Ford Motor Company
(Ford), Michigan, USA, and in the photoreactor at the Copenhagen
Center for Atmospheric Research (CCAR) at University of Copen-
hagen, Denmark. Fourier transform infrared (FTIR) smog chamber
techniques were used to determine the kinetics of the gas-phase
reactions of Cl atoms, OH radicals, and O3 with cis-CF3CH CHCl.
The IR spectrum of cis-CF3CH CHCl was measured and the global
warming potential (GWP) of cis-CF3CH CHCl was calculated.
Recognition of the environmental consequences of the release
of chlorofluorocarbons (CFCs) and halons into the atmosphere [1,2]
has led to an international effort to replace these compounds with
environmentally acceptable alternatives. While protection of the
ozone layer has been the focus of these efforts, concerns related
to global climate change are becoming an increasingly important
consideration in the choice of alternative compounds.
Saturated hydrofluorocarbons (HFCs), such as CF3CFH2 (HFC-
134a), have become widely used CFC replacements. HFCs do not
contain chlorine and therefore do not contribute to chlorine-based
catalytic destruction of stratospheric ozone [3]. Haloolefins are a
new generation of CFC replacements which are being developed.
Haloolefins have a greater reactivity than HFCs toward OH radi-
cals and hence have shorter atmospheric lifetimes and smaller
global warming potentials. cis-1-chloro-3,3,3-trifluoropropene
(cis-CF3CH CHCl, HCFO-1233zd(Z)) is a haloolefin which has been
developed for use in degreasing of mechanical parts and in dry
cleaning. cis-CF3CH CHCl contains a chlorine atom that potentially
can participate in the destruction of the ozone layer. However,
2. Experimental method
The experimental procedures are described in detail elsewhere
[4] and only a brief summary is given here. Chlorine atoms were
generated by photolysis of molecular chlorine:
∗
Corresponding author.
E-mail address: lene lla@hotmail.com (L.L. Andersen).
Cl2 + hv → 2Cl
(1)
http://dx.doi.org/10.1016/j.cplett.2015.09.008
0009-2614/© 2015 Elsevier B.V. All rights reserved.

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L.L. Andersen et al. / Chemical Physics Letters 639 (2015) 289–293
Hydroxyl radicals (OH) were generated by UV irradiation of
methyl nitrite (CH3ONO) in air in the presence of nitric oxide:
CH3ONO was synthesized by drop-wise addition of concen-
trated H2SO4 to a saturated solution of NaNO2 in methanol and was
devoid of any detectable impurities using FTIR analysis. All other
reagents were obtained from commercial sources at purities >99%.
CH3ONO + hv → CH3O + NO
(2)
(3)
(4)
CH3O + O2 → HO2 + HCHO
2.2. FTIR photoreactor at University of Copenhagen
HO2 + NO → OH + NO2
The CCAR photoreactor consists of a 101 liter quartz reactor con-
nected to a Bruker IFS 66 v/s FTIR spectrometer [6]. Experiments
were performed at 296 1 K in 700 Torr of air diluent. The IR spectra
were derived from 64 co-added interferograms with a spectral res-
olution of 0.25 cm−1 and an analytical path length between 50.01
and 53.42 m. Reactant and reference compounds were monitored
using absorption features over the following wavenumber ranges:
The concentrations of reactants and products were monitored
using in situ FTIR spectroscopy. Analysis of the spectra was carried
out by a process of spectral stripping in which scaled reference
spectra were subtracted from the sample spectrum. Reference
spectra were acquired by expanding known volumes of reference
compounds into the reaction chambers.
The relative rate method is a well-established technique for
measuring the rate coefficients of chlorine atoms or OH radicals
with organic compounds. Kinetic data were derived by monitoring
the loss of cis-CF3CH CHCl relative to one or more reference com-
pounds. The decays of the reactant and reference are then plotted
using the expression:
C2H2, 650–800 cm−1
; ; cis-CF3CH CHCl,
C2H4, 900–1000 cm−1
850–890 and 1610–1670 cm−1; O3, 2720–2785 cm−1
.
Ozone was produced using a commercially available ozone gen-
erator from O3-Technology. The ozone was preconcentrated using a
silica gel trap, reducing the amount of O2 introduced into the cham-
ber. All other reagents were obtained from commercial sources at
purities >99%.
ꢀ
ꢁ
ꢀ
ꢁ
cis-CF CH CHCl
[
]
[Reference]t
0
3
kReactant
t
0
Ln
=
Ln
(I)
cis-CF CH CHCl
[
kReference
[Reference]t
]
3
t
3. Results and discussion
where cis-CF CH CHCl , [cis-CF3CH CHCl]t, [Reference] and
[
]
3
t
t
0
[Reference]t are the conce0ntrations of cis-CF CH CHCl and the ref-
3
3.1. Relative rate study of Cl + cis-CF3CH CHCl
erence compound at times t0 and t. The slope is then the ratio of the
rate coefficient for reaction of either Cl atoms or OH radicals toward
cis-CF3CH CHCl and the corresponding reaction for the reference
compound.
The rate of reaction (6) was measured relative to reactions (7)
and (8):
The kinetics of the O3 reaction were studied using an absolute
rate method, in which the pseudo first order loss of reactant was
measured in the presence of excess O3. A linear plot of the pseudo-
first order rate coefficients versus the initial O3 concentration gives
a slope of k5.
Cl + cis-CF3CH CHCl → Products
Cl + C2H4 → Products
(6)
(7)
(8)
Cl + C2H2 → Products
O3 + cis-CF3CH CHCl → Products
(5)
The initial mixtures consisted of 4.41–15.8 mTorr cis-
CF3CH CHCl, 58.8–106 mTorr Cl2 and either 4.17–6.69 mTorr
C2H4 or 4.41–4.85 mTorr C2H2 in a total pressure of 700 Torr air or
N2 diluent. The loss of cis-CF3CH CHCl is plotted against the loss
In smog chamber experiments unwanted loss of reactants, refer-
ence compounds, and products via photolysis and heterogeneous
reactions need to be considered. To test for the presence of het-
erogeneous reactions, mixtures obtained after UV irradiation were
allowed to stand in the dark in the chamber for 30 min. There was
no observable (<2%) loss of reactants or products, suggesting that
heterogeneous reactions are not a significant complication in the
present experiments.
Potential systematic uncertainties inherent in the analysis of
the IR spectra are typically 1% of the initial reactant concentra-
tion. Unless otherwise stated, we choose to cite final values with
error limits, which include two standard deviations from the least
squares regression and 5% uncertainty in the reactant calibrations.
cis-CF3CH CHCl was supplied by Honeywell International Inc. with
a purity of >99%. The sample was degassed in several freeze-pump-
thaw cycles before use.
2.1. FTIR smog chamber system at ford
Experiments were performed in a 140 liter Pyrex reactor con-
nected to a Mattson Sirus 100 FTIR spectrometer [5]. The reactor
was surrounded by 22 fluorescent black lamps (GE F40BLB),
which were used to photochemically initiate the experiments.
Experiments were performed at 296 1 K in 700 Torr of air
or N2 diluent. The IR spectra were derived from 32 co-added
interferograms with a spectral resolution of 0.25 cm−1 and an ana-
lytical path length of 27.6 m. Reactant and reference compounds
were monitored using absorption features over the following
Figure 1. Loss of cis-CF3CH CHCl relative to C2H4 (squares and circles) and C2H2
(triangles) in the presence of chlorine atoms in 700 Torr total pressure of air (solid
symbols) or N2 (open symbols), 296 1 K. Experiments were performed at Ford
(triangles and circles) and CCAR (squares). The error bars reflect the uncertainty in
the determination of the reactant concentrations.
wavenumber ranges: C2H2, 650–800 cm−1; C2H4, 900–1000 cm−1
cis-CF3CH CHCl, 850–890 cm−1
;
.

L.L. Andersen et al. / Chemical Physics Letters 639 (2015) 289–293
291
of the reference compound in Figure 1. Indistinguishable results
were obtained from experiments performed in air and N2 diluent.
Linear least squares analysis of the data in Figure 1 gives
k6/k7 = 0.65 0.04 and k6/k8 = 1.28 0.08. Using k7 = (9.29 0.51)
× 10−11 and k8 = (5.07 0.34) × 10−11 [7] gives k6 = (6.03 0.48)
× 10–11 and (6.49 0.61) × 10–11 cm3 molecule–1 s–1, respectively.
The fact that consistent values of k6 were derived from experi-
ments using different reference compounds suggests the absence
of significant systematic errors in the present work. We choose
that Cl atoms are released during the OH initiated oxidation of
CF3CH CHCl [9]:
CF3CHCH(OH)Cl + M → Cl + CF3CH CH(OH) + M
(12)
The Cl atoms will react with cis-CF3CH CHCl and pose a chal-
lenge for the OH relative rate measurement of k9. Ideally, to
minimize such complications a competitor would be added to the
reaction mixtures to scavenge the Cl atoms. Alkanes, such as C2H6,
are often used as chlorine atom scavengers but are not suitable
for use in the present experiments because their reactivity toward
OH radicals is comparable to that of cis-CF3CH CHCl and hence
would scavenge both chlorine atoms and OH radicals. To account
for additional loss of cis-CF3CH CHCl in the OH relative rate exper-
iments caused by Cl atoms the system was modeled numerically. A
model was constructed which incorporated the concentrations of
cis-CF3CH CHCl, C2H4, and C2H2 used in the experiments, values
of k6–k8 and k9–k11 given above, and a chlorine atom yield of 40%
from OH radical initiated oxidation as found for trans-CF3CH CHCl
[9]. The value of k9 in the model was iterated starting with an uncor-
rected value, computing a correction, and then using the corrected
value in the model to reevaluate the correction. The correction
was larger for the experiments using C2H4 as reference than for
those using C2H2 as reference. This reflects the fact that there is an
approximately 5-fold difference in the rate coefficient ratios k6/k7
and k9/k10, while there is only approximately 10% difference in the
rate coefficient ratios k6/k8 and k9/k11. The corrections applied to
the C2H4 data were approximately 20% while those to the C2H2 data
were approximately 5%. Correcting for the impact of chlorine atoms
and propagating an additional 5% uncertainty to account for uncer-
tainties in the correction procedure gives k9/k10 = 0.103 0.014 and
k9/k11 = 0.960 0.082.
to quote
a final value for k6 which is the average of the
individual determinations together with uncertainties that encom-
pass the extremes of the two individual determinations, hence,
k6 = (6.26 0.84) × 10–11 cm3 molecule–1 s–1
.
This is the first study of the reaction of chlorine atoms with cis-
CF3CH CHCl. We have previously studied the reactivity of chlorine
atoms toward trans-CF3CH CHCl. The rate coefficient ratios mea-
sured for the trans isomer using C2H4 and C2H2 references were
approximately 10% smaller [8] than those measured here showing
that the cis isomer is slightly more reactive than the trans isomer
toward chlorine atoms. This difference may be explained by steric
hindrance.
3.2. Relative rate study of OH + cis-CF3CH CHCl
The kinetics of reaction (9) were measured relative to reactions
(10) and (11):
OH + cis-CF3CH CHCl → Products
OH + C2H4 → Products
(9)
(10)
(11)
OH + C2H2 → Products
Using k10 = 8.52 × 10−12 [10] and k11 = 8.45 × 10−13 [11]
gives k9 = (8.78 1.19) × 10–13 and (8.11 0.69) × 10–13 cm3
molecule–1 s–1. The fact that consistent values of k9 were derived
from experiments using different reference compounds sug-
gests the absence of significant systematic errors in the present
work. We choose to quote a final value for k9, which is the
average of the individual determinations with uncertainties that
encompass the extremes of the individual determinations, hence,
k9 = (8.45 1.52) × 10–13 cm3 molecule–1 s–1. This result is con-
sistent with the value of (9.46 0.22) × 10–13 cm3 molecule–1 s–1
reported by Gierczak et al. [12].
Initial reaction mixtures consisted of 58.5–63.2 mTorr cis-
CF3CH CHCl, 108–205.7 mTorr CH3ONO, and 7.05–7.35 mTorr
C2H4 or 4.26–7.35 mTorr C2H2, and 0–14.7 mTorr NO in a total
pressure of 700 Torr air and N2 diluent. Figure 2 shows the loss
of cis-CF3CH CHCl plotted as a function of the loss of the reference
compound.
Linear least squares analysis of the data in Figure 2 gives
k9/k10 = 0.129 0.016 and k9/k11 = 1.01 0.07. We have shown
3.3. Relative rate study of OH + trans-CF3CH CHCl
We have previously conducted a relative rate study of the kinet-
ics of the reaction of OH radicals with trans-CF3CH CHCl using
C2H4 and C2H2 as references and reported rate coefficient ratios
of k13/k10 = 0.053 0.003 and k13/k11 = 0.506 0.031 [8].
OH + trans-CF3CH CHCl → Products
(13)
As discussed above, the formation of chlorine atoms is an
unavoidable complication in relative rate studies of the reac-
tion of OH radicals with CF3CH CHCl. To compute corrections
to account for chlorine chemistry in the OH experiments a
model was constructed which incorporated the concentrations
of trans-CF3CH CHCl, C2H4, and C2H2 used in the previous
experiments, values of k6, k7, k8, k10, k11, and k13, and a chlo-
rine atom yield of 40% from OH radical initiated oxidation of
trans-CF3CH CHCl. The corrections applied to the C2H4 data
were approximately 20% while those for the C2H2 data were
approximately 15%. Correcting for the impact of chlorine atoms
and propagating an addition 5% uncertainty to account for uncer-
tainties in the correction procedure gives k13/k10 = 0.042 0.004
and k13/k11 = 0.430 0.034. Using k10 = 8.52 × 10−12 [10] and
k11 = 8.45 × 10−13 [11] gives k13 = (3.58 0.34) × 10–13 and
Figure 2. Loss of cis-CF3CH CHCl relative to C2H4 (circles) and C2H2 (triangles) in
the presence of OH radicals in 700 Torr total pressure of air and N2, 296 1 K. The
error bars reflect the uncertainty in the determination of the reactant concentra-
tions.

292
L.L. Andersen et al. / Chemical Physics Letters 639 (2015) 289–293
Figure 4. IR spectrum of cis-CF3CH CHCl in 700 Torr of air at 295 K (Ford).
and
a propagated 5% uncertainty in the O3 calibration, of
k5 = (1.53 0.12) × 10–21 cm3 molecule–1 s–1
.
This is the first study of the reaction of O3 with cis-
CF3CH CHCl. We have previously reported
a
value of
Figure 3. Pseudo-first order loss of cis-CF3CH CHCl versus O3 concentration. All
data were obtained at CCAR. The inset shows the data obtained for 0.61, 0.85, 1.6,
2.3, and 2.80 Torr of O3 in 700 Torr total pressure of air diluent, 295 1 K.
(1.46 0.12) × 10–21 cm3 molecule–1 s–1 for the trans isomer, trans-
CF3CH CHCl [8]. The reactivities of cis- and trans-CF3CH CHCl
toward O3 are indistinguishable.
(3.63 0.29) × 10–13 cm3 molecule–1 s–1, respectively. We choose
to quote a final value for k13, which is the average of the
individual determinations with uncertainties that encom-
pass the extremes of the individual determinations, hence,
3.5. Infrared spectrum of cis-CF3CH CHCl
IR spectra were obtained by expanding known volumes of
cis-CF3CH CHCl into the chambers and recording spectra for dif-
ferent concentrations of cis-CF3CH CHCl. The IR spectra obtained
at Ford and CCAR were in good agreement (within 5%). Below
and in the following sections, we proceed using the spectrum
obtained at Ford. Figure 4 shows the IR spectrum of cis-CF3CH CHCl
recorded in 700 Torr air diluent at 296 1 K. As seen from the
inset in Figure 4 the intensity of the absorption features increased
linearly with the cis-CF3CH CHCl concentration. The integrated
absorption cross-section of cis-CF3CH CHCl (600–2000 cm−1) is
(1.48 0.07) × 10–16 cm molecule−1. Gierczak et al. [12] report a
value of (1.60 0.01) × 10–16 cm molecule−1 which is consistent
with our measurement within the expected combined experimen-
tal uncertainties.
k13 = (3.61 0.37) × 10–13 cm3 molecule–1 s–1
.
This
value
is
in agreement with the value of (3.76 0.06) × 10–13 (296 K)
reported by Gierczak et al. [12] and the value of (3.29 0.10)
× 10–13 cm3 molecule–1 s–1 (298 K) reported by Orkin et al. [13].
Interestingly, the trans isomer is approximately a factor of 2 less
reactive than the cis isomer toward OH radicals. An investigation
of the significant difference between the rate coefficients for the
trans and the cis isomer could be performed with a computational
study, but is beyond the scope of the present study.
3.4. Absolute rate of O3 + cis-CF3CH CHCl
The kinetics of reaction (5) were studied by observing the decay
of cis-CF3CH CHCl when exposed to O3 in the reaction chamber at
CCAR:
4. Implications for atmospheric chemistry
The present work improves our understanding of the
atmospheric chemistry of cis-CF3CH CHCl. Cl atoms, OH
radicals, and O3 react with cis-CF3CH CHCl with rate
O3 + cis-CF3CH CHCl → Products
(5)
Cyclohexane was added to the reaction mixture as OH scav-
enger to avoid potential problems associated with the loss of
cis-CF3CH CHCl via reaction with OH radicals formed in reaction
(5) [10]. Initial reaction mixtures consisted of 4.07–4.17 mTorr cis-
CF3CH CHCl, 3.96–31.79 mTorr cyclohexane, and 0.61–2.82 Torr
O3 in a total pressure of 700 Torr air diluent. Variation in the
[cyclohexane]/[cis-CF3CH CHCl] ratio over the range of 0.9–7.6 had
no discernable effect on the observed decay of cis-CF3CH CHCl sug-
gesting that loss via reaction with OH radicals is not a significant
complication.
coefficients of (6.26 0.84) × 10–11
,
(8.45 1.52) × 10−13
, and
(1.53 0.12) × 10–21 cm3 molecule–1 s–1
,
respectively. Organic
compounds are removed from the atmosphere via photolysis, wet
and dry deposition, and gas-phase reaction with OH radicals, O3,
and Cl atoms. cis-CF3CH CHCl does not absorb at wavelengths
greater than 200 nm and is volatile and hence will not be lost via
photolysis or wet or dry deposition to any appreciable extent [14].
The value of k(OH + cis-CF3CH CHCl) derived in the present work
can be used to provide an estimate of the atmospheric lifetime
of cis-CF3CH CHCl. Using a global tropospheric 24 h average OH
concentration of 1.0 × 106 molecule cm−3 [15] gives an estimated
lifetime with respect to reaction with OH radicals of 14 days. The
approximate nature of this lifetime should be stressed. The aver-
age daily concentration of OH radicals in the atmosphere varies
significantly with location and season [16] and local atmospheric
lifetimes of cis-CF3CH CHCl will vary similarly.
The loss of cis-CF3CH CHCl followed pseudo first-order kinet-
ics in all experiments. The insert in Figure 3 shows the data
obtained for 0.61, 0.85, 1.6, 2.3, and 2.80 Torr of O3. A plot
of the pseudo first-order decay of cis-CF3CH CHCl versus O3
concentration is shown in Figure 3.
A linear least squares
fit gives k5 = (1.53 0.09) × 10–21 cm3 molecule–1 s–1. We choose
to cite a final value for k5 with error limits which include
two standard deviations from the least squares regression
Our value for k(O3 + cis-CF3CH CHCl) can be combined with the
global background concentration of O3 of approximately 35 ppb

L.L. Andersen et al. / Chemical Physics Letters 639 (2015) 289–293
293
[17] to provide an estimate of the atmospheric lifetime of cis-
CF3CH CHCl with respect to reaction with O3 of 24 years, which
is clearly of minor importance compared to the OH reaction path-
way. Reaction with Cl atoms is a negligible fate for cis-CF3CH CHCl
as the atmospheric concentration of Cl atoms is generally low [17].
Assuming a global average Cl atom concentration of 103 cm−3 we
derive a lifetime with respect to Cl atom reaction of 6 months.
We proceed on the assumption that the atmospheric lifetime of
cis-CF3CH CHCl is dictated by reaction with OH radicals and is
approximately 14 days.
cis-CF3CH CHCl is approximately half that of the trans isomer and
hence the ODP for cis-CF3CH CHCl will be even lower than for
trans-CF3CH CHCl. We conclude that cis-CF3CH CHCl will make
negligible contributions to stratospheric ozone depletion and to
radiative forcing of climate change.
Acknowledgements
We acknowledge financial support from the Villum Kann Ras-
mussen Foundation and EUROCHAMP2.
The radiative efficiency for cis-CF3CH CHCl calculated using the
method of Pinnock et al. [18] and the IR spectrum in Figure 4
was 0.19 W m−2 ppb−1. For short-lived compounds, such as cis-
CF3CH CHCl, non-uniform horizontal and vertical mixing in the
atmosphere need to be taken into account. Hodnebrog et al. [19]
provide a correction factor of relative efficiencies for very short-
lived compounds (Eq. (II)) that accounts for non-uniform horizontal
and vertical mixing:
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aꢀb
1 + cꢀd
f (ꢀ) =
(II)
where ꢀ is the lifetime of cis-CF3CH CHCl, a, b, c, and d are constants
with values of 2.962, 0.9312, 2.994, and 0.9302, respectively. Using
ꢀ = 0.038 years gives f(ꢀ) = 0.122. Hence we arrive at a final value of
cis-CF3CH CHCl of 0.0231 W m−2 ppb−1
.
Using Eq. (III) the global warming potential (GWP) can be calcu-
lated:
ꢄ
ꢀ
ꢂ
ꢃ
t
ꢂ
ꢃ
Fx exp −t/ꢀx dt
0
GWP x(tꢀ)
=
(III)
ꢄ
ꢀ FCO2 R(t)dt
t
0
where FCO is the radiative efficiency of CO2, R(t) is the response
2
function that describes the decay of an instantaneous pulse of
CO2, Fx is the radiative efficiency of cis-CF3CH CHCl, and ꢀx is its
atmospheric lifetime. The denominator in Eq. (III) is the absolute
global warming potential (AGWP) for CO2. Using the IPCC AR5
FCO of 1.7517 × 10–15 W m–2 kg–1 [20] with the time-integrated
2
[18] S. Pinnock, M.D. Hurley, K.P. Shine, T.J. Wallington, T.J. Smyth, J. Geophys. Res.:
Atmos. 100 (1995) 23227.
[19] Ø. Hodnebrog, M. Etminan, J.S. Fuglestvedt, G. Marston, G. Myhre, C.J. Nielsen,
K.P. Shine, T.J. Wallington, Rev. Geophys. 51 (2013) 300.
airborne CO2 fractions evaluated by Joos et al. [21] for different
time horizons, we arrive at AGWPs for CO2 of 0.194, 0.715 and
2.512 W m−2 ppb−1 for 20, 100, and 500 year time horizons, respec-
tively.
[20] G. Myhre, D. Shindell, F.-M. Bréon, W. Collins, J. Fuglestvedt, J. Huang, D. Koch,
J.-F. Lamarque, D. Lee, B. Mendoza, T. Nakajima, A. Robock, G. Stephens, T. Take-
mura, H. Zhang, in: T.F. Stocker, D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J.
Boschung, A. Nauels, Y. Xia, V. Bex, P.M. Midgley (Eds.), Climate Change 2013:
The Physical Science Basis. Contribution of Working Group I to the Fifth Assess-
ment Report of the Intergovernmental Panel on Climate Change., 2013.
[21] F. Joos, R. Roth, J.S. Fuglestvedt, G.P. Peters, I.G. Enting, W. von Bloh, V. Brovkin,
E.J. Burke, M. Eby, N.R. Edwards, T. Friedrich, T.L. Frölicher, P.R. Halloran, P.B.
Holden, C. Jones, T. Kleinen, F.T. Mackenzie, K. Matsumoto, M. Meinshausen,
G.K. Plattner, A. Reisinger, J. Segschneider, G. Shaffer, M. Steinacher, K. Strass-
mann, K. Tanaka, A. Timmermann, A.J. Weaver, Atmos. Chem. Phys. 13 (2013)
2793.
Using the radiative efficiency of 0.0231 W m−2 ppb−1 and atmo-
spheric lifetime of 14 days, GWP values for cis-CF3CH CHCl are
estimated to 2, 0, and 0, for 20, 100, and 500 year horizons respec-
tively. Gierczak et al. report a GWP100 value of approximately 3 [12]
which is consistent with our result. cis-CF3CH CHCl has a negligi-
ble GWP and will not make a significant contribution to radiative
forcing of climate change. Patten and Wuebbles [22] conducted a
modeling study and derived an ozone depleting potential (ODP)
for trans-CF3CH CHCl of 0.00034. The atmospheric lifetime of
[22] K.O. Patten, D.J. Wuebbles, Atmos. Chem. Phys. 10 (2010) 10867.