-
N. Butchart,
I. Cionni,
V. Eyring,
T. G. Shepherd,
D. W. Waugh,
H Akiyoshi,
J. Austin,
C. Brühl,
M. P. Chipperfield, E. Cordero, [......],
C. McLandress,
S. Pawson,
G. Pitari,
D. A. Plummer,
E. Rozanov,
F. Sassi,
J. F. Scinocca,
K Shibata,
B. Steil,
W Tian
[show abstract]
[hide abstract]
ABSTRACT: The response of stratospheric climate and circulation to increasing amounts of greenhouse gases (GHGs) and ozone recovery in the twenty-first century is analyzed in simulations of 11 chemistry-climate models using near-identical forcings and experimental setup. In addition to an overall global cooling of the stratosphere in the simulations (0.59 ± 6 0.07 K decade(-1) at 10 hPa), ozone recovery causes a warming of the Southern Hemisphere polar lower stratosphere in summer with enhanced cooling above. The rate of warming correlates with the rate of ozone recovery projected by the models and, on average, changes from 0.8 to 0.48 K decade(-1) at 100 hPa as the rate of recovery declines from the first to the second half of the century. In the winter northern polar lower stratosphere the increased radiative cooling from the growing abundance of GHGs is, in most models, balanced by adiabatic warming from stronger polar downwelling. In the Antarctic lower stratosphere the models simulate an increase in low temperature extremes required for polar stratospheric cloud (PSC) formation, but the positive trend is decreasing over the twenty-first century in all models. In the Arctic, none of the models simulates a statistically significant increase in Arctic PSCs throughout the twenty-first century. The subtropical jets accelerate in response to climate change and the ozone recovery produces a westward acceleration of the lower-stratospheric wind over the Antarctic during summer, though this response is sensitive to the rate of recovery projected by the models. There is a strengthening of the Brewer-Dobson circulation throughout the depth of the stratosphere, which reduces the mean age of air nearly everywhere at a rate of about 0.05 yr decade(-1) in those models with this diagnostic. On average, the annual mean tropical upwelling in the lower stratosphere (similar to 70 hPa) increases by almost 2% decade(-1), with 59% of this trend forced by the parameterized orographic gravity wave drag in the models. This is a consequence of the eastward acceleration of the subtropical jets, which increases the upward flux of (parameterized) momentum reaching the lower stratosphere in these latitudes.
Journal of Climate, v.23, 5349-5374 (2010).
-
V. Eyring,
N. Butchart,
D. W. Waugh,
H Akiyoshi,
J. Austin,
S. Bekki,
G. E. Bodeker,
B. A. Boville,
C. Brühl,
M. P. Chipperfield, [......],
G. Pitari,
D. A. Plummer,
E. Rozanov,
M. Schraner,
T. G. Shepherd,
K Shibata,
R. S. Stolarski,
H. Struthers,
W Tian,
M. Yoshiki
Journal of Geophysical Research-Atmospheres, v.111 (2006).
-
V. Eyring,
D.W. Waugh,
G.E. Bodeker, E. Cordero,
H. Akiyoshi,
J. Austin,
S.R. Beagley,
B. Boville,
P. Braesicke,
C. Brühl, [......],
E. Rozanov,
M. Schraner,
J.F. Scinocca,
K. Semeniuk,
T.G. Shepherd,
K. Shibata,
B. Steil,
R. Stolarski,
W. Tian,
M. Yoshiki
[show abstract]
[hide abstract]
ABSTRACT: Simulations from eleven coupled chemistry-climate models (CCMs) employing
nearly identical forcings have been used to project the evolution of stratospheric ozone
throughout the 21st century. The model-to-model agreement in projected temperature
trends is good, and all CCMs predict continued, global mean cooling of the stratosphere
over the next 5 decades, increasing from around 0.25 K/decade at 50 hPa to around 1 K/
decade at 1 hPa under the Intergovernmental Panel on Climate Change (IPCC) Special
Report on Emissions Scenarios (SRES) A1B scenario. In general, the simulated ozone
evolution is mainly determined by decreases in halogen concentrations and continued
cooling of the global stratosphere due to increases in greenhouse gases (GHGs). Column
ozone is projected to increase as stratospheric halogen concentrations return to 1980s
levels. Because of ozone increases in the middle and upper stratosphere due to GHGinduced
cooling, total ozone averaged over midlatitudes, outside the polar regions, and
globally, is projected to increase to 1980 values between 2035 and 2050 and before lowerstratospheric
halogen amounts decrease to 1980 values. In the polar regions the CCMs
simulate small temperature trends in the first and second half of the 21st century in midwinter. Differences in stratospheric inorganic chlorine (Cly) among the CCMs are key to diagnosing the intermodel differences in simulated ozone recovery, in particular in the Antarctic. It is found that there are substantial quantitative differences in the simulated Cly, with the October mean Antarctic Cly peak value varying from less than 2 ppb to over 3.5 ppb in the CCMs, and the date at which the Cly returns to 1980 values varying from before 2030 to after 2050. There is a similar variation in the timing of recovery of Antarctic
springtime column ozone back to 1980 values. As most models underestimate peak Cly near 2000, ozone recovery in the Antarctic could occur even later, between 2060 and 2070. In the Arctic the column ozone increase in spring does not follow halogen decreases as closely as in the Antarctic, reaching 1980 values before Arctic halogen amounts decrease
Journal of Geophysical Research. 112(2007-D16303):1-24.
-
Neal Butchart,
I. Cionni,
V. Eyring,
T.G. Shepherdyring,
D.W. Waugh,
H. Akiyoshi,
J. Austin,
C. Brühl,
M. Chipperfield, E. Cordero, [......],
C. McLandress,
S. Pawson,
G. Pitari,
D.A. Plummer,
E. Rozanov,
F. Sassi,
J.F. Scinocca,
K. Shibata,
B. Steil,
W. Tian
[show abstract]
[hide abstract]
ABSTRACT: The response of stratospheric climate and circulation to increasing amounts of greenhouse gases (GHGs) and ozone recovery in the twenty-first century is analyzed in simulations of 11 chemistry–climate models using near-identical forcings and experimental setup. In addition to an overall global cooling of the stratosphere in the simulations (0.59 ± 0.07 K decade−1 at 10 hPa), ozone recovery causes a warming of the Southern Hemisphere polar lower stratosphere in summer with enhanced cooling above. The rate of warming correlates with the rate of ozone recovery projected by the models and, on average, changes from 0.8 to 0.48 K decade−1 at 100 hPa as the rate of recovery declines from the first to the second half of the century. In the winter northern polar lower stratosphere the increased radiative cooling from the growing abundance of GHGs is, in most models, balanced by adiabatic warming from stronger polar downwelling. In the Antarctic lower stratosphere the models simulate an increase in low temperature extremes required for polar stratospheric cloud (PSC) formation, but the positive trend is decreasing over the twenty-first century in all models. In the Arctic, none of the models simulates a statistically significant increase in Arctic PSCs throughout the twenty-first century. The subtropical jets accelerate in response to climate change and the ozone recovery produces a westward acceleration of the lower-stratospheric wind over the Antarctic during summer, though this response is sensitive to the rate of recovery projected by the models. There is a strengthening of the Brewer–Dobson circulation throughout the depth of the stratosphere, which reduces the mean age of air nearly everywhere at a rate of about 0.05 yr decade−1 in those models with this diagnostic. On average, the annual mean tropical upwelling in the lower stratosphere (70 hPa) increases by almost 2% decade−1, with 59% of this trend forced by the parameterized orographic gravity wave drag in the models. This is a consequence of the eastward acceleration of the subtropical jets, which increases the upward flux of (parameterized) momentum reaching the lower stratosphere in these latitudes.
Journal of Climate. 23(2010):5349-5374.
-
V. Eyring,
D. W. Waugh,
G. E. Bodeker, E. Cordero,
H Akiyoshi,
J. Austin,
S. R. Beagley,
B. A. Boville,
P. Braesicke,
C. Brühl, [......],
E. Rozanov,
M. Schraner,
J. F. Scinocca,
K. Semeniuk,
T. G. Shepherd,
K Shibata,
B. Steil,
R. S. Stolarski,
W Tian,
M. Yoshiki
Journal of Geophysical Research-Atmospheres, v.112 (2007).
-
V. Eyring,
N. Butchart,
D. W. Waugh,
H Akiyoshi,
Geophysical Fluid Dynamics Laboratory,
NOAA,
Princeton,
New Jersey,
USA,
S. Bekki, [......],
A. Garcia,
A. Gettelman,
M. Giorgetta,
V. Grewe,
L. Jourdain,
D. E. Kinnison,
Istituto Nazionale di Geofisica e Vulcanologia,
Sezione Bologna,
Bologna,
Italia
[show abstract]
[hide abstract]
ABSTRACT: Simulations of the stratosphere from thirteen coupled chemistry-climate models (CCMs) are evaluated to provide guidance for the interpretation of ozone predictions made by the same CCMs. The focus of the evaluation is on how well the fields and processes that are important for determining the ozone distribution are represented in the simulations of the recent past. The core period of the evaluation is from 1980 to 1999 but long-term trends are compared for an extended period (1960–2004). Comparisons of polar high-latitude temperatures show that most CCMs have only small biases in the Northern Hemisphere in winter and spring, but still have cold biases in the Southern Hemisphere spring below 10 hPa. Most CCMs display the correct stratospheric response of polar temperatures to wave forcing in the Northern, but not in the Southern Hemisphere. Global long-term stratospheric temperature trends are in reasonable agreement with satellite and radiosonde observations. Comparisons of simulations of methane, mean age of air, and propagation of the annual cycle in water vapor show a wide spread in the results, indicating differences in transport. However, for around half the models there is reasonable agreement with observations. In these models the mean age of air and the water vapor tape recorder signal are generally better than reported in previous model intercomparisons. Comparisons of the water vapor and inorganic chlorine (Cly) fields also show a large intermodel spread. Differences in tropical water vapor mixing ratios in the lower stratosphere are primarily related to biases in the simulated tropical tropopause temperatures and not transport. The spread in Cly, which is largest in the polar lower stratosphere, appears to be primarily related to transport differences. In general the amplitude and phase of the annual cycle in total ozone is well simulated apart from the southern high latitudes. Most CCMs show reasonable agreement with observed total published D22308 JCR Journal
