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NASA NTRS2002

The Temperature of the Arctic and Antarctic Lower Stratosphere

The temperature of the polar lower stratosphere during spring is the key factor in changing the magnitude of ozone loss in the polar vortices. In this talk, we will review the results of Newman et al. [2000] that quantitatively demonstrate that the polar lower stratospheric temperature is primarily controlled by planetary-scale waves. In particular, the tropospheric eddy heat flux in middle to late winter (January--February) is highly correlated with the mean polar stratospheric temperature during March. Strong midwinter planetary wave forcing leads to a warmer spring Arctic lower stratosphere in early spring, while weak midwinter forcing leads to cooler spring Arctic temperatures. In addition, this planetary wave driving also has a strong impact on the strength of the polar vortex. These results from the Northern Hemisphere will be contrasted with the Southern Hemisphere.

Newman, Paul A.↗
NASA NTRS2002

Stratospheric Analysis and Forecasting in the Northern Winter of 1999/2000: The NASA DAO's GEOS-3 System

An evaluation is presented of the performance in the northern winter 1999/2000 of the GEOS-3 troposphere-stratosphere data assimilation system (DAS). The impacts of the two main input data types are assessed: upper-air soundings (sondes) provide wind and temperature information and satellite-based (Tiros Operational Vertical Sounders: TOVS) give estimates of the thermal structure. It is shown that in the low stratosphere (300-70hPa) the analyses are generally slightly warmer than the sonde data, but colder than the TOVS data; this relationship reverses between 70 and 10 hPa. There are geographical biases, related to the spatial and temporal coverage of the observation types and to the statistical weights assigned to them in the DAS. Forecasts show a tendency to reduce zonal asymmetries in the atmospheric flow and to suppress stratospheric temperature minima. In the DAS, the analysis increments compensate for this, but it leads to important biases in the multi-day forecasts. The analysis increments are as large as the diabatic forcing in the lower polar stratosphere, indicating a substantial model bias. The results provide important insights into the roles of different data types and the circulation model in producing accurate analyses for studies of polar chemistry and physical processes.

Pawson, Steven↗
NASA NTRS2002

Upper-Stratospheric Ozone Trends 1979-1998

Extensive analyses of ozone observations between 1978 and 1998 measured by Dobson Umkehr, Stratospheric Aerosol and Gas Experiment (SAGE) I and II, and Solar Backscattered Ultraviolet (SBUV) and (SBUV)/2 indicate continued significant ozone decline throughout the extratropical upper stratosphere from 30-45 km altitude. The maximum annual linear decline of -0.8 +/- 0.2 %/yr(2sigma) occurs at 40 km and is well described in terms of a linear decline modulated by the 11-year solar variation. The minimum decline of -0.110.1% yr-1(2o) occurs at 25 km in midlatitudes, with remarkable symmetry between the Northern and Southern Hemispheres at 40 km altitude. Midlatitude upper-stratospheric zonal trends exhibit significant seasonal variation (+/- 30% in the Northern Hemisphere, +/- 40% in the Southern Hemisphere) with the most negative trends of -1.2%/yr occurring in the winter. Significant seasonal trends of -0.7 to -0.9%/yr occur at 40 km in the tropics between April and September. Subjecting the statistical models used to calculate the ozone trends to intercomparison tests on a variety of common data sets yields results that indicate the standard deviation between trends estimated by 10 different statistical models is less than 0.1%/yr in the annual-mean trend for SAGE data and less than 0.2%/yr in the most demanding conditions (seasons with irregular, sparse data) [World Meteorological Organization (WMO), 1998]. These consistent trend results between statistical models together with extensive consistency between the independent measurement-system trend observations by Dobson Umkehr, SAGE I and II, and SBUV and SBUV/2 provide a high degree of confidence in the accuracy of the declining ozone amounts reported here. Additional details of ozone trend results from 1978 to 1996 (2 years shorter than reported here) along with lower-stratospheric and tropospheric ozone trends, extensive intercomparisons to assess relative instrument drifts, and retrieval algorithm details are given by WMO [1998].

Newchurch, M. J.↗
NASA NTRS2003

Extratropical Stratosphere-Troposphere Mass Exchange

Global net mass flux between the troposphere and the stratosphere can be computed simply by estimating the heating rate along the 380K isentropic surface and the time rate of change of the lower most stratosphere (region between the tropopause and 380K). Given the net tropopause mass flux and the cross tropopause diabatic flux, the residual adiabatic mass flux can be estimated. These fluxes have been computed using three different meteorological data sets, the FVGCM and two assimilation data sets, FVDAS, and UKMO, using the 3.5 PVU defined tropopause. For all three data sets, the extratropical diabatic flux across the tropopause is generally to be larger than the net flux cross tropopause flux implying that there is a net extra-tropical adiabatic flux of air from the troposphere into the middle world stratosphere. This adiabatic flux is four to five times larger than the flux into the stratosphere across the tropical tropopause. For the FVDAS, the tropopause diabatic flux is smaller than UKMO as a result of colder tropopause temperatures. The difference in the diabatic mass fluxes by almost a factor of two between the two data assimilation meteorological analyses is much larger than the interannual variability in the UKMO or FVGCM data sets. Compared to radiosonde estimated tropopause temperatures, both data assimilation tropopause temperatures are warm biased due to a low bias in the tropopause heights. These comparisons point to the PV determination of the tropopause height as the source of the differences in the mass fluxes.

Schoeberl, Mark↗
NASA NTRS2004

Balloon Borne Soundings of Water Vapor, Ozone and Temperature in the Upper Tropospheric and Lower Stratosphere as Part of the Second SAGE III Ozone Loss and Validation Experiment (SOLVE-2)

The main goal of our work was to provide in situ water vapor and ozone profiles in the upper troposphere and lower stratosphere as reference measurements for the validation of SAGE III water vapor and ozone retrievals. We used the NOAA/CMDL frost point hygrometer and ECC ozone sondes on small research balloons to provide continuous profiles between the surface and the mid stratosphere. The NOAA/CMDL frost point hygrometer is currently the only lightweight balloon borne instrument capable of measuring water vapor between the lower troposphere and middle stratosphere. The validation measurements were based in the arctic region of Scandinavia for northern hemisphere observations and in New Zealand for southern hemisphere observations and timed to coincide with overpasses of the SAGE III instrument. In addition to SAGE III validation we also tried to coordinate launches with other instruments and studied dehydration and transport processes in the Arctic stratospheric vortex.

Voemel, Holger↗
NASA NTRS2004

Mesosphere-Stratosphere Coupling: Implications for Climate Variability and Trends

A key aspect of this project is the establishment of a causal link from circulation anomalies in the lower mesosphere and stratopause region downward through the stratosphere to the troposphere. The observational link for stratospheric sudden warmings and surface climate is fairly clear. However, our understanding of the dynamics is incomplete. We have been making significant progress in the area of dynamical mechanisms by which circulation anomalies in the stratosphere affect the troposphere. We are trying to understand the details and sequence of events that occur when a middle atmosphere (wind) anomaly propagates downward to near the tropopause. The wind anomaly could be caused by a warming or solar variations in the low-latitude stratopause region, or could have other causes. The observations show a picture that is consistent with a circulation anomaly that descends to the tropopause region, and can be detected as low as the mid-troposphere. Processes near the stratopause in the tropics appear to be important precursors to the wintertime development of the northern polar vortex. This may affect significantly our understanding of the process by which low-latitude wind anomalies in the low mesosphere and upper stratosphere evolve through the winter and affect the polar vortex.

Baldwin, Mark P.↗
NASA NTRS1996

Balloon observations of organic and inorganic chlorine in the stratosphere: the role of HClO4 production on sulfate aerosols

Simultaneous observations of stratospheric organic and inorganic chlorine were made in September 1993 out of Fort Sumner, New Mexico, using JPL balloon-borne MkIV interferometer. Between 15 and 20 km, a significant fraction (20-60%) of the inorganic chlorine could not be accounted for by the sum of measured HCl, ClONO2, and HOCl. Laboratory measurements of the reaction of ClO radicals on sulfuric acid solutions have indicated that, along with HCl, small amounts of perchloric acid, HClO4, were formed. Very little is known about the fate of HClO4 in the stratosphere and we use a photochemical box model to determine the impact of this new species on the partitioning of inorganic chlorine in the stratosphere. Assuming that HClO4 is photochemically stable, it is shown that in the enhanced aerosol loading conditions resulting from Mt. Pinatubo's eruption, HClO4 could represent a significant reservoir of chlorine in the lower stratosphere, sequestering up to 0.2 ppbv (or 50%) of the total inorganic chlorine at 16 km. The occurrence of this new species could bring to closure the inorganic chlorine budget deficiency made apparent by recent ER-2 aircraft in situ measurements of HCl.

unmanned↗
NASA NTRS2004

Stratospheric Impact of Varying Sea Surface Temperatures

The Finite-Volume General Circulation Model (FVGCM) has been run in 50 year simulations with the: 1) 1949-1999 Hadley Centre sea surface temperatures (SST), and 2) a fixed annual cycle of SSTs. In this presentation we first show that the 1949-1999 FVGCM simulation produces a very credible stratosphere in comparison to an NCEP/NCAR reanalysis climatology. In particular, the northern hemisphere has numerous major and minor stratospheric warming, while the southern hemisphere has only a few over the 50-year simulation. During the northern hemisphere winter, temperatures are both warmer in the lower stratosphere and the polar vortex is weaker than is found in the mid-winter southern hemisphere. Mean temperature differences in the lower stratosphere are shown to be small (less than 2 K), and planetary wave forcing is found to be very consistent with the climatology. We then will show the differences between our varying SST simulation and the fixed SST simulation in both the dynamics and in two parameterized trace gases (ozone and methane). In general, differences are found to be small, with subtle changes in planetary wave forcing that lead to reduced temperatures in the SH and increased temperatures in the NH.

Newman, Paul A.↗
NASA NTRS2003

Evidence for slowdown in stratospheric ozone loss: First stage of ozone recovery

Global ozone trends derived from the Stratospheric Aerosol and Gas Experiment I and II (SAGE I/II) combined with the more recent Halogen Occultation Experiment (HALOE) observations provide evidence of a slowdown in stratospheric ozone losses since 1997. This evidence is quantified by the cumulative sum of residual differences from the predicted linear trend. The cumulative residuals indicate that the rate of ozone loss at 35- 45 km altitudes globally has diminished. These changes in loss rates are consistent with the slowdown of total stratospheric chlorine increases characterized by HALOE HCI measurements. These changes in the ozone loss rates in the upper stratosphere are significant and constitute the first stage of a recovery of the ozone layer.

Newchurch, M. J.↗
NASA NTRS2008

The Relationship of Loss, Mean Age of Air and the Distribution of CFC's to Stratospheric Circulation and Implications for Atmospheric Lifetimes

Model-derived estimates of the annually integrated destruction and lifetime for various ozone depleting substances (ODSs) depend on the simulated stratospheric transport and mixing in the global model used to produce the estimate. Observations in the middle and high latitude lower stratosphere show that the mean age of an air parcel (i.e., the time since its stratospheric entry) is related to the fractional release for the ODs (i.e., the amount of the ODS that has been destroyed relative to the amount at the time of stratospheric entry). We use back trajectory calculations to produce an age spectrum, and explain the relationship between the mean age and the fractional release by showing that older elements in the age spectrum have experienced higher altitudes and greater ODs destruction than younger elements. In our study, models with faster circulations produce distributions for the age-of-air that are 'young' compared to a distribution derived from observations. These models also fail to reproduce the observed relationship between the mean age of air and the fractional release. Models with slower circulations produce both realistic distributions for mean age and a realistic relationship between mean age and fractional release. These models also produce a CFCl3 lifetime of approximately 56 years, longer than the 45 year lifetime used to project future mixing ratios. We find that the use of flux boundary conditions in assessment models would have several advantages, including consistency between ODS evolution and simulated loss even if the simulated residual circulation changes due to climate change.

Douglas, A. R.↗
NASA NTRS2008

Observations and Modeling of Composition of Upper Troposphere/Lower Stratosphere (UTILS): Isentropic Mixing Events and Morphology of HNO3 as Observed by HIRDLS and Comparison with Results from Global Modeling Initiative

isentropic exchange of air masses between the tropical upper troposphere and mid-latitude lowermost stratosphere (the so-called "middle world") is an important pathway for stratospheric-tropospheric exchange. A seasonal, global view of this process has been difficult to obtain, in part due to the lack of the vertical resolution in satellite observations needed to capture the laminar character of these events. Ozone observations at a resolution of about 1 km from the High Resolution Dynamic Limb Sounder (HIRDLS) on NASA's Aura satellite show instances of these intrusions. Such intrusions should also be observable in HN03 observations; however, the abundances of nitric acid could be additionally controlled by chemical processes or incorporation and removal into ice clouds. We present a systematic examination of the HIRDLS data on O3 and HNO3 to determine the seasonal and spatial characteristics of the distribution of isentropic intrusions. At the same time, we compare the observed distributions with those calculated by the Global Modeling Initiative combined tropospheric-stratospheric model, which has a vertical resolution of about I km. This Chemical Transport Model (CTM) is driven by meteorological fields obtained from the GEOS-4 system of NASA/Goddard Global Modeling and Assimilation Office (GMAO), for the Aura time period, at a vertical resolution of about 1 km. Such comparison brings out the successes and limitations of the model in representing isentropic stratospheric-tropospheric exchange, and the different processes controlling HNO3 in the UTAS.

Rodriquez, J. M.↗
NASA NTRS2007

The Relationship of Loss, Mean Age of Air and the Distribution of CFCs to Stratospheric Circulation and Implications for Atmospheric Lifetimes

Man-made molecules called chlorofluorcarbons (CFCs) are broken apart in the stratosphere by high energy light, and the reactive chlorine gases that come from them cause the ozone hole. Since the ozone layer stops high energy light from reaching low altitudes, CFCs must be transported to high altitudes to be broken apart. The number of molecules per volume (the density) is much smaller at high altitudes than near the surface, and CFC molecules have a very small chance of reaching that altitude in any particular year. Many tons of CFCs were put into the atmosphere during the end of the last century, and it will take many years for all of them to be destroyed. Each CFC has an atmospheric lifetime that depends on the amount of energy required to break them apart. Two of the gases that were made the most are CFC13 and CF2C12. It takes more energy to break apart CF2C12 than CFC13, and its lifetime is about 100 years, nearly twice as long as the lifetime for CFC13. It is hard to figure out the lifetimes from surface measurements because we don't know exactly how much was released into the air each year. Atmospheric models are used to predict what will happen to ozone and other gases as the CFCs decrease and other gases like C02 continue to increase during the next century. CFC lifetimes are used to predict future concentrations and all assessment models use the predicted future concentrations. The models have different circulations and the amount of CFC lost according to the model may not match the loss that is expected according to the lifetime. In models the amount destroyed per year depends on how fast the model pushes air into the stratosphere and how much goes to high altitudes each year. This paper looks at the way the model circulation changes the lifetimes, and looks at measurements that tell us which model is more realistic. Some models do a good job reproducing the age-of-air, which tells us that these models are circulating the stratospheric air at the right speed. These same models also do a good job reproducing the amount of CFCs in the lower atmosphere where they were measured by instruments on NASA's ER-2, a research plane that flies in the lower stratosphere. The lifetime for CFC13 that is calculated using the models that do the best job matching the data is about 25% longer than most people thought. This paper shows that using these measurements to decide which models are more realistic helps us understand why their predictions are different from each other and also to decide which predictions are more likely.

Douglass, A. R.↗
NASA NTRS2006

SABER (TIMED) and MLS (UARS) Temperature Observations of Mesospheric and Stratospheric QBO and Related Tidal Variations

More than three years of temperature observations from the SABER (TIMED) and MLS WARS) instruments are analyzed to study the annual and inter-annual variations extending from the stratosphere into the upper mesosphere. The SABER measurements provide data from a wide altitude range (15 to 95 km) for the years 2002 to 2004, while the MLS data were taken in the 16 to 55 km altitude range a decade earlier. Because of the sampling properties of SABER and MLS, the variations with local solar time must be accounted for when estimating the zonal mean variations. An algorithm is thus applied that delineates with Fourier analysis the year-long variations of the migrating tides and zonal mean component. The amplitude of the diurnal tide near the equator shows a strong semiannual periodicity with maxima near equinox, which vary from year to year to indicate the influence from the Quasi-biennial Oscillation (QBO) in the zonal circulation. The zonal mean QBO temperature variations are analyzed over a range of latitudes and altitudes, and the results are presented for latitudes from 48"s to 48"N. New results are obtained for the QBO, especially in the upper stratosphere and mesosphere, and at mid-latitudes. At Equatorial latitudes, the QBO amplitudes show local peaks, albeit small, that occur at different altitudes. From about 20 to 40 km, and within about 15" of the Equator, the amplitudes can approach 3S K for the stratospheric QBO or SQBO. For the mesospheric QBO or MQBO, we find peaks near 70 km, with temperature amplitudes reaching 3.5"K, and near 85 km, the amplitudes approach 2.5OK. Morphologically, the amplitude and phase variations derived from the SABER and MLS measurements are in qualitative agreement. The QBO amplitudes tend to peak at the Equator but then increase again pole-ward of about 15" to 20'. The phase progression with altitude varies more gradually at the Equator than at mid-latitudes. A comparison of the observations with results from the Numerical Spectral Model (NSM) reveals that there is qualitative agreement. The NSM generates the QBO extending from the stratosphere into the upper mesosphere, with temperature variations extending to mid latitudes, but the predicted amplitudes are smaller than those observed.

Huang, Frank T.↗
NASA NTRS2008

CALIPSO Observations of Volcanic Aerosol in the Stratosphere

In the stratosphere, the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) has observed the presence of aerosol plumes associated with the eruptions several volcanoes including Montserrat (May 2006), Chaiten (May 2008), and Kasatochi (August 2008). While the dense ash plumes from these eruptions dissipate relatively quickly, CALIPSO continued to detect an enhanced aerosol layer from the Montserrat eruption from the initial observations in June 2006 well into 2008. Solar occultation missions were uniquely capable of monitoring stratospheric aerosol. However, since the end of long-lived instruments like the Stratospheric Aerosol and Gas Experiment (SAGE II), there has been no clear space-based successor instrument. A number of active instruments, some employing new techniques, are being evaluated as candidate sources of stratospheric aerosol data. Herein, we examine suitability of the CALIPSO 532-nm aerosol backscatter coefficient measurements.

Thomason, Larry W.↗
NASA NTRS2009

The Impact of Geoengineering Aerosols on Stratospheric Temperature and Ozone

Anthropogenic greenhouse gas emissions are warming the global climate at an unprecedented rate. Significant emission reductions will be required soon to avoid a rapid temperature rise. As a potential interim measure to avoid extreme temperature increase, it has been suggested that Earth's albedo be increased by artificially enhancing stratospheric sulfate aerosols. We use a 3D chemistry climate model, fed by aerosol size distributions from a zonal mean aerosol model, to simulate continuous injection of 1-10 Mt/a into the lower tropical stratosphere. In contrast to the case for all previous work, the particles are predicted to grow to larger sizes than are observed after volcanic eruptions. The reason is the continuous supply of sulfuric acid and hence freshly formed small aerosol particles, which enhance the formation of large aerosol particles by coagulation and, to a lesser extent, by condensation. Owing to their large size, these particles have a reduced albedo. Furthermore, their sedimentation results in a non-linear relationship between stratospheric aerosol burden and annual injection, leading to a reduction of the targeted cooling. More importantly, the sedimenting particles heat the tropical cold point tropopause and, hence, the stratospheric entry mixing ratio of H2O increases. Therefore, geoengineering by means of sulfate aerosols is predicted to accelerate the hydroxyl catalyzed ozone destruction cycles and cause a significant depletion of the ozone layer even though future halogen concentrations will be significantly reduced.

Heckendorn, P.↗
NASA NTRS2009

On the Influence of Anthropogenic Forcings on Changes in the Stratospheric Mean Age

A common feature of stratospheric simulations of the past or future is an increase in tropical upwelling and a decrease in mean age. Possible causes or these changes include (1) increases in tropical sea surface temperatures (SSTs) driven by increases in well-mixed greenhouse gases (WMGHGs), (2) the direct radiative effect of increases in WMGHGs, and (3) changes in ozone. Here we examine a suite of simulations from the Goddard Earth Observing System chemistry-climate model (GEOS CCM) to isolate the relative role of these three factors. Our analysis indicates that all three factors cause changes in the mean age, but the relative impact of each factor depends on the time period analyzed. Over the past 30-40 years ozone depletion is the major factor causing the decrease in mean age, with negligible changes due to direct radiative impact of WMGHG's. However, ozone is predicted to recover back to 1970 levels during the next 50-60 years, and this causes an increase in the mean age, whereas the continued increase in SSTs from increased levels of WMGHGs and the direct radiative impact of WMGHGs will still cause a decrease in the mean age. The net impact of these factors will still result in a decreasing mean age although the rate will be smaller than that of the past. The decreases in mean age are primarily caused by increases in upwelling in the tropical lower stratosphere. The increased upwelling from both increased tropical SSTs and polar ozone loss appears to be related to changes in zonal winds and increases in wave activity propagating into the stratosphere. The different contributions of changes in SSTs, WMGHGs, and ozone to the circulation of the stratosphere may help explain the large spread in the rate of change of tropical upwelling seen in previous studies.

Oman, Luke↗
NASA NTRS2010

Cassini/CIRS Observations of Water Vapor in Saturn's Stratosphere

The Composite Infrared Spectrometer (CIRS) on the Cassini spacecraft has obtained numerous spectra of Saturn at varying spectral and spatial resolutions since Saturn Orbit Insertion in 2001. Emission lines due to water vapor in Saturn's stratosphere were first detected using whole-disk observations from the Infrared Space Observatory [1] and subsequently confirmed by the Submillimeter Wave Astronomy Satellite [2], CIRS has detected water and the data permit the retrieval of the latitudinal variation of water on Saturn. Emission lines of H2O on Saturn are very weak in the CIRS data. Thus, large spectral averages as well as improvements in calibration are necessary to detect water vapor. long integrations at the full 0.5/cm spectral resolution were performed at targeted latitudes on Saturn. High emission angles were chosen to enhance stratospheric emission. Over the course of the prime and extended mission a set of observations has been built up spaced roughly every 10 degrees of latitude. Stratospheric temperatures in the 0.5 - 5.0 mbar range were obtained by inverting spectra of CH4 in the v'4 band centered at 1501/cm. The origin of water vapor is believed to be from the ablation of micrometeorites containing eater ice, followed by photochemistry. This external source of oxygen originates either from the Saturn system (from the rings or perhaps from Enceladus) or from the interplanetary medium. Connerney [3] proposed a mechanism to transport water from the inner edge of the B-ring along magnetic field lines to specific latitudes (50N and 44S) on Saturn. Prange et al [4] interpreted a minimum in the abundance of acetylene from ultraviolet spectra gear 41S on Saturn as possibly due to an enhanced influx of water. We will be able to test the "ring rain" mechanism by searching, for localized water vapor enhancement at mid-latitudes. Our results may be used to constrain photochemical models of Saturn's stratosphere [5].

Bjoraker, Gordon↗
NASA NTRS2011

A Model Study of the Impact of Source Gas Changes on the Stratosphere for 1850-2100

The long term stratospheric impacts due to emissions of CO2, CH4, N2O, and ozone depleting substances (ODSs) are investigated using an updated version of the Goddard two-dimensional (2D) model. Perturbation simulations with the ODSs, CO2, CH4, and N2O varied individually are performed to isolate the relative roles of these gases in driving stratospheric changes over the 1850-2100 time period. We also show comparisons with observations and the God- 40 dard Earth Observing System chemistry-climate model simulations for the time period 1970-2100 to illustrate that the 2D model captures the basic processes responsible for longterm stratospheric change. The 2D simulations indicate that prior to 1940, the 45 ozone increases due to CO2 and CH4 loading outpace the ozone losses due to increasing N2O and carbon tetrachloride (CCl4) emissions, so that ozone reaches a broad maximum during the 1920s-1930s. This preceeds the significant ozone depletion during approx. 1960-2050 driven by the ODS loading. During the latter half of the 21st century as ODS emissions diminish, CO2, N2O, and CH4 loading will all have significant impacts on global total ozone based on the IPCC AIB (medium) scenario, with CO2 having the largest individual effect. Sensitivity tests illustrate that due to the strong chemical interaction between methane and chlorine, the CH4 impact on total ozone becomes significantly more positive with larger ODS loading. The model simulations also show that changes in stratospheric temperature, Brewer-Dobson circulation (BDC), and age of air during 1850-2100 are controlled mainly by the CO2 and ODS loading. The simulated acceleration of the BDC causes the age of air to decrease by approx. 1 year from 1860-2100. The corresponding photochemical lifetimes of N2O, CFCl3, CF2Cl2, and CCl4 decrease by 11-13% during 1960-2100 due to the acceleration of the BDC, with much smaller lifetime changes 4%) caused by changes in the photochemical loss rates.

Fleming, E. L.↗