scholarly journals Ozone and temperature decadal trends in the stratosphere, mesosphere and lower thermosphere, based on measurements from SABER on TIMED

2014 ◽  
Vol 32 (8) ◽  
pp. 935-949 ◽  
Author(s):  
F. T. Huang ◽  
H. G. Mayr ◽  
J. M. Russell ◽  
M. G. Mlynczak
Keyword(s):  
Stratospheric Ozone ◽  
Lower Thermosphere ◽  
Definitive Evidence ◽  
Broadband Emission ◽  
Stratospheric Temperature ◽  
Temperature Trends ◽  
Time Period ◽  
Ozone Trends ◽  
Ozone Trend ◽  
The Tropics

Abstract. We have derived ozone and temperature trends from years 2002 through 2012, from 20 to 100 km altitude, and 48° S to 48° N latitude, based on measurements from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on the Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics (TIMED) satellite. For the first time, trends of ozone and temperature measured at the same times and locations are obtained, and their correlations should provide useful information about the relative importance of photochemistry versus dynamics over the longer term. We are not aware of comparable results covering this time period and spatial extent. For stratospheric ozone, until the late 1990s, previous studies found negative trends (decreasing amounts). In recent years, some empirical and modeling studies have shown the occurrence of a turnaround in the decreasing ozone, possibly beginning in the late 1990s, suggesting that the stratospheric ozone trend is leveling off or even turning positive. Our global results add more definitive evidence, expand the coverage, and show that at mid-latitudes (north and south) in the stratosphere, the ozone trends are indeed positive, with ozone having increased by a few percent from 2002 through 2012. However, in the tropics, we find negative ozone trends between 25 and 50 km. For stratospheric temperatures, the trends are mostly negatively correlated to the ozone trends. The temperature trends are positive in the tropics between 30 and 40 km, and between 20 and 25 km, at approximately 24° N and at 24° S latitude. The stratospheric temperature trends are otherwise mostly negative. In the mesosphere, the ozone trends are mostly flat, with suggestions of small positive trends at lower latitudes. The temperature trends in this region are mostly negative, showing decreases of up to ~ −3 K decade−1. In the lower thermosphere (between ~ 85 and 100 km), ozone and temperature trends are both negative. The ozone trend can approach ~ −10% decade−1, and the temperature trend can approach ~ −3 K decade−1. Aside from trends, these patterns of ozone–temperature correlations are consistent with previous studies of ozone and temperature perturbations such as the quasi-biennial (QBO) and semiannual (SAO) oscillations, and add confidence to the results.

The Impact of Ozone-Depleting Substances on Tropical Upwelling, as Revealed by the Absence of Lower-Stratospheric Cooling since the Late 1990s

2017 ◽  
Vol 30 (7) ◽  
pp. 2523-2534 ◽  
Author(s):  
Lorenzo M. Polvani ◽  
Lei Wang ◽  
Valentina Aquila ◽  
Darryn W. Waugh
Keyword(s):  
Greenhouse Gases ◽  
Lower Stratosphere ◽  
Stratospheric Temperature ◽  
Temperature Trends ◽  
Ozone Trends ◽  
Primary Driver ◽  
Stratospheric Cooling ◽  
Ozone Depleting Substances ◽  
The Tropics ◽  
The Impact

The impact of ozone-depleting substances on global lower-stratospheric temperature trends is widely recognized. In the tropics, however, understanding lower-stratospheric temperature trends has proven more challenging. While the tropical lower-stratospheric cooling observed from 1979 to 1997 has been linked to tropical ozone decreases, those ozone trends cannot be of chemical origin, as active chlorine is not abundant in the tropical lower stratosphere. The 1979–97 tropical ozone trends are believed to originate from enhanced upwelling, which, it is often stated, would be driven by increasing concentrations of well-mixed greenhouse gases. This study, using simple arguments based on observational evidence after 1997, combined with model integrations with incrementally added single forcings, argues that trends in ozone-depleting substances, not well-mixed greenhouse gases, have been the primary driver of temperature and ozone trends in the tropical lower stratosphere until 1997, and this has occurred because ozone-depleting substances are key drivers of tropical upwelling and, more generally, of the entire Brewer–Dobson circulation.

scholarly journals Seasonal stratospheric ozone trends over 2000–2018 derived from several merged data sets

2020 ◽  
Vol 20 (11) ◽  
pp. 7035-7047 ◽  
Author(s):  
Monika E. Szeląg ◽  
Viktoria F. Sofieva ◽  
Doug Degenstein ◽  
Chris Roth ◽  
Sean Davis ◽  
...  
Keyword(s):  
Stratospheric Ozone ◽  
Equatorial Region ◽  
Data Sets ◽  
Opposite Pattern ◽  
The North ◽  
Stratospheric Temperature ◽  
Temperature Trends ◽  
Ozone Trends ◽  
Seasonal Dependence

Abstract. In this work, we analyze the seasonal dependence of ozone trends in the stratosphere using four long-term merged data sets, SAGE-CCI-OMPS, SAGE-OSIRIS-OMPS, GOZCARDS, and SWOOSH, which provide more than 30 years of monthly zonal mean ozone profiles in the stratosphere. We focus here on trends between 2000 and 2018. All data sets show similar results, although some discrepancies are observed. In the upper stratosphere, the trends are positive throughout all seasons and the majority of latitudes. The largest upper-stratospheric ozone trends are observed during local winter (up to 6 % per decade) and equinox (up to 3 % per decade) at mid-latitudes. In the equatorial region, we find a very strong seasonal dependence of ozone trends at all altitudes: the trends vary from positive to negative, with the sign of transition depending on altitude and season. The trends are negative in the upper-stratospheric winter (−1 % per decade to −2 % per decade) and in the lower-stratospheric spring (−2 % per decade to −4 % per decade), but positive (2 % per decade to 3 % per decade) at 30–35 km in spring, while the opposite pattern is observed in summer. The tropical trends below 25 km are negative and maximize during summer (up to −2 % per decade) and spring (up to −3 % per decade). In the lower mid-latitude stratosphere, our analysis points to a hemispheric asymmetry: during local summers and equinoxes, positive trends are observed in the south (+1 % per decade to +2 % per decade), while negative trends are observed in the north (−1 % per decade to −2 % per decade). We compare the seasonal dependence of ozone trends with available analyses of the seasonal dependence of stratospheric temperature trends. We find that ozone and temperature trends show positive correlation in the dynamically controlled lower stratosphere and negative correlation above 30 km, where photochemistry dominates. Seasonal trend analysis gives information beyond that contained in annual mean trends, which can be helpful in order to better understand the role of dynamical variability in short-term trends and future ozone recovery predictions.

scholarly journals Stratospheric Temperature Trends over 1979–2015 Derived from Combined SSU, MLS, and SABER Satellite Observations

2016 ◽  
Vol 29 (13) ◽  
pp. 4843-4859 ◽  
Author(s):  
William J. Randel ◽  
Anne K. Smith ◽  
Fei Wu ◽  
Cheng-Zhi Zou ◽  
Haifeng Qian
Keyword(s):  
Solar Cycle ◽  
Lower Stratosphere ◽  
Stratospheric Ozone ◽  
Volcanic Eruptions ◽  
Weighting Functions ◽  
Stratospheric Temperature ◽  
Temperature Trends ◽  
Decadal Scale ◽  
Data Record ◽  
The Tropics

Abstract Temperature trends in the middle and upper stratosphere are evaluated using measurements from the Stratospheric Sounding Unit (SSU), combined with data from the Aura Microwave Limb Sounder (MLS) and Sounding of the Atmosphere Using Broadband Emission Radiometry (SABER) instruments. Data from MLS and SABER are vertically integrated to approximate the SSU weighting functions and combined with SSU to provide a data record spanning 1979–2015. Vertical integrals are calculated using empirically derived Gaussian weighting functions, which provide improved agreement with high-latitude SSU measurements compared to previously derived weighting functions. These merged SSU data are used to evaluate decadal-scale trends, solar cycle variations, and volcanic effects from the lower to the upper stratosphere. Episodic warming is observed following the volcanic eruptions of El Chichón (1982) and Mt. Pinatubo (1991), focused in the tropics in the lower stratosphere and in high latitudes in the middle and upper stratosphere. Solar cycle variations are centered in the tropics, increasing in amplitude from the lower to the upper stratosphere. Linear trends over 1979–2015 show that cooling increases with altitude from the lower stratosphere (from ~−0.1 to −0.2 K decade−1) to the middle and upper stratosphere (from ~−0.5 to −0.6 K decade−1). Cooling in the middle and upper stratosphere is relatively uniform in latitudes north of about 30°S, but trends decrease to near zero over the Antarctic. Mid- and upper-stratospheric temperatures show larger cooling over the first half of the data record (1979–97) compared to the second half (1998–2015), reflecting differences in upper-stratospheric ozone trends between these periods.

scholarly journals Seasonal stratospheric ozone trends over 2000–2018 derived from several merged data sets

2020 ◽  
Author(s):  
Monika E. Szeląg ◽  
Viktoria F. Sofieva ◽  
Doug Degenstein ◽  
Chris Roth ◽  
Sean Davis ◽  
...  
Keyword(s):  
Stratospheric Ozone ◽  
Equatorial Region ◽  
Data Sets ◽  
Opposite Pattern ◽  
The North ◽  
Stratospheric Temperature ◽  
Temperature Trends ◽  
Ozone Trends ◽  
Seasonal Dependence

Abstract. In this work, we analyse the seasonal dependence of ozone trends in the stratosphere using four long-term merged datasets: SAGE-CCI-OMPS, SAGE-OSIRIS-OMPS, GOZCARDS and SWOOSH which provide more than 30 years of monthly zonal mean ozone profiles in the stratosphere. We focus here on trends between 2000 and 2018. All datasets show similar results, although some discrepancies are observed. In the upper stratosphere, the trends are positive throughout all seasons and the majority of latitudes. The largest upper stratospheric ozone trends are observed during local winter (up to 6 % dec−1) and equinox (up to 3 % dec−1) at mid-latitudes. In the equatorial region, we find a very strong seasonal dependence of ozone trends at all altitudes: the trends vary from positive to negative, with the sign of transition depending on altitude and season. The trends are negative in the upper stratospheric winter (−1 to −2 % dec−1) and in the lower stratospheric spring (−2 to −4 % dec−1), but positive (2–3 % dec−1) at 30–35 km in spring, while the opposite pattern is observed in summer. The tropical trends below 25 km are negative and maximize during summer (up to −2 % dec−1) and spring (up to −3 % dec−1). In the lower mid-latitude stratosphere, our analysis indicates hemispheric asymmetry: during local summers and equinoxes, positive trends are observed in the South (+1 to +2 % dec−1) while negative trends are observed in the North (−1 to −2 % dec−1). We compare the seasonal dependence of ozone trends with available analyses of the seasonal dependence of stratospheric temperature trends. We find that ozone and temperature trends show positive correlation in the dynamically controlled lower stratosphere, and negative correlation above 30 km, where photochemistry dominates. Seasonal trend analysis gives information beyond that contained in annual mean trends, which can be helpful in order to better understand the role of dynamical variability in short-term trends and future ozone recovery predictions.

scholarly journals Inconsistencies between chemistry–climate models and observed lower stratospheric ozone trends since 1998

2020 ◽  
Vol 20 (16) ◽  
pp. 9737-9752
Author(s):  
William T. Ball ◽  
Gabriel Chiodo ◽  
Marta Abalos ◽  
Justin Alsing ◽  
Andrea Stenke
Keyword(s):  
Large Scale ◽  
Climate Models ◽  
Stratospheric Ozone ◽  
Internal Variability ◽  
Ozone Layer ◽  
Montreal Protocol ◽  
Total Column Ozone ◽  
Temperature Trends ◽  
Ozone Trends ◽  
The Tropics

Abstract. The stratospheric ozone layer shields surface life from harmful ultraviolet radiation. Following the Montreal Protocol ban on long-lived ozone-depleting substances (ODSs), rapid depletion of total column ozone (TCO) ceased in the late 1990s, and ozone above 32 km is now clearly recovering. However, there is still no confirmation of TCO recovery, and evidence has emerged that ongoing quasi-global (60∘ S–60∘ N) lower stratospheric ozone decreases may be responsible, dominated by low latitudes (30∘ S–30∘ N). Chemistry–climate models (CCMs) used to project future changes predict that lower stratospheric ozone will decrease in the tropics by 2100 but not at mid-latitudes (30–60∘). Here, we show that CCMs display an ozone decline similar to that observed in the tropics over 1998–2016, likely driven by an increase in tropical upwelling. On the other hand, mid-latitude lower stratospheric ozone is observed to decrease, while CCMs that specify real-world historical meteorological fields instead show an increase up to present day. However, these cannot be used to simulate future changes; we demonstrate here that free-running CCMs used for projections also show increases. Despite opposing lower stratospheric ozone changes, which should induce opposite temperature trends, CCMs and observed temperature trends agree; we demonstrate that opposing model–observation stratospheric water vapour (SWV) trends, and their associated radiative effects, explain why temperature changes agree in spite of opposing ozone trends. We provide new evidence that the observed mid-latitude trends can be explained by enhanced mixing between the tropics and extratropics. We further show that the temperature trends are consistent with the observed mid-latitude ozone decrease. Together, our results suggest that large-scale circulation changes expected in the future from increased greenhouse gases (GHGs) may now already be underway but that most CCMs do not simulate mid-latitude ozone layer changes well. However, it is important to emphasise that the periods considered here are short, and internal variability that is both intrinsic to each CCM and different to observed historical variability is not well-characterised and can influence trend estimates. Nevertheless, the reason CCMs do not exhibit the observed changes needs to be identified to allow models to be improved in order to build confidence in future projections of the ozone layer.

scholarly journals Large-Scale Waves in the Mesosphere and Lower Thermosphere Observed by SABER

2005 ◽  
Vol 62 (12) ◽  
pp. 4384-4399 ◽  
Author(s):  
Rolando R. Garcia ◽  
Ruth Lieberman ◽  
James M. Russell ◽  
Martin G. Mlynczak
Keyword(s):  
Large Scale ◽  
Middle Atmosphere ◽  
Lower Thermosphere ◽  
Normal Modes ◽  
Zonal Winds ◽  
Broadband Emission ◽  
Summer Hemisphere ◽  
Mean Structure ◽  
Mesosphere And Lower Thermosphere ◽  
The Tropics

Abstract Observations made by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on board NASA’s Thermosphere–Ionosphere–Mesosphere Energetics and Dynamics (TIMED) satellite have been processed using Salby’s fast Fourier synoptic mapping (FFSM) algorithm. The mapped data provide a first synoptic look at the mean structure and traveling waves of the mesosphere and lower thermosphere (MLT) since the launch of the TIMED satellite in December 2001. The results show the presence of various wave modes in the MLT, which reach largest amplitude above the mesopause and include Kelvin and Rossby–gravity waves, eastward-propagating diurnal oscillations (“non-sun-synchronous tides”), and a set of quasi-normal modes associated with the so-called 2-day wave. The latter exhibits marked seasonal variability, attaining large amplitudes during the solstices and all but disappearing at the equinoxes. SABER data also show a strong quasi-stationary Rossby wave signal throughout the middle atmosphere of the winter hemisphere; the signal extends into the Tropics and even into the summer hemisphere in the MLT, suggesting ducting by westerly background zonal winds. At certain times of the year, the 5-day Rossby normal mode and the 4-day wave associated with instability of the polar night jet are also prominent in SABER data.

scholarly journals Constraining Future Summer Austral Jet Stream Positions in the CMIP5 Ensemble by Process-Oriented Multiple Diagnostic Regression*

2016 ◽  
Vol 29 (2) ◽  
pp. 673-687 ◽  
Author(s):  
Sabrina Wenzel ◽  
Veronika Eyring ◽  
Edwin P. Gerber ◽  
Alexey Yu. Karpechko
Keyword(s):  
Stratospheric Ozone ◽  
Coupled Model ◽  
Jet Stream ◽  
Rcp Scenarios ◽  
Future Projections ◽  
Stratospheric Temperature ◽  
Temperature Trends ◽  
Wide Range ◽  
Ensemble Mean ◽  
Process Oriented

Abstract Stratospheric ozone recovery and increasing greenhouse gases are anticipated to have a large impact on the Southern Hemisphere extratropical circulation, shifting the jet stream and associated storm tracks. Models participating in phase 5 of the Coupled Model Intercomparison Project poorly simulate the austral jet, with a mean equatorward bias and 10° latitude spread in their historical climatologies, and project a wide range of future trends in response to anthropogenic forcing in the representative concentration pathway (RCP) scenarios. Here, the question is addressed whether the unweighted multimodel mean (uMMM) austral jet projection of the RCP4.5 scenario can be improved by applying a process-oriented multiple diagnostic ensemble regression (MDER). MDER links future projections of the jet position to processes relevant to its simulation under present-day conditions. MDER is first targeted to constrain near-term (2015–34) projections of the austral jet position and selects the historical jet position as the most important of 20 diagnostics. The method essentially recognizes the equatorward bias in the past jet position and provides a bias correction of about 1.5° latitude southward to future projections. When the target horizon is extended to midcentury (2040–59), the method also recognizes that lower-stratospheric temperature trends over Antarctica, a proxy for the intensity of ozone depletion, provide additional information that can be used to reduce uncertainty in the ensemble mean projection. MDER does not substantially alter the uMMM long-term position in jet position but reduces the uncertainty in the ensemble mean projection. This result suggests that accurate observational constraints on upper-tropospheric and lower-stratospheric temperature trends are needed to constrain projections of the austral jet position.

scholarly journals An exploration of ozone changes and their radiative forcing prior to the chlorofluorocarbon era

2002 ◽  
Vol 2 (5) ◽  
pp. 363-374 ◽  
Author(s):  
D. T. Shindell ◽  
G. Faluvegi
Keyword(s):  
Ozone Depletion ◽  
Tropospheric Ozone ◽  
Radiative Forcing ◽  
Stratospheric Ozone ◽  
Data Sets ◽  
Independent Data ◽  
Spatial Coverage ◽  
Ozone Trends ◽  
Ozone Trend

Abstract. Using historical observations and model simulations, we investigate ozone trends prior to the mid-1970s onset of halogen-induced ozone depletion. Though measurements are quite limited, an analysis based on multiple, independent data sets (direct and indirect) provides better constraints than any individual set of observations. We find that three data sets support an apparent long-term stratospheric ozone trend of -7.2 ± 2.3 DU during 1957-1975, which modeling attributes primarily to water vapor increases. The results suggest that 20th century stratospheric ozone depletion may have been roughly 50% more than is generally supposed. Similarly, three data sets support tropospheric ozone increases over polluted Northern Hemisphere continental regions of 8.2 ± 2.1 DU during this period, which are mutually consistent with the stratospheric trends. As with paleoclimate data, which is also based on indirect proxies and/or limited spatial coverage, these results must be interpreted with caution. However, they provide the most thorough estimates presently available of ozone changes prior to the coincident onset of satellite data and halogen dominated ozone changes. If these apparent trends were real, the radiative forcing by stratospheric ozone since the 1950s would then have been -0.15 ± 0.05 W/m2, and -0.2 W/m2 since the preindustrial. For tropospheric ozone, it would have been 0.38 ± 0.10 W/m2 since the late 1950s. Combined with even a very conservative estimate of tropospheric ozone forcing prior to that time, this would be larger than current estimates since 1850 which are derived from models that are even less well constrained. These calculations demonstrate the importance of gaining a better understanding of historical ozone changes.

scholarly journals Total ozone trends from 1979 to 2016 derived from five merged observational datasets – the emergence into ozone recovery

2017 ◽  
Author(s):  
Mark Weber ◽  
Melanie Coldewey-Egbers ◽  
Vitali E. Fioletov ◽  
Stacey M. Frith ◽  
Jeannette D. Wild ◽  
...  
Keyword(s):  
Total Ozone ◽  
Recovery Phase ◽  
The Arctic ◽  
Polar Regions ◽  
Time Period ◽  
Merging Procedure ◽  
Ozone Trends ◽  
Recent Trends ◽  
The Tropics ◽  
Uncertainty Level

Abstract. We report on updated trends using different merged datasets from satellite and groundbased observations for the time period 1979 until 2016. Trends were determined by application of a multiple linear regression (MLR) to annual mean zonal mean data. Merged datasets used are NASA MOD V8.6 and NOAA MERGE V8.6, both based upon data from the series of SBUV and SBUV-2 satellite instruments (1978–present) and the GTO (GOME-type Total Ozone) and GSG (GOME-SCIAMACHY-GOME2) merged datasets (1995–present) that are mainly composed of satellite data from GOME, SCIAMACHY, and GOME-2A. The fifth dataset are the monthly mean zonal mean data from ground data collected at WOUDC (World Ozone and UV Data Center). The addition of four more years of data since the last WMO Ozone Assessment (2013–2016) show that for most datasets and regions the trends since the stratospheric halogens reached maximum (~ 1996 globally and ~ 2000 in polar regions) are mostly not significantly different from zero. However, for some latitudes, in particular the southern hemisphere extratropics and northern hemisphere subtropics, several datasets show small positive trends of slightly below +1 %/decade that are barely statistically significant at the 2σ uncertainty level. In the tropics only two datasets show significant trends of +0.5 to +0.8 %/decade}, while the other show near zero trends. Positive trends since 2000 are observed over Antarctic in September, but near zero trends in October as well as in March over the Arctic. Since uncertainties due to possible drifts between the datasets as well as from the merging procedure used in the satellite datasets or due to the low sampling of ground data are not accounted for, the retrieved trends can be only considered being at the brink of becoming significant, but there are indications that we are about to emerge into the expected recovery phase. Nevertheless, the recent trends are still considerably masked by the observed large year-to-year variability in total ozone.

scholarly journals Drift corrected Odin-OSIRIS ozone product: algorithm and updated stratospheric ozone trends

2017 ◽  
Author(s):  
Adam E. Bourassa ◽  
Chris Z. Roth ◽  
Daniel J. Zawada ◽  
Landon A. Rieger ◽  
Chris A. McLinden ◽  
...  
Keyword(s):  
Stratospheric Ozone ◽  
Stratospheric Aerosol ◽  
Retrieval Algorithm ◽  
Number Density ◽  
Short Term ◽  
Time Period ◽  
Infrared Imager ◽  
Ozone Profile ◽  
Ozone Trends

Abstract. A small, long-term drift in the Optical Spectrograph and Infrared Imager System (OSIRIS) stratospheric ozone product, manifested mostly since 2012, is quantified and attributed to a changing bias in the limb pointing knowledge of the instrument. A correction to this pointing drift using a predictable shape in the measured limb radiance profile is implemented and applied within the OSIRIS retrieval algorithm. This new data product, version 5.10, displays substantially better both long- and short-term agreement with MLS ozone throughout the stratosphere due to the pointing correction. Previously reported stratospheric ozone trends over the time period 1984–2013, which were derived by merging the altitude/number density ozone profile measurements from the Stratospheric Aerosol and Gas Experiment (SAGE) II satellite instrument (1984–2005) and from OSIRIS (2002–2013) are recalculated using the new OSIRIS version 5.10 product, and extended to 2017. These results still show statistically significant positive trends throughout the upper stratosphere since 1997, but at weaker levels that are more closely in line with estimates from other data records.

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