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NASA NTRS1994

Four years of ground-based total ozone measurements by visible spectrometry in Antarctica

Visible spectrometers SAOZ have been developed at Service d'Aeronomie for permanent ground-based ozone monitoring at all latitudes up to the polar circle in winter. Observations are made by looking at the sunlight scattered at zenith in the visible range, twice a day, at sunrise and sunset. Compared to ozone observations in the UV generally in use, visible observations in the small Chappuis bands at twilight have the advantages of being independent of stratospheric temperature, little contaminated by tropospheric ozone and multiple scattering, and of permitting observations even in winter at the polar circle. SAOZ instruments have been installed since 1988 at several stations in the Antarctic and the Arctic. More than four years data at Dumont d'Urville in Terre Adelie (67 deg S) are now available. The station is generally located at the edge of the vortex in spring and therefore the ozone hole is seen there only occasionally. The lowest values (140 DU) were reported in early October 1991. According to these first regular observations throughout the whole winter ozone seems to increase in late autumn and winter. Its decay does not start before the end of August. Although of smaller amplitude than with the previous version five data, the ratio between the groundbased and satellite/TOMS measurements displays a systematic seasonal variation correlated partly to the sun zenith angle of observations from orbit and partly to the temperature of the stratosphere. Since ground-based measurements are always made at 90 deg SZA, the SZA dependence must come from the satellite data interpretation (TOMS observations are between 43 to 88 deg SZA). The temperature dependence could be partly due to variations of ozone absorption cross-sections in the ultraviolet used by the satellite spectrometer, and partly to a systematic seasonal cycle of the air mass factor use in the interpretation of the ground based observations. However, the last contribution appears to be too small to compensate the ozone increase in winter reported by SAOZ, which is then real.

Goutail, F.↗

NASA NTRS1990

Calculations of ozone destruction during the 1988/89 Arctic winter

Calculations of ozone depletion during the 1988/89 Arctic winter using a Lagrangian coupled photochemical-microphysical model are presented. Abundances of ClO in excess of 1 ppbv were observed at the end of the Airborne Arctic Stratospheric Expedition on February 10, 1989. These are shown to be consistent with the removal of more than 90 percent of the reactive nitrogen and the conversion of more than 80 percent of reservoir chlorine to active forms. This chemical state implies that ozone losses of more than 20 ppbv/day can be sustained in heavily denitrified air throughout much of February according to current photochemistry. As much as 74 percent of the loss is calculated to be due to ClO dimer photolysis. Following the warming of the vortex in mid-February 1989, ozone loss through ClO dimer photolysis becomes less effective as the rate of thermal decomposition of the ClO dimer increases. Thus, model results suggest that thermal decomposition of the dimer plays an important role in limiting ozone loss in the Arctic spring.

Mckenna, D. S.↗

NASA NTRSDate not supplied

Updated PSC Climatology Based on Caliop Measurements From 2006-2023

After more than three decades of research, the roles of polar stratospheric clouds (PSCs) in stratospheric ozone depletion are well established. Heterogeneous reactions on PSCs convert the stable chlorine reservoirs HCl and ClONO2 to chlorine radicals that destroy ozone catalytically. PSCs also prolong ozone depletion by delaying chlorine deactivation through the removal of gas-phase HNO3 and H2O by sedimentation of large nitric acid trihydrate (NAT) and ice particles. A substantial recovery of the ozone layer is expected by the middle of this century with reduced global production of ozone depleting substances in accordance with the Montreal Protocol and subsequent amendments. But as climate changes, leading to a colder and perhaps wetter stratosphere and upper troposphere, reliable model predictions of recovery of the Antarctic ozone hole and of potentially more severe ozone depletion in the Arctic are challenging. This is due both to a lack of detailed understanding of the underlying physics and the fact that many global models use simple parameterizations that do not accurately represent PSC processes. A more complete picture of PSC processes on vortex-wide scales has emerged from the CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) instrument on the CALIPSO satellite that has been observing PSCs at latitudes up to 82 degrees in both hemispheres since June 2006. The CALIOP Version 2.0 (v2) PSC algorithm was recently developed to address known deficiencies in previous algorithms and includes additional refinements to increase the robustness of the inferred PSC composition. In this paper, we present an updated PSC reference data record and comprehensive climatology constructed by applying the v2 algorithm to the more than 17-year CALIOP spaceborne lidar dataset. In addition, we will examine the potential impact of aerosol and water vapor injections into the stratosphere from the January 2022 Hunga Tonga eruption on PSC occurrence in both the Arctic and Antarctic regions.

polar stratospheric clouds↗

NASA NTRS1999

Is There an Arctic Ozone Hole?

Total ozone observations from the Total Ozone Mapping Spectrometer (TOMS) instruments during March 1997 revealed an extensive region of low column densities in the Arctic region centered near the north pole. Values were below 250 Dobson units for nearly a two week period during this period, and were correlated with the position of the northern lower stratospheric polar vortex. The March 1997 average total ozone column densities were more than 30% lower than the average of column densities observed during the 1979-1982 March period. Both the northern spring seasons of 1998 and 1999 have shown much higher levels of total ozone. In this presentation, we will discuss the causes of the low total ozone values in 1997 and contrast those low values with the higher 1998 and 1999 observations. The reason for my travel to the University of Valparaiso is to give this seminar and provide information to my colleagues on our work here at GSFC. The benefit to NASA is to interact with my Univ. of Valparaiso colleagues, gain their insights and input into this research, and establish collaborations with the current research efforts at the University.

Newman, Paul A.↗

NASA NTRS2000

Is There an Arctic Ozone Hole?

Total ozone observations from the Total Ozone Mapping Spectrometer (TOMS) instruments during March 1997 revealed an extensive region of low column densities in the Arctic region centered near the north pole. Values were below 250 Dobson units for nearly a two week period during this period, and were correlated with the position of the northern lower stratospheric polar vortex. The March 1997 average total ozone column densities were more than 30% lower than the average of column densities observed during the 1979-1982 March period. Both the northern spring seasons of 1998 and 1999 have shown much higher levels of total ozone. In this presentation, we will discuss the causes of the low total ozone values in 1997 and contrast those low values with the higher 1998 and 1999 observations. I will additionally discuss the just completed SOLVE campaign and the March 2000 ozone values.

Newman, Paul A.↗

NASA NTRS1993

Airborne observations of the 1992 Arctic winter stratosphere by FTIR solar absorption spectroscopy

The JPL MkIV interferometer, a Fourier Transform Infra-Red (FTIR) spectrometer designed specifically for atmospheric remote sensing, made measurements of the composition of the Arctic stratosphere in January, February and March 1992. These measurements were made from the NASA DC-8 aircraft as part of the AASE2 campaign. The data reveal that despite 5 to 6 km of subsidence inside the vortex, which more than doubled the vertically integrated column amounts (burdens) of HF and HNO3 with respect to outside the vortex, considerable losses of NO2, HCl and ClNO3 were evident by mid-January. Temporary freeze-out of HNO3 was observed only on one occasion, Jan. 19, and was accompanied by substantial reductions in HCl and ClNO3. During February and March, ClNO3 and NO2 amounts increased dramatically. HCl also recovered but at a much slower rate, so that by March ClNO3 was the major reservoir of inorganic chlorine, at times exceeding HCl by a factor 2.

Toon, G. C.↗

NASA NTRS1996

Comparison of U.K. Meteorological Office and U.S. National Meteorological Center Stratospheric Analyses During Northern and Southern Winter

Meteorological data from the United Kingdom Meteorological Office (UKMO), produced using a data assimilation system, and the U.S. National Meteorological Center (NMC), produced using an objective analysis procedure, are compared for dynamically active periods during the Arctic and Antarctic winters of 1992. The differences seen during these periods are generally similar to those seen during other winter periods. Both UKMO and NMC analyses capture the large-scale evolution of the stratospheric circulation during northern hemisphere (NH) and southern hemisphere (SH) winters. Stronger vertical and horizontal temperature gradients develop in the UKMO than in the NMC data during stratospheric warmings; comparison with satellite measurements with better vertical resolution suggests that the stronger vertical temperature gradients are more realistic. The NH polar vortex is slightly stronger in the UKMO analyses than in the NMC in the middle and upper stratosphere, and midstratospheric temperatures are slightly lower. The SH polar vortex as represented in the UKMO analyses is stronger and colder in the midstratosphere than its representation in the NMC analyses. The UKMO analyses on occasion exhibit some difficulties in representing cross-polar flow or changes in curvature of the wind field at very high latitudes. In addition to the above study of two wintertime periods, a more detailed comparison of lower-stratospheric temperatures is done for all Arctic and Antarctic winter periods since the launch of the Upper Atmosphere Research Satellite. In the NH lower stratosphere during winter, NMC temperatures are consistently lower than UKMO temperatures and closer to radiosonde temperatures than are UKMO temperatures. Conversely, in the SH lower stratosphere during winter, UKMO temperatures are typically lower than NMC and are closer to radiosonde temperature observations.

Manney, G. L.↗

NASA NTRS2001

Evidence for the Widespread Presence of Liquid-Phase Particles During the 1999-2000 Arctic Winter

In-situ Multi-Angle Spectrometer Probe (MASP) particle measurements have been analyzed to determine the typical behaviour of sulphate particles during the SOLVE campaign. The analysis has focussed on variations in the total particle concentration measured by MASP, which is a diagnostic that is primarily sensitive to the growth of small particles (those which are initially smaller than 0.2 micrometers in radius). At all levels of the stratosphere, the total MASP concentration varies continuously with temperature. This behaviour is well-reproduced by assuming that the sulphate aerosols are liquid ternary solutions, but cannot be reproduced if the aerosol is assumed to be frozen. This liquid-like behaviour is apparent for all measurements made during SOLVE, both inside and outside the vortex, and even at the coldest temperatures sampled during the campaign. The only anomalous measurements were made during the flight of January 14th, 2001; however, this midlatitude flight is very unlikely to contain SAT particles based on the recent warm temperatures experienced by the air. At the levels with the coldest measured temperatures, at least 90% of the particles grow as liquids. Therefore, the freezing that occurred during the 1999-2000 Arctic winter was selective, causing most of the particles to remain liquid even in the presence of a small number of frozen particles.

Drdla, K↗

NASA NTRS1990

Measurements of total reactive nitrogen during the Airborne Arctic Stratospheric Expedition

Composite distributions of measured total reactive nitrogen NO(y), from the NASA ER-2 during the Airborne Arctic Stratospheric Expedition are presented. The observed features of these distributions are discussed in terms of the controlling dynamical, chemical and microphysical processes. In the latitudinal profile from 58 deg N to within about 4 deg poleward of the polar vortex boundary, NO(y) conforms closely to predictions of NO(y) based on N2O measurements. Poleward of 5 deg of latitude within the boundary, the average NO(y) decreases sharply and is significantly lower than that predicted from N2O. This feature is consistent with loss of NO(y) through sedimentation of particles containing NO(y) in polar stratospheric clouds.

Kawa, S. R.↗

NASA NTRS2009

Representations of the Stratospheric Polar Vortices in Versions 1 and 2 of the Goddard Earth Observing System Chemistry-Climate Model (GEOS CCM)

This study will document the behavior of the polar vortices in two versions of the GEOS CCM. Both versions of the model include the same stratospheric chemistry, They differ in the underlying circulation model. Version 1 of the GEOS CCM is based on the Goddard Earth Observing System, Version 4, general circulation model which includes the finite-volume (Lin-Rood) dynamical core and physical parameterizations from Community Climate Model, Version 3. GEOS CCM Version 2 is based on the GEOS-5 GCM that includes a different tropospheric physics package. Baseline simulations of both models, performed at two-degree spatial resolution, show some improvements in Version 2, but also some degradation, In the Antarctic, both models show an over-persistent stratospheric polar vortex with late breakdown, but the year-to-year variations that are overestimated in Version I are more realistic in Version 2. The implications of this for the interactions with tropospheric climate, the Southern Annular Mode, will be discussed. In the Arctic both model versions show a dominant dynamically forced variabi;ity, but Version 2 has a persistent warm bias in the low stratosphere and there are seasonal differences in the simulations. These differences will be quantified in terms of climate change and ozone loss. Impacts of model resolution, using simulations at one-degree and half-degree, and changes in physical parameterizations (especially the gravity wave drag) will be discussed.

Pawson, S.↗

NASA NTRS1990

Nitric oxide measurements in the Arctic winter stratosphere

Measurements of NO from five flights of the NASA ER-2 aircraft during the Airborne Arctic Stratospheric Expedition are presented. The NO values and vertical gradient near 60 deg N latitude are similar to previous measurements near 50 deg N in winter (Ridley et al., 1984, 1987). The NO latitudinal gradient is distinctly negative outside of the polar vortex, approaching zero at the boundary of the vortex, and remaining below the 20 pptv detection limit inside the vortex. Steady state NO2 and NO(x) (NO + NO2) are calculated from measured NO, O3, and ClO, and modeled photodissociation rates. NO(x) outside the vortex shows a negative dependence on latitude and solar zenith angle. Low NO(x) and NO(x)/NO(y), inside and near the vortex boundary may be indications of heterogeneous removal of ClONO2 and N2O5.

Fahey, D. W.↗

NASA NTRS1994

Comparison of column abundances from three infrared spectrometers during AASE 2

Three Fourier transform infrared (FTIR) spectromenters were based on board the NASA DC-8 during the second Airborne Arctic Stratospheric Expedition (AASE II) in 1992. Two FTIRs used solar absorption and one used thermal emission. We compare over 2000 measurements from these 3 FTIRs, on 12 DC-8 flights, for closely coincident air masses and times, both inside and outside the polar vortex. In the majority of cases the offset biases are quite small, in the range 1-4%, and comparable to the absolute precisions expected. In most cases the rms scatter is in the range 4-11%; this scatter is unlikely to be geophysical, but rather is probably instrumental or analytical in origin.

Traub, W. A.↗

NASA NTRS1991

Depletion of Arctic ozone in the winter 1990

Ozone mixing ratios were measured by ozonesondes on board balloons launched from Esrange, near Kiruna, Sweden (68 deg N, 20 deg E) from January 11 to February 9, 1990. The data obtained prior to a sudden warming on February 7, 1990 show that at potential temperatures between 460 and 640 K, the ozone mixing ratio just inside the polar vortex was systematically smaller than that outside, the largest difference being 29 percent at around 525 K. The ozone mixing ratio at 525 K inside the vortex decreased at a rate of about 1.5 percent per day between January 26 and February 4. The temperatures simultaneously observed were quite often low enough to allow for formation of nitric acid trihydrate particles around this altitude. Depletion of ozone due to highly perturbed chemical conditions in late January and early February is strongly suggested.

Koike, M.↗

NASA NTRS1994

Fine-scale, poleward transport of tropical air during AASE 2

The poleward transport of tropical air in the lower stratosphere during the winter period of the second Airborne Arctic Stratospheric Expedition (AASE 2) (December 1991-March 1992) is examined using contour advection calcutions. These calculations show that filaments of tropical air extend into mid-latitudes, and are wrapped around the equatorward edge of the polar jet. Simultaneously filaments are drawn from the polar vortex and are intermingled with the filaments of tropical air. The tropical filaments are consistent with measurements of chemical tracers taken aboard the ER-2 and DC-8 aircraft which show localized regions, in mid-latitudes, of air with the characteristics of tropical air.

Waugh, D. W.↗

NASA NTRS1986

Characteristics of Arctic polar stratospheric clouds and as measured by airborne lidar

Airborne lidar measurements of backscattering from polar stratospheric clouds (PSCs) obtained in January 1984 are examined. The flights, principal characteristics of the lidar system, and the meteorological conditions during the flights are described. The characteristics and conditions for the formation of PSCs and the optical characteristics of the clouds are discussed. The properties of the North Polar vortex and El Chichon stratospheric aerosol are studied. Variations in the aerosol optical properties with temperature and water vapor concentrations are analyzed and modeled using a model based on volcanic aerosols and water vapor concentration. The modeled and experimental backscattering-temperature relationship are compared and good correlation is observed at pressure levels of 100 and 70 mb.

Kent, G. S.↗

DOE OSTI2023

Impact of Ural Blocking on Early Winter Climate Variability Under Different Barents‐Kara Sea Ice Conditions

Abstract Ural blocking (UB) is a prominent mode of variability of the Northern Hemisphere atmospheric circulation, particularly in fall. It can persist for several days and exert a lagged influence on the wintertime NH circulation, providing predictability at the subseasonal time scale. Using two atmospheric models, we explore how the early winter atmospheric circulation responds to a 2‐week persistent UB anomaly imposed in early November. Experiments are carried out with two different configurations of Barents‐Kara (BK) sea‐ice concentration to examine whether it plays a role in how UB impacts atmospheric variability. In both models, the UB anomaly is followed by a weakening of the stratospheric polar vortex and a negative phase of the North Atlantic Oscillation (NAO), which lasts up to 2 months after the forcing is released. Interestingly, the response is more persistent under low BK sea‐ice conditions, that is, BK sea ice modulates the atmospheric response to UB. Additional experiments with prescribed sea ice concentration anomalies alone suggest that BK sea ice exerts a limited influence on early winter NH atmospheric variability. The response to UB involves a weakening of the polar vortex that persists longer under low BK sea ice, which explains the more persistent response in that configuration. Our study highlights that UB variability in November is a robust precursor for early winter NAO/polar stratosphere anomalies, and this may be more relevant in the context of declining Arctic sea‐ice extent. Provided that climate models accurately capture this teleconnection, it has the potential to improve subseasonal predictions of the NH wintertime climate.

Meteorology & Atmospheric Sciences↗

NASA NTRS1990

Radiative heating rates during AAOE and AASE

Radiative transit computations of heating rates utilizing data from the 1987 Airborne Antarctic Ozone Experiment (AAOE) (Tuck et al., 1989) and the 1989 Airborne Arctic Stratospheric Experiment (AASE) (Turco et al., 1990) are described. Observed temperature and ozone profiles and a radiative transfer model are used to compute the heating rates for the Southern Hemisphere during AAOE and the Northern Hemisphere during AASE. The AASE average cooling rates computed inside the vortex are in good agreement with the diabatic cooling rates estimated from the ER-2 profile data for N2O for the AASE period (Schoeberl et al., 1989).

Rosenfield, Joan E.↗

DOE OSTI2024

Higher‐Order Gravity Waves and Traveling Ionospheric Disturbances From the Polar Vortex Jet on 11–15 January 2016: Modeling With HIAMCM‐SAMI3 and Comparison With Observations in the Thermosphere and Ionosphere

Abstract In Vadas et al. (2024, https://doi.org/10.1029/2024ja032521 ), we modeled the atmospheric gravity waves (GWs) during 11–14 January 2016 using the HIAMCM, and found that the polar vortex jet generates medium to large‐scale, higher‐order GWs in the thermosphere. In this paper, we model the traveling ionospheric disturbances (TIDs) generated by these GWs using the HIAMCM‐SAMI3 and compare with ionospheric observations from ground‐based Global Navigation Satellite System (GNSS) receivers, Incoherent Scatter Radars (ISR) and the Super Dual Auroral Radar Network (SuperDARN). We find that medium to large‐scale TIDs are generated worldwide by the higher‐order GWs from this event. Many of the TIDs over Europe and Asia have concentric ring/arc‐like structure, and most of those over North/South America have planar wave structure and occur during the daytime. Those over North/South America propagate southward and are generated by higher‐order GWs from Europe/Asia which propagate over the Arctic. These latter TIDs can be misidentified as arising from geomagnetic forcing. We find that the higher‐order GWs that propagate to Africa and Brazil from Europe may aid in the formation of equatorial plasma bubbles (EPBs) there. We find that the simulated GWs, TIDs and EPBs agree with EISCAT, PFISR, GNSS, and SuperDARN measurements. We find that the higher‐order GWs are concentrated at N at 200 km, in agreement with GOCE and CHAMP data. Thus the polar vortex jet is important for generating TIDs in the northern winter ionosphere via multi‐step vertical coupling through GWs.

Vadas, Sharon L. [Northwest Research Associates Bo↗