Radiative and Dynamical Influences on Polar Stratospheric Temperature Trends

Abstract Radiative and dynamical heating rates control stratospheric temperatures. In this study, radiative temperature trends due to ozone depletion and increasing well-mixed greenhouse gases from 1980 to 2000 in the polar stratosphere are directly evaluated, and the dynamical contributions to temperature trends are estimated as the residual between the observed and radiative trends. The radiative trends are obtained from a seasonally evolving fixed dynamical heating calculation with the Parallel Offline Radiative Transfer model using four different ozone datasets, which provide estimates of observed ozone changes. In the spring and summer seasons, ozone depletion leads to radiative cooling in the lower stratosphere in the Arctic and Antarctic. In Arctic summer there is weak wave driving, and the radiative cooling due to ozone depletion is the dominant driver of observed trends. In late winter and early spring, dynamics dominate the changes in Arctic temperatures. In austral spring and summer in the Antarctic, strong dynamical warming throughout the mid- to lower stratosphere acts to weaken the strong radiative cooling associated with the Antarctic ozone hole and is indicative of a strengthening of the Brewer–Dobson circulation. This dynamical warming is a significant term in the thermal budget over much of the Antarctic summer stratosphere, including in regions where strong radiative cooling due to ozone depletion can still lead to net cooling despite dynamical terms. Quantifying the contributions of changes in radiation and dynamics to stratospheric temperature trends is important for understanding how anthropogenic forcings have affected the historical trends and necessary for projecting the future.

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Radiative Relaxation Time Scales Quantified from Sudden Stratospheric Warmings

Journal of the Atmospheric Sciences ◽

10.1175/jas-d-20-0015.1 ◽

2021 ◽

Vol 78 (1) ◽

pp. 269-286

Author(s):

Kevin Bloxam ◽

Yi Huang

Keyword(s):

Negative Temperature ◽

Recovery Phase ◽

Radiative Heating ◽

Radiative Transfer Model ◽

Radiative Cooling ◽

Transfer Model ◽

Relaxation Rates ◽

Heating Rates ◽

Radiative Relaxation ◽

Stratospheric Temperature

AbstractSudden stratospheric warmings (SSWs) are impressive events that occur in the winter hemisphere’s polar stratosphere and are capable of producing temperature anomalies upward of +50 K within a matter of days. While much work has been dedicated toward determining how SSWs occur and their ability to interact with the underlying troposphere, one underexplored aspect is the role of radiation, especially during the recovery phase of SSWs. Using a radiative transfer model and a heating rate analysis for distinct layers of the stratosphere averaged over the 60°–90°N polar region, this paper accounts for the radiative contribution to the removal of the anomalous temperatures associated with SSWs. In total 17 events are investigated over the 1979–2016 period. This paper reveals that in the absence of dynamical heating following major SSWs, longwave radiative cooling dominates and often results in a strong negative temperature anomaly. The polar winter stratospheric temperature change driven by the radiative cooling is characterized by an exponential decay of temperature with an increasing e-folding time of 5.7 ± 2.0 to 14.6 ± 4.4 days from the upper to middle stratosphere. The variability of the radiative relaxation rates among the SSWs was determined to be most impacted by the initial temperature of the stratosphere and the combined dynamic and solar heating rates following the onset of the events. We also found that trace-gas anomalies have little impact on the radiative heating rates and the temperature evolution during the SSWs in the mid- to upper stratosphere.

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Extreme ozone depletion in the 2010–2011 Arctic winter stratosphere as observed by MIPAS/ENVISAT using a 2-D tomographic approach

Atmospheric Chemistry and Physics ◽

10.5194/acp-12-9149-2012 ◽

2012 ◽

Vol 12 (19) ◽

pp. 9149-9165 ◽

Cited By ~ 39

Author(s):

E. Arnone ◽

E. Castelli ◽

E. Papandrea ◽

M. Carlotti ◽

B. M. Dinelli

Keyword(s):

Ozone Depletion ◽

Potential Temperature ◽

Michelson Interferometer ◽

The Arctic ◽

Late Winter ◽

Infrared Measurements ◽

Depletion Rate ◽

Horizontal Inhomogeneity ◽

Stratospheric Clouds ◽

The Antarctic

Abstract. We present observations of the 2010–2011 Arctic winter stratosphere from the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) onboard ENVISAT. Limb sounding infrared measurements were taken by MIPAS during the Northern polar winter and into the subsequent spring, giving a continuous vertically resolved view of the Arctic dynamics, chemistry and polar stratospheric clouds (PSCs). We adopted a 2-D tomographic retrieval approach to account for the strong horizontal inhomogeneity of the atmosphere present under vortex conditions, self-consistently comparing 2011 to the 2-D analysis of 2003–2010. Unlike most Arctic winters, 2011 was characterized by a strong stratospheric vortex lasting until early April. Lower stratospheric temperatures persistently remained below the threshold for PSC formation, extending the PSC season up to mid-March, resulting in significant chlorine activation leading to ozone destruction. On 3 January 2011, PSCs were detected up to 30.5 ± 0.9 km altitude, representing the highest PSCs ever reported in the Arctic. Through inspection of MIPAS spectra, 83% of PSCs were identified as supercooled ternary solution (STS) or STS mixed with nitric acid trihydrate (NAT), 17% formed mostly by NAT particles, and only two cases by ice. In the lower stratosphere at potential temperature 450 K, vortex average ozone showed a daily depletion rate reaching 100 ppbv day−1. In early April at 18 km altitude, 10% of vortex measurements displayed total depletion of ozone, and vortex average values dropped to 0.6 ppmv. This corresponds to a chemical loss from early winter greater than 80%. Ozone loss was accompanied by activation of ClO, associated depletion of its reservoir ClONO2, and significant denitrification, which further delayed the recovery of ozone in spring. Once the PSC season halted, ClO was reconverted primarily into ClONO2. Compared to MIPAS observed 2003–2010 Arctic average values, the 2010–2011 vortex in late winter had 15 K lower temperatures, 40% lower HNO3 and 50% lower ozone, reaching the largest ozone depletion ever observed in the Arctic. The overall picture of this Arctic winter was remarkably closer to conditions typically found in the Antarctic vortex than ever observed before.

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Past and future conditions for polar stratospheric cloud formation simulated by the Canadian Middle Atmosphere Model

Atmospheric Chemistry and Physics ◽

10.5194/acp-9-483-2009 ◽

2009 ◽

Vol 9 (2) ◽

pp. 483-495 ◽

Cited By ~ 22

Author(s):

P. Hitchcock ◽

T. G. Shepherd ◽

C. McLandress

Keyword(s):

Climate Change ◽

Low Temperature ◽

Ozone Depletion ◽

Lower Stratosphere ◽

Middle Atmosphere ◽

The Arctic ◽

Temperature Extremes ◽

Polar Stratospheric Cloud ◽

Atmosphere Model ◽

The Antarctic

Abstract. We analyze here the polar stratospheric temperatures in an ensemble of three 150-year integrations of the Canadian Middle Atmosphere Model (CMAM), an interactive chemistry-climate model which simulates ozone depletion and recovery, as well as climate change. A key motivation is to understand possible mechanisms for the observed trend in the extent of conditions favourable for polar stratospheric cloud (PSC) formation in the Arctic winter lower stratosphere. We find that in the Antarctic winter lower stratosphere, the low temperature extremes required for PSC formation increase in the model as ozone is depleted, but remain steady through the twenty-first century as the warming from ozone recovery roughly balances the cooling from climate change. Thus, ozone depletion itself plays a major role in the Antarctic trends in low temperature extremes. The model trend in low temperature extremes in the Arctic through the latter half of the twentieth century is weaker and less statistically robust than the observed trend. It is not projected to continue into the future. Ozone depletion in the Arctic is weaker in the CMAM than in observations, which may account for the weak past trend in low temperature extremes. In the future, radiative cooling in the Arctic winter due to climate change is more than compensated by an increase in dynamically driven downwelling over the pole.

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Characteristics of Tropopause Polar Vortices Based on Observations over the Greenland Ice Sheet

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-20-0004.1 ◽

2020 ◽

Vol 59 (11) ◽

pp. 1933-1947

Author(s):

Sarah M. Borg ◽

Steven M. Cavallo ◽

David D. Turner

Keyword(s):

Potential Vorticity ◽

Greenland Ice Sheet ◽

Radiative Heating ◽

The Arctic ◽

Radiative Transfer Model ◽

Radiative Cooling ◽

Transfer Model ◽

Reanalysis Dataset ◽

Clear Sky ◽

Atmospheric State

AbstractTropopause polar vortices (TPVs) are long-lived, coherent vortices that are based on the dynamic tropopause and characterized by potential vorticity anomalies. TPVs exist primarily in the Arctic, with potential impacts ranging from surface cyclone generation and Rossby wave interactions to dynamic changes in sea ice. Previous analyses have focused on model output indicating the importance of clear-sky and cloud-top radiative cooling in the maintenance and evolution of TPVs, but no studies have focused on local observations to confirm or deny these results. This study uses cloud and atmospheric state observations from Summit Station, Greenland, combined with single-column experiments using the Rapid Radiative Transfer Model to investigate the effects of clear-sky, ice-only, and all-sky radiative cooling on TPV intensification. The ground-based observing system combined with temperature and humidity profiles from the European Centre for Medium-Range Weather Forecasts’s fifth major global reanalysis dataset, which assimilates the twice-daily soundings launched at Summit, provides novel details of local characteristics of TPVs. Longwave radiative contributions to TPV diabatic intensity changes are analyzed with these resources, starting with a case study focusing on observed cloud properties and associated radiative effects, followed by a composite study used to evaluate observed results alongside previously simulated results. Stronger versus weaker vertical gradients in anomalous clear-sky radiative heating rates, contributing to Ertel potential vorticity changes, are associated with strengthening versus weakening TPVs. Results show that clouds are sometimes influential in the intensification of a TPV, and composite results share many similarities to modeling studies in terms of atmospheric state and radiative structure.

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Past and future conditions for polar stratospheric cloud formation simulated by the Canadian Middle Atmosphere Model

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-8-16555-2008 ◽

2008 ◽

Vol 8 (4) ◽

pp. 16555-16583

Author(s):

P. Hitchcock ◽

T. G. Shepherd ◽

C. McLandress

Keyword(s):

Climate Change ◽

Low Temperature ◽

Ozone Depletion ◽

Lower Stratosphere ◽

Middle Atmosphere ◽

The Arctic ◽

Temperature Extremes ◽

The Future ◽

Atmosphere Model ◽

The Antarctic

Abstract. Observations of the Arctic winter lower stratosphere over the past four decades suggest that the thermodynamic conditions required for the formation of polar stratospheric clouds (PSCs) have become increasingly widespread in the Northern Hemisphere. The trend is apparent only in the coldest winters during which the Arctic stratosphere is minimally disturbed by upwelling wave activity from the troposphere. The mechanism responsible for this increase remains unclear. In an effort to evaluate possible mechanisms, we analyze here the polar stratospheric temperatures in an ensemble of three 150-year integrations of the Canadian Middle Atmosphere Model (CMAM), an interactive chemistry-climate model which simulates ozone depletion and recovery, as well as climate change. We find that in the Antarctic winter lower stratosphere, the low temperature extremes required for PSC formation increase in the model as ozone is depleted, but remain steady through the twenty-first century as the warming from ozone recovery roughly balances the cooling from climate change. Thus, ozone depletion itself plays a major role in the Antarctic response. The model trend in low temperature extremes in the Arctic through the latter half of the twentieth century is weaker and less statistically robust than the observed trend. It is not projected to continue into the future. Ozone depletion in the Arctic is weaker in the CMAM than in observations, which may account for the weak past trend in low temperature extremes. In the future, radiative cooling in the Arctic winter due to climate change is more than compensated by an increase in dynamically driven downwelling over the pole.

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Rapid motion of the 1989 Arctic ozone crater as viewed with TOMS data

Canadian Journal of Physics ◽

10.1139/p91-167 ◽

1991 ◽

Vol 69 (8-9) ◽

pp. 1087-1092 ◽

Cited By ~ 2

Author(s):

F. E. Bunn ◽

F. W. Thirkettle ◽

W. F. J. Evans

Keyword(s):

Soviet Union ◽

Ozone Depletion ◽

Total Ozone ◽

Stratospheric Ozone ◽

Ozone Layer ◽

The Arctic ◽

Late Winter ◽

Western Canada ◽

Baffin Island ◽

The Antarctic

The data from the NIMBUS-7 TOMS instrument were used to study the Arctic ozone layer in late winter and spring, 1989. This paper presents an analysis of TOMS total ozone values, to produce a picture of the morphology of the Arctic stratospheric ozone crater in winter–spring 1989. The Arctic crater formed in late January when the vortex moved off the pole to over Scandinavia. The TOMS data clearly show the Arctic ozone-crater feature over Scandinavia and the western Soviet Union, on February 2, 1989. It later moved south to Baffin Island and then, in March, down over Toronto, and eventually to western Canada, near Edmonton. A similar, unexpected, crater was present in the Antarctic fall, on March 15, 1989. This phenomenon is mainly produced by dynamic uplift, but there may be ozone depletion occurring as well owing to reduced temperatures.

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Refinement of the ice absorption spectrum in the visible using radiance profile measurements in Antarctic snow

10.5194/tc-2016-146 ◽

2016 ◽

Author(s):

Ghislain Picard ◽

Quentin Libois ◽

Laurent Arnaud

Keyword(s):

Absorption Coefficient ◽

Fiber Optics ◽

Estimation Method ◽

Radiative Transfer Model ◽

Transfer Model ◽

Snow Layer ◽

Antarctic Snow ◽

Order Of Magnitude ◽

The Difference ◽

The Antarctic

Abstract. Ice is a highly transparent material in the visible. According to the most widely used database (Warren and Brandt, 2008; IA2008), the ice absorption coefficient reaches values lower than 10−3 m−1 around 400 nm. These values were obtained from a radiance profile measured in a single snow layer at Dome C in Antarctica. We reproduced this experiment using a fiber optics inserted in the snow to record 56 profiles from which 70 homogeneous layers were identified. Applying the same estimation method on every layer yields 70 ice absorption spectra with a significant variability and overall larger than IA2008 by one order of magnitude. We devise another estimation method based on Bayesian inference. It reduces the statistical variability and confirms the higher absorption, around 2 × 10−2 m−1 near the minimum at 440 nm. We explore potential instrumental artifacts by developing a 3D radiative transfer model able to explicitly account for the presence of the fiber in the snow. The simulation results show that the radiance profile is indeed perturbed by the fiber intrusion but the error on the ice absorption estimate is not larger than a factor 2. This is insufficient to explain the difference between our new estimate and IA2008. Nevertheless, considering the number of profiles acquired for this study and other estimates from the Antarctic Muon and Neutrino Detector Array (AMANDA), we estimate that ice absorption values around 10−2 m−1 at the minimum are more likely than under 10−3 m−1. We provide a new estimate in the range 400–600 nm for future modeling of snow, cloud, and sea-ice optical properties. Most importantly we recommend that modeling studies take into account the large uncertainty of the ice absorption coefficient in the visible.

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Seasonal and interannual variations in the propagation of photosynthetically available radiation through the Arctic atmosphere

Elem Sci Anth ◽

10.1525/elementa.2020.00083 ◽

2021 ◽

Vol 9 (1) ◽

Author(s):

J. Laliberté ◽

S. Bélanger ◽

M. Babin

Keyword(s):

Large Data ◽

The Arctic ◽

Radiative Transfer Model ◽

Transfer Model ◽

The Sun ◽

Photosynthetically Available Radiation ◽

Data Set ◽

Melt Ponds ◽

Arctic Atmosphere ◽

Marine Productivity

The Arctic atmosphere–surface system transmits visible light from the Sun to the ocean, determining the annual cycle of light available to microalgae. This light is referred to as photosynthetically available radiation (PAR). A known consequence of Arctic warming is the change at the atmosphere–ocean interface (longer ice-free season, younger ice), implying an increase in the percentage of PAR being transferred to the water. However, much less is known about the recent changes in how much PAR is being transferred by the overlaying atmosphere. We studied the transfer of PAR through the atmosphere between May 21 and July 23 at a pan-Arctic scale for the period ranging from 2000 to 2016. By combining a large data set of atmospheric and surface conditions into a radiative transfer model, we computed the percentage of PAR transferred to the surface. We found that typical Arctic atmospheres convey between 60% and 70% of the incident PAR received from the Sun, meaning the Arctic atmosphere typically transmits more light than most sea ice surfaces, with the exception of mature melt ponds. We also found that the transfer of PAR through the atmosphere decreased at a rate of 2.3% per decade over the studied period, due to the increase in cloudiness and the weaker radiative interaction between the atmosphere and the surface. Further investigation is required to address how, in the warmer Arctic climate, this negative trend would compensate for the increased surface transmittance and its consequences on marine productivity.

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Radiative forcing over the Arctic of aerosols from the August 2017 Canadian and Greenlandic wildfires

10.5194/egusphere-egu21-7405 ◽

2021 ◽

Author(s):

Filippo Calì Quaglia ◽

Daniela Meloni ◽

Alcide Giorgio di Sarra ◽

Tatiana Di Iorio ◽

Virginia Ciardini ◽

...

Keyword(s):

Radiative Transfer ◽

Radiative Forcing ◽

Solar Zenith Angle ◽

Surface Albedo ◽

High Arctic ◽

The Arctic ◽

Radiative Transfer Model ◽

Transfer Model ◽

Aerosol Layer ◽

Radiative Effect

Extended and intense wildfires occurred in Northern Canada and, unexpectedly, on the Greenlandic West coast during summer 2017. The thick smoke plume emitted into the atmosphere was transported to the high Arctic, producing one of the largest impacts ever observed in the region. Evidence of Canadian and Greenlandic wildfires was recorded at the Thule High Arctic Atmospheric Observatory (THAAO, 76.5&#176;N, 68.8&#176;W, www.thuleatmos-it.it) by a suite of instruments managed by ENEA, INGV, Univ. of Florence, and NCAR. Ground-based observations of the radiation budget have allowed quantification of the surface radiative forcing at THAAO.&#160;Excess biomass burning chemical tracers such as CO, HCN, H2CO, C2H6, and NH3 were&#160; measured in the air column above Thule starting from August 19 until August 23. The aerosol optical depth (AOD) reached a peak value of about 0.9 on August 21, while an enhancement of wildfire compounds was&#160; detected in PM10. The measured shortwave radiative forcing was -36.7 W/m2 at 78&#176; solar zenith angle (SZA) for AOD=0.626.MODTRAN6.0 radiative transfer model (Berk et al., 2014) was used to estimate the aerosol radiative effect and the heating rate profiles at 78&#176; SZA. Measured temperature profiles, integrated water vapour, surface albedo, spectral AOD and aerosol extinction profiles from CALIOP onboard CALIPSO were used as model input. The peak&#160; aerosol heating rate (+0.5 K/day) was&#160; reached within the aerosol layer between 8 and 12 km, while the maximum radiative effect (-45.4 W/m2) is found at 3 km, below the largest aerosol layer.The regional impact of the event that occurred on August 21 was investigated using a combination of atmospheric radiative transfer modelling with measurements of AOD and ground surface albedo from MODIS. The aerosol properties used in the radiative transfer model were constrained by in situ measurements from THAAO. Albedo data over the ocean have been obtained from Jin et al. (2004). Backward trajectories produced through HYSPLIT simulations (Stein et al., 2015) were also employed to trace biomass burning plumes.The radiative forcing efficiency (RFE) over land and ocean was derived, finding values spanning from -3 W/m2 to -132 W/m2, depending on surface albedo and solar zenith angle. The fire plume covered a vast portion of the Arctic, with large values of the daily shortwave RF (< -50 W/m2) lasting for a few days. This large amount of aerosol is expected to influence cloud properties in the Arctic, producing significant indirect radiative effects.

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Polar Stratospheric Clouds detection at Belgrano II Antarctic station from DOAS measurements

10.5194/egusphere-egu21-3054 ◽

2021 ◽

Author(s):

Laura Gómez Martín ◽

Daniel Toledo ◽

Margarita Yela ◽

Cristina Prados-Román ◽

José Antonio Adame ◽

...

Keyword(s):

Radiative Transfer ◽

Color Index ◽

Radiative Transfer Model ◽

Optical Absorption Spectroscopy ◽

Transfer Model ◽

Meteorological Model ◽

Weather Forecasts ◽

Stratospheric Temperature ◽

Stratospheric Clouds

Ground-based zenith DOAS (Differential Optical Absorption Spectroscopy) measurements have been used to detect and estimate the altitude of PSCs over Belgrano II Antarctic station during the polar sunrise seasons of 2018 and 2019. The method used in this work studies the evolution of the color index (CI) during twilights. The CI has been defined here as the ratio of the recorded signal at 520 and 420 nm. In the presence of PSCs, the CI shows a maximum at a given solar zenith angle (SZA). The value of such SZA depends on the altitude of the PSC. By using a spherical Monte Carlo radiative transfer model (RTM), the method has been validated and a function relating the SZA of the CI maximum and the PSC altitude has been calculated. Model simulations also show that PSCs can be detected and their altitude can be estimated even in presence of optically thin tropospheric clouds or aerosols. Our results are in good agreement with the stratospheric temperature evolution obtained through the ERA5 data reanalysis from the global meteorological model ECMWF (European Centre for Medium Range Weather Forecasts) and the PSCs observations from CALIPSO (Cloud-Aerosol-Lidar and Infrared Pathfinder Satellite Observations).The methodology used in this work could also be applied to foreseen and/or historical measurements obtained with ground-based spectrometers such e. g. the DOAS instruments dedicated to trace gas observation in Arctic and Antarctic sites. This would also allow to investigate the presence and long-term evolution of PSCs.Keywords: Polar stratospheric clouds; color index; radiative transfer model; visible spectroscopy.

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