Mitigation of Global Cooling by Stratospheric Chemistry Feedbacks in a Simulation of the Last Glacial Maximum

Noda, S.; Kodera, Kunihiko; Adachi, Yoshiyuki; Deushi, Makoto; Mizuta, Ryo; Murakami, Shigenori; Yoshida, Kohei; Yoden, Shigeo

doi:10.1029/2017jd028017

Cited by 10 publications

(12 citation statements)

References 54 publications

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“…During the Last Glacial Maximum (LGM), the stratosphere, including stratospheric ozone, is expected to be different from the PI climate because of lower greenhouse gas concentrations (e.g., CO 2 , CH 4 , and N 2 O), widespread ice sheets (up to 3–4 km thick) in the Northern Hemisphere (NH) and lower sea surface temperatures (SSTs). Compared to the rich literature on stratospheric ozone for the current and future climates, there are only a few studies on stratospheric ozone in the LGM (Crutzen & Brühl, 1993; Martinerie et al, 1995; Murray et al, 2014; Noda et al, 2018; Rind et al, 2009). From a lack of better knowledge, past model simulations of the glacial climate have often assumed that stratospheric ozone is similar to the PI climate (e.g., Kaplan et al, 2006; Levine et al, 2011; Valdes et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Stratospheric Ozone in the Last Glacial Maximum

Wang

Solomon

et al. 2020

JGR Atmospheres

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Using the Whole Atmosphere Community Climate Model version 6, stratospheric ozone in the Last Glacial Maximum (LGM) is investigated. It is shown that, compared with preindustrial (PI) times, LGM modeled stratospheric temperatures are increased by up to 8 K, leading to faster ozone destruction rates for gas phase reactions, especially via the Chapman mechanism. On the other hand, stratospheric hydroxyl radical (OH) and nitrogen oxides (NO x) concentrations are decreased by 10-20%, which decreases catalytic ozone destruction, thereby decreasing ozone loss rates. The net effect of these two compensating mechanisms in the upper stratosphere (above 15 hPa) is a vertically integrated 1-3 Dobson unit (DU) decrease during the LGM. In the lower stratosphere (tropopause to 15 hPa), changes in the stratospheric overturning circulation and resulting transport dominate changes in ozone. Consistent with a weakening of the residual circulation in the LGM, lower stratospheric ozone is increased by 2-5 DU in the tropics and decreased by 5-10 DU in the extratropics, but the latter is partly compensated by ozone increases due to a lower tropopause. It is found that tropospheric ozone is decreased by about 5 DU in the LGM versus PI. Combined changes in stratospheric and tropospheric ozone lead to a decrease in total ozone column everywhere except over the northeast North America, equatorial Indian and West Pacific Oceans. Surface ultraviolet radiation in the LGM versus PI is increased over the Northern Hemisphere middle and high latitudes, especially over the ice caps, and over the Southern Hemisphere near 60°S.

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Section: Introductionmentioning

confidence: 99%

Stratospheric Ozone in the Last Glacial Maximum

Wang

Solomon

et al. 2020

JGR Atmospheres

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“…The stratosphere during the Last Glacial Maximum (LGM) is expected to be considerably different than in the preindustrial and modern climate because of reduced CO 2 , CH 4 , and N 2 O concentrations; the presence of large ice sheets in the Northern Hemisphere (NH); and lower sea surface temperature (SST) [1][2][3]. Modeling studies show a slower Brewer-Dobson circulation (BDC) during the LGM than in the modern climate [4][5][6], which is consistent with model-projected BDC strengthening in response to greenhouse gas-induced warming [7][8][9][10][11][12][13][14]. The latter is supported by satellite observations [15,16].…”

Section: Introductionmentioning

confidence: 99%

Quasi-Biennial Oscillation and Sudden Stratospheric Warmings during the Last Glacial Maximum

Wang

White

et al. 2020

Atmosphere

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The quasi-biennial oscillation (QBO) and sudden stratospheric warmings (SSWs) during the Last Glacial Maximum (LGM) are investigated in simulations using the Whole Atmosphere Community Climate Model version 6 (WACCM6). We find that the period of QBO, which is 27 months in the preindustrial and modern climate simulations, was 33 months in the LGM simulation using the proxy sea surface temperatures (SSTs) and 41 months using the model-based LGM SSTs. We show that the longer QBO period in the LGM is due to weaker wave forcing. The WACCM6 simulations of the LGM, preindustrial, and modern climates do not support previous modeling work that suggests that the QBO amplitude is smaller (larger) in a warmer (colder) climate. We find that SSWs in the LGM occurred later in the year, as compared to the preindustrial and modern climate, but that time of the final warming was similar. The difference in SSW frequency is inconclusive.

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“…As the interactive chemistry module in a climate model is computationally very expensive, it is necessary to elucidate alternative representations of ozone for long-term climate simulations. To date, the importance of interactive chemistry in climate models has mainly been evaluated for experimental settings that have focused on the effect of an altered external forcing, such as a change in solar irradiance or CO 2 concentrations (e.g., Polvani, 2016, 2017;Dietmüller et al, 2014;Noda et al, 2018;Nowack et al, 2017Nowack et al, , 2018b. In these studies CCM simulations were compared to model simulations forced with a constant ozone field (e.g., based on preindustrial control conditions), which did not include the ozone response to the changing external forcing.…”

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confidence: 99%

“…It was shown that the ozone response to the external forcing has an important damping effect on the surface climate response to the external forcing. That is to say, under such conditions, including interactive chemistry reduces the model's climate sensitivity (e.g., Chiodo and Polvani, 2016;Dietmüller et al, 2014;Noda et al, 2018;Nowack et al, 2018b) and connected surface responses, such as the tropospheric jet (e.g. Chiodo and Polvani, 2017) or El Niño-Southern Oscillation trends (e.g., Nowack et al, 2017).…”

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confidence: 99%

The importance of interactive chemistry for stratosphere–troposphere coupling

Haase

Matthes

2019

Atmos. Chem. Phys.

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Abstract. Recent observational and modeling studies suggest that stratospheric ozone depletion not only influences the surface climate in the Southern Hemisphere (SH), but also impacts Northern Hemisphere (NH) spring, which implies a strong interaction between dynamics and chemistry. Here, we systematically analyze the importance of interactive chemistry with respect to the representation of stratosphere–troposphere coupling and in particular the effects on NH surface climate during the recent past. We use the interactive and specified chemistry version of NCAR's Whole Atmosphere Community Climate Model coupled to an ocean model to investigate differences in the mean state of the NH stratosphere as well as in stratospheric extreme events, namely sudden stratospheric warmings (SSWs), and their surface impacts. To be able to focus on differences that arise from two-way interactions between chemistry and dynamics in the model, the specified chemistry model version uses a time-evolving, model-consistent ozone field generated by the interactive chemistry model version. We also test the effects of zonally symmetric versus asymmetric prescribed ozone, evaluating the importance of ozone waves in the representation of stratospheric mean state and variability. The interactive chemistry simulation is characterized by a significantly stronger and colder polar night jet (PNJ) during spring when ozone depletion becomes important. We identify a negative feedback between lower stratospheric ozone and atmospheric dynamics during the breakdown of the stratospheric polar vortex in the NH, which contributes to the different characteristics of the PNJ between the simulations. Not only the mean state, but also stratospheric variability is better represented in the interactive chemistry simulation, which shows a more realistic distribution of SSWs as well as a more persistent surface impact afterwards compared with the simulation where the feedback between chemistry and dynamics is switched off. We hypothesize that this is also related to the feedback between ozone and dynamics via the intrusion of ozone-rich air into polar latitudes during SSWs. The results from the zonally asymmetric ozone simulation are closer to the interactive chemistry simulations, implying that under a model-consistent ozone forcing, a three-dimensional (3-D) representation of the prescribed ozone field is desirable. This suggests that a 3-D ozone forcing, as recommended for the upcoming CMIP6 simulations, has the potential to improve the representation of stratospheric dynamics and chemistry. Our findings underline the importance of the representation of interactive chemistry and its feedback on the stratospheric mean state and variability not only in the SH but also in the NH during the recent past.

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Mitigation of Global Cooling by Stratospheric Chemistry Feedbacks in a Simulation of the Last Glacial Maximum

Cited by 10 publications

References 54 publications

Stratospheric Ozone in the Last Glacial Maximum

Stratospheric Ozone in the Last Glacial Maximum

Quasi-Biennial Oscillation and Sudden Stratospheric Warmings during the Last Glacial Maximum

The importance of interactive chemistry for stratosphere–troposphere coupling

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