Historical and Projected Changes in the Southern Hemisphere Surface Westerlies

Geophysical Research Letters, Journal Year: 2021, Volume and Issue: 48(4)

Published: Jan. 21, 2021

Abstract The Southern Hemisphere (SH) surface westerlies fundamentally control regional patterns of air temperature, storm tracks, and precipitation while also regulating ocean circulation, heat transport carbon uptake. Wind‐forced perturbation experiments commonly apply idealized poleward wind shifts ranging between 0.5 10 degrees latitude intensification factors 10% 300%. In addition, changes in winds are often prescribed ad hoc as a zonally uniform anomaly that neglects important seasonal differences. Here we quantify historical projected SH westerly based on examination CMIP5, CMIP6, reanalysis data. We find significant reduction the location bias CMIP6 ensemble an associated shift compared to CMIP5. Under high emission scenario, end 21st Century mean increase ∼10% ∼0.8° latitude, although there variations.

Language: Английский

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Evaluating stratospheric ozone and water vapour changes in CMIP6 models from 1850 to 2100

Atmospheric chemistry and physics, Journal Year: 2021, Volume and Issue: 21(6), P. 5015 - 5061

Published: March 31, 2021

Abstract. Stratospheric ozone and water vapour are key components of the Earth system, past future changes to both have important impacts on global regional climate. Here, we evaluate long-term in these species from pre-industrial period (1850) end 21st century Coupled Model Intercomparison Project phase 6 (CMIP6) models under a range emissions scenarios. There is good agreement between CMIP multi-model mean observations for total column (TCO), although there substantial variation individual CMIP6 models. For mean, TCO has increased ∼ 300 DU 1850 305 1960, before rapidly declining 1970s 1980s following use emission halogenated ozone-depleting substances (ODSs). projected return 1960s values by middle SSP2-4.5, SSP3-7.0, SSP4-3.4, SSP4-6.0, SSP5-8.5 scenarios, SSP3-7.0 scenarios be 10 higher than 2100. However, SSP1-1.9 SSP1-1.6 not despite reductions ODSs due decreases tropospheric mixing ratios. This pattern similar patterns, except tropics where most values, either through SSP1-2.6, or lower stratospheric resulting an acceleration Brewer–Dobson circulation other Shared Socioeconomic Pathways (SSPs). In contrast TCO, poorer observed ratios, with underestimating ratios 0.5 ppmv at 70 hPa. tropical stratosphere present-day increase further century. The largest increases (∼ 2 ppmv) simulated highest assumed forcing pathway (e.g. SSP5-8.5). Tropical vapour, lesser extent shows large variations explosive volcanic eruptions.

Language: Английский

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Effective radiative forcing from emissions of reactive gases and aerosols – a multi-model comparison

Atmospheric chemistry and physics, Journal Year: 2021, Volume and Issue: 21(2), P. 853 - 874

Published: Jan. 21, 2021

Abstract. This paper quantifies the pre-industrial (1850) to present-day (2014) effective radiative forcing (ERF) of anthropogenic emissions NOX, volatile organic compounds (VOCs; including CO), SO2, NH3, black carbon, and concentrations methane, N2O ozone-depleting halocarbons, using CMIP6 models. Concentration emission changes reactive species can cause multiple in composition radiatively active species: tropospheric ozone, stratospheric water vapour, secondary inorganic aerosol, methane. Where possible we break down ERFs from each emitted into contributions changes. The are calculated for models that participated AerChemMIP experiments as part project, where relevant model output was available. 1850 2014 multi-model mean (± standard deviations) −1.03 ± 0.37 W m−2 SO2 emissions, −0.25 0.09 carbon (OC), 0.15 0.17 (BC) −0.07 0.01 NH3. For combined aerosols (in piClim-aer experiment) it is −1.01 0.25 m−2. means well-mixed greenhouse gases (including any effects on ozone aerosol chemistry) 0.67 methane (CH4), 0.26 0.07 nitrous oxide (N2O) 0.12 0.2 halocarbons (HC). Emissions precursors nitrogen oxides (NOx), both together (O3) lead 0.14 0.13, 0.20 respectively. differences different reflect complexity their chemistry schemes, especially case captures increased production.

Language: Английский

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Global climate-related predictors at kilometer resolution for the past and future

Earth system science data, Journal Year: 2022, Volume and Issue: 14(12), P. 5573 - 5603

Published: Dec. 16, 2022

Abstract. A multitude of physical and biological processes on which ecosystems human societies depend are governed by the climate, understanding how these altered climate change is central to mitigation efforts. We developed a set climate-related variables at as yet unprecedented spatiotemporal detail basis for environmental ecological analyses. downscaled time series near-surface relative humidity (hurs) cloud area fraction (clt) under consideration orography wind well speed (sfcWind) using delta-change method. Combining grids with mechanistically information temperature, precipitation, solar radiation, we then calculated vapor pressure deficit (vpd), surface downwelling shortwave radiation (rsds), potential evapotranspiration (pet), moisture index (cmi), site water balance (swb) monthly temporal 30 arcsec spatial resolution globally from 1980 until 2018 (time-series variables). At same resolution, further estimated climatological normals frost frequency (fcf), snow cover days (scd), net primary productivity (npp), growing degree (gdd), season characteristics periods 1981–2010, 2011–2040, 2041–2070, 2071–2100, considering three shared socioeconomic pathways (SSP126, SSP370, SSP585) five Earth system models (projected Time-series showed high accuracy when validated against observations meteorological stations compared alternative products. Projected were also highly correlated observations, although some notable biases, e.g., days. Together, CHELSA-BIOCLIM+ dataset presented here (https://doi.org/10.16904/envidat.332, Brun et al., 2022) allows improvement our patterns that including impact recent future changes world's associated services societies.

Language: Английский

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How well do the CMIP6 models simulate dust aerosols?

Atmospheric chemistry and physics, Journal Year: 2022, Volume and Issue: 22(3), P. 2095 - 2119

Published: Feb. 15, 2022

Abstract. Mineral dust impacts key processes in the Earth system, including radiation budget, clouds, and nutrient cycles. We evaluate aerosols 16 models participating sixth phase of Coupled Model Intercomparison Project (CMIP6) against multiple reanalyses observations. note that both observations used here have their limitations particularly emission deposition are poorly constrained. Most models, multi-model ensemble mean (MEM), capture spatial patterns seasonal cycles global well. However, large uncertainties inter-model diversity found. For example, emissions, primarily driven by model-simulated surface winds, vary a factor 5 across while MEM estimate is double amount reanalyses. The ranges CMIP6 emission, deposition, burden, optical depth (DOD) larger than previous generations models. Models present considerable disagreement over North China America. Here, DOD values overestimated most with 1.2–1.7 times compared to satellite reanalysis datasets. Such overestimates can reach up individual also fail reproduce some features regional distribution, such as accumulation along southern edge Himalayas. Overall, there still models' simulated processes, which feature inconsistent biases throughout life cycle between relationship connecting mass DOD. Our results imply modelled becoming more uncertain become sophisticated. More detailed output size-resolved variables particular, relating future intercomparison projects, needed enable better constraints potential identification observationally constrained links properties.

Language: Английский

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