Migrations of tropical rain belt driven by tectonic dynamics over the past 250 Ma

2021 ◽  
Author(s):  
Ji Nie ◽  
jing Han ◽  
yongyun hu
Keyword(s):  
Hemispheric Asymmetry ◽  
Climate Model ◽  
Intertropical Convergence Zone ◽  
Radiation Budget ◽  
Ocean Heat Transport ◽  
Rain Belt ◽  
The Past ◽  
Changes Over Time ◽  
General Climate ◽  
Tectonic Dynamics

<p><br>The tropical rainfall, which contributes on about half of global rainfall, is manifested as a quasi-global rain belt called the intertropical convergence zone (ITCZ). This study examines the linkage between continental configurations and the annual mean latitude of ITCZ over the tectonic timescale. Over the past 250Ma, the break of supercontinent Pangea led to dramatic changes of continental mass distribution driven by tectonic dynamics. With a series of slicewise general climate model (GCM, CESM1.0) simulations over the past 250Ma, we investigate how is the latitude of ITCZ changes over time and how do the continental configurations set the latitude of ITCZ. With an energetic framework of the ITCZ latitude, we examined the contributions of the hemispheric asymmetry of radiation budget and ocean heat transport on the ITCZ latitude, and further demonstrate that those factors are largely driven by the continental configurations.</p>

Evaluation of net shortwave radiation over China with a regional climate model

2020 ◽  
Vol 80 (2) ◽  
pp. 147-163
Author(s):  
X Liu ◽  
Y Kang ◽  
Q Liu ◽  
Z Guo ◽  
Y Chen ◽  
...  
Keyword(s):  
Regional Climate Model ◽  
Climate Model ◽  
Regional Climate ◽  
Radiant Energy ◽  
Energy System ◽  
Radiation Budget ◽  
Shortwave Radiation ◽  
Monsoon Region ◽  
Clear Sky ◽  
Sky Conditions

The regional climate model RegCM version 4.6, developed by the European Centre for Medium-Range Weather Forecasts Reanalysis, was used to simulate the radiation budget over China. Clouds and the Earth’s Radiant Energy System (CERES) satellite data were utilized to evaluate the simulation results based on 4 radiative components: net shortwave (NSW) radiation at the surface of the earth and top of the atmosphere (TOA) under all-sky and clear-sky conditions. The performance of the model for low-value areas of NSW was superior to that for high-value areas. NSW at the surface and TOA under all-sky conditions was significantly underestimated; the spatial distribution of the bias was negative in the north and positive in the south, bounded by 25°N for the annual and seasonal averaged difference maps. Compared with the all-sky condition, the simulation effect under clear-sky conditions was significantly better, which indicates that the cloud fraction is the key factor affecting the accuracy of the simulation. In particular, the bias of the TOA NSW under the clear-sky condition was <±10 W m-2 in the eastern areas. The performance of the model was better over the eastern monsoon region in winter and autumn for surface NSW under clear-sky conditions, which may be related to different levels of air pollution during each season. Among the 3 areas, the regional average biases overall were largest (negative) over the Qinghai-Tibet alpine region and smallest over the eastern monsoon region.

A hemispheric asymmetry in poleward ocean heat transport across climates: Implications for overturning and polar warming

2021 ◽  
Vol 568 ◽  
pp. 117033
Author(s):  
Emily R. Newsom ◽  
Andrew F. Thompson ◽  
Jess F. Adkins ◽  
Eric D. Galbraith
Keyword(s):  
Heat Transport ◽  
Hemispheric Asymmetry ◽  
Ocean Heat Transport

Atmospheric production and transport of 7Be activity by cosmic rays: Modelling with the chemistry-climate model SOCOLv3.0 and comparison with direct measurements

2021 ◽  
Author(s):  
Kseniia Golubenko ◽  
Eugene Rozanov ◽  
Genady Kovaltsov ◽  
Ari-Pekka Leppänen ◽  
Ilya Usoskin
Keyword(s):  
Cosmic Rays ◽  
Climate Changes ◽  
Climate Model ◽  
Cosmic Ray ◽  
Galactic Cosmic Rays ◽  
Cosmogenic Isotopes ◽  
Cosmogenic Isotope ◽  
The Past ◽  
Direct Measurements ◽  
First Results

&lt;p&gt;We present the first results of modelling of the short-living cosmogenic isotope &lt;sup&gt;7&lt;/sup&gt;Be production, deposition, and transport using the chemistry-climate model SOCOLv&lt;sub&gt;3.0&lt;/sub&gt; aimed to study solar-terrestrial interactions and climate changes. We implemented an interactive deposition scheme, &amp;#160;based on gas tracers with and without nudging to the known meteorological fields. Production of &lt;sup&gt;7&lt;/sup&gt;Be was modelled using the 3D time-dependent Cosmic Ray induced Atmospheric Cascade (CRAC) model. The simulations were compared with the real concentrations (activity) and depositions measurements of &lt;sup&gt;7&lt;/sup&gt;Be in the air and water at Finnish stations. We have successfully reproduced and estimated the variability of the cosmogenic isotope &lt;sup&gt;7&lt;/sup&gt;Be produced by the galactic cosmic rays (GCR) on time scales longer than about a month, for the period of 2002&amp;#8211;2008. The agreement between the modelled and measured data is very good (within 12%) providing a solid validation for the ability of the SOCOL CCM to reliably model production, transport, and deposition of cosmogenic isotopes, which is needed for precise studies of cosmic-ray variability in the past.&amp;#160;&lt;/p&gt;

scholarly journals Future Changes in the Ozone Quasi-Biennial Oscillation with Increasing GHGs and Ozone Recovery in CCMI Simulations

2017 ◽  
Vol 30 (17) ◽  
pp. 6977-6997 ◽  
Author(s):  
Hiroaki Naoe ◽  
Makoto Deushi ◽  
Kohei Yoshida ◽  
Kiyotaka Shibata
Keyword(s):  
Zonal Wind ◽  
Climate Model ◽  
Vertical Shear ◽  
Quasi Biennial Oscillation ◽  
The Past ◽  
Meteorological Research Institute ◽  
Climate Simulations ◽  
The Future ◽  
Ozone Depleting Substances ◽  
Biennial Oscillation

The future quasi-biennial oscillation (QBO) in ozone in the equatorial stratosphere is examined by analyzing transient climate simulations due to increasing greenhouse gases (GHGs) and decreasing ozone-depleting substances under the auspices of the Chemistry–Climate Model Initiative. The future (1960–2100) and historical (1979–2010) simulations are conducted with the Meteorological Research Institute Earth System Model. Three climate periods, 1960–85 (past), 1990–2020 (present), and 2040–70 (future) are selected, corresponding to the periods before, during, and after ozone depletion. The future ozone QBO is characterized by increases in amplitude by 15%–30% at 5–10 hPa and decreases by 20%–30% at 40 hPa, compared with the past and present climates; the future and present ozone QBOs increase in amplitude by up to 60% at 70 hPa, compared with the past climate. The increased amplitude at 5–10 hPa suggests that the temperature-dependent photochemistry plays an important role in the enhanced future ozone QBO. The weakening of vertical shear in the zonal wind QBO is responsible for the decreased amplitude at 40 hPa in the future ozone QBO. An interesting finding is that the weakened zonal wind QBO in the lowermost tropical stratosphere is accompanied by amplified QBOs in ozone, vertical velocity, and temperature. Further study is needed to elucidate the causality of amplification about the ozone and temperature QBOs under climate change in conditions of zonal wind QBO weakening.

scholarly journals Anti-Memorials and the Art of Forgetting: Critical Reflections on a Memorial Design Practice

2008 ◽  
Vol 15 ◽  
Author(s):  
SueAnne Ware
Keyword(s):  
Human Activity ◽  
The Other ◽  
Complex Spectrum ◽  
Design Practice ◽  
Design Work ◽  
The Past ◽  
Heroin Overdose ◽  
The Future ◽  
Changes Over Time ◽  
Over Time

Andreas Huyssen writes, ‘Remembrance as a vital human activity shapes our links to the past, and the ways we remember define us in the present. As individuals and societies, we need the past to construct and to anchor our identities and to nurture a vision of the future.’ Memory is continually affected by a complex spectrum of states such as forgetting, denial, repression, trauma, recounting and reconsidering, stimulated by equally complex changes in context and changes over time. The apprehension and reflective comprehension of landscape is similarly beset by such complexities. Just as the nature and qualities of memory comprise inherently fading, shifting and fleeting impressions of things which are themselves ever-changing, an understanding of a landscape, as well as the landscape itself, is a constantly evolving, emerging response to both immense and intimate influences. There is an incongruity between the inherent changeability of both landscapes and memories, and the conventional, formal strategies of commemoration that typify the constructed landscape memorial. The design work presented in this paper brings together such explorations of memory and landscape by examining the ‘memorial’. This article examines two projects. One concerns the fate of illegal refugees travelling to Australia: The SIEVX Memorial Project. The other, An Anti-Memorial to Heroin Overdose Victims, was designed by the author as part of the 2001 Melbourne Festival.

scholarly journals A simplified empirical method for determination of aerosol hygroscopicity and composition

2010 ◽  
Vol 10 (10) ◽  
pp. 23627-23656
Author(s):  
C. H. Chan ◽  
A. Y. S. Cheng ◽  
A. Viseu
Keyword(s):  
Atmospheric Aerosols ◽  
Climate Model ◽  
Empirical Method ◽  
Radiation Budget ◽  
Cloud Formation ◽  
Monthly Variation ◽  
Aerosol Composition ◽  
Remote System ◽  
Aerosol Hygroscopicity

Abstract. Atmospheric aerosols have substantial influence on the Earth's radiation budget, visibility, cloud formation and precipitation. The aerosol hygroscopicity and the composition of aerosols are of vital importance for solar radiation budget calculation, cloud formation mechanism, and measurement of aerosol spatiotemporal distribution through remote sensing, such as Lidar, MODIS and sun/star photometer. In this paper, hourly averaged records of humidity, visibility and aerosol concentration, conducted in Macao, P.R.C. from 1 February 2006 to 31 December 2008 (LT), are used to estimate aerosol hygroscopicity and composition with a simplified empirical method. The result of monthly variation of aerosol hygroscopicity indicates the important role of aerosol composition on optical properties, which is in agreement with the previous study. This aerosol composition pattern is also consistent with the Asiatic Monsoon pattern and vicinity, such as Hong Kong. The monthly variation of aerosol hygroscopicity and composition also shows the necessity to consider such a factor for the aerosols monitoring by remote system and aerosols forcing simulated by climate model.

scholarly journals How alkaline compounds control atmospheric aerosol particle acidity

2021 ◽  
Vol 21 (19) ◽  
pp. 14983-15001
Author(s):  
Vlassis A. Karydis ◽  
Alexandra P. Tsimpidi ◽  
Andrea Pozzer ◽  
Jos Lelieveld
Keyword(s):  
Public Health ◽  
Aerosol Particle ◽  
Atmospheric Chemistry ◽  
Climate Model ◽  
Control Strategies ◽  
Atmospheric Particulate Matter ◽  
Cloud Formation ◽  
Mass Composition ◽  
The Past ◽  
Aerosol Hygroscopicity

Abstract. The acidity of atmospheric particulate matter regulates its mass, composition, and toxicity and has important consequences for public health, ecosystems and climate. Despite these broad impacts, the global distribution and evolution of aerosol particle acidity are unknown. We used the comprehensive atmospheric multiphase chemistry–climate model EMAC (ECHAM5/MESSy Atmospheric Chemistry) to investigate the main factors that control aerosol particle acidity and uncovered remarkable variability and unexpected trends during the past 50 years in different parts of the world. Aerosol particle acidity decreased strongly over Europe and North America during the past decades while at the same time it increased over Asia. Our simulations revealed that these particle acidity trends are strongly related to changes in the phase partitioning of nitric acid, production of sulfate in aqueous aerosols, and the aerosol hygroscopicity. It is remarkable that the aerosol hygroscopicity (κ) has increased in many regions following the particle pH. Overall, we find that alkaline compounds, notably ammonium and to a lesser extent crustal cations, regulate the particle pH on a global scale. Given the importance of aerosol particles for the atmospheric energy budget, cloud formation, pollutant deposition, and public health, alkaline species hold the key to control strategies for air quality and climate change.

scholarly journals The advective Brewer-Dobson circulation in the ERA5 reanalysis: variability and trends

2020 ◽  
Author(s):  
Mohamadou Diallo ◽  
Manfred Ern ◽  
Felix Ploeger
Keyword(s):  
Gravity Wave ◽  
Large Scale ◽  
Climate Model ◽  
Southern Oscillation ◽  
Natural Variability ◽  
Radiation Budget ◽  
Residual Circulation ◽  
Quasi Biennial Oscillation ◽  
Acceleration Rate ◽  
Good Agreement

Abstract. The stratospheric Brewer-Dobson circulation (BDC) is an important element of climate as it determines the transport and distributions of key radiatively active atmospheric trace gases, which affect the Earth’s radiation budget and surface climate. Here, we evaluate the inter-annual variability and trends of the BDC in the ERA5 reanalysis and inter-compare with the ERA-Interim reanalysis for the 1979–2018 period. We also assess the modulation of the circulation by the Quasi-Biennial Oscillation (QBO) and the El Niño-Southern Oscillation (ENSO), and the forcings of the circulation by the planetary and gravity wave drag. A comparison of ERA5 and ERA-Interim reanalyses shows a very good agreement in the morphology of the BDC and in its structural modulations by the natural variability related to QBO and ENSO. Despite the good agreement in the spatial structure, there are substantial differences in the strength of the BDC and of the natural variability impacts on the BDC between the two reanalyses, particularly in the upper troposphere and lower stratosphere (UTLS), and in the upper stratosphere. Throughout most regions of the stratosphere, the variability and trends of the advective BDC are stronger in the ERA5 reanalysis due to stronger planetary and gravity wave forcings, except in the UTLS below 20 km where the tropical upwelling is about 40 % weaker due to a weaker gravity wave forcings at the equatorial flank of the subtropical jet. In the extra-tropics, the large-scale downwelling is stronger in ERA5 than in ERA-Interim linked to significant differences in planetary and gravity wave forcings. Analysis of the BDC trend shows a global acceleration of the annual mean residual circulation with an acceleration rate of about 1.5 % per decade at 70 hPa due to the long-term intensification in gravity and planetary wave breaking, consistent with observed and future climate model predicted BDC changes.

scholarly journals Improving the simulation of global aerosol with size-segregated anthropogenic number emissions

2017 ◽  
Author(s):  
Filippo Xausa ◽  
Pauli Paasonen ◽  
Risto Makkonen ◽  
Mikhail Arshinov ◽  
Aijun Ding ◽  
...  
Keyword(s):  
Particle Number ◽  
Climate Models ◽  
Climate Model ◽  
Dominant Role ◽  
Particle Diameter ◽  
Radiation Budget ◽  
Size Distributions ◽  
Anthropogenic Aerosol ◽  
Accumulation Mode ◽  
Climate Interactions

Abstract. Climate models are important tools that are used for generating climate change projections, in which aerosol-climate interactions are one of the main sources of uncertainties. In order to quantify aerosol-radiation and aerosol-cloud interactions, detailed input of anthropogenic aerosol number emissions is necessary. However, the anthropogenic aerosol number emissions are usually converted from the corresponding mass emissions in precompiled emission inventories through a very simplistic method depending uniquely on chemical composition, particle size and density, which are defined for a few very wide main source sectors. In this work, the anthropogenic particle number emissions converted from the AeroCom mass in the ECHAM-HAM climate model were replaced with the recently-formulated number emissions from the Greenhouse Gas and Air Pollution Interactions and Synergies (GAINS)-model, where the emission number size distributions vary, for example, with respect to the fuel and technology. A special attention in our analysis was put on accumulation mode particles (particle diameter dp > 100 nm) because of (i) their capability of acting as cloud condensation nuclei (CCN), thus forming cloud droplets and affecting Earth's radiation budget, and (ii) their dominant role in forming the coagulation sink and thus limiting the concentration of sub-100 nanometers particles. In addition, the estimates of anthropogenic CCN formation, and thus the forcing from aerosol-climate interactions are expected to be affected. Analysis of global particle number concentrations and size distributions reveal that GAINS implementation increases CCN concentration compared with AeroCom, with regional enhancement factors reaching values as high as 10. A comparison between modeled and observed concentrations shows that the increase in number concentration for accumulation mode particle agrees well with measurements, but it leads to a consistent underestimation of both nucleation mode and Aitken mode (dp > 100 nm) particle number concentrations. This suggests that revisions are needed in the new particle formation and growth schemes currently applied in global modeling frameworks.

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