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5 results on '"Lembo, Valerio"'

1. Review article: Interdisciplinary perspectives on climate sciences – highlighting past and current scientific achievements.

Author

Galfi, Vera Melinda, Alberti, Tommaso, De Cruz, Lesley, Franzke, Christian L. E., and Lembo, Valerio

Subjects
CLIMATOLOGY, GEOPHYSICAL fluid dynamics, STATISTICAL physics, DYNAMICAL systems, SYSTEMS theory
Abstract

In the online seminar series "Perspectives on climate sciences: from historical developments to future frontiers", which took place during 2020–2021, well-known and established scientists from several fields – including mathematics, physics, climate science and ecology – presented their perspectives on the evolution of climate science and on relevant scientific concepts. This special issue aims to create a platform for a more detailed elaboration of the topics discussed in the seminars but also to publish new scientific findings. In this paper, we first give an overview of the content of the seminar series, and then we introduce the written contributions to this special issue. In line with the spirit of the seminar series, this paper is structured along thematic areas of the broad field of climate science, conveying different perspectives on the climate system: geophysical fluid dynamics, dynamical systems theory, multiscale processes, statistical physics, paleoclimate and the human dimension. [ABSTRACT FROM AUTHOR]

Published
2024
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2. Interdisciplinary Perspectives on Climate Sciences - Highlighting Past and Current Scientific Achievements.

Author

Galf, Vera Melinda, Alberti, Tommaso, De Cruz, Lesley, Franzke, Christian L. E., and Lembo, Valerio

Subjects
CLIMATOLOGY, GEOPHYSICAL fluid dynamics, STATISTICAL physics, DYNAMICAL systems, PALEOCLIMATOLOGY
Abstract

In the online seminar series "Perspectives on Climate Sciences: from Historical Developments to Future Frontiers", which took place during 2020-2021, well-known and established scientists from several fields - including mathematics, physics, climate science and ecology - presented their perspectives on the evolution of climate science and on relevant scientific concepts. This special issue aims to create a platform for a more detailed elaboration of the topics discussed in the seminars but also to publish new scientific findings. In this paper, we first give an overview of the content of the seminar series, and then we introduce the written contributions to this special issue. In line with the spirit of the seminar series, this paper is structured along thematic areas of the broad field of climate science, conveying different perspectives on the climate system: geophysical fluid dynamics, dynamical systems theory, multiscale processes, statistical physics, paleoclimate and the human dimension. [ABSTRACT FROM AUTHOR]

Published
2023
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3. Inter-hemispheric differences in energy budgets and cross-equatorial transport anomalies during the 20th century

Author

Piero Lionello, Martin Wild, Doris Folini, Valerio Lembo, Lembo, Valerio, Folini, Dori, Wild, Martin, and Lionello, Piero

Subjects
Earth's energy budget, Atmospheric Science, GHG forcing, 010504 meteorology & atmospheric sciences, Anomaly (natural sciences), Northern Hemisphere, Forcing (mathematics), Global energy budget, 010502 geochemistry & geophysics, 01 natural sciences, Atmosphere, CMIP5 historical simulation, Climatology, Environmental science, Outgoing longwave radiation, Ocean heat content, Southern Hemisphere, Cross-equatorial heat transport, 0105 earth and related environmental sciences
Abstract

We analyze the evolution of inter-hemispheric asymmetries in the energy budgets (EBs) and near-surface temperature anomalies during the 20th century, as given in Coupled Model Inter-comparison Project, phase 5 (CMIP5) simulations. We also consider the cross-equatorial energy transports (CET) in the atmosphere and in the oceans, in order to evidence how EB asymmetries affect the redistribution of energy between the two hemispheres. Two different experimental settings have been considered, one including only the spatially homogeneous evolving greenhouse gas forcing (GHG), and another one a realistic superposition of all known evolving forcings (ALL), such as aerosols and volcanic eruptions. This study shows that, according to the CMIP5 models, the response of the climate system to the ongoing forcing during the 20th century has differed substantially from what would have resulted from an increase in GHG concentration alone. In the GHG ensemble the Northern Hemisphere (NH) warms more than the Southern Hemisphere (SH), while both hemispheres exhibit similar and positive EB anomalies at the TOA, mainly due to increasing shortwave absorption and with no significant variations of cross-equatorial energy transports. On the contrary, in the ALL ensemble the two hemispheres warm similarly, while the SH exhibits a positive EB anomaly twice as large as in the NH, due to a reduced LW emission (Outgoing Longwave Radiation, OLR) in the SH, with oceanic CET anomalies directed towards the NH. The EB asymmetry in ALL is ascribed to the asymmetry in OLR changes, which is explained by the different role of clouds in the two hemispheres. The ocean heat content (OHC) tendency per unit surface area is similar in the two hemispheres, so that the asymmetries in ALL EB determine CET changes. We evidence that CET changes in the ALL ensemble are associated with the inter-hemispheric asymmetry in the aerosol forcing, which is stronger in the NH than in the SH. We find no significant relation between CETs and inter-hemispheric near-surface temperature asymmetries in GHG, partly due to the large model spread. Generally, deficits in modeled CET for present-day conditions are not ascribed to forcings and feedbacks, rather they are intrinsic to the models.

Published
2018

4. Energy budgets and transports: global evolution and spatial patterns during the twentieth century as estimated in two AMIP-like experiments

Author

Valerio Lembo, Martin Wild, Piero Lionello, Doris Folini, Lembo, Valerio, Folini, Dori, Wild, Martin, and Lionello, Piero

Subjects
Earth's energy budget, Atmospheric Science, 010504 meteorology & atmospheric sciences, Northern Hemisphere, Atmospheric Model Intercomparison Project, Meridional energy transports, Forcing (mathematics), 010502 geochemistry & geophysics, Atmospheric sciences, Global energy budget, 01 natural sciences, Aerosol, Atmosphere, Sea surface temperature, Climatology, Aerosol forcing, ERA-20CM, Environmental science, Sea ice concentration, 0105 earth and related environmental sciences
Abstract

This study describes characteristics and evolution of the residual of the Earth energy budget (EB) individual components and the implied meridional transports during the twentieth century. This analysis considers two ensembles of AMIP-like experiments (Atmospheric Model Intercomparison Project) with prescribed evolution of sea surface temperature and sea ice concentration (SST-SIC), greenhouse gases (GHG), anthropogenic and volcanic aerosols over the entire twentieth century: ERA-20CM and ECHAM5-HAM model simulations. With the latter, additional sensitivity experiments are carried out by constraining either SST-SIC or aerosols to climatological values. The two models provide compatible estimates of the EBs and implied transport absolute values in recent decades. They are not in agreement in terms of global scale evolution: in the 1970s ERA-20CM shows a fast transition from negative to positive EBs at top of atmosphere (TOA) that is not found in ECHAM5-HAM. Climatological SST-SIC sensitivity experiments evidence that the aerosol forcing affects TOA and surface EBs by setting up an inter-hemispheric gradient after 1960. This is also reflected by an increased total transport in the Northern Hemisphere, while decreased in the Southern Hemisphere. ERA-20CM shows no evidence of a similar aerosol forcing. Sensitivity experiments with fixed pre-industrial aerosols show that transient SST are responsible for irregular spatio-temporal anomalies of surface and atmospheric EBs and transports. Surface and atmospheric anomalies oppose each other, and transient SSTs do not influence the EB changes at TOA. Impact of transient SST and GHG forcing on EBs and implied transports are robust across the two models.

Published
2017

5. Variability and extremes of meridional atmospheric heat transport.

Author

Messori, Gabriele, Czaja, Arnaud, Geen, Ruth, Lembo, Valerio, Lucarini, Valerio, and Graversen, Rune

Subjects
*ROSSBY waves, *ATMOSPHERIC transport, *CHOICE of transportation, *CLIMATE extremes, *CLIMATOLOGY
Abstract

Meridional atmospheric heat transport is a fundamentally sporadic process. Here, we analyse the spatial and temporal variability of such transport, and show that transient motions – diagnosed in terms of deviations from a long term climatology – drive large local transport values. This implies that, at any given location in the extra-tropics, the net seasonal heat transport by the transients is heavily affected by a few extreme days every season. A large variability with notable extreme events also emerges when considering zonally integrated meridional transport values. We next perform a scale decomposition of the total, zonally integrated transport to separate the roles of the mean meridional flow, the planetary (zonal wavenumber 1 to 5) and the synoptic (zonal wavenumber 6 to 10) waves. In both the winter and summer months, poleward transport extremes result from a constructive interference of transport performed by planetary and synoptic motions, while the contribution of the mean meridional circulation is close to climatology (and predominantly equatorward). Instances of this constructive interference have been previously associated with extreme heat and moisture transports to the high latitudes. The pattern is different for extreme equatorward transport anomalies. In winter, the mean meridional flow mostly drives a net equatorward transport (thus acting counter-gradient), while the planetary and synoptic modes chiefly (but not always) transport energy poleward. In summer, the transport by mean meridional circulation is weak and close to climatological values, the planetary modes mostly transport energy equatorward and the synoptic modes again drive a poleward transport. This translates into a systematic destructive interference between the transport by planetary waves and by synoptic motions. The existence of such pronounced variability in the meridional heat transport, associated with complex scale interactions, has important consequences for the interplay between mid-latitude dynamics and the energy balance of the high latitudes. [ABSTRACT FROM AUTHOR]

Published
2019

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