seminari corsi meteorologia
Environmental Meteorology Seminar: Giorgia Fosser

Per la serie Environmental Meteorology Seminar segnaliamo il seminario di Giorgia Fosser (IUSS) dal titolo “Climate model jungle: how to choose the “right” one to study climate change”, organizzato dall’Università di Trento per giovedì 16 giugno, ore 14:30.

Il seminario si terrà in presenza nella Lecture Room 1P – DICAM, in Via Mesiano 77, a Trento. Sarà comunque possibile seguire l’evento online via zoom al seguente link:

https://unitn.zoom.us/j/81369394924
Meeting ID: 813 6939 4924
Passcode: 997153

seminari corsi meteorologia
Weather and Climate Seminar: Caroline Muller

Si terrà martedì 14 giugno alle ore 15:30 l’ultimo seminario del ciclo “Weather and Climate: From Fundamentals to Applications”.

Titolo del seminario è “How Do Ocean Temperature Anomalies Favor or Disfavor the Aggregation of Deep Convective Clouds?“, e sarà tenuto da Caroline Muller, Assistant Professor all’Istituto di Scienze e Tecnologia (ISTA) di Klosterneuburg, in Austria.

Maggiori informazioni sull’iniziativa, così come il modulo di pre-registrazione Zoom ed il programma completo possono essere trovati a questo link.

Abstract

Convective organization at mesoscales (hundreds of kilometres) is
ubiquitous in the tropics, but the physical processes behind it are
still poorly understood. Organization can be forced by the large scales,
such as surface temperature gradients. But convective organization can
also arise from internal feedbacks, such as "self-aggregation"
feedbacks. Self-aggregation refers to the spectacular ability of deep
clouds to spontaneously cluster in space despite spatially homogeneous
conditions and no large-scale forcing, in high-resolution
cloud-resolving models (CRMs).Because of the idealized settings in which
self-aggregation has been studied (typically radiative-convective
equilibrium (RCE) over homogeneous sea-surface temperature (SST)), its
relevance to the real tropics is debated. In this presentation, we will
investigate the impact of removing some of these idealizations on the
aggregation process. Specifically, we will investigate the impact of
inhomogeneous SSTs on convective aggregation.

In a first step, we will investigate how an idealized warm circular SST
anomaly, referred to as "hot-spot", helps organize convection, and how
self-aggregation feedbacks modulate this organization. The presence of a
hot-spot significantly accelerates aggregation, particularly for larger
domains and warmer/larger hot-spots, and extends the range of SSTs for
which aggregation occurs. In that case, the aggregation onset results
from a large-scale circulation induced by the hot-spot. In a second
step, we will investigate the interaction of aggregation with an
interactive surface (local SST evolving according to the surface energy
budget). The results will be interpreted in light of a simple model for
the boundary layer circulation.
seminari corsi meteorologia
Weather and Climate Seminar: Kathleen Schiro

Martedì 31 maggio alle ore 15.30 si terrà via Zoom il nono seminario della serie “Weather and Climate: From Fundamentals to Applications”. Maggiori informazioni sull’iniziativa, così come il modulo di pre-registrazione Zoom ed il programma completo possono essere trovati a questo link.

Il seminario, dal titolo “Impacts of Deep Convection on the Tropical Low Cloud Feedback and Climate Sensitivity“, sarà ospitato dall’Università di Trento e tenuto da Kathleen Schiro (UVA).

Abstract: Climate model simulations are known to be sensitive to parameter choices in the sub grid-scale representation of deep convection, as deep convection plays a critical role in the transport of heat and momentum globally. Over the years, it has also become evident that the intermodel spread in the warming response to anthropogenic forcing is largely driven by uncertainties in the magnitude of the cloud feedback in the tropics, specifically the low cloud feedback. In this talk, I will discuss how parameterization differences among models and changes to deep convection in response to anthropogenic warming are likely contributing significantly to the intermodel spread in the tropical cloud feedback. I will present evidence of two physical pathways linking deep convection to low clouds and their response to anthropogenic forcing: the "Radiation-Subsidence" Pathway and the "Stability" Pathway. In a warmer world, the tropical overturning circulation is projected to weaken. We find that the overturning circulation does not weaken as much in climate models with more stable tropospheres, which ultimately leads to a more positive low cloud feedback (Stability Pathway). Differences in deep convective parameterization modifying deep convection onset thresholds – such as the fractional rate of entrainment into convective updrafts – can contribute significantly to this intermodel spread in static stability. Additionally, changes to the total area occupied by deep convection in the tropics modify the high cloud fraction, which is linked to subsidence changes and the low cloud feedback (Radiation-Subsidence Pathway). Results from both the Coupled Model Intercomparison Project (CMIP6) and a perturbation physics ensemble in the Community Earth System model (NCAR CESM) will be presented and discussed.

seminari corsi meteorologia
Weather and Climate Seminar: Elizabeth Barnes

Martedì 10 maggio alle ore 15.30 si terrà via Zoom il settimo seminario della serie “Weather and Climate: From Fundamentals to Applications”. Maggiori informazioni sull’iniziativa, così come il modulo di pre-registrazione Zoom ed il programma completo possono essere trovati a questo link.

Il seminario, dal titolo Viewing Anthropogenic Change Through an AI Lens, sarà ospitato dall’Università di Trento e tenuto da Elizabeth Barnes (Colorado State University).

Abstract: Humans are vastly modifying the earth system, with identifiable impacts across the land surface, ocean and atmosphere. Here, we will explore three example applications of how explainable AI (XAI) techniques can help us visualize and quantify these changes over time. First, we will demonstrate how we can utilize XAI methods to quantify the footprint of human activity across the global land surface in near-real time. Second, we will demonstrate the utility of XAI for extracting forced climate patterns through time amidst a sea of climate noise and model disagreement. Third, we will show how XAI can help us better understand and predict temporal variations in decadal warming trends. All three parts of this talk serve as examples of how viewing our climate through an AI lens has the power to uncover new insights into anthropogenic change - allowing scientists to ask "why?" but now with the power of machine learning.
seminari corsi meteorologia
Weather and Climate Seminar: Annalisa Bracco

Martedì 3 maggio alle ore 15.30 si terrà via Zoom il sesto seminario della serie “Weather and Climate: From Fundamentals to Applications”. Maggiori informazioni sull’iniziativa, così come il modulo di pre-registrazione Zoom ed il programma completo possono essere trovati a questo link.

Il seminario, dal titolo Exploring the Manifold of the Tropical Pacific in Observations and
Models
, sarà ospitato dall’Università di Trento e tenuto da Annalisa Bracco (Earth and Atmospheric Sciences, Georgia Institute of Technology).

Abstract: The climate system is multiscale, multidimensional and nonlinear. Here
we propose a robust framework for visualizing and analyzing its
dynamics, accounting for both dependencies and nonlinearities. At each
time t, the system is uniquely described by a state space vector
parameterized by N variables and their spatial variability. The dynamics
is confined on a manifold with dimension lower than the full state space
and a strategy for manifold learning is presented via linear and
nonlinear algorithms. We focus on the Tropical Pacific Ocean using a
reanalysis as observational proxy (ERA5) and two state-of-the-art models
from the CMIP6 catalog, MPI and EC-Earth3.

The analysis spans four variables over two 40 years periods at daily
frequency, during historical times and in the SSP585 scenario. The
manifold learning step allows for comparing nonlinear contributions as
well as the relative role of each variable in the system's dynamics.
Instantaneous properties of the high dimensional attractor are then
quantified through the local dimension and persistence metrics, recently
introduced to the climate community.

These metrics quantify geometrical properties of the manifold and the
stability of local motions. Both models underestimate the average
dimension and overestimate the potential predictability of Tropical
Pacific climate compared to ERA5, which is indicative of common and
persistent differences between modelled and observed dynamics. These
model's biases are nearly identical during the historical period while
diverging in the global warming scenario analyzed.
seminari corsi meteorologia
Weather and Climate Seminar: David Thompson

Martedì 26 aprile alle ore 15.30 si terrà via Zoom il quinto seminario della serie “Weather and Climate: From Fundamentals to Applications”. Maggiori informazioni sull’iniziativa, il modulo di pre-registrazione Zoom, ed il programma completo a questo link.

Il seminario di martedì prossimo, dal titolo Understanding the Processes that Drive Surface Temperature Variability, sarà ospitato dall’Università di Trento e tenuto da David Thompson (Colorado State University, University of East Anglia).

Abstract: In this talk I will provide highlights of two different - but overlapping - research topics. Both relate to the processes that drive surface temperature variability.
In the first part I will focus on the role of ocean dynamics in driving sea-surface temperature variability. The key conclusion is that ocean dynamics act - in the net - to damp rather than drive low-frequency SST variability. The upshot is that the observed decadal variability - such as that associated with Atlantic decadal variability and the Pacific Decadal Oscillation - can not be traced to ocean processes.
In the second part I will focus on changes in temperature persistence under climate change. Here the key finding is that temperature persistence is certain to change across the globe, but that the signs of the changes depend critically on various physical processes. I will argue that one key but overlooked process is the changes in radiative damping timescales under climate change.