Assaf Hochman

Assaf Hochman
Hebrew University of Jerusalem Karlsruhe Institute of Technology

Doctor of Philosophy

About

38
Publications
5,381
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349
Citations
Introduction
The predictability of weather and climate is the estimation of uncertainty in model predictions. Atmospheric predictability is strongly dependent on the accuracy of initial conditions, on the representation of sub grid-scale processes and on climate change scenarios. The main purpose of my research is in reducing climate and weather prediction uncertainties across spatial and temporal scales, especially over vulnerable populated regions. My work addresses the issue of weather and climate predictability from different perspectives including: Physical observations, computer modelling and mathematical/statistical theory.
Additional affiliations
July 2022 - present
Hebrew University of Jerusalem
Position
  • Professor (Assistant)

Publications

Publications (38)
Preprint
The atmospheres of rocky exoplanets are close to being characterized by astronomical observations, in part due to the commissioning of the James Webb Space Telescope. These observations compel us to understand exoplanetary atmospheres, in the voyage to find habitable planets. With this aim, we investigate the effect that CO$_2$ partial pressure (pC...
Article
Full-text available
Here, we analyze future projections of cyclone activity in the Mediterranean region at the end of the twenty-first century based on an ensemble of state-of-the-art fully-coupled Regional Climate System Models (RCSMs) from the Med-CORDEX initiative under the Representative Concentration Pathway (RCP) 8.5. Despite some noticeable biases, all the RCSM...
Article
Full-text available
Regional and local wind systems are often complex, particularly near coastal areas with a highly variable orography. Thus, the realistic representation of regional wind systems in weather and climate models is of strong relevance. Here, we evaluate the ability of a 13‐year convection‐permitting climate simulation in reproducing the interaction of s...
Article
Full-text available
Gaining a holistic understanding of extreme weather, from its physical drivers to its impacts on society and ecosystems, is key to supporting future risk reduction and preparedness measures. Here, we provide an overview of the state of the art, knowledge gaps and key open questions in the study of extreme weather events over the vulnerable eastern...
Article
Full-text available
The accurate prediction of extreme weather events is an important and challenging task, and has typically relied on numerical simulations of the atmosphere. Here, we combine insights from numerical forecasts with recent developments in dynamical systems theory, which describe atmospheric states in terms of their persistence (θ−1) and local dimensio...
Article
Full-text available
Proxy-based hydro-climatic reconstructions over the Levant suggest enhanced water availability during the Last Glacial Maximum (LGM) compared to present-day conditions. To date, the governing hypothesis is that additional water availability may be directly linked to increased Cyprus Low frequency and intensity over the region. However, this paradig...
Article
Full-text available
The subseasonal variability of the extratropical large-scale atmospheric flow is characterized by recurrent or quasi-stationary circulation anomalies, termed weather regimes. Despite the usefulness of these regimes in numerous meteorological and socioeconomic applications, there is an ongoing debate as to whether they represent physical modes of th...
Conference Paper
Full-text available
The subseasonal variability of the extratropical large-scale atmospheric flow is characterized by recurrent or quasi-stationary circulation anomalies, termed weather regimes. Despite the usefulness of these regimes in numerous meteorological and socioeconomic applications, there is an ongoing debate as to whether they represent physical modes of th...
Preprint
Full-text available
Gaining a holistic understanding of extreme weather, from its physical drivers to its impacts on society and ecosystems, is key to supporting future risk reduction and preparedness measures. Here, we provide an overview of the state-of-the-art, knowledge gaps and key open questions in the study of extreme weather events over the vulnerable eastern...
Article
Full-text available
Skillful forecasts of extreme weather events have a major socioeconomic relevance. Here, we compare two complementary approaches to diagnose the predictability of extreme weather: recent developments in dynamical systems theory and numerical ensemble weather forecasts. The former allows us to define atmospheric configurations in terms of their pers...
Article
Full-text available
The Eastern Mediterranean resides on the border between the temperate and semi-arid and arid climate zones, and is thus influenced by both mid-latitude and sub-tropical weather systems. Precipitation and extreme weather in this region are mainly associated with either Cyprus Lows or the ‘wet’ Red Sea Troughs. Current regional climate projections in...
Article
Global health threats including epidemics and climate change, know no political borders and require regional collaboration if they are to be dealt with effectively. This paper starts with a review of the COVID-19 outbreak in Israel, Palestine and Jordan, in the context of the regional health systems, demography and politics. We suggest that Israel...
Article
Background The Middle East (ME) is expected to be influenced by climate changes that will significantly affect human health. An increase in temperature and in the intensity, length and frequency of heat waves, alongside a decrease in precipitation, have been observed, and longer summers and shorter winters are expected. Population growth intensifie...
Article
The prediction of the occurrence of infectious diseases is of crucial importance for public health, as clearly seen in the ongoing COVID-19 pandemic. Here, we analyze the relationship between the occurrence of a winter low-pressure weather regime - Cyprus Lows - and the seasonal Influenza in the Eastern Mediterranean. We find that the weekly occurr...
Preprint
Full-text available
Skillful forecasts of extreme weather events have a major socio-economic relevance. Here, we compare two complementary approaches to diagnose the predictability of extreme weather: recent developments in dynamical systems theory and numerical ensemble weather forecasts. The former allows us to define atmospheric configurations in terms of their per...
Article
Full-text available
Summary Risks associated with public health have no borders, as the recent Corona virus (COVID-19) pandemic developing during the course of the workshop, clearly demonstrated. Thus, the 15 challenges climate change pose to society and especially to public health can only be properly met with inter-disciplinary regional collaborations. In January 27...
Presentation
Full-text available
A short video presentation of the paper entitled 'A New Dynamical Systems Perspective on Atmospheric Predictability; Eastern Mediterranean Weather Regimes as a Case Study'.
Article
Full-text available
The Mediterranean region is projected to be significantly affected by climate change through warming and drying. The Eastern Mediterranean (EM) is particularly vulnerable since the bulk of the precipitation in the region is associated with a specific circulation pattern, known as Cyprus Low (CL). Here, we study the influence of increased greenhouse...
Thesis
Full-text available
The Mediterranean has been recognized as a ‘hot spot’, currently influenced by climate change, and predicted to be strongly affected in the future by significant warming and drying. This trend is expected to be expressed in changes in the occurrence and intensity of Mediterranean cyclones, in general, and of East Mediterranean, i.e., Cyprus Lows, i...
Article
Global climate models provide only partial information on local‐scale phenomenon, such as precipitation, primarily due to their coarse resolution. In this study, statistical downscaling algorithms, based on both weather regimes and past analogues, are operated for eighteen Israeli rain gauges with an altitude ranging between ‐200 and ~1000 m ASL. I...
Article
The Continuous Wavelet Transform (CWT) is a frequently used tool to study periodicity in climate and other time series. Periodicity plays a significant role in climate reconstruction and prediction. In numerous studies, the use of CWT revealed Dominant Periodicity (DP) in climatic time series. Several studies suggested that these “natural oscillati...
Article
Full-text available
The atmosphere is a chaotic system displaying recurrent large-scale configurations. Recent developments in dynamical systems theory allow us to describe these configurations in terms of the local dimension-a proxy for the active number of degrees of freedom-and persistence in phase space, which can be interpreted as persistence in time. These prope...
Article
Full-text available
High resolution climate projections over Israel (about 8 km) have been obtained with the regional model COSMO-CLM, nested into the CORDEX-MENA simulations at 25 km resolution. This simulation provides high-resolution spatial variability of total precipitation and precipitation intensity. Projections are presented not only in terms of average proper...
Conference Paper
Full-text available
The eastern Mediterranean (EM) is expected to be influenced by climate changes that will significantly affect ecosystems, human health and socioeconomic aspects. One aspect of climate change in this vulnerable area is the length of the seasons especially that of the rainy winter season against the warm and dry summer. Here, the synoptic seasons' de...
Conference Paper
Full-text available
The Mediterranean has been recognized as a ‘hot spot’, currently influenced by climate change, and predicted to be strongly affected in the future by significant warming and drying. This trend is expected to be expressed in changes in the occurrence and intensity of Mediterranean cyclones, in general, and of East Mediterranean (EM), i.e., Cyprus Lo...
Article
The eastern Mediterranean (EM) is expected to be influenced by climate changes that will significantly affect ecosystems, human health and socioeconomic aspects. One aspect of climate change in this vulnerable area is the length of the seasons, especially that of the rainy winter season against the warm and dry summer. Here, the synoptic seasons' d...
Article
An evaluation of 23 models, participating in the Coupled Model Inter-comparison Project phase 5 (CMIP5), in representing extreme precipitation indices (EPI), over the Eastern Mediterranean (EM) and the Fertile Crescent (FC), was performed. The models ensemble was then used to predict the EPIs evolution in the 21st century under (Representative Conc...
Chapter
Full-text available
Changes in wind speed in the Mediterranean region will have serious consequences in different fields. A decrease in wind speed can weaken the thermohaline circulation due to both a reduction in wind stress and heat flux. Changes in wind patterns can have significant implications for the potential of wind as an energy resource and more generally can...
Presentation
Full-text available
The Mediterranean has been recognized as a region (‘hot spot’), currently influenced by climate change, which is predicted to be strongly affected in the future, mainly by warming and drying. Among the natural processes affecting this region are synoptic scale phenomena such as Mediterranean cyclones. Forthcoming changes in the occurrence of Easter...
Presentation
Full-text available
The Mediterranean has been recognized as a ‘hot spot’, currently influenced by climate change, and predicted to be strongly affected in the future by warming and drying. This trend is expected to be expressed in changes in the occurrence and intensity of Mediterranean cyclones, in general, and of East Mediterranean (EM), i.e., Cyprus Lows (CL), in...
Article
The Regional Climate Model (RCM) COSMO-CLM capability to reproduce the climate characteristics, including extreme values, over the Eastern Mediterranean (EM) was tested. Model configuration has been chosen based on a previously performed sensitivity analysis, aimed to ascertain the accuracy of model performances over Israel. Three simulations drive...
Article
24 The Mediterranean has been recognized as a 'hot spot', currently influenced by 25 climate change, and predicted to be strongly affected in the future by significant 26 warming and drying. This trend is expected to be expressed in changes in the 27 occurrence and intensity of Mediterranean cyclones, in general, and of East 28 Mediterranean (EM),...
Article
Full-text available
This work presents a statistical reconstruction of average mid-winter (DJF) temperature in Jerusalem since 1750. It is a first comprehensive attempt to reconstruct the temperature in Jerusalem, as a good representation of the Eastern Mediterranean (EM) climate. This representativeness is verified here. The data has been reconstructed by using a sta...

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Projects

Projects (5)
Project
The purpose of this project is to research the dynamics of weather regimes over the eastern Mediterranean in the present and in future scenarios.