The Response of the Midlatitude Jet to Regional Polar Heating in a Simple Storm-Track Model

Given the recent changes in the Arctic sea ice, understanding the effects of the resultant polar warming on the global climate is of great importance. However, the interaction between the Arctic and midlatitude circulation involves a complex chain of mechanisms, which leaves state-of-the-art general circulation models unable to represent this interaction unambiguously. This study uses an idealized general circulation model to provide a process-based understanding of the sensitivity of the midlatitude circulation to the location of high-latitude warming. A simplified atmosphere is simulated with a single zonally localized midlatitude storm track, which is analogous to the storm tracks in the Northern Hemisphere. It is found that even small changes in the position of the forcing relative to that storm track can lead to very different responses in the midlatitude circulation. More specifically, it is found that heating concentrated in one region may cause a substantially stronger global response compared to when the same amount of heating is distributed across all longitudes at the same latitude. Linear interference between climatological and anomalous flow is an important component of the response, but it does not explain differences between different longitudes of the forcing. Feedbacks from atmospheric transient eddies are found to be associated with this strong response. A dependence between the climatological jet latitude and the jet response to polar surface heating is found. These results can be used to design and interpret experiments with complex state-of-the-art models targeted at Arctic–midlatitude interactions

The role of upper-ocean heat content in the regional variability of Arctic sea ice at sub-seasonal timescales

In recent decades, the Arctic Ocean has undergone changes associated with enhanced poleward inflow of Atlantic and Pacific waters and increased heat flux exchange with the atmosphere in seasonally ice-free regions. The associated changes in upper-ocean heat content can alter the exchange of energy at the ocean–ice interface. Yet, the role of ocean heat content in modulating Arctic sea ice variability at sub-seasonal timescales is still poorly documented. We analyze ocean heat transports and surface heat fluxes between 1980–2021 using two eddy-permitting global ocean reanalyses, C-GLORSv5 and ORAS5, to assess the surface energy budget of the Arctic Ocean and its regional seas. We then assess the role of upper-ocean heat content, computed in the surface mixed layer (Qml) and in the 0–300 m layer (Q300), as a sub-seasonal precursor of sea ice variability by means of lag correlations. Our results reveal that in the Pacific Arctic regions, sea ice variability in autumn is linked with Qml anomalies leading by 1 to 3 months, and this relationship has strengthened in the Laptev and East Siberian seas during 2001–2021 relative to 1980–2000, primarily due to reduced surface heat loss since the mid-2000s. Q300 anomalies act as a precursor for wintertime sea ice variability in the Barents and Kara seas, with considerable strengthening and expansion of this link from 1980–2000 and 2001–2021 in both reanalyses. Our results highlight the role played by upper-ocean heat content in modulating the interannual variability of Arctic sea ice at sub-seasonal timescales. Heat stored in the ocean has important implications for the predictability of sea ice, calling for improvements in forecast initialization and a focus upon regional predictions in the Arctic region.</p

Key economic drivers enabling municipal renewable energy communities’ benefits in the Italian context

Community energy is a buzzword that has historically included various type of experiences. In 2018, the Renewable Energy Directive (RED II) legally defined renewable energy communities (RECs). Based on the first pilot projects and on the Italian legal framework, a possible REC configuration of municipal initiative with a high replicability potential is one in which a photovoltaic system is installed in educational buildings and shares energy with neighbouring residential consumers. This analysis presents an economical evaluation of different possible scenarios depending on variables such as solar radiation, system capacity, fraction of self-consumption within the REC, installation costs and energy prices. All the scenarios identified and analysed show positive economic indexes, although the energy and economic results may significantly vary depending on the variables studied. In the analysed case studies, the Net Present Value (after 20 years) is between kEUR 51 and kEUR 478; the internal rate of return is between 9.5% and 88%; the payback time is between 13.6 years and 1.1 years. The results of this analysis are relevant as they allow us to better understand the critical factors that can enable REC in providing local economic and social benefits to have a real impact on energy poverty or on the provision of local social services

Progress of the Member States in implementing the Energy Performance of Building Directive

Overall, the EPBD policy framework laid down the foundation for:i) setting cost-optimal minimum energy performance standards in new buildings and existing buildings under major renovation;ii) ensuring that prospective buyers or renters are well informed through Energy Performance Certificates and thereby encouraged to choose higher than minimum standards in their decision making processes;iii) speeding up the rate at which investors engage in energy efficiency projectsthrough national long-term renovation strategies and financemechanisms.In accordance with the policy assessment of 2017 it is expected that the EPBD islikely to deliver the expected impacts by 2020, with 48.9 Mtoe additional final energy savings and a reduction of 63 Mt of CO2.However, the new Climate agenda set higher ambition targets and together with the Covid-19 crisis, the scenario has changed consistently and the next decade will be very challenging. The energy renovation of buildings can be a pillar of both the European decarbonisation process and the economic recovery after the pandemic.This report provides a snap shot of the EPBD implementation progresses by Member States over the last years. In particular, the focus is mainly on: cost-optimal calculations to set minimum energy performance requirements, Energy Performance Certificates (EPC), Nearly Zero-Energy Buildings (NZEB), financial incentives and market barriers, Long-term Renovation Strategies (LTRS). In order to contextualize the European scenario, some general trendsare presented and discussed in the introduction

Observational evidence of intensified nocturnal urban heat island during heatwaves in European cities

A heatwave (HW) is a large-scale meteorological event characterised by persistent and extremely high-temperature condition. At the local scale, the urban heat island (UHI) is another thermal-related phenomenon defined as an urban area warmer than its surrounding regions due to different surfaces’ capabilities to absorb and store heat. However, the assessment about the effect produced on UHI by HW events is not homogeneous. Indeed, regarding the capability of HWs to influence the urban-rural temperature difference, several studies report different conclusions describing both an exacerbation and a reduction of UHI during HW events. In this context, the present study analyses in situ long records of temperature measurements (20 years) to provide observational shreds of evidence of UHI modification under HW conditions. We examine data from the European Climate Assessment &amp; Dataset and World Meteorological Organization computing the UHI index (UHII) to quantify the UHI effect intensity in 37 European cities during the last 20 summers. The results show an UHII intensification for 28 of the 32 cities affected by positive UHI during extremely high temperatures at night, while substantial variations are not observed during the daytime. The time evolution of UHI during a HW highlights that a more significant and persistent urban-rural temperature gradient explains the UHI intensification. Finally, the relationship between the large and local-scale temperature phenomena reveals that continental high-temperature periods are often associated with prominent temperature differences between small-scale urban and rural environments, assessing the impact of large-scale features on thermal stress at the local scale

La Cicogna bianca (Ciconia ciconia) in Piemonte e in Provincia di Torino dal 1996 al 2014

Viene presentata un’analisi della popolazione di Cicogna bianca (Ciconia ciconia) in Piemonte nord occidentale e, specificatamente, in provincia di Torino negli ultimi 20 anni. Il primo tentativo di nidificazione risale al 1980, ma è solo a partire dal 1996 che si è registrata una colonizzazione del territorio torinese con la presenza di un massimo di 8 coppie (2014). Parallelamente, anche il numero di individui svernanti nella stessa area, particolarmente in prossimità di discariche di rifiuti urbani, è aumentato. Viene indicata una correlazione tra l’aumento del numero di individui non migranti e il numero di coppie nidificanti nella stessa area

The Response of the Midlatitude Jet to Regional Polar Heating in a Simple Storm-Track Model

Given the recent changes in the Arctic sea ice, understanding the effects of the resultant polar warming on the global climate is of great importance. However, the interaction between the Arctic and midlatitude circulation involves a complex chain of mechanisms, which leaves state-of-the-art general circulation models unable to represent this interaction unambiguously. This study uses an idealized general circulation model to provide a process-based understanding of the sensitivity of the midlatitude circulation to the location of high-latitude warming. A simplified atmosphere is simulated with a single zonally localized midlatitude storm track, which is analogous to the storm tracks in the Northern Hemisphere. It is found that even small changes in the position of the forcing relative to that storm track can lead to very different responses in the midlatitude circulation. More specifically, it is found that heating concentrated in one region may cause a substantially stronger global response compared to when the same amount of heating is distributed across all longitudes at the same latitude. Linear interference between climatological and anomalous flow is an important component of the response, but it does not explain differences between different longitudes of the forcing. Feedbacks from atmospheric transient eddies are found to be associated with this strong response. A dependence between the climatological jet latitude and the jet response to polar surface heating is found. These results can be used to design and interpret experiments with complex state-of-the-art models targeted at Arctic–midlatitude interactions