The North Atlantic Oscillation signal in a regional climate simulation for the European region

The North Atlantic Oscillation (NAO) is a dominant pattern of large-scale variability in the Northern Hemisphere, with important regional effects on the winter climate of Europe. Nested regional climate models (RCMs) can be useful tools for studying the regional signal of the NAO. Therefore, it is important to assess whether they can reproduce the observed NAO signal over Europe when driven by lateral boundary conditions from global climate models. In this paper we investigate the NAO-related winter variability over Europe in a RCM simulation driven by large-scale fields from an atmospheric global model simulation forced with historic sea surface temperature and sea ice distribution for the period 1961–1990. We show that (1) the NAO-related winter variability signal over the European region shows substantial topographically induced fine-scale features, both for temperature and precipitation, and (2) the model is capable of reproducing many aspects of this fine-scale regional signal and, in particular, the topographically forced regional response of precipitation to NAO-type circulations. We conclude that nested regional climate models can be used to study the fine-scale regional signature of the NAO under different climatic conditions

Past and future climate projections and their relevance for human society – a journey in time

Present climate change issues have reached the top on the agenda of decision makers on national, regional and global level. Climate science directly contributes to socio-economic planning in our society despite the unavoidable uncertainties associated to the research tools we have used. The presentation reviews the research related to climate modeling as a tool for generating knowledge applied to past and present climate changes in Earth and human history and associated uncertainties from the perspective of future society development.  The presentation shows that, in the context of adaptation to present climate change, ignoring knowledge together with related uncertainties about past and future climate might lead to high social, economic and environmental costs.</p

The North Atlantic Oscillation signal in a regional climate simulation for the European region

The North Atlantic Oscillation (NAO) is a dominant pattern of large-scale variability in the Northern Hemisphere, with important regional effects on the winter climate of Europe. Nested regional climate models (RCMs) can be useful tools for studying the regional signal of the NAO. Therefore, it is important to assess whether they can reproduce the observed NAO signal over Europe when driven by lateral boundary conditions from global climate models. In this paper we investigate the NAO-related winter variability over Europe in a RCM simulation driven by large-scale fields from an atmospheric global model simulation forced with historic sea surface temperature and sea ice distribution for the period 1961–1990. We show that (1) the NAO-related winter variability signal over the European region shows substantial topographically induced fine-scale features, both for temperature and precipitation, and (2) the model is capable of reproducing many aspects of this fine-scale regional signal and, in particular, the topographically forced regional response of precipitation to NAO-type circulations. We conclude that nested regional climate models can be used to study the fine-scale regional signature of the NAO under different climatic conditions

TEMPERATURE-BASED CLIMATE INDICATORS RELEVANT FOR AGRICULTURE SECTOR IN THE CONTEXT OF CLIMATE CHANGES IN OLTENIA

We present an analysis of changes of several thermal-based climate indicators relevant for agriculture in the context of climate changes for the near-future (2021-2040), aiming to highlight the extremes of these changes. To this end, we use bias-corrected results of climate projections performed with 5 regional climate models in the context of RCP45 and RCP85 scenarios at European scale, available from Joint Research Centre (https://data.jrc.ec.europa.eu/dataset/jrc-liscoast-10011). We firstly identify the models` simulations which lead to the lowest increase in the mean air temperature at national scale in the context of RCP45 scenario and respectively to the highest increase, in the RCP85 scenario.  We further use these instances to estimate the changes in 5 temperature-based indicators which are relevant for the agriculture sector. The indices characterize the bounding seasons (i.e. heating degree days) or are more specifically oriented for the growing season (i.e. Growing degree days; Winkler index).The target area is Oltenia, a region situated in the SW of the country and an important agricultural basin, which is analyzed in the context of changes over the entire territory. The results may provide additional elements for further studies focusing on the impact of climate change and adaptation solutions in this region

Holiday Climate Index: Urban—Application for Urban and Rural Areas in Romania

Nature, landscape, relaxation, and outdoor activities are important motivations when choosing rural destinations for vacations. Therefore, when selecting a rural area as a vacation destination, we assume that climate features are important. We investigated the appropriateness of the holiday climate index: urban (HCI:urban) in quantitatively describing the relationship between climate and tourism fluxes in such destinations. We employed data from 94 urban and rural tourist destinations in Romania and correlated the monthly mean HCI:urban values with sectoral data (overnight tourists) for 2010–2018. The results show that weather and climate influenced tourism fluxes similarly in rural and urban destinations, supporting the hypothesis that HCI:urban may be used for rural areas as well. The information derived from HCI:urban may be useful for tourists when planning their vacations as well as for tourism investors in managing their businesses and reducing the weather and climate-related seasonality in tourism fluxes

ASSESSEMENT OF THERMAL REGIME IN OLTENIA USING TEMPERATURE-BASED CLIMATE INDICATORS RELEVANT FOR AGRICULTURE SECTOR

We present a quantitative evaluation of current climate (1981-2010) thermal conditions relevant for the agriculture sector by using seven agrometeorological climate indices computed based on the ROCADA dataset. The temperature-related indicators characterize the cold period of the year (i.e. sums of minimum air temperatures ≤‐10°C recorded in December‐February interval), the bounding seasons (e.g. zero crossing days), heating degree days) or are more specifically oriented for the growing season (i.e. Growing degree days; growing season mean temperature during April‐October/ May-September interval; Winkler index). The indices are computed for the entire Romanian territory, highlighting the thermal climatic features of the Oltenia region

Variability and Change in Water Cycle at the Catchment Level

This study proposes a simple methodology for assessing future-projected evolution of water cycle components (precipitation, potential evapotranspiration, and potential runoff) based on the two-level Palmer model of the soil and their impact on drought conditions at basin level. The Palmer Drought Severity Index (PDSI) is used as drought metric. The catchments of rivers Arges, Mures, Prut, Siret and Somes (mid- and lower Danube basin) have been chosen as case studies. The present climate data consist of Romanian gridded dataset, monthly precipitation and values of streamflow from Romania and Republic of Moldova and potential evapotranspiration-related data from the Climate Research Unit (University of East Anglia). We used as future projections five numerical experiments with regional models obtained through the EURO-CORDEX initiative, under two Representative Concentration Pathway scenarios. The correlations between observed streamflow at the river basin outlets and PDSI-related components of the water cycle show that PDSI represents reasonably well processes taking place in the selected catchments. Depending on the specific scenario and catchment, droughts that in the Palmer classification were deemed as incipient, mild or severe under present climate will become a normal summer feature toward the end of this century, especially over catchments situated in the lower Danube basin

IR-BASED SATELLITE PRODUCTS FOR THE MONITORING OF ATMOSPHERIC WATER VAPOR OVER THE BLACK SEA

The amount of precipitable water (TPW) in the atmospheric column is one of the important information used weather forecasting. Some of the studies involving the use of TPW relate to issues like lightning warning system in airports, tornadic events, data assimilation in numerical weather prediction models for short-range forecast, TPW associated with intense rain episodes. Most of the available studies on TPW focus on properties and products at global scale, with the drawback that regional characteristics – due to local processes acting as modulating factors - may be lost. For the Black Sea area, studies on the climatological features of atmospheric moisture are available from sparse or not readily available observational databases or from global reanalysis. These studies show that, although a basin of relatively small dimensions, the Black Sea presents features that may significantly impact on the atmospheric circulation and its general characteristics. Satellite observations provide new opportunities for extending the knowledge on this area and for monitoring atmospheric properties at various scales. In particular, observations in infrared (IR) spectrum are suitable for studies on small-scale basins, due to the finer spatial sampling and reliable information in the coastal areas. As a first step toward the characterization of atmospheric moisture over the Black Sea from satellite-based information, we investigate three datasets of IR-based products which contain information on the total amount of moisture and on its vertical distribution, available in the area of interest. The aim is to provide a comparison of these data with regard to main climatological features of moisture in this area and to highlight particular strengths and limits of each of them, which may be helpful in the choice of the most suitable dataset for a certain application

Thermal stress information as a tourism-oriented climate product: Performance analysis for selected urban destinations in Romania and Italy

The study addresses the characteristics of a climate service targeting tourists and discusses the evaluation of its products with a particular focus on the thermal stress information. Furthermore, an assessment of the impact of input data on the accuracy and relevance of the thermal stress product is presented. The thermal stress is expressed through UTCI (Universal Thermal Climate Index) and it is computed from UERRA regional reanalysis and E-OBS gridded dataset, for summer season during 2011–2018. The analysis targets 10 cities with different characteristics located in Romania and Italy. It focuses on the impact of three temperature-related input data (instantaneous temperature at 12:00 UTC, daily maximum and daily mean temperature) on the thermal stress intensity. The results show that differences up to 4 days in the pronounced thermal stress category may appear when employing daily maximum temperature compared to the use 12:00 UTC instantaneous temperature, while the use of daily mean temperature leads to strong underestimation of thermal stress in this category. The findings are of interest in defining the technical choices of products to be incorporated in a climate service for tourism in order to assure a good user uptake