Climate projections over the Antarctic Peninsula region to the end of the 21st century. Part 1: cold temperature indices

Objective. This paper deals with an estimation of the climate change at the Antarctic Peninsula region. During last decades, the most significant warming is observed in Polar regions, particularly in the Antarctic Peninsula region, where the Ukrainian Antarctic Akademik Vernadsky station is located. Therefore, the providing of the complex estimation of climate change trend is an important task for the region. These changes are taking place nowadays and will happen in the future. So, the main objective of the study is to estimate changes of climate characteristics in the Antarctic Peninsula region in the 21st century, based on calculation of the relevant climate indices. The projections of the temperature and precipitation characteristics in the Antarctic Peninsula region and Akademik Vernadsky station area for RCP4.5 and RCP8.5 scenarios are the objects of the research.Стаття присвячена оцінці змін, що відбуваються в районі Антарктичного півострова. Впродовж останніх десятиліть найсуттєвіше потепління в кліматичній системі спостерігається в полярних регіонах, зокрема в районі Антарктичного півострова, де розташована Українська антарктична станція «Академік Вернадський». У зв’язку з цим необхідно забезпечити кращу комплексну оцінку тенденцій кліматичних змін, які вже зафіксовані та прогнозуються в майбутньому. Мета дослідження — оцінити зміни кліматичних характеристик в регіоні Антарктичного півострова в ХХІ столітті, на основі обчислення відповідних кліматичних показників. Об’єкт дослідження: проекції характеристик температури повітря та режиму зволоження в районі Антарктичного півострову та Української антарктичної станції «Академік Вернадський» за сценаріями RCP4.5 та RCP8.5 (Representative Concentration Pathway, RCP, Траєкторії репрезентативних концентрацій). Методами дослідження є чисельне моделювання та статистичний аналіз даних регіональних кліматичних моделей

Enviro-HIRLAM model estimates of elevated black carbon pollution over Ukraine resulted from forest fires

Funding Information: The study is part of the Enviro–PEEX on the ECMWF (Pan-Eurasian Experiment (PEEX; https://www.atm.helsinki.fi/peex , last access: last access: 8 December 2022) Modelling Platform research and development of online coupled integrated meteorology–chemistry–aerosols feedback and interactions in weather, climate, and atmospheric composition multi-scale modelling) project (2018–2020). The Enviro-HIRLAM model simulations were performed on the CSC (Center for Science Computing) Sisu HPC (Finland) during the Enviro-HIRLAM and HARMONIE research training course at the Institute for Atmospheric and Earth System Research (INAR) of the University of Helsinki (UHEL). The authors also gratefully acknowledge the computer resources and technical support provided by the Center for Science Computing (CSC) HPC (Finland). This study was carried out within the framework of the State Emergency Service of Ukraine and National Academy of Sciences of Ukraine. The work has been partially supported by Academy of Finland via a Flagship programme for Atmospheric and Climate Competence Center (ACCC, 337549) and Academy of Finland projects (334792, 328616, 345510) and European Commission via a project “Non-CO Forcers and Their Climate, Weather, Air Quality and Health Impacts”, (FOCI) and the project “Research Infrastructures Services Reinforcing air quality monitoring capacities in European URBAN & Industrial areaS” (RI-URBANS), no. 101036245. Funding Information: This research has been supported by a grant within the ENVRIplus project for multi-domain access to RI platforms (H2020-INFRAIA-2014-2015, grant no.: 654182). The work has been partially performed under the Project HPC-EUROPA3 (INFRAIA-2016-1-730897) with the support of the EC Research Innovation Action under the H2020 Programme. Publisher Copyright: © 2022 Copernicus GmbH. All rights reserved.Biomass burning is one of the biggest sources of atmospheric black carbon (BC), which negatively impacts human health and contributes to climate forcing. In this work, we explore the horizontal and vertical variability of BC concentrations over Ukraine during wildfires in August 2010. Using the Enviro-HIRLAM modelling framework, the BC atmospheric transport was modelled for coarse, accumulation, and Aitken mode aerosol particles emitted by the wildfire. Elevated pollution levels were observed within the boundary layer. The influence of the BC emissions from the wildfire was identified up to 550hPa level for the coarse and accumulation modes and at distances of about 2000km from the fire areas. BC was mainly transported in the lowest 3km layer and mainly deposited at night and in the morning hours due to the formation of strong surface temperature inversions. As modelling is the only available source of BC data in Ukraine, our results were compared with ground-level measurements of dust, which showed an increase in concentration of up to 73% during wildfires in comparison to average values. The BC contribution was found to be 10%-20% of the total aerosol mass near the wildfires in the lowest 2km layer. At a distance, BC contribution exceeded 10% only in urban areas. In the areas with a high BC content represented by both accumulation and coarse modes, downwelling surface long-wave radiation increased up to 20Wm-2, and 2m air temperature increased by 1-4°C during the midday hours. The findings of this case study can help to understand the behaviour of BC distribution and possible direct aerosol effects during anticyclonic conditions, which are often observed in mid-latitudes in the summer and lead to wildfire occurrences.Peer reviewe

Climate change scenarios for an assessment of vulnerability of forests in Ukraine in the 21st century

Forests are among the most valuable resources of any country not only as wood, but as a key component of bio-ecological system. Excluding anthropogenic factors, forests are mostly vulnerable by wildfire, droughts, pest invasions, hazardous and extreme weather events, etc. In fact, all these non-anthropogenic impacts could be significantly intensified by projected climate change in the 21st century. That is why future conditions for sustainable forest growth should be evaluated accounting for projected climate change preferably under different scenarios. It is well known that global climate change reveals different regional aspects. Therefore, special scenarios have been elaborated processing data of regional climate models (RCMs) from the FP-6 project ENSEMBLES with spatial resolution of 25 km. Verified over the territory of Ukraine ensembles of 10 RCMs for air temperature and 4 RCMs for precipitation calculated for IPCC scenario A1B, which is characterized by balanced consumption of fossil and renewable energy sources and considered by climate change science as one of most likely future development of the world, were applied. Taking into account that the expected dryness of regional climate could generate major challenges for vulnerability of Ukrainian forests, a modification of A1B scenario that is characterized by increasing temperature and decreasing precipitation (A1B+T-P) was proposed. In overall, the impacts of climate change on Ukrainian forests are diverse dependently upon geographical location, geomorphology and large land forms (mountains, plains), forest types and regimes of forest management. The biggest vulnerability was recognized in forests growing in steppe and southern forest steppe, where there is a high probability of impoverishment, degradation and death of forests over large areas. At the same time, there is also a threat of critical increase of vulnerability in other regions, particularly under more tough scenarios of climate change. The study was supported via the EU-funded ClimaEast project CEEF2015-036-UA “Building capacity for the assessment of vulnerability of Ukraine’s flatland forests to climate change”

Performance Comparison of Linear and Nonlinear Feature Selection Methods for the Analysis of Large Survey Datasets

Large survey databases for aging-related analysis are often examined to discover key factors that affect a dependent variable of interest. Typically, this analysis is performed with methods assuming linear dependencies between variables. Such assumptions however do not hold in many cases, wherein data are linked by way of non-linear dependencies. This in turn requires applications of analytic methods, which are more accurate in identifying potentially non-linear dependencies. Here, we objectively compared the feature selection performance of several frequently-used linear selection methods and three non-linear selection methods in the context of large survey data. These methods were assessed using both synthetic and real-world datasets, wherein relationships between the features and dependent variables were known in advance. In contrast to linear methods, we found that the non-linear methods offered better overall feature selection performance than linear methods in all usage conditions. Moreover, the performance of the non-linear methods was more stable, being unaffected by the inclusion or exclusion of variables from the datasets. These properties make non-linear feature selection methods a potentially preferable tool for both hypothesis-driven and exploratory analyses for aging-related datasets

Кліматичні проекції опалювального періоду в Україні до середини ХХІ сторіччя

The paper presents projections for the balanced scenario A1B of specialized climatic indicators of the heating period for the territory of Ukraine for decades until the middle of the 21st century. Prediction of mean temperature, duration and heating degree-days are based on calculations of the previously formed and adapted to Ukraine ensemble of 10 regional climate models from the European project ENSEMBLES. The main and specialized climatic indicators calculated on all nodes of a regular grid of 25×25 km were verified by E-Obs data for the period 2001―2010. A negligible bias in the heating period mean temperature (in average less than 0.01°C) and an acceptable bias in duration (with a mean value of less than 6,4 days or <4 %) were found in the verification that resulted in obtaining an average bias in heating degree-days by about 4 %. Forecasting of specialized indicators of the heating season for future periods was performed with corresponding bias corrections. The spatial and temporal changes of heating period indices for the decades to the middle of the 21st century have been analyzed and averaging values for administrative units of Ukraine have been calculated. Obtained insignificant, within the limits of 0―0,2 °С, increase of the mean heating period temperature for most of the country in the modern decade of 2011―2020 in relation to the base period of 2001―2010, reducing the heating period duration by an average of 3 days and reducing values of heating degree-days by 2―3 %. By the middle of the 21st century the mean heating period temperature will increase significantly with maximum values of 1,5 °С in the northeastern, central and eastern parts of the country, and the least increasing of 0,8 °С to the south, southwest and the Crimea. The heating period duration will be reduced by 15―18 days in average, with a maximum of 20 days to the south. The values of heating degree-days will decrease in most areas by 12―16 %, with maximum by 20 % in the Crimea, and the minimum reduction by 9―12 % in the Carpathians. Results obtained in the study may be used, primarily, for the calculation of heating costs and other needs of the energy sector and other national economy sectors for the overall development of infrastructure and other needs of any settlement in the territory of Ukraine.В работе представлен прогноз по сбалансированному сценарию А1В специализированных климатических показателей отопительного периода для территории Украины по десятилетиям до середины XXI ст. Прогноз средней температуры, продолжительности и величины градусо-дней составлен на расчетах ансамбля 10 региональных климатических моделей Европейского проекта ENSEMBLES, предварительно сформированного и адаптированного для Украины. Рассчитаные во всех узлах регулярной сетки 25₅25 км основные и специализированные климатические показатели были верифицированы данными Е-Оbs для периода 2001―2010 гг. Обнаружены незначительная погрешность средней температуры отопительного периода, усредненное значение которой на всей территории меньше 0,01 °С, и приемлемая погрешность продолжительности с усредненным значением менее 6,4 дня (<4 %), что в результате позволило получить осредненную погрешность градусо-дней около 4 %. Прогнозирование на будущие периоды специализированных показателей отопительного сезона проводилось с учетом полученных в базовом периоде ошибок. Проанализированы пространственно-временные изменения показателей отопительного периода по десятилетиям к середине XXI ст. и рассчитаны усредненные значения для административных единиц Украины. Получен несущественный, в пределах 0―0,2 °С, рост средней температуры отопительного периода на большей части территории страны в современном десятилетии 2011―2020 гг. относительно базового периода 2001―2010 гг., сокращение продолжительности отопительного периода в среднем на 3 дня и уменьшение величины градусо-дней на 2―3 %. К середине XXI ст. существенно возрастут средние температуры отопительного периода с максимальными приростами в 1,5 °С на северо-востоке, в центре и на Левобережье и наименьшими, до 0,8 °С, — на юге, юго-западе и в Крыму. Продолжительность периода будет сокращаться на 15―18 суток, максимально на 20 суток на юге. Величины градусо-дней уменьшатся на большей части территории на 12―16 %, максимально в Крыму на 20 %, а минимальное снижение получено для Карпат — 9―12 %. Полученные в исследовании результаты можно использовать прежде всего для проведения расчетов расходов энергии на отопление и прочие потребности энергетического сектора, а также других отраслей экономики для общего развития инфраструктуры и разнообразных потребностей любого населенного пункта на территории Украины.У роботі представлений прогноз щодо збалансованого сценарієм А1В спеціалізованих кліматичних показників опалювального періоду для території України по десятиліттях до середини XXI ст. Прогноз середньої температури, тривалості та величини градусо-днів складено на розрахунках ансамблю 10 регіональних кліматичних моделей Європейського проекту ENSEMBLES, попередньо сформованого і адаптованого для України. Розраховані в усіх вузлах регулярної сітки 25₅25 км основні та спеціалізовані кліматичні показники були верифіковані даними Е-Оbs для періоду 2001-2010 рр. Виявлено незначна похибка середньої температури опалювального періоду, усереднене значення якої на всій території менше 0,01 ° С, і прийнятна похибка тривалості з середнім значенням менше 6,4 дня (<4%), що в результаті дозволило отримати осредненную похибка градусо-днів близько 4%. Прогнозування на майбутні періоди спеціалізованих показників опалювального сезону проводилося з урахуванням отриманих в базовому періоді помилок. Проаналізовано просторово-часові зміни показників опалювального періоду по десятиліттях до середини XXI ст. і розраховані усереднені значення для адміністративних одиниць України. Отримано несуттєвий, в межах 0-0,2 ° С, зростання середньої температури опалювального періоду на більшій частині території країни в сучасному десятилітті 2011-2020 рр. щодо базового періоду 2001-2010 рр., скорочення тривалості опалювального періоду в середньому на 3 дні і зменшення величини градусо-днів на 2-3%. До середини XXI ст. істотно зростуть середні температури опалювального періоду з максимальними приростами в 1,5 ° С на північному сході, в центрі і на Лівобережжі та найменшими, до 0,8 ° С, - на півдні, південному заході та в Криму. Тривалість періоду буде скорочуватися на 15-18 діб, максимально на 20 діб на півдні. Величини градусо-днів зменшаться на більшій частині території на 12-16%, максимально в Криму на 20%, а мінімальне зниження отримано для Карпат - 9-12%. Отримані в дослідженні результати можна використовувати перш за все для проведення розрахунків витрат енергії на опалення та інші потреби енергетичного сектора, а також інших галузей економіки для загального розвитку інфраструктури та різноманітних потреб будь-якого населеного пункту на території України

Pharmacokinetic/pharmacodynamic modelling approaches in paediatric infectious diseases and immunology.

Pharmacokinetic/pharmacodynamic (PKPD) modelling is used to describe and quantify dose-concentration-effect relationships. Within paediatric studies in infectious diseases and immunology these methods are often applied to developing guidance on appropriate dosing. In this paper, an introduction to the field of PKPD modelling is given, followed by a review of the PKPD studies that have been undertaken in paediatric infectious diseases and immunology. The main focus is on identifying the methodological approaches used to define the PKPD relationship in these studies. The major findings were that most studies of infectious diseases have developed a PK model and then used simulations to define a dose recommendation based on a pre-defined PD target, which may have been defined in adults or in vitro. For immunological studies much of the modelling has focused on either PK or PD, and since multiple drugs are usually used, delineating the relative contributions of each is challenging. The use of dynamical modelling of in vitro antibacterial studies, and paediatric HIV mechanistic PD models linked with the PK of all drugs, are emerging methods that should enhance PKPD-based recommendations in the future

Modelling imperfect adherence to HIV induction therapy

Abstract Background Induction-maintenance therapy is a treatment regime where patients are prescribed an intense course of treatment for a short period of time (the induction phase), followed by a simplified long-term regimen (maintenance). Since induction therapy has a significantly higher chance of pill fatigue than maintenance therapy, patients might take drug holidays during this period. Without guidance, patients who choose to stop therapy will each be making individual decisions, with no scientific basis. Methods We use mathematical modelling to investigate the effect of imperfect adherence during the inductive phase. We address the following research questions: 1. Can we theoretically determine the maximal length of a possible drug holiday and the minimal number of doses that must subsequently be taken while still avoiding resistance? 2. How many drug holidays can be taken during the induction phase? Results For a 180 day therapeutic program, a patient can take several drug holidays, but then has to follow each drug holiday with a strict, but fairly straightforward, drug-taking regimen. Since the results are dependent upon the drug regimen, we calculated the length and number of drug holidays for all fifteen protease-sparing triple-drug cocktails that have been approved by the US Food and Drug Administration. Conclusions Induction therapy with partial adherence is tolerable, but the outcome depends on the drug cocktail. Our theoretical predictions are in line with recent results from pilot studies of short-cycle treatment interruption strategies and may be useful in guiding the design of future clinical trials

A Stochastic Model of Latently Infected Cell Reactivation and Viral Blip Generation in Treated HIV Patients

Motivated by viral persistence in HIV+ patients on long-term anti-retroviral treatment (ART), we present a stochastic model of HIV viral dynamics in the blood stream. We consider the hypothesis that the residual viremia in patients on ART can be explained principally by the activation of cells latently infected by HIV before the initiation of ART and that viral blips (clinically-observed short periods of detectable viral load) represent large deviations from the mean. We model the system as a continuous-time, multi-type branching process. Deriving equations for the probability generating function we use a novel numerical approach to extract the probability distributions for latent reservoir sizes and viral loads. We find that latent reservoir extinction-time distributions underscore the importance of considering reservoir dynamics beyond simply the half-life. We calculate blip amplitudes and frequencies by computing complete viral load probability distributions, and study the duration of viral blips via direct numerical simulation. We find that our model qualitatively reproduces short small-amplitude blips detected in clinical studies of treated HIV infection. Stochastic models of this type provide insight into treatment-outcome variability that cannot be found from deterministic models