Frost Days Research Articles

Spatio‐temporal changes in the mean and extreme temperature indices for Serbia

AbstractThis study provides a comprehensive analysis of changes in mean and extreme temperature indices for Serbia using a high‐resolution daily gridded temperature data set during the period of 1951–2020. The annual and seasonal trends of the indices in the gridded fields were computed and tested for statistical significance using the nonparametric Mann–Kendall test and the Sen's slope estimator. The t‐test was applied to check the stability of means of temperature indices between two standard periods (1961–1990 and 1991–2020). A correlation analysis was used in order to investigate the connections of the large‐scale circulation patterns and the mean and extreme temperature indices. Results showed that a warming trend dominated for the last 70 years, with slightly more intense changes for the mean maximum temperatures (TXM) than for the mean minimum temperatures (TNM). An increase was recorded for indices based on the maximum temperature (TXM, hottest days, warm days, summer days) and minimum temperature (TNM, coldest nights, warm nights, tropical nights). The highest increase was observed for warm nights (7 days⋅decade−1) during the summer season. The negative change in cool days (−1.5 days⋅decade−1) and cool nights (−2 days⋅decade−1) was recorded in almost all seasons, being significant for the both annual and summer values. The correlation between the temperature indices and large‐scale circulation patterns revealed that the East Atlantic (EA) pattern had a highly positive correlation with warm temperature indices (hottest days, warm days, warm nights, summer days, and tropical nights) and a negative correlation with cold indices (coldest nights, cool days, cool nights, frost days, and ice days). The North Atlantic Oscillation, the most important teleconnection pattern during the winter months in Europe, had weaker influence on temperature indices in Serbia than the EA pattern, but stronger than the EA/Western Russia pattern.

Disaster event-based spring frost damage identification indicator for tea plants and its applications over the region north of the Yangtze River, China

Spring frost damage (SFD) is the main meteorological disaster limiting the tea industry in the region of the north of the Yangtze River (NYR) in China. Research regarding an SFD indicator for tea plants is of great significance for prevention and control of spring frosts, as well as for timely monitoring and early warning. Based on daily minimum air temperatures (Tmin) and spring frost disaster records in NYR from 1961 to 2020, the Receiver Operating Characteristic curve (ROC) was used to evaluate the accuracy of frost identification, and the critical temperature threshold for SFD to tea plants was determined by jointly comparing Overall Accuracy and the Youden Index. The results showed that the area under the ROC curve was 0.977, indicating that Tmin performed well in identifying frost events. The critical temperature threshold for spring frost in NYR was determined as Tmin of 3.7 °C, and 93 % of frost occurrences were correctly identified. Based on the determined critical threshold of SFD, the number of spring frost days, first frost date (FFD), and last frost date (LFD) in NYR from 1961 to 2020 were analyzed. The results showed that the number of spring frost days in NYR decreased from north to south. FFD appeared earlier and LFD ended later in northern NYR than in southern NYR. These results provide theoretical and technical support for the monitoring and evaluation of spring frosts in NYR, and also for implementing SFD prevention and control measurements for tea plants by use of a critical temperature threshold.

Surviving on the edge: present and future effects of climate warming on the common frog (Rana temporaria) population in the Montseny massif (NE Iberia).

The Montseny massif shelters the southernmost western populations of common frogs (Rana temporaria) that live in a Mediterranean climate, one which poses a challenge for the species' persistence in a scenario of rising temperatures. We evaluated the effect of climate change at three levels. First, we analysed if there has been an advancement in the onset of spawning period due to the increase in temperatures. Second, we analysed the impact of climatic variables on the onset of the spawning period and, third, how the distribution of this species could vary according to the predictions with regard to rising temperatures for the end of this century. From 2009 to 2021, we found there had been an increase in temperatures of 0.439 °C/decade, more than the 0.1 °C indicated by estimates for the second half of the previous century. We found an advancement in the onset of the reproduction process of 26 days/decade for the period 2009-2022, a change that has been even more marked during the last eight years, when data were annually recorded. Minimum temperatures and the absence of frost days in the week prior to the onset of the spawning period determine the start of reproduction. Predictions on habitat availability for spawning provided by climatic niche analysis for the period 2021-2100 show a potential contraction of the species range in the Montseny and, remarkably, much isolation from the neighbouring populations.

Pest categorisation of Nipaecoccus viridis.

The EFSA Panelon Plant Health performed a pest categorisation of Nipaecoccus viridis (Hemiptera: Sternorrhyncha: Pseudococcidae), the spherical scale, for the EU. It is of Asian origin and occurs widely in southern Asia, Africa and tropical Australia. It has been introduced to a few countries in the Americas. In the Mediterranean basin it is found in Algeria, Egypt, Israel, Syria and Turkey, where it is limited to the Marmara region. It has not been reported within the EU. It is not listed in Annex II of Commission Implementing Regulation (EU) 2019/2072. It reproduces sexually, has three generations each year in citrus orchards in South Africa, and all stages can overwinter. First instar nymphs may move to neighbouring plants by crawling or be passively dispersed by wind or hitchhiking on clothing, equipment or animals. It is highly polyphagous, feeding on plants in 115 genera and 46 families. It is an important pest of citrus (Citrus spp.), cotton (Gossypium spp.), mango (Mangifera indica), avocado (Persea americana) and stored potatoes (Solanum tuberosum). It also feeds on a wide range of other fruit (apple Malus domestica, olive Olea europea, pear Pyrus communis and grape Vitis vinifera) and vegetable crops (tomato Solanum lycopersicum), and ornamental plants (roses, Rosa spp.) that are widely grown in the EU. Plants for planting, fruits, vegetables, and cut flowers are the main potential pathways for entry of N. viridis into the EU. Climatic conditions and availability of host plants in southern parts of the EU where there are few days of frost each year would likely allow this species to successfully establish and spread. Reductions in yield and quality of cultivated hosts including avocado, citrus, cotton and mango is anticipated if establishment occurs. Phytosanitary measures are available to reduce the likelihood of entry and spread. N. viridis meets the criteria that are within the remit of EFSA to assess for this species to be regarded as a potential Union quarantine pest.

Pest categorisation of Icerya aegyptiaca.

The EFSA Panelon Plant Health performed a pest categorisation of Icerya aegyptiaca (Hemiptera: Sternorrhyncha: Monophlebidae), the Egyptian fluted scale, for the EU. This insect is established in several countries in tropical and subtropical regions of the world. Within the EU, the pest has not been reported. It is not listed in Annex II of Commission Implementing Regulation (EU) 2019/2072. It is highly polyphagous, feeding on plants in 128 genera and 66 families, with some preference for avocado (Persea americana), banana (Musa sp.), citrus (Citrus spp.), coconut (Coccos nucifera), common pear (Pyrus communis), fig (Ficus spp.), guava (Psidium guajava), maize (Zea mays), mango (Mangifera indica), white mulberry (Morus alba), and grapevine (Vitis vinifera). It has also been recorded feeding on tomato (Solanum lycopersicum), as well as on ornamental plants. Plants for planting and fruits, vegetables and cut flowers are the main potential pathways for entry of I. aegyptiaca into the EU. Climatic conditions and availability of host plants in parts of the EU where there are very few days of frost each year would likely allow this species to successfully establish and spread. Economic impact in cultivated hosts including citrus, grapes, maize, peppers, sunflowers, tomatoes and ornamental crops is anticipated if establishment occurs. Phytosanitary measures are available to reduce the likelihood of entry and spread. I. aegyptiaca meets the criteria that are within the remit of EFSA to assess for this species to be regarded as a potential Union quarantine pest.

Grapevine Yield Big-data for Soil and Climate Zoning. A case study in Languedoc-Roussillon, France

New winegrower and resource datasets appear to be a great opportunity to understand which are the environmental factors involved in grapevine yield spatially. Such analysis can help regional label managers and winegrowers for the conception of local adaptation strategies to climate change, reducing yield gaps. In the present study, we aggregated yield a big dataset obtained from Pays d’Oc winegrowers (n = 96677) between 2010 and 2018 at the municipality level (n = 606), located in the Languedoc-Roussillon region, in the South of France. We used a backward stepwise model selection process using linear mixed-effect models to discriminate and select significant indicators capable of estimating grapevine yield at the municipality level, these include: Soil Available Water Capacity (SAWC), soil pH, Huglin Index, the Climate Dryness Index, the number of Very Hot Days and Days of Frost. We then determined spatial zones by creating clusters of municipalities with similar soil and climate characteristics. The seven zones presented two marked yield levels. Yet, all zones had municipalities with both high yield and high yield gaps. On each zone, grapevine yield was found to be driven by a combination of climate and soil factors, rather than just by a single environmental factor. Environmental factors at this scale largely explained yield variability across the municipalities, but they were not performant in terms of annual yield prediction. Further research is required on the interactions between environmental factors, plant material and farming practices.

Effect of organic fertilizers in growing alfalfa for seed and forage

To have a high yield of alfalfa planted in autumn, it is necessary to ensure that the seeds germinate in a short period of time, and to create optimal conditions for the rapid growth of sprouts. Then the alfalfa grows up to 30 cm, takes root well, and becomes strong until the frost days. Until recently, low-yielding local varieties were planted in our republic, but now, as a result of scientific research in the field of alfalfa, a number of high-yielding, protein-rich, alfalfa varieties suitable for the conditions of each region have been established in comparison to local varieties. adapted varieties have been created. Alfalfa has a great agrotechnical and amelioration value, it is a good predecessor of most crops. The experiment consists of five variants and four iterations. During the experiment autumn was selected as a plantim time, and besides, 16kg/ha of seeds were sown in the field, where fertilizers at different level were applied in the various variant. The results showed that the highest yield was in the variants with Sila Silicon, accounted for 89-101.5 q/ha additional crop yield.

Accelerated multiphase water transformation in global mountain regions since 1990

<p>Mountains are sensitive to climate change, and while amplified warming at high elevations is widely observed and fairly well understood, changes in the water cycles of mountain regions remain poorly quantified. Due to low temperatures at higher elevations, these changes involve multiphase water transformation (MWT). Through analyzing extensive data from global mountain regions, we determined that under the accelerating warming and lengthening ablation period since the 1990s, the strengthening solid�Cliquid transformation can be confirmed for 45 glacier basins or single glaciers. This is marked by an increase of 21.5 km<sup>2</sup>/10a in glacier area retreat rate, 387.65 mm for average negative glacier mass balance, and 60 m/10a for average glacier length retreat rate (of 414 glaciers) from the study period before the 1990s until the period after the 1990s. The accelerating liquid�Csolid transformation was indicated by an increase of 31.2 d/10a for the delaying trend of complete freeze time, an increase of 4.3 d/10a for the advancing trend of complete melting time, and an increase of 3.9 d/10a for the decreasing trend of ice cover duration for 22 lakes from the period before the 1990s until the period after the 1990s. The accelerating liquid�Cgas transformation can be confirmed by an increase of 1 and 0.69 mm/d/10a in the variation trend of actual evaporation and bare-soil evaporation from 1980�C1990 to 1990�C2017, respectively. Snow sublimation decreased by 0.69 mm/d/10a during 1980�C1990, followed by a statistically significant increase of 1.66 mm/d/10a during 1990�C2017, further confirming the accelerating solid�Cgas transformation. The accelerating gas�Csolid transformation can be reflected by an increase of 0.3 d/10a for the decreasing trend of frost days from 1960�C1990 to 1990�C2017. The moisture recycling ratio decreased by �C0.042 %/10a during 1980�C1990 and then increased by 0.443 %/10a during 1990�C2017, with the corresponding average values of 12.3% and 13.6%, respectively, which indicates an accelerating gas�Cliquid transformation. Approximately 59 rivers displayed an increase of 108.60 m<sup>3</sup>/s/10a for the runoff variation trend from the period before the 1990s until the period after the 1990s. In addition, the trends for lake number and lake area in the Tibetan Plateau increased 3.86 and 5.75 times, respectively, from 1976�C1995 to 1995�C2019. This acceleration can significantly change the spatiotemporal pattern of water resources and increase the frequency and intensity of disaster events, such as glacial lake outbursts, flooding, and waterlogging. Consequently, most mountain regions will require strong adaptation efforts to sustain water, food, and ecological security.</p>

Annual Electricity and Energy Consumption Forecasting for the UK Based on Back Propagation Neural Network, Multiple Linear Regression, and Least Square Support Vector Machine

The long-term demand forecast for annual national electricity and energy consumption plays a vital role in future strategic planning, power system installation programming, energy investment planning, and next-generation unit construction. Three machine learning algorithms of BP-NN, MLR, and LS-SVM were chosen for training forecasting models, with the data on population, GDP, mean temperature, sunshine, rainfall, and frost days in 1993–2019 serving as the input variables. The total data were divided by 70% into the training set (1993–2011) and 30% into the test set (2012–2019), in chronological order. RMSE, MAPE, and MaxError were adopted as the performance criteria. The statistical results show that the gross population of the UK increases year by year from 1993 to 2020. The GDP generally increases before 2007 but has a decline, and then varies with a large amplitude afterward. The electricity and energy consumption of the UK generally increase from 1993 and reach a peak around 2005. Afterward, a decline occurs basically year by year until 2019. The simulation results reveal that all three models predict well on the training set but have some overestimation on the test set. The LS-SVM model has the best forecasting performance among the three models on the training set. The results show that it is feasible to use machine learning algorithms to predict the future electricity and energy consumption of a country based on past economic and livelihood data. In this way, economic decision-makers can rely on the predicted values to make a well-founded layout for future energy construction and investment to avoid waste or a shortage of resources.

Spatiotemporal Evolution of Seasonal Crop-Specific Climatic Indices under Climate Change in Greece Based on EURO-CORDEX RCM Simulations

This study presents an updated assessment of the projected climate change over Greece in the near future (2021–2050) and at the end of the 21st century (2071–2100) (EOC), relative to the reference period 1971–2000, and focusing on seasonal crop-specific climatic indices. The indices include days (d) with: a maximum daily near-surface temperature (TASMAX) > 30 °C in Spring, a TASMAX > 35 °C in Summer (hot days), a minimum daily near-surface temperature (TASMIN) < 0 °C (frost days) in Spring, a TASMIN > 20 °C (tropical nights) in Spring–Summer and the daily precipitation (PR) > 1 mm (wet days) in Spring and Summer covering the critical periods in which wheat, tomatoes, cotton, potato, grapes, rice and olive are more sensitive to water and/or temperature stress. The analysis is based on an ensemble of 11 EURO-CORDEX regional climate model simulations under the influence of a strong, a moderate, and a no mitigation Representative Concentration Pathway (RCP2.6, RCP4.5 and RCP8.5, respectively). The indices related to TASMAX are expected to increase by up to 11 days in Spring and 40 days in Summer, tropical nights to rise by up to 50 days, frost days to decrease by up to 20 days, and wet days to decline by up to 9 days in Spring and Summer, at the EOC with an RCP8.5. The increased heat stress and water deficit are expected to have negative crop impacts, in contrast to the positive effects anticipated by the decrease in frost days. This study constitutes a further step towards identifying the commodities and/or regions in Greece which, under climate change, are or will be significantly impacted.

Climate change impacts on long-term field experiments in Germany

CONTEXTLong-Term Field Experiments (LTEs) were implemented to study the long-term effects of different management practices, including tillage, fertilization and crop rotation under otherwise constant conditions. Climate change is expected to change these conditions, challenging interpretation of LTE data with regard to the distinction between climate change and management effects. OBJECTIVEThe objective of the study was to quantify the expected, spatially differentiated changes of agroclimatic conditions for the German LTE sites as a precondition for modelling and LTE data interpretation. METHODSWe developed a framework combining spatially distributed climate data and LTE metadata to identify the possible climatic changes at 247 LTE sites with experiments running for 20 years or more. The LTEs were classified using the following categories: fertilization, tillage, crop rotation, field crops or grassland, conventional or organic. We utilized climate variables (temperature, precipitation) and agroclimatic indicators (aridity, growing degree days, etc.) to compare a baseline (1971–2000) with future periods (2021−2100) under the IPCC's Shared Socio-economic Pathways (SSP). A comprehensive LTE risk assessment was conducted, based on changes in climate variables and agroclimatic indicators between baseline and future scenarios. RESULTS AND CONCLUSIONSUnder the most extreme scenario (SSP585), 150 LTEs are expected to shift from humid and dry sub-humid to semi-arid conditions. Frost days in LTE areas are expected to decline by 81%, and the growing season to lengthen by up to 92%. The spatial differentiation of expected climate change also facilitates the identification of suitable sites for future agricultural practices and may inform the design of new LTEs. SIGNIFICANCEOur results may guide the interpretation of LTE data regarding the effect of climate change, facilitating future soil crop modelling studies with LTE data and providing information for planning new LTE sites to support future agricultural research and/or adapting management on existing LTE sites. The framework we developed can easily be transferred to LTE sites in agricultural regions worldwide to support LTE research on climate change impacts and adaptation.

Trends in Air Temperature and Precipitation in Southeastern Czech Republic, 1961-2020

This study presents a summary of sixty years of air temperature and precipitation measurements at the Žabčice weather station, located in the southeastern Czech Republic and operated by Mendel University in Brno. An instrumental dataset spanning two climatological normal periods (1961- 1990 and newly established 1991-2020) is analyzed for long term linear trends with monthly data presented in full span in Appendices. In the new climate normal period, the mean annual temperature increased from 9.3 °C to 10.3 °C with growing trend of 0.34 °C/10 years (p < 0.001). Every calendar month of year is warmer, with the highest and fastest increase in August (+2.0 °C, 0.64 °C/10 years, p < 0.001) and the lowest in October (+0.2 °C). Annual precipitation sum increased negligibly (+11.1 mm), however, the quarterly distribution significantly changes towards drier second quarter (-22.9 mm, p < 0.05) and wetter third quarter (+37.1 mm, p < 0.05). Number of tropical days (maximum daily air temperature > 30 °C) significantly increased (+4.44/10 years, p < 0.001), whereas number of frost days is negligibly decreasing (-0.88/10 years). Temperature derived Huglin index for vineyards increased by 369 °C to a seasonal sum 2062 °C (+84 °C/10 years, p < 0.001). This study provides evidence of the rate of changing climate at this southern Moravia lowland site. This study provided a summary and trend analysis of instrumental air temperature and precipitation dataset measured at Žabčice locality during the period 1961-2020, supplemented with selected agroclimatic indices. The dataset was utilized to establish a new climatological normal for the period 1991-2020 and both normal periods 1961-1990 and 1991-2020 were compared. We can conclude, that the mean air temperature is increasing on monthly, quarterly and yearly timescales. The fastest warming trend was observed during the growing season, peaking in June-August. There is an evident increase in extreme heat waves and other temperature-related indices, such as the Huglin index, suggesting a further rise in air temperature in the near future. Annual precipitation sums increased negligible, however, we can confirm a change in temporal distribution on an annual scale, in terms of decrease in the second quarter and increase in the third quarter. Supported by the Ministry of Education, Youth and Sports of the Czech Republic for the project SustES - Adaptation Strategies for the Sustainability of Ecosystem Services and Food Security in Adverse Natural Conditions, Project No. CZ.02.1.01/0.0/0.0/16_019/0000797, and by the National Agency for Agricultural Research, Ministry of Agriculture of the Czech Republic, Project No. QK1910338 "Early warning agrometeorological system for biotic and abiotic risks".

Experimental thermo-hydric study to simulate natural weathering conditions

• Development of an experimental setup realistically reproducing thermo-hydric strain. • Estimation and localization of the generated thermo-hydric stress. • Comparison of stones through the assessment of long-term stone weathering. Laboratory aging tests allow to indirectly study stones behaviors on a monument. Classic aging tests are designed to compare materials resistance to different weathering mechanisms: they are more intense than the on-site conditions and do not reflect the real weathering intensity and kinetics. To study the real weathering on a monument and the materials behavior, an experimental setup using realistic experimental conditions was designed. The stones of a monument in Reims (France) were studied through this experimental setup: the Courville limestone (original stone) and the Savonnières limestone (restoration stone). The environmental variations were taken into account through a previous climatic monitoring of the monument. The realistic experimental setup was designed to reproduce, in a stone sample, the thermal and hydric strains experienced by a stone on a vertical wall. Temperature and humidity variations were applied unidirectionally through one surface, defined as the exposed surface. The temperature and humidity variations were based on typical variations identified with an in-situ monitoring of the basilica: sunny day, cold and warm rainy days, and frost day. The mild conditions, similar to the on-site conditions, did not visibly damage the samples and their behavior was studied through temperature and strain variations. The Courville limestone appeared more sensitive to the thermo-hydric variations of the typical days, particularly by the presence of water in the porous network than the Savonnières. Water generated high stress in the wet layer due to hydric expansion and at the wet/dry interface due to strain difference. Furthermore, the ice formation in the wet layer could induce high stress. On the contrary, the Savonnières limestone did not appear sensitive and little to no stress was generated during the typical days. The realistic setup allowed a simulation of the temperature and water repartitions in the samples close to on-site conditions. It provided relevant information in this specific environment and could help anticipate stone weathering on the monument.

Late frost protection – what to retain from the Champagne experience?

With the occurrence of frost, sensitive plants are susceptible to damage. One of the most counter-intuitive impacts of climate change is the increasing frequency of spring frost. Studies have warned of this problem (Inouye, 2008), describing an earlier budburst due to higher temperatures during winter and the last day of frost remaining around the same date. The risk of polar jet stream destabilisation by quick warming has also been mentioned (Molitor et al., 2014). Since 2016, Western European vineyards have suffered from frost damage almost every year (Rochard et al., 2019).

Climate change threats to cultural and natural heritage UNESCO sites in the Mediterranean

The study presents a time-dependent analysis of threats from man-made climate change at 244 UNESCO cultural and natural heritage sites in the Mediterranean. The hazards in our research are estimated by indices based on extremes of heat, fire weather conditions, heavy rainfall days, frost days, changes in mean sea level and aridity at each site. These indices were calculated from regional EUROCORDEX simulations, cover the period 1971–2100 and refer to two IPCC emission scenarios, namely RCP4.5 and RCP8.5. A combined threat index was next calculated, as explained in the text, together with its synergy with local exposure geophysical threats, such as seismicity, topography and proximity to forests and seas. All indices related to man-made climate change show an overall increasing trend from present to the end of the twenty-first century. Some of these increasing trends are intensified after the 2030s and 2040s, except for the case of the days with frost. As the global warming evolves, in both IPCC scenarios studied, the combined threat to the majority of UNESCO sites studied increases. Notable is the amplification of the threat at sites vulnerable to seismic activity and to other local or regional topography and geophysical regional characteristics. Our conclusion is that the majority of heritage sites in the Mediterranean are vulnerable to an increasing rate of threats from man-made global warming and extreme events. Seismic activity is magnifying these threats only at the sites in which that additional hazard applies. Based on the proposed combined threat index, for the worst-case scenario (RCP8.5) 35 monument sites fall within the “high hazard” and 12 sites fall under the category “extreme hazard”.

Spatiotemporal Changes in Frost Indicators in Southeastern Spain (1950–2020): Influence of the East Atlantic Index (EA)

Abstract The southeastern interior of the Iberian Peninsula (Spain) is characterized by a complex orography, which determines a pronounced altitudinal gradient, significant slopes, and marked valleys with important temperature inversion processes. In this work, to analyze the yearly and seasonal evolution of minimum temperatures, six indicators related to minimum temperatures were used: the frost days (FD) and number of days with minimum temperature below −2°C (TNltm2), 10th temperature minimum percentile (TN10p), absolute minimum temperatures (TNn), average minimum temperatures (TNm), and cold-spell duration index (CSDI). For this, the Spearman nonparametric statistical test was used to analyze data from a total of 22 meteorological stations (1950–2020), using a daily resolution of minimum temperatures. Significant changes during the study period were revealed, especially between the 1960s and 1990s. In most cases, there has been a statistically significant increase in the minimum temperatures in the study area, except in the western (most mountainous) part, where the dynamics differed from the rest of the interior of the southeast of the peninsula. Nine large global teleconnection patterns were analyzed in relation to the average minimum temperatures in the study area. These are well-characterized indices for the Northern Hemisphere, which show a very high correlation of the average minimum temperatures with the temporal evolution of the global climate pattern of the east Atlantic (EA) index, especially in the Mediterranean region of the Iberian Peninsula, where it seems to have a very marked influence. Significance Statement We analyzed variation in observed minimum temperatures during 1950–2020 in inland southeastern Spain. Temporal analysis of “east Atlantic index” cycles and their interrelation with frost days and minimum temperatures is very relevant for seasonal meteorological prediction in the study area, where agroindustry represents 20% of GDP. The results show a significant decrease in frost days and an increase in average minimum temperature, especially in coastal and prelittoral areas. The variations are less important mountainous western areas, where frost days have even increased. This is explained by a change in the atmospheric dynamics in midlatitudes of the Atlantic Ocean, quantified by the east Atlantic global teleconnection index, which has a high statistical correlation with Spanish minimum temperatures, especially in winter.

Frost Conditions Due to Climate Change in South-Eastern Europe via a High-Spatiotemporal-Resolution Dataset

Frost incidents comprise significant extreme weather events owing to climate change, possibly endangering the agricultural sector of the already impacted south-eastern European area. Thus, the comprehensive evaluation of the frost conditions under the climate regime for eleven countries was conducted by calculating relevant frost agroclimatic indicators under three time horizons (1985 to 2015, 2005 to 2035 and 2015 to 2045). The Frost Days (FD), Free of Frost Days (FFD), Last Spring Frost (LSF) and First Autumn Frost (FAF) were estimated daily over a grid of 25 × 25 km. We demonstrated that the FD will be reduced according to the balanced A1B emissions scenario over the entire examined area with the mountainous and continental regions being most affected. From 2005 to 2035, a higher LSF reduction is expected over Greece and Albania and the earlier FAF in high altitude areas. All examined regions are projected to face delayed FAF, from 2015 to 2045. In general, all countries will face an increase in the growing season duration owing to the increase of the FFD.

Analysis of Frost Probabilities in Aydın, Türkiye

Frost events are of particular importance for plants. Its occurrence determines growing season. Early or late frost events may cause injuries and damage in plants which have not yet entered dormancy in fall/winter, and for plants in flowering period in winter/spring. Global average temperature increase has been accompanied by changes in extreme temperature events. Observations have shown that there has been a decreasing pattern in frequencies and intensities of frost events. In this sense, it is aimed in this study to analyse probabilities of frost occurrences within the latest 30-year climatic normal period, from the cold period of 1991-1992 to that of 2020-2021, at five locations (Aydın, Kuşadası, Nazilli, Söke ve Sultanhisar) in the province Aydın, western Türkiye. Six frost indices were selected, and three temperature thresholds to define frost were considered when daily minimum temperature (TMIN) being equal to or less than 0.0, -1.2 or -2.3°C.The selected frost indices are first fall frost (FFF), last spring frost (LSF), frost period (FP), number of frost days (NFD), dates of frost occurrences (DFO) and consecutive frost days (CFD). The results revealed that Nazilli and Sultanhisar are characterized by the highest probabilities of frost in terms of frequency, intensity and duration, along with the earliest occurrence of first fall frost and latest occurrences of last spring frost, and with longest duration of frost period. On the other hand, Kuşadası and Söke have opposite characteristics in comparison to Nazilli an Sultanhisar. Aydın lies in between them. The results are expected to provide information to schedule the agricultural activities, and to avoid detrimental impacts of frost events.

Changes in temperature and precipitation extremes in the arid regions of China during 1960–2016

Extreme climate events have a greater impact on natural and human systems than average climate. The spatial and temporal variation of 16 temperature and nine precipitation extremal indices was investigated using the daily maximum and minimum surface air temperature and precipitation records from 113 meteorological stations in China’s arid regions from 1960 to 2016. The warmth indices [warm spell duration (WSDI); numbers of warm nights, warm days, tropical nights (TR), and summer days (SU)] increased significantly. On the contrary, the cold indices [numbers of frost days (FD), ice days (ID), cool days, and cool nights; cold spell duration (CSDI)] decreased significantly. The number of FD decreased fastest (−3.61 days/decade), whereas the growing season length (GSL) increased fastest (3.17 days/decade). The trend was strongest for diurnal temperature range (DTR) (trend rate = −7.29, P < 0.001) and minimum night temperature (trend rate = 7.70, P < 0.001). The cold extreme temperature events increased with increasing latitude, but the warm extreme temperature events decreased. Compared with temperature indices, the precipitation indices exhibited much weaker changes and less spatial continuity. Overall, changes in precipitation extremes present wet trends, although most of the changes are insignificant. The regionally averaged total annual precipitation for wet days increased by 4.78 mm per decade, and extreme precipitation events have become more intense and frequent during the study period. The spatial variability of extreme precipitation in the region was primarily influenced by longitude. Furthermore, the climate experienced a warm-wet abrupt climate change during 1990s.

Climate induced phenological shifts in pears – A crop of economic importance in the UK

Phenological advancements in flowering have been well documented in many food crop, ornamental, and native plant species. However, there is lack of information on how flowering times in crop species, especially fruit trees will react to future climate scenarios. This is important as changes in phenology could have significant implications for ecosystem services and function, biological interactions and agronomic outputs. Using 60 years of data from pear (Pyrus communis L.) orchards in two research organisations in Kent, UK we explored temporal changes in flowering phenology, identified the weather variables driving this change, and predicted how flowering times may be altered by 2080 with respect to future emissions scenarios. We show pear flowering (1990–2020) in the last 30 years has advanced 11.44 days compared to historical data (1960–1989). Furthermore, we highlight this advancement is apparent in all twelve pear cultivars and the four phenological stages analysed, including Conference, the most common UK pear cultivar. Our results indicate that this advancement in flowering began after 1982; that air temperature and frost days significantly impact pear flowering; and this change in flowering phenology is likely to continue under future climate scenarios. Four Representative Concentration Pathways from the UK Climate Projections 2018 report were used to model the impact of future climate, including low, medium, medium-high and high emission scenarios. Under all scenarios a phenological advancement in flowering time was predicted by 2080 with the greatest advancement in flowering time observed under the high emission scenario. Earlier flowering and budburst could result in phenological mismatches between plant and pollinators, alter agricultural spraying regimes, increase risk of frost exposure and exacerbate impacts of pest populations within an agroecosystem, thus it is vital to monitor advancements in flowering phenology.