Mean Winter Temperature Research Articles

The Roles of Climate Extremes, Ecological Succession, and Hydrology in Repeated Permafrost Aggradation and Degradation in Fens on the Tanana Flats, Alaska

AbstractThe Tanana Flats in central Alaska are a hot spot for thermokarst that is rapidly transforming the landscape. Time series analysis of high‐resolution imagery showed that permafrost degradation increased the area of three large fens by 26% from 1949 to 2018, but surprisingly permafrost also aggraded in small areas. Permafrost soils in adjacent birch forests frequently had fen peat near the surface indicating recent permafrost degradation and aggradation. We attribute groundwater as the primary driver of recent permafrost degradation, while climate extremes (especially cold, less snowy winters) caused recent permafrost aggradation, but only after ecological succession provided conditions favorable for permafrost formation. Near‐surface groundwater temperatures during early winters (2–6°C during 2011–2014) contributed to a near steady rate of lateral permafrost degradation (0.36 m/yr) over three periods. Fairbanks climate records (1904–2019) showed large ranges in mean winter temperatures (12°C) and snow depths (69 cm) between cold, less snowy winters and warm, snowy winters. During ecological succession from the collapsing margins to the fen centers over a ~250‐yr period, vegetation transitioned from aquatic forbs to shrubs and mosses, water depths decreased, and the soil carbon stock of new peat increased. These interactions among permafrost, groundwater, climate warming, and succession complicate our ability to project future ecological transitions and soil carbon changes across this dynamic boreal lowland landscape. The more frequent warm, snowy winters since 2014 and model projections for warmer winters, however, indicate that the region has crossed a tipping point where permafrost will no longer form and permafrost loss is irreversible.

Warming winters threaten peripheral Arctic charr populations of Europe

As the global climate warms, the fate of lacustrine fish is of huge concern, especially given their sensitivity as ectotherms to changes in water temperature. The Arctic charr (Salvelinus alpinus L.) is a salmonid with a Holarctic distribution, with peripheral populations persisting at temperate latitudes, where it is found only in sufficiently cold, deep lakes. Thus, warmer temperatures in these habitats particularly during early life stages could have catastrophic consequences on population dynamics. Here, we combined lake temperature observations, a 1-D hydrodynamic model, and a multi-decadal climate reanalysis to show coherence in warming winter water temperatures in four European charr lakes near the southernmost limit of the species’ distribution. Current maximum and mean winter temperatures are on average ~ 1 °C warmer compared to early the 1980s, and temperatures of 8.5 °C, adverse for high charr egg survival, have frequently been exceeded in recent winters. Simulations of winter lake temperatures toward century-end showed that these warming trends will continue, with further increases of 3–4 °C projected. An additional 324 total accumulated degree-days during winter is projected on average across lakes, which could impair egg quality and viability. We suggest that the perpetuating winter warming trends shown here will imperil the future status of these lakes as charr refugia and generally do not augur well for the fate of coldwater-adapted lake fish in a warming climate.

Pervasive tree-growth reduction in Tibetan juniper forests

Recent forest declines have been reported at many sites across the world and attributed largely to global-warming induced droughts. Occurrence of forest declines before the global warming is not well understood, especially with regard to its long-term characteristics. Here, we use tree-ring data to detect periods of growth reduction in 1429 juniper trees from 48 sites on the Tibetan Plateau (TP). We find that tree-growth reduction has occurred intermittently and dispersedly over the TP in the past 350 years. The growth reductions among trees could be synchronized at site level in different time, reflecting episodes of decreased forest health. Tree-growth reduction has been alleviated since the 1980s; sites that do show growth reduction events in recent decades are located at higher elevations and are more sensitive to winter mean temperature. We conclude that the pervasive tree-growth reductions may be related to irregular natural disturbances than climatic anomalies. The state of forest health can be estimated by identifying episodes of synchronous tree-growth reduction. Our findings help account for historical growth reduction in the assessment of forest health risks under future climate change.

What is a possible response of forest biomass to changes in Eurasian air temperature and precipitation? A special case for the genus Betula spp

Forest ecosystems, as sinks of atmospheric carbon, play an important role in reducing greenhouse gas release and preventing air temperatures from rising. Simultaneously, climate change entails changes in forest cover. We describe the change of Betula spp. stand biomass (tha-1) along the trans-Eurasian gradients of rainfall and temperature using the harvest data from 650 forest stands and climate data. Birch stand biomass increased with growing rainfall within the evaluated range from 200 to 800 mm per year, as well as with increasing the mean winter temperature from -40°C to + 10°C regardless of the rainfall level. The comparison of our results for birches with analogous results for coniferous species shows that forest responses to changes in climate indices are species-specific.

Are There Differences in the Reaction of the Light-Tolerant Subgenus Pinus spp. Biomass to Climate Change as Compared to Light-Intolerant Genus Picea spp.?

Currently, the problem of the impact of climate change on the productivity of forest ecosystems and their carbon-depositing capacity is far from being solved. Therefore, this paper presents the models for the stand biomass of the two-needled subgenus’ (Pinus spp.) and the genus Picea spp.’s trends along the trans-Eurasian hydrothermal gradients, designed for pure stands in a number of 2110- and 870-sample plots with Pinus and Picea correspondingly. It was found that in the case of an increase in mean winter temperatures by 1 °C, pine and spruce respond by increasing the biomass of most components, and in the case of an increase in the annual sum of precipitation by 100 mm, the total, aboveground, stem and root biomasses of pine and spruce react the same way, but crown biomass reacts in the opposite way. Therefore, all identified trends are species-specific.

Modulations of North American and European Weather Variability and Extremes by Interdecadal Variability of the Atmospheric Circulation over the North Atlantic Sector

AbstractThe dominant mode of wintertime interdecadal covariability between subseasonal surface air temperature (SAT) variability and midtropospheric circulation over the North Atlantic sector is identified through maximum covariance analysis applied to century-long reanalysis data. This mode highlights a tendency for subseasonal temperature variability over Europe and eastern North America to be enhanced during decades when the negative phase of the North Atlantic Oscillation (NAO) prevails. This interdecadal NAO is characterized by a stationary Rossby wave train that originates from the subtropical Atlantic, propagates northward into the subpolar Atlantic, and finally refracts toward Europe and the Middle East. A decadal increase in precipitation in the subtropics under the enhanced supply of heat and moisture from the Gulf Stream and its surroundings appears to act as a source for this wave train. The influence of the interdecadal NAO on subseasonal SAT variability is explained primarily by the modulated efficiency of baroclinic conversion of available potential energy from the background atmospheric flow to subseasonal eddies. The combination of enhanced subseasonal variability and low winter-mean temperature anomalies associated with the negative phase of the interdecadal NAO increases the frequency of cold extremes affecting Europe and the eastern United States.

Analysis of Record-High Temperature over Southeast Coastal China in Winter 2018/19: The Combined Effect of Mid- to High-Latitude Circulation Systems and SST Forcing over the North Atlantic and Tropical Western Pacific

AbstractIn winter 2018/19, southeastern coastal China experienced extreme warm temperatures that were due to a weak East Asian winter monsoon. On the basis of observations from 10 meteorological stations and reanalysis data, the large-scale circulation patterns associated with this extreme warm winter and the possible driving mechanism of its related sea surface temperature (SST) anomalies are investigated in this study. During this winter, many places in this region reached their highest winter mean temperature record and had more extreme warm days and fewer extreme cold days relative to climatology. According to the circulation patterns during winter 2018/19, several large-scale circulation conditions associated mainly with the weak East Asian winter monsoon are identified: the eastward shift of the Siberian high and a shallower East Asian trough, which is related to the low blocking frequency over the Aleutian region, are both unfavorable for cold-air intrusion southward. Meanwhile, strong low-level southerly wind anomalies over southeastern China are related mainly to the 2018/19 El Niño event. Furthermore, the possible role of SST anomalies over the North Atlantic and tropical western Pacific Oceans is examined by using an atmospheric general circulation model, suggesting that both the “tripole pattern” of North Atlantic SST and tropical western Pacific SST anomalies in winter 2018/19 played a role in influencing the East Asian trough. The combined effect of all of these factors seems to be responsible for this extreme warm winter over southeastern coastal China.

Analysis of 24 years of mesopause region OH rotational temperature observations at Davis, Antarctica – Part 2: Evidence of a quasi-quadrennial oscillation (QQO) in the polar mesosphere

Abstract. Observational evidence of a quasi-quadrennial oscillation (QQO) in the polar mesosphere is presented based on the analysis of 24 years of hydroxyl (OH) nightglow rotational temperatures derived from scanning spectrometer observations above Davis research station, Antarctica (68∘ S, 78∘ E). After removal of the long-term trend and solar cycle response, the residual winter mean temperature variability contains an oscillation over an approximately 3.5–4.5-year cycle with a peak-to-peak amplitude of 3–4 K. Here we investigate this QQO feature in the context of the global temperature, pressure, wind, and surface fields using satellite, meteorological reanalysis, sea surface temperature, and sea ice concentration data sets in order to understand possible drivers of the signal. Specifically, correlation and composite analyses are made with data sets from the Microwave Limb Sounder on the Aura satellite (Aura/MLS v4.2) and the Sounding of the Atmosphere using Broadband Emission Radiometry instrument on the Thermosphere Ionosphere Mesosphere Energetics Dynamics satellite (TIMED/SABER v2.0), ERA5 reanalysis, the Extended Reconstructed Sea Surface Temperature (ERSST v5), and Optimum-Interpolation (OI v2) sea ice concentration. We find a significant anti-correlation between the QQO temperature and the meridional wind at 86 km altitude measured by a medium-frequency spaced antenna radar at Davis (R2∼0.516; poleward flow associated with warmer temperatures at ∼0.83±0.21 K (ms−1)−1). The QQO signal is also marginally correlated with vertical transport as determined from an evaluation of carbon monoxide (CO) concentrations in the mesosphere (sensitivity 0.73±0.45 K ppmv−1 CO, R2∼0.18). Together this relationship suggests that the QQO is plausibly linked to adiabatic heating and cooling driven by the meridional flow. The presence of quasi-stationary or persistent patterns in the ERA5 data geopotential anomaly and the meridional wind anomaly data during warm and cold phases of the QQO is consistent with tidal or planetary waves influencing its formation, which may act on the filtering of gravity waves to drive an adiabatic response in the mesosphere. The QQO signal plausibly arises from an ocean–atmosphere response, and appears to have a signature in Antarctic sea ice extent.

Variability and decadal trends in the Isfjorden (Svalbard) ocean climate and circulation – An indicator for climate change in the European Arctic

Isfjorden, a broad Arctic fjord in western Spitsbergen, has shown significant changes in hydrography and inflow of Atlantic Water (AW) the last decades that only recently have been observed in the Arctic Ocean north of Svalbard. Variability and trends in this fjord’s climate and circulation are therefore analysed from observational and reanalysis data during 1987 to 2017. Isfjorden experienced a shift in summer ocean structure in 2006, from AW generally in the bottom layer to AW (with increasing thickness) higher up in the water column. This shift, and a concomitant shift to less fast ice in Isfjorden are linked to positive trends in the mean sea surface temperature (SST) and volume weighted mean temperature (VT) in winter (SSTw/VTw: 0.7 ± 0.1/0.9 ± 0.3 °C 10 yr−1) and summer (SSTS/VTS: 0.7 ± 0.1/0.6 ± 0.1 °C 10 yr−1). Hence, the local mean air temperature shows similar trends in winter (1.9 ± 0.4 °C 10 yr−1) and summer (0.7 ± 0.1 °C 10 yr−1). Positive trends in volume weighted mean salinity in winter (0.21 ± 0.06 10 yr−1) and summer (0.07 ± 0.05 10 yr−1) suggest increased AW advection as a main reason for Isfjorden’s climate change. Local mean air temperature correlates significantly with sea ice cover, SST, and VT, revealing the fjord’s impact on the local terrestrial climate.In line with the shift in summer ocean structure, Isfjorden has changed from an Arctic type fjord dominated by Winter Deep and Winter Intermediate thermal and haline convection, to a fjord dominated by deep thermal convection of Atlantic type water (Winter Open). AW indexes for the mouth and Isfjorden proper show that AW influence has been common in winter over the last decade. Alternating occurrence of Arctic and Atlantic type water at the mouth mirrors the geostrophic control imposed by the Spitsbergen Polar Current (carrying Arctic Water) relative to the strength of the Spitsbergen Trough Current (carrying AW). During high AW impact events, Atlantic type water propagates into the fjord according to the cyclonic circulation along isobaths corresponding to the winter convection. Tides play a minor role in the variance in the currents, but are important in the side fjords where exchange with the warmer Isfjorden proper occurs in winter. This study demonstrates that Isfjorden and its ocean climate can be used as an indicator for climate change in the Arctic Ocean. The used methods may constitute a set of helpful tools for future studies also outside the Svalbard Archipelago.

Meteorological factors driving airborne grass pollen concentration in central Iberian Peninsula

Grasses are a taxonomic group of considerable environmental importance, playing a major ecological role as well as making a significant contribution to the world’s economy, since they include valuable crop and pasture species. Grass pollen allergens are also among the main causes of respiratory allergies worldwide. The interpretation of airborne grass pollen concentrations is a particularly complex task, given the marked diversity of pollen-emitting species and the influence of weather-related variables. This paper examines the influence of meteorological variables on flowering in the species contributing most to airborne grass pollen concentrations. This study was carried out in the surroundings of the city of Toledo (Spain), a Mediterranean city located in the center of the Iberian Peninsula. Temperature was the variable most influencing flowering onset, which was also affected by relative humidity, rainfall and hours of sunlight. The flowering period of grass species that flower at the start of spring (Bromus rubens and Hordeum leporinum) began earlier in years with higher mean winter temperatures, while the species that flower from mid to late spring (Trisetaria panicea and Dactylis glomerata subsp. hispanica), the flowering period began earlier in years with higher cumulative rainfall in winter and spring, which were also the years with the highest mean temperatures. Research into the influence of weather-related variables on grass phenology can shed important light on variations in airborne pollen concentrations, which determine the potential period of exposure for allergy sufferers.

Analysis of 24 years of mesopause region OH rotational temperature observations at Davis, Antarctica – Part 1: long-term trends

Abstract. The long-term trend, solar cycle response, and residual variability in 24 years of hydroxyl nightglow rotational temperatures above Davis research station, Antarctica (68∘ S, 78∘ E) are reported. Hydroxyl rotational temperatures are a layer-weighted proxy for kinetic temperatures near 87 km altitude and have been used for many decades to monitor trends in the mesopause region in response to increasing greenhouse gas emissions. Routine observations of the OH(6-2) band P-branch emission lines using a scanning spectrometer at Davis station have been made continuously over each winter season since 1995. Significant outcomes of this most recent analysis update are the following: (a) a record-low winter-average temperature of 198.3 K is obtained for 2018 (1.7 K below previous low in 2009); (b) a long-term cooling trend of -1.2±0.51 K per decade persists, coupled with a solar cycle response of 4.3±1.02 K per 100 solar flux units; and (c) we find evidence in the residual winter mean temperatures of an oscillation on a quasi-quadrennial (QQO) timescale which is investigated in detail in Part 2 of this work. Our observations and trend analyses are compared with satellite measurements from Aura/MLS version v4.2 level-2 data over the last 14 years, and we find close agreement (a best fit to temperature anomalies) with the 0.00464 hPa pressure level values. The solar cycle response (3.4±2.3 K per 100 sfu), long-term trend (-1.3±1.2 K per decade), and underlying QQO residuals in Aura/MLS are consistent with the Davis observations. Consequently, we extend the Aura/MLS trend analysis to provide a global view of solar response and long-term trend for Southern and Northern Hemisphere winter seasons at the 0.00464 hPa pressure level to compare with other observers and models.

EFFECTS OF THE WATER TEMPERATURE ON TIMING OF SPAWNING AND THE SPAT SETTLING FOR YESSO SCALLOP (MIZUHOPECTEN YESSOENSIS JAY, 1857) IN THE POSYET BAY (PETER THE GREAT BAY, JAPAN SEA)

The water temperature influence on timing of spawning and the spat settling is considered for yesso scallop (Mizuhopecten (=Patinopecten) yessoensis Jay, 1857) in the Minonosok Bay (Posyet Bay, Peter the Great Bay) on the data of observations in 1970–2011. The date of the spawning start varied from May 1 to June 9 (within 40 days) and the start of the scallop spat settling onto collectors of marine farm varied from June 4 to July 5 (within 32 days). Usually the spawning was delayed in the years with long cold season and big sum of daily temperatures below zero or low mean temperature in winter months and April, when the pre-spawning period with the temperature above zero before May 1 was too short. The spat settling was delayed in the years with severe winter or low mean temperature in the pre-spawning period (r = –0.46); the early settling was observed in the years with early warming above 0o C. The higher sum of positive daily temperatures accumulated till May 1 and till June 1, or within April and May, the earlier the spat settling on collectors (r = –0.58; –0.60; –0.55; –0.42, respectively). Prognostic equations for 10-day and 15-day forecasting of the dates of scallop spawning start and spat settling start are proposed and tested; accuracy of these forecasts is 70% for the spawning and 60 % for the spat settling.

Changes in extremely heavy and light snow-cover winters due to global warming over high mountainous areas in central Japan

To investigate future changes in snow cover and snowfall over mountainous areas in central Japan, we conducted regional climate projections using a high-resolution non-hydrostatic regional climate model (NHRCM) with 5 km and 1 km grid spacings. Boundary conditions are derived from the database for Policy Decision making for Future climate change (d4PDF) 20 km regional climate projections (d4PDF20). The d4PDF20 assumes two future climates when global mean surface air temperatures are approximately 2 K and 4 K warmer than in the preindustrial period. Experiments with 5 km grid spacing are conducted by NHRCM for 372 years in d4PDF20 in each climate. Experiments with 1 km grid spacing are performed focusing on 5 years with heavy, median, and light snow cover of mountainous areas in each climate. In the years with heavy snow cover in 2 K and 4 K warming climates, snowfall is enhanced from late December to February at more than 2000 m above sea level (mASL) in the northern parts of Japan’s Northern Alps, resulting in heavy snow cover comparable to that in the present climate. Heavy daily snowfall remarkably increases due to global warming in the years with heavy snow cover. At low elevations below 500 mASL, snowfall decreases in all ranges of snowfall intensity in the 4 K warming climate, while the frequency of heavy daily snowfall increases in the 2 K warming climate. Precipitation is enhanced around the Japan-Sea Polar-airmass Convergence Zone and the mountainous area facing the Sea of Japan, resulting in strengthened heavy snowfall at high elevations where the winter mean temperature is approximately − 10 °C in the present climate. On the other hand, remarkable reductions in snow cover and snowfall are projected in years with light snow cover. Our results indicate that global warming causes heavy and light mid-winter snowfalls at high elevations of Japan’s Northern Alps that are more extreme than those in the present climate.Graphical abstract

Barents-Kara sea ice and European winters in EC-Earth

The potential link between decreasing Barents-Kara sea ice and cold winters in Europe is investigated using the enhanced resolution (horizontal atmospheric resolution of sim 80,hbox {km}) global, coupled climate model EC-Earth. Nudging sea ice only in the Barents-Kara Seas, five configurations of sea ice covers are used to assess the importance of the amount of sea ice in this region. Nudging in the coupled model is achieved by modifying the non-solar surface heat flux into the ice/ocean interface. The mean winter temperature response suggests a weak but statistically significant non-linear response with cooling over eastern Europe for moderate sea ice reductions in the Barents-Kara Seas, a weaker but still cold anomaly for minor reductions and warming for major reductions. However, this non-linear response is not reflected in the circulation. Instead, a negative mean sea level pressure anomaly over Barents-Kara Seas intensifies with sea ice reduction. In contrast to this, is the response in the coldest winters over central Europe: the larger the sea ice reduction, the stronger the Scandinavian pattern and the associated easterlies need to be to obtain cold winters over central Europe. The use of a coupled climate model is a potential explanation for the link between the intensified Scandinavian pattern and the cooling over Europe seen in this study, that is not observed in some atmosphere-only model studies.

Long-term changes in winter abundance of the barbastelle Barbastella barbastellus in Poland and the climate change – Are current monitoring schemes still reliable for cryophilic bat species?

Warmer winters may lead to changes in the hibernation behaviour of bats, such as the barbastelle Barbastella barbastellus, which prefers to hibernate at low temperatures. The species is also known for its large annual fluctuations in the number of wintering individuals, so inference about population trends should be based on long-term data. Prior to 2005, analyses indicated stable or even increasing barbastelle population in Poland. We analysed the results of 13 winter bat counts (2005–2017) of the species from 15 of the largest hibernacula, and additional site of 47 small bunkers, in Poland. The total number of wintering individuals remained stable during the study period, because the barbastelle is not a long-distance migrant, this likely reflects the national population trend. On the basis of mean winter air temperatures we divided the country into four thermal regions. Analyses of barbastelle abundance in hibernacula in the four regions revealed a 4.8% annual mean increase in numbers in the coldest region, where mean winter temperatures were below -2°C, annual mean declines of 3.3% and 3.1% in two warmer regions of western Poland, but no trend in the region of intermediate mean winter temperatures of between -1°C and -2°C. Overall, there was a significant, but weak, negative correlation between the abundance of hibernating individuals and the mean winter temperature. On the other hand, the number of individuals hibernating in small bunkers increased, even though the site was located in one of the warm regions. The results indicate a warming climate will likely reduce the use of large, well-insulated winter roosts by species that prefer colder conditions–and that this is already happening. For forest-dwelling bats, such as the barbastelle, for which monitoring schemes are primarily based on winter surveys of large hibernacula, estimations of population trends may consequently become less reliable.

Long‐term study of the reproductive timing of the Neotropical catfish Iheringichthys labrosus (Lütken, 1874): Influence of temperature and river discharge

AbstractUnravelling the effect of climate variability on species biology has been one of the main goals of ecological studies. Environmental factors such as river discharge and temperature have being proposed as triggers of reproductive cycle in fish. In temperate climates, fish reproduction is affected mainly by temperature, while is influenced by flood pulses in large tropical rivers. We evaluated the influence of temperature and river discharge as triggers of Iheringichthys labrosus’ reproduction. We studied the following reproductive variables: gonadosomatic index (GSI), hepatosomatic index (HSI) and condition factor (K). Females of I. labrosus were examined in a time series of ten years along three sites located in Lower Uruguay River at the beginning (last week of November‐first week of December, spring) and by the end of the reproductive period (middle‐end of April, autumn). Generalised linear models detected a positive effect of mean winter temperature and site on the spring mature female GSI. Site was significant in addition to the interaction between temperature and site. Moreover, the effect of winter temperature was stronger than water discharge in triggering reproductive timing of I. labrosus, contrary to the model proposed for other species in tropical systems. Additionally, a literature review suggested a latitudinal gradient on reproduction, occurring earlier and prolonged with decreasing latitude (and increasing temperature). In this study, we stated the effect of temperature on the life history in a Neotropical fish using a multifaceted approach, particularly important in the current context of global climate warming.

Analysis of the climate change signal in Mexico City given disagreeing data sources and scattered projections

Study regionThis study investigates the annual and seasonal trends in precipitation and temperature at meteorological stations in Mexico City, and compares them with gridded datasets and projections from General Circulation Models. Study Focus: The outputs of climatic trend analysis are highly sensitive to the quality and continuity of data, as well as natural variability effects including low frequency persistence. This study evaluates the changes in average annual precipitation and temperature from approximately 1950–2013, and projected changes for 2036–2065. New hydrological insights for the regionResults shows statistically significant increasing trends in the winter mean temperature and the summer precipitation by average rates of 0.1 °C/decade and 17.8 mm/decade, respectively. Within the next 30 years, temperature is projected to continue to increase between 1℃ to 3℃ with an unclear signal in precipitation change, but possibly an increase in late-season monsoon rainfall.

Mean temperature evolution on the Spanish mainland 1916-2015

An analysis of the evolution of annual and seasonal mean temperatures on the Spanish mainland (western Mediterranean basin) was carried out, using the new MOnthly TEmperature Dataset of Spain century (MOTEDAS_century) data set. This data set was developed by combining archives from the National Meteorological Agency and newly digitised legacy data from the Annual Books published between 1916 and 1949. Both the annual and seasonal regional mean temperature series experienced increasing trends during the study period. However, the increment was neither constant in time (monotonic) nor homogeneous between seasons. Four main periods were identified in the annual mean regional series. The first 3 corresponded to those previously confirmed in global temperature series (rise-pause-rise); a second pause or hiatus was also detected at the end of the period of analysis. The seasonal regional series followed specific patterns: winter mean temperature only increased in the second rising period, autumn in the first and spring and summer during the 2 rising periods. Also, negative trends were found in extended areas in the first pause in spring, and to a lesser extent in summer. From the middle of the 1980s, the trends in annual and seasonal mean values were not significant up until 2015. Furthermore, spatial variations were found in the significance of the trends, revealing regional differences in the intensity of warming through the seasons. In comparison with other versions of secular mean temperature series developed for the Spanish mainland, MOTEDAS_century seems to better capture the spatial variability.

Projected temperature changes in Kolašin (Montenegro) up to 2100 according to EBU-POM and ALADIN regional climate models

This paper deals with the temperature projections of two regonal climate models, actually three scenarios by 2100: the A2 scenario of the EBU-POM model and the RCP4.5 and RCP8.5 scenarios, the latest projections of the ALADIN model. Kolasin was chosen, because the altitude of the place is the average height of the northern region of Montenegro (about 1000 m). A total of 22 temperature parameters for the period 2011–2100 were analyzed. The upward trend of projected seasonal and annual (TY, TYx, and TYn) mean, mean maximum, and mean minimum temperatures by 2100 is very significant. According to the RCP4.5 and RCP8.5 scenarios, in 2011-2100, the trend of projected mean winter (TW) temperatures will be from 0.2 to 0.37 °C per decade, and the trend of projected mean summer (TSu) temperatures will be from 0.24 to 0.54 °C per decade. Compared to the base period (1981–2010), the average annual temperature in 2071–2100 is expected to be higher than 2.2 (RCP4.5) to 3.6 °C (A2 and RCP8.5). Also, by the end of the 21st century, a significant increase in the number of summer and tropical days (SD and TD) together with a decrease in the number of frost and ice days (FD and ID) are expected. During the instrumental period, a temperature higher than 37 °C was not recorded. According to projections, in the late 21st century, in summer, maximum temperatures of 40 °C are possible, even in the milder variant (RCP4.5) scenario. According to projections of the used models, Kolasin and the northern region of Montenegro expect a warmer future with more frequent extreme temperatures in a positive direction.

Projected spatial patterns in precipitation and air temperature for China's northwest region derived from high‐resolution regional climate models

AbstractDerived from realistic global warming scenarios, long‐term projections of spatial patterns in precipitation and temperature in hydrology and climatology can serve to evaluate climate risk, explore sources of renewable energies and allow local‐scale data to inform decisions regarding agricultural, ecosystem, social, recreational and economic activities. Under the CORDEX‐EA project, the precipitation and temperature projections (2020–2045) for the economically and socially important region of Northwestern China were derived from high‐resolution regional climate model (RCM) simulations for RCP 4.5 and 8.5 scenarios, and compared against a historical period or baseline of 1980–2005. Drawing data from four key RCMs [Weather Research and Forecasting (WRF); Regional Spectral Model (RSM); Regional Climate Model version 4.0 (RegCM4); Mesoscale Model version 5 (MM5)], reliable local‐scale projections were generated by applying suitable bias correction that accords with the multivariate bias correction (MBC) approach. To validate this approach and then evaluate climate change impacts, the adjusted precipitation and temperature estimated from bias‐corrected models for the historical period were compared to the observed data. The results showed that the simulated spatiotemporal distribution of multiyear average precipitation and temperature appear to fit relatively well with the observations, however, the wet‐cold and dry‐warm climate‐related biases were still evident for the high altitude regions. Bias‐corrected future projections of RCMs indicated spatially averaged annual precipitation is expected to rise by about 23.6 and 35.3 mm under the RCP 4.5 and 8.5 scenarios, respectively, while spatially averaged annual temperature is expected to rise by about 1.95 and 1.10°C. Precipitation is projected to increase in all seasons, albeit, more so in the cold season (i.e., boreal winter and spring) than the warm season (i.e., boreal summer and autumn). The annual increase is expected to be about 56.7% under the RCP 4.5 scenario, compared to 67.6% under the RCP 8.5 scenario. The changes of mean temperature in winter are expected to be significant, −37.8% under both RCP scenarios. For spring, the mean temperature will rise by 23.1% (28.9%) under the RCP 4.5 (8.5) scenario. A MBC approach was found to be effective in yielding reliable projected changes in precipitation and temperature variables. The proposed approach has important implications for climatological studies and evaluation of climate change impacts on localized regions, not only in China, but also in other similar areas of the world, where decisions for managing climate risk must be implemented by policy makers, government, industry and stakeholders.