Summer Air Temperature Research Articles

ADAPTIVE POTENTIAL OF FENUGREEK SPECIES AT DIFFERENT SOWING TIMES

Among the unexplored technological elements of growing fenugreek in the conditions of Ukraine is the creation of conveyor cultivation of the culture. Therefore, the problem of the influence of sowing dates on the growth and development of plants, the parameters of the harvest and the qualitative composition of marketable products is acute. The purpose of this study was to substantiate the optimal sowing dates of fenugreek species to increase the yield of dried products in the conditions of Polissia on sod-podzolic soils. The leading methods employed to investigate this issue were the field method – to find the interaction of the object of research with biotic and abiotic factors, statistical method – to evaluate the research results to find the parameters of fenugreek’s adaptive capacity. During 2012-2014, for different sowing periods, the average yield of dry mass in blue fenugreek varied from 0.5 to 1.3 t/ha, and in hay fenugreek – from 0.6 to 1.5 t/ha. The early spring period and the late spring period of the 1st sowing period were characterized by the highest overall adaptive capacity. The highest value of the specific adaptive capacity was established during the late spring 2nd sowing period. The relative stability index ranged from 2.6 to 11.4. Blue fenugreek during the late spring 1st and 2nd sowing periods responds well to improved growing conditions (bi >1), and fenugreek hay during the late spring 2nd and summer sowing periods. Early spring and late spring 1st sowing period samples are characterized by high breeding value. An increase in the sum of effective temperatures by 1°C contributed to the fluctuation of green mass yield from 4.82 to 128 kg/ha, and dry mass yield from 0.401 to 6.63 kg/ha. At the same time, an increase in precipitation by 1 mm affected the fluctuation of the yield of green mass from 15.0 to 146 kg/ha, and of dry mass from 0.145 to 25.9 kg/ha. Commercial production of fenugreek species was formed within the range of the sum of air temperatures (>10°C) 383.9-487.1°C, the amount of precipitation 70.7-144.3 mm, and the growing season ranged from 35 to 55 days. The highest productivity of fenugreek species was found during sowing from the second decade of April to the first decade of May. The materials of this paper are of practical value for expanding the species diversity of vegetables and increasing the supply of the population with valuable food products and during the application of new and improved elements of technologies for growing valuable rare crops to achieve the maximum effect of fulfilling the genetic potential of plants

No evidence for a negative effect of growing season photosynthesis on leaf senescence timing.

The length of the growing season has a large influence on the carbon, water, and energy fluxes of global terrestrial ecosystems. While there has been mounting evidence of an advanced start of the growing season mostly due to elevated spring air temperatures, the mechanisms that control the end of the growing season (EOS) in most ecosystems remain relatively less well understood. Recently, a strong lagged control of EOS by growing season photosynthesis has been proposed, suggesting that more productive growing seasons lead to an earlier EOS. However, this relationship has not been extensively tested with in-situ observations across a variety of ecosystems. Here, we use observations from 40 eddy-covariance flux tower sites in temperate and boreal ecosystems in the northern hemisphere with more than 10years of observations (594site-years), ground observations of phenology, satellite observations from the Moderate Resolution Imaging Spectroradiometer (MODIS), and three leaf senescence models to test the extent of a relationship between growing season photosynthesis and end of season senescence. The results suggest that there is no significant negative relationship between growing season photosynthesis and observed leaf senescence, flux-inferred EOS estimates, or remotely sensed phenological metrics, in most ecosystems. On the contrary, while we found negative effects of summer air temperatures and autumn vapor pressure deficit on EOS, more productive growing seasons were typically related to a later, not earlier, EOS. Our results challenge recent reports of carry-over effects of photosynthesis on EOS timing, and suggest those results may not hold over a large range of ecosystems.

Effect of the roadside tree canopy structure and the surrounding on the daytime urban air temperature in summer

As an important component of urban forests, roadside trees provide cooling and humidification effects, thereby improving the microclimate and human thermal comfort during hot summer weather by blocking, reflecting and absorbing solar radiation. However, the complex three-dimensional (3D) structure of roadside trees, diverse planting types and complex landscape heterogeneity complicate efforts to quantify the effects of these factors on above-road air temperatures. In this study, a terrestrial laser scanner (TLS) is used to accurately estimate roadside tree morphological parameters, such as the tree height (TH) and the diameter at breast height (DBH), and canopy structural parameters, such as the canopy thickness (CT), the canopy cover above the road (CCAD), canopy volume over the road (CVAD) and the leaf area index (LAI), to evaluate different 3D canopy geometries (pyramidal, spherical, pileate and cylindrical). A moving meteorological station was used to continuously obtain the horizontal air temperature (AT) distribution to investigate the effects of the canopy structural parameters, the planting types and the land cover types on the above-road AT. The value of ΔAT was positively correlated with TH, CVAD, LAI and CCAD. These structural variables were most significantly correlated with ΔAT under the pileate canopy shape. However, there were no significant correlations between these factors under the cylindrical canopy shape. The physiological equivalent temperature (ΔPET) reached 7.4, 15.8, 4.5 and 17 °C under the cylindrical, spherical, pyramidal and pileate shapes, respectively. The ΔAT of a two-sided planting was approximately 1.7 times greater than that of a one-sided planting; the ΔRH showed a similar trend. Within 230 m of a lake, the ΔAT exhibited a logarithmic relationship with the distance from a given point to the lake. Our study quantifies the influence of the roadside tree structure on the thermal environment, which can serve as a meaningful reference for urban tree species selection and arrangement.

Color Shade Nets Affect Plant Growth and Seasonal Leaf Quality of Camellia sinensis Grown in Mississippi, the United States.

Shading modifies the microenvironment and can provide plants with some protection from frequent heat, drought, frost, and hail induced by climate change and has the potential to improve plant growth, yield, and quality. Tea (Camellia sinensis) is an ancient plant originating from tropical and subtropical regions and prefers to grow in partial shade under the forest canopy. The emerging tea industry in the United States (US) requires research support on establishing tea fields in novel environmental conditions as well as on producing high-quality tea products. This study investigated the effects of black, blue, and red shade nets on tea plant growth and seasonal leaf qualities in the southeastern US with a humid subtropical climate. When compared to no-shade control, black, blue, and red shade nets increased plant growth index (PGI), net photosynthetic rate (Pn), and stomatal conductance (gs), decreased air and leaf surface temperatures in summer, and reduced cold damage in winter. No significant difference was found among the black, blue, and red shade nets on tea plant growth. Varying contents of total polyphenols, carbohydrates, free amino acids, L-theanine, gallic acid, caffeine, and catechins in fresh tea leaves were observed among different shade treatments and harvesting seasons. 69.58% of the variations were depicted in a biplot by principal component analysis. Red shade was considered helpful for improving green tea quality by increasing the content of L-theanine and free amino acids in tea leaves collected in spring and fall when compared to no-shade control.

Projections of changes in maximum air temperature and hot days in Poland

AbstractThe aim of the study was to determine changes in maximum air temperature (Tmax) in summer, and occurrence of hot days in the period 1966–2020, as well as to forecast the direction and rate of changes in near and far future. The research showed an increase in Tmax in the summer season. In the analysed period, the changes intensified over the last 20 years, as suggested by, among others, the occurrence of the 10 warmest years in the study period, mostly after 2000. According to model projections, an increase in Tmax will be recorded both in the near and far future. The consequence of the current increase in Tmax has been an increase in the frequency of hot days. Further increase in the number of hot days in Poland is projected for the upcoming decades. The smallest changes are projected for areas with most intensive changes in Tmax, and the largest in areas with moderate changes in the Tmax.

Effect of Selected Meteorological Variables on Full Flowering of Some Forest Herbs in the Western Carpathians

At present, temperate forest ecosystems are endangered by both abiotic and biotic factors. The effects of abiotic components, e.g., meteorological variables, are constantly studied. However, the detailed mechanisms affecting the phenology of plants are still unknown. Two meteorological variables (air temperature and cumulative precipitation) were analysed for the period from 1995 to 2020 in order to determine which factor which has a more significant effect on onset of the full-flowering (FF) phenophase. A set of nine forest herbs, representing different phenological groups from the viewpoint of flowering, was examined (early spring: Petasites albus and Pulmonaria officinalis; mid-spring: Carex pilosa and Dentaria bulbifera; late spring: Fragaria visa and Galium odoratum; early summer: Veronica officinalis; mid-summer: Mycelis muralis; and late summer: Campanula trachelium). Temperature-sum requirements and temporal trends in the onset of FF were also studied. The research conducted at the Ecological Experimental Station in the Kremnické vrchy Mountains (central Slovakia) at an altitude of 500 m asl. Our results show that the air temperature correlated more significantly with the date of onset of FF (r > 0.6, p < 0.001) than with precipitation. On average, the air-temperature sums, calculated for the threshold temperatures of 0 °C and 5 °C, increased from 142.9 °C (Petasites albus) to 1732.9 °C (Campanula trachelium) and from 223.4 °C (Petasites albus) to 1820.8 °C (Campanula trachelium), respectively. Temporal trends in the onset of FF over the last 26 years confirm shifts to earlier dates for most species (excepting early spring Petasites albus). In spring flowering species, shifts ranged from 2 days (0.07 day/year) for Pulmonaria officinalis to 8 days (0.30 day/year) for Carex pilosa. As for summer species, the onset of flowering shifted more significantly to earlier dates—from 7 days (0.27 day/year) for Campanula trachelium to 12 days (0.46 day/year) for Veronica officinalis. The observed trends were statistically significant (p < 0.05) for five examined species (Carex pilosa, Dentaria bulbifera, Fragaria vesca, Veronica officinalis and Mycelis muralis).

A multi-scale dendroclimatological analysis of four common species in the southern Canadian boreal forest

A comprehensive assessment of the tree growth/climate relationship was undertaken to better understand the potential impacts of climate change on the growth dynamics of four widespread and common boreal tree species, namely jack pine (Pinus banksiana), black spruce (Picea mariana), eastern larch (Larix laricina), and trembling aspen (Populus tremuloides), located at the southern limits of the Canadian boreal forest. Over intra-annual time scales, results show that precipitation is likely the main driver of stem radius change (∆R), with jack pine radius exhibiting the most consistent positive relationship. Precipitation had a stronger relationship with stem radius variation in black spruce and eastern larch during periods when volumetric water content (VWC) in the root zone was below average, pointing to the likelihood that certain species rely more heavily on available moisture in the uppermost layers of the soil column to replenish stem water, especially during extended dry periods. Warm air temperatures had an immediate negative impact on stem water content due to transpiration. This was most marked during periods of reduced moisture availability in the root zone, when trees are more susceptible to net water volume loss. During periods when moisture was not limiting, a positive relationship between lagged air temperature and ∆R was detected. Warm air temperatures may therefore play an important role in stimulating radial growth when moisture requirements are met. At annual temporal resolution, the growth/climate relationship changed over the lifetime of our study species. Over the last several decades, the relationship between precipitation and annual radial tree growth has weakened, while positive relationships between spring and summer air temperature and annual radial tree growth have emerged, likely signaling a decrease in moisture limitations, and a positive response to spring warming. Our findings reveal that boreal forest tree species may benefit from spring and summer warming over the near term, providing there is sufficient moisture to support growth. Over the long term, rates of evapotranspiration are expected to overshadow gains in moisture related to an increase in precipitation. Under these circumstances, we are likely to see reduced growth rates and an increasingly negative response of boreal tree species growth to warm air temperatures.

A novel ensemble learning for post-processing of NWP Model's next-day maximum air temperature forecast in summer using deep learning and statistical approaches

A reliable and accurate extreme air temperature in summer is necessary to prepare for and respond to thermal disasters such as heatstroke and power outages. The numerical weather prediction (NWP) model is commonly used to forecast air temperature using dynamic mechanisms. Because of its high uncertainty from coarse spatial resolution and unstable parameterization, however, it requires post-processing. Recent studies have proposed advanced post-processing methods using machine learning and deep learning techniques. This study compared various individual post-processing models—multi-linear regression (MLR), support vector regression (SVR), gated recurrent units (GRU), and convolutional neural network (CNN). It also proposed a novel multi-model ensemble (MMESS) that aggregates individual post-processing models based on the skill score (SS) for the Local Data Assimilation and Prediction System (LDAPS, a local NWP model over Korea) model's next-day maximum air temperature (Tmax) forecast data in two different domains: South Korea and Seoul. The pressure and surface data of the present-day analysis and next-day forecast fields of LDAPS were used as input variables. As a result of hindcast validation, CNN showed good overall performance (root mean square error (RMSE) of 1.41 °C in South Korea and 1.50 °C in Seoul) among individual models. We found that CNN demonstrated lower RMSE (1.17–1.58 °C) than other post-processing models (1.43–2.17 °C) at stations where the bias of LDAPS changes, using surrounding spatial information. The proposed MMESS exhibited more reliable, robust results than the individual models did. A further comparison to the simple average ensemble and the constrained linear squares-based MMEsupported the proposed MMESS as a more suitable ensemble method for next-day Tmax forecast, considering the relative significance of the individual models.

Improvement of the variety of intensive gardening in Dagestan

Abstract. The issues of horticulture development, improvement of the assortment taking into account the vertical zoning of the territory of the republic, which are sharply distinguished by heterogeneity in climatic factors and cannot be used for fruit crops with equal efficiency, are highlighted. For the development of horticulture in the Primorsky lowland, the southern part is of great importance, which is characterized by relatively mild winters and hot summers, with an average annual air temperature of 11, 6–12,6 °C and the sum of active temperatures of 4000–4600 °C. The south-eastern foothills are represented by a more arid climate. The average annual air temperature is 11.80 °C, the sum of active air temperatures is reached up to 3500 °C, on average, 300–400mm of precipitation falls per year. The Central Foothills play an important role in the gardening of the republic. The climate here is moderately warm, the average annual air temperature ranges from 9.7 to 10.3 °C, the sum of the average daily temperatures above 10 °C reaches 3420 °C., the average annual precipitation in.

Effects of temperature on Acyrthosiphon pisum and Therioaphis trifolii (Hemiptera: Aphididae) abundance in alfalfa crops: A case study in northern Serbia

Populations of the most abundant alfalfa aphids, Acyrthosiphon pisum and Therioaphis trifolii, have periodic fluctuations, and many factors affect their dynamics. In the present study, we examined the impact of daily air temperatures on the abundance of two alfalfa aphids in field conditions. The numbers of these two aphids on alfalfa were documented at two locations in a representative alfalfa growing area in Serbia during a three-year field study. Based on the records of aphid abundance and daily air temperatures during the whole study, it was found that a correlation between the sum of optimal daily air temperatures for aphid development, the sum of maximum daily air temperatures and the number of recorded aphid peaks was significant and can therefore be considered for the detection of suitable temperature conditions to increase aphid abundance. The study shows that the highest correlations were between a high density of A. pisum and the sum of optimal daily air temperatures for its development (Ck=0.569) and between a high density of T. trifolii and the sum of maximum daily air temperatures (Ck=0.595). The length of time required for the growth of populations of the two alfalfa aphids differed: 30 days for A. pisum and 5 days for T. trifolii. The association of temperature data to alfalfa aphid abundance enables a projection of their population behavior in changed future climate conditions. This study suggests increased population sizes of T. trifolii and decreased population sizes of A. pisum on alfalfa under the warmer conditions that are expected to prevail in the future.

Investigation of Coastal Atmospheric Boundary Layer and Particle by Unmanned Aerial Vehicle under Different Land-sea Temperature

During summer daytime, the surface PM2.5 concentration tends to rise briefly in the west coast of Bohai Sea, which might be related to the thermal internal boundary layer (TIBL) formed by the land-sea thermal interaction. In this study, we investigated the relationship between land-sea air temperature and pollutant concentration in summer over a coastal region of northern China using an unmanned aerial vehicle (UAV)-measurement platform to obtain vertical meteorological data and pollutant concentration. In midday, when only considered onshore winds, PM2.5 concentration was significantly higher than that in not considered onshore winds, meanwhile the high positive correlation between land-sea temperature difference and particle concentration was identified. It can be seen from the UAV observed profiles that the TIBLs were formed at the bottom of the atmospheric layer in the daytime with height values in the range of 44–97 m, resulting from the impact of onshore winds caused by land-sea thermal difference. This land-sea thermal difference influences the atmospheric boundary layer (ABL) and TIBL structures, also the PM2.5 concentration diffusion. We found that larger land-sea temperature difference could induce lower coastal ABL height and larger potential temperature vertical gradients below TIBL, even delaying the stable layer establishment. When TIBL and ABL heights increased, as a result, the height of the maximum PM2.5 concentration also increased. In addition, TIBL could lead to an increase in surface PM2.5 concentration lasting for 2 hours during the daytime. Our results establish the relationship between land-sea temperature difference and particle diffusion, and have an important role in coastal air quality forecast.

Influence of long-term use of fertilization systems on the productivity of winter grain crops

In the conditions of the Vyatka-Kama agricultural province, a study was carried out of the effect of long-term use of various fertilization systems on the productivity of winter grain crops and the fertility of soddy medium podzolic soil in terms of agrochemical indicators. Long-term use of the mineral fertilization system in doses of N69P68K53 on soddy medium podzolic medium loamy soil contributed to an increase in winter grain crops’ productivity on average per year in relation to the control without fertilizers – 1.83 tons of grain units/ha. Long-term use of an organic fertilization system against lime background provided an increase in the productivity of winter crops of 0.64 tons of grain units/ha in relation to control. The most effective was the organomineral fertilization system, which contributed to the productivity increase of the studied winter crops in long-term use by 2.64 tons of grain units/ha in relation to control. As a result of a long-term field experiment, it was revealed that the productivity of winter grain crops in the Vyatka-Kama agricultural province significantly depends on agro-climatic conditions. A close inverse interrelation of productivity from the sum of active temperatures and average air temperature was revealed. For expanded fertility reproduction of soddy medium podzolic medium loamy soil in the Vyatka-Kama agricultural province of Russia, an organic-mineral fertilizer system should be used against liming background.

The analysis of annual and seasonal surface air temperature trends of southern and southeastern Bosnia and Herzegovina from 1961 to 2017

In some areas of the world, regional climate change is in good agreement with global climate change. This study brings new information about what defines climate change in the contact area of Adriatic Sea and Southeastern Europe, and conclusions are based on trend analysis of annual and seasonal temperatures in the southern and southeastern parts of Bosnia and Herzegovina. Trend analysis was applied on mean annual surface air temperatures, mean maximum temperatures, and mean minimum temperatures of all four seasons. This study used 4 meteorological stations: Livno, Bileća, Mostar, and Ivan Sedlo for 56 years. The main statistical method is the Mann-Kendall test. The total number of analysis is 48. A statistically significant positive trend was determined in 36 analysis, while in the rest of the tests this was not the case. The highest amount of temperature increase is present in the mean maximum summer air temperatures in Livno and Ivan Sedlo. Mean minimum autumn air temperatures had the smallest increase. Negative trend is present in the mean autumn surface air temperatures and mean maximum autumn temperatures. Using a geographical information system resulted in visualizing regional differences in the spatial distribution of isotherms. The study area has combined the influence of orography and maritime effects of the Adriatic Sea. Having in mind these results, the growing temperature has been recognized as a problem which needs more attention in Bosnia and Herzegovina. Unfortunately, official documents which propose economic adaptation on climate change in this country are not at a satisfactory level.

ASSESSMENT OF THE CURRENT STATE AND EXPECTED CHANGES IN AGRO-CLIMATIC RESOURCES OF THE GUBA-KHACHMAZ ECONOMIC REGION OF THE REPUBLIC OF AZERBAIJAN

The article discusses some issues of assessing the current state and expected changes in agro-climatic resources of the Guba-Khachmaz economic region. Research methods are selected and substantiated. The issues of interpretation of agro-climatic information are considered to determine modern "norms" of agro-climatic indicators and assess the impact of regional climate change on these resources. To assess the impact of climate change on agroclimatic resources, such indicators as the date of the transition of the average daily air temperature above 10 °C in the spring and below 10 °C in the fall, the length of the warm period, the sum of active air temperatures above 10 °C, the sum of precipitation and the hydrothermal coefficient Selyaninov for the warm season. For example, it is shown that with the expected increase in air temperature by 2 °C, the beginning of the warm period will begin in the lowland, foothill and mid-mountain zones by 8-10 days, and in the highlands by 22 days earlier than in the modern period. In autumn, the end of the warm period is expected 11-15 days later; the length of the warm period is expected to increase by 20-23 days in the lowland, foothill and mid-mountain zones and by 37 days in the high-mountain zone. It is also expected that the sum of active temperatures will increase by 581-665 °C for the warm period. It was revealed that the most susceptible to the influence of an increase in global air temperature by 2 °C will be medium and high mountain zones. With an increase in air temperature in the future by 4 °C and a decrease in atmospheric precipitation by 20 %, the frequency of occurrence of the 1st group of drought with height will increase from 6 % to 33 %, the frequency of occurrence of the 2-nd group will change from -14 % to + 50 %, and the first group will decrease by 13-57 %. With an increase in air temperature in the future by 2 °C and a decrease in atmospheric precipitation by 20 %, the frequency of occurrence of various groups of drought will be similar to the previous variant. Also, an assessment was made of possible changes in the frequency of drought with different intensities.

Estimation of the anthropogenic aerosol emission effect on the rate of summer warming in Europe

A relationship between aerosol air pollutions and summer air temperatures in Europe was studied. High correlation coefficients between the latitudinal distributions of the zone-averaged trends of the mentioned parameters were found. The potential effects of decrease in the aerosol emission on the cloud optical depth, in the air temperature, and the amount of precipitation in the territory of Europe were estimated on the basis of the obtained regression equations. It was shown that due to the aerosol emission decrease, the average summer temperature in Europe in 2000–2020 could increase by 0.53 °С, which is ~73 % of total summer warming in the region. The empirical estimates obtained in the work were confirmed by the satellite observation data and the numerical calculations of changes in radiation balance components at the top of the atmosphere. It was shown that the radiation emission decrease in the territory of Europe could increase the average radiation balance in Europe in summer months by 2.27 W/m², which is ~65 % of its total change. The increase in the carbon dioxide content in the atmosphere during the same period contributed much less to the observed change in the radiation balance (17.5 %), which supports the hypothesis about the dominant role of aerosols in summer warming in Europe.

Enhanced Warming in Global Dryland Lakes and Its Drivers

Lake surface water temperature (LSWT) is sensitive to climate change. Previous studies have found that LSWT warming is occurring on a global scale and is expected to continue in the future. Recently, new global LSWT data products have been generated using satellite remote sensing, which provides an inimitable opportunity to study the LSWT response to global warming. Based on the satellite observations, we found that the warming rate of global lakes is uneven, with apparent regional differences. Indeed, comparing the LSWT warming in different climate zones (from arid to humid), the lakes in drylands experienced more significant warming (0.28 °C decade−1) than those in semi-humid and humid regions (0.19 °C decade−1) during previous decades (1995–2016). By further quantifying the impact factors, it showed that the LSWT warming is attributed to air temperature (74.4%), evaporation (4.1%), wind (9.9%), cloudiness (4.3%), net shortwave (3.1%), and net longwave (4.0%) over the lake surface. Air temperature is the main driving force for the warming of most global lakes, so the first estimate quantification of future LSWT trends can be determined from air temperature projections. By the end of the 21st century, the summer air temperature would warm up to 1.0 °C (SSP1-2.6) and 6.3 °C (SSP5-8.5) over lakes, with a more significant warming trend over the dryland lakes. Combined with their higher warming sensitivity, the excess summer LSWT warming in drylands is expected to continue, which is of great significance because of their high relevance in these water-limited regions.

Ice in caves and its effect on thermal inversion and permafrost in the case of the Velika ledena jama v Paradani, Smrekova draga and neighbouring dolines

In the Velika ledena jama v Paradani, in the karstic blowholes on the slopes of Smrekova draga and in the nearby dolines I measured and interpreted air temperatures and the effect of the summer outflow of cold air from them into the surrounding area. In winter, cold air enters the cave, radically cooling the entrance part of the cave, where for this reason there is permanent cave ice. The summertime circulation is reversed: emerging from the inner part of cave, which has an average temperature of around 4° C, is air which only when it transits through the sub-cooled entrance part is then cooled to around 1° C. This air comes to the surface and in the hollow at the cave entrance maintains a distinct thermal inversion during the warm part of the year. There is a similar air circulation and similar development of annual temperatures observed at the vents, where cave air emerges through rubble spread over cave entrances on slopes or at the bottom of dolines. The stable summer air temperatures of around 1° C in the vents where I conducted measurements indicate that underneath them there is also permafrost or sub-cooled rock and permanent ice. This is created and preserved, just like in the caves, due to the advection of cold air in winter. In Trnovski gozd, such karstic permafrost is found at an altitude of 1,100 m above sea level. The outflow of cold air from the vents in the summer, just like inside the cave, causes a distinct thermal inversion in dolines on the surface.

Evaluation of multidimensional simulations of summer air temperature in China from CMIP5 to CMIP6 by the BCC models: From trends to modes

To determine whether the capability of the CMIP6 version of Beijing Climate Center (BCC) models (BCC-ESM1 and BCC-CSM2-MR) in simulating China summer surface air temperature (SAT) has improved, we presented a multidimensional evaluation of the summer SAT in China including the trends, modes, and influencing factors. Critical comparisons are also made with the results of CMIP5 (BCC-CSM1.1 and BCC-CSM1.1m). In general, the CMIP6, especially BCC-CSM2-MR, has smaller deviations in the trends, the means, the mutations, the maximum centers, the variances, and the spatial patterns of the dominant modes from observatio relative to those of CMIP5. However, the BCC CMIP6 models still underestimate the SAT variation in the Qinghai‒Tibetan Plateau and the northeastern regions of China, and the performance is unsatisfactory with respect to the physical drivers of the dominant modes. Importantly, all the BCC models can capture the spatio-temporal characteristics of the first mode well and can, in general, characterize the spatial pattern of the second mode, but none of the models perform well in the principal component of the second mode (PC2) due to the low performance with respect to the interannual variation of PC2. Furthermore, the factors influencing the leading two modes are evaluated. The two CMIP6 can simulate better the Northern Hemisphere subtropical high northern boundary affecting the first mode. Another factor, the Asia polar vortex area, can only be simulated better by two low-resolution models (BCC-CSM1.1 and BCC-ESM1). For the second mode, all four models simulate the influence of Asian zonal circulation well, but poorly simulate that of the southern Indian Ocean dipole due to a large deviation in the Indian Ocean surface temperature.

Influence of temperature regime on climate change in Kapshagai reservoir

Solar radiation, along with other important meteorological elements, characterizes the comfort of the environment for recreational activities in a particular area with data on air temperature, humidity and precipitation. Each of these meteorological parameters reflects to some extent the recreational potential of the earth. However, the comfort of the region is evaluated primarily by the air temperature. In this regard, the article considers the influence of the Kapchagai reservoir and its adjacent stations on the climate by statistical analysis of the temperature regime from 1950 to 2012. The study examined changes in air temperature before the construction of the Kapchagai reservoir and after its opening, as well as the nature of their impact on the climate. According to meteorological observations, in a sharply continental climate, reservoirs lead to a warming of the winter period, which increases the duration of the warm period by 1-2 weeks within a radius of 1-50 km, depending on the size of the reservoir, despite a decrease in air temperature in summer.

The Effects of Climate Change on Interregional Electricity Market Dynamics on the U.S. West Coast

AbstractThe United States (U.S.) West Coast power system is strongly influenced by variability and extremes in air temperatures (which drive electricity demand) and streamflows (which control hydropower availability). As hydroclimate changes across the West Coast, a combination of forces may work in tandem to make its bulk power system more vulnerable to physical reliability issues and market price shocks. In particular, a warmer climate is expected to increase summer cooling (electricity) demands and shift the average timing of peak streamflow (hydropower production) away from summer to the spring and winter, depriving power systems of hydropower when it is needed the most. Here, we investigate how climate change could alter interregional electricity market dynamics on the West Coast, including the potential for hydroclimatic changes in one region (e.g., Pacific Northwest (PNW)) to “spill over” and cause price and reliability risks in another (e.g., California). We find that the most salient hydroclimatic risks for the PNW power system are changes in streamflow, while risks for the California system are driven primarily by changes in summer air temperatures, especially extreme heat events that increase peak system demand. Altered timing and amounts of hydropower production in the PNW do alter summer power deliveries into California but show relatively modest potential to impact prices and reliability there. Instead, our results suggest future extreme heat in California could exert a stronger influence on prices and reliability in the PNW, especially if California continues to rely on its northern neighbor for imported power to meet higher summer demands.