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Jelena Tihana - One of the best experts on this subject based on the ideXlab platform.

  • Experimental testing of phase change materials in a warm-summer humid Continental Climate
    Energy and Buildings, 2019
    Co-Authors: Maris Sinka, Diana Bajare, Andris Jakovics, Janis Ratnieks, Stanislavs Gendelis, Jelena Tihana
    Abstract:

    Abstract The construction industry (and buildings) is one of the largest energy consuming and CO2 emitting sectors in the world. To counter this, more lightweight structures are being used and energy saving applications are being developed. Phase change materials (PCM) are materials that can be considered to tackle these new challenges. It has been proven that PCMs can be passively used to improve the thermal mass of lightweight structures, which improves thermal comfort and reduces peak cooling and heating loads and therefore provides energy savings. To use these materials in an active way, they should be used together with ventilation, cooling or heating equipment, and collectors to accumulate or return the energy stored in the rooms through these systems. PCMs in buildings are predominantly experimentally applied and tested in hot Climates, but they have not been extensively studied for either cooling or heating in a warm-summer humid Continental Climate. Within the framework of this research, an experimental compound consisting of five test buildings, used in previous studies to assess the performance of different building materials and heating, ventilation and air conditioning (HVAC) systems in the Latvian Climate, was used. Two types of PCM were used to carry out the three different experiments in situ, as well as modelling and validation of obtained data: the main goal was to increase the thermal mass of lightweight buildings. The preliminary results indicated that, in the case of overheating, additional mechanical ventilation during the night should be used due to the high temperatures at night, which are a little below the solidification temperatures of PCM during overheating periods. The highest efficiency of PCM was obtained when it was used in conjunction with capillary ceiling cooling, providing a lower indoor temperature of 3–4 °C during the day, but additional investigations are necessary to calculate the economic gains. In general, experiments have shown that PCMs can be used in buildings to increase their energy effectiveness in the Latvian Climate, but complex control systems are required to operate such systems with the highest efficiency.

Jean-louis Dufresne - One of the best experts on this subject based on the ideXlab platform.

  • Improved Near‐Surface Continental Climate in IPSL‐CM6A‐LR by Combined Evolutions of Atmospheric and Land Surface Physics
    Journal of Advances in Modeling Earth Systems, 2020
    Co-Authors: Frédérique Cheruy, Agnès Ducharne, Frédéric Hourdin, Ionela Musat, Étienne Vignon, Guillaume Gastineau, Vladislav Bastrikov, Nicolas Vuichard, Binta Diallo, Jean-louis Dufresne
    Abstract:

    This work is motivated by the identification of the land-atmosphere interactions as one of the key sources of uncertainty in Climate change simulations. It documents new developments in related processes, namely, boundary layer/convection/clouds parameterizations and land surface parameterization in the Earth System Model of the Institut Pierre Simon Laplace (IPSL). Simulations forced by prescribed oceanic conditions are produced with different combinations of atmospheric and land surface parameterizations. They are used to explore the sensitivity to the atmospheric physics and/or soil physics of • major biases in the near surface variables over continents, • the energy and moisture coupling established at the soil/atmosphere interface in not too wet (energy limited) and not too dry (moisture limited) soil moisture regions also known as transition or "hot-spot" regions, • the river runoff at the outlet of major rivers. The package implemented in the IPSL-Climate Model for the Phase 6 of the Coupled Models Intercomparison Project (CMIP6) allows us to reduce several biases in the surface albedo, the snow cover, and the Continental surface air temperature in summer as well as in the temperature profile in the surface layer of the polar regions. The interactions between soil moisture and atmosphere in hotspot regions are in better agreement with the observations. Rainfall is also significantly improved in volume and seasonality in several major river basins leading to an overall improvement in river discharge. However, the lack of consideration of floodplains and human influences in the model, for example, dams and irrigation, impacts the realism of simulated discharge. Plain Language Summary Land surface-atmosphere interactions play an essential role in the Climate system. They strongly modulate the regional Climates and have impacts on the global scale for instance through freshwater release into the oceans. Climate hazards (heat waves, droughts) and their impacts on populations also strongly depend on interactions between land and atmosphere and on their evolution with Climate change. Climate models are precious tools to investigate how the Earth Climate behaves. The sixth phase of the Climate Model Intercomparison Project (CMIP6) provides important tools to measure the progress and address the remaining open questions regarding the Continental Climate modeling. The representation of the land-atmosphere coupled system by the IPSL-Climate Model involved in CMIP6 is thoroughly evaluated against observations and compared with simulations using the CMIP5 version. Several biases concerning the temperature over land and over the ice sheets and with the snow cover are significantly reduced. Numerous improvements were made developping advanced parameterizations and tuning of the radiation and of the turbulent mixing in the atmospheric model. The realism of the seasonal

  • improved near surface Continental Climate in ipsl cm6a lr by combined evolutions of atmospheric and land surface physics
    Journal of Advances in Modeling Earth Systems, 2020
    Co-Authors: Frédérique Cheruy, Agnès Ducharne, Frédéric Hourdin, Ionela Musat, Étienne Vignon, Guillaume Gastineau, Vladislav Bastrikov, Nicolas Vuichard, Binta Diallo, Jean-louis Dufresne
    Abstract:

    This work is motivated by the identification of the land-atmosphere interactions as one of the key sources of uncertainty in Climate change simulations. It documents new developments in related processes, namely, boundary layer/convection/clouds parameterizations and land surface parameterization in the Earth System Model of the Institut Pierre Simon Laplace (IPSL). Simulations forced by prescribed oceanic conditions are produced with different combinations of atmospheric and land surface parameterizations. They are used to explore the sensitivity to the atmospheric physics and/or soil physics of • major biases in the near surface variables over continents, • the energy and moisture coupling established at the soil/atmosphere interface in not too wet (energy limited) and not too dry (moisture limited) soil moisture regions also known as transition or "hot-spot" regions, • the river runoff at the outlet of major rivers. The package implemented in the IPSL-Climate Model for the Phase 6 of the Coupled Models Intercomparison Project (CMIP6) allows us to reduce several biases in the surface albedo, the snow cover, and the Continental surface air temperature in summer as well as in the temperature profile in the surface layer of the polar regions. The interactions between soil moisture and atmosphere in hotspot regions are in better agreement with the observations. Rainfall is also significantly improved in volume and seasonality in several major river basins leading to an overall improvement in river discharge. However, the lack of consideration of floodplains and human influences in the model, for example, dams and irrigation, impacts the realism of simulated discharge. Plain Language Summary Land surface-atmosphere interactions play an essential role in the Climate system. They strongly modulate the regional Climates and have impacts on the global scale for instance through freshwater release into the oceans. Climate hazards (heat waves, droughts) and their impacts on populations also strongly depend on interactions between land and atmosphere and on their evolution with Climate change. Climate models are precious tools to investigate how the Earth Climate behaves. The sixth phase of the Climate Model Intercomparison Project (CMIP6) provides important tools to measure the progress and address the remaining open questions regarding the Continental Climate modeling. The representation of the land-atmosphere coupled system by the IPSL-Climate Model involved in CMIP6 is thoroughly evaluated against observations and compared with simulations using the CMIP5 version. Several biases concerning the temperature over land and over the ice sheets and with the snow cover are significantly reduced. Numerous improvements were made developping advanced parameterizations and tuning of the radiation and of the turbulent mixing in the atmospheric model. The realism of the seasonal

Iraj Eskandari - One of the best experts on this subject based on the ideXlab platform.

  • Conservation tillage practices for winter wheat–fallow farming in the temperate Continental Climate of northwestern Iran
    Field Crops Research, 2004
    Co-Authors: Abbas Hemmat, Iraj Eskandari
    Abstract:

    Abstract Soil water is the most limiting resource for crop growth in dryland areas. Conservation tillage has been proposed as a promising strategy to improve soil and water conservation in these areas. A 3-year field experiment to determine the feasibility of conservation tillage for wheat ( Triticum aestivum L.) production was initiated in 1999 on a clay loam (Vertic Calcixerepts) soil in the temperate Continental Climate of northwestern Iran, with an average annual precipitation of 375 mm. The tests were conducted using conventional (moldboard plow), reduced (chisel plow), minimum (sweep plow) and direct drilling (in standing stubble/total residue) tillage systems. In the first year of the experiment (1999–2000), treatments were applied as pre-seeding tillage on a fall chisel tilled fallowed site, whereas in the second and third years, the tillage treatments were applied during fallow with direct drilling of the following wheat. Wheat grain yields were significantly affected by tillage. The same yield trend was observed for the tillage treatments in all years. Yields under reduced tillage were consistently higher (35%) than yields from conventional tillage. Grain yields under direct drilling were similar to those obtained using the reduced-tillage system and superior to yields obtained by conventional tillage system. The minimum till system applied as pre-seeding or fallow tillage reduced crop yields compared to reduced tillage. The overall results showed that tillage intensity could be reduced to the level of reduced tillage or direct drilling with an increase in crop yields.

G.r. Coy - One of the best experts on this subject based on the ideXlab platform.

  • Wheat yield and weed population as influenced by three tillage systems on a clay soil in temperate Continental Climate.
    Soil and Tillage Research, 1994
    Co-Authors: Muhammad Arshad, K. S. Gill, G.r. Coy
    Abstract:

    The potential benefits of conservation tillage practices depend mainly on the soil and climatic conditions of the site. A study was conducted to determine the effects of three tillage systems (conventional, CT; reduced, RT; zero, ZT) on spring wheat (Triticum aestivum L.) and weed growth on a clay soil in temperate Continental Climate, northern Alberta (55°43′N, 118°41′W), Canada. A medium duty cultivator with 25 cm sweeps spaced 22 cm apart and a working depth of 8–10 cm was used for tillage in the CT (once in fall and twice in spring) and RT (once in spring) plots. The ZT plots received a harrowing to spread straw and a preseeding application of Roundup (glyphosate) to control weeds. Experimental design was a randomized complete block with four replications and the tillage systems were fixed in space for the 1989, 1990 and 1991 seasons. The RT treatment resulted in higher yields than the CT or ZT treatments. However, the differences were not always significant. The ZT treatment produced higher yields than CT in 1989 and 1991, whereas its yields were lower than CT in 1990. The 3 year means of total dry matter (TDM) were 3899 kg ha−1, 3640 kg ha−1 and 3331 kg ha−1 for the RT, ZT and CT treatments, respectively. The corresponding grain yields were 1728 kg ha−1, 1573 kg ha−1 and 1530 kg ha−1. The concentration of total N in plants and grains of wheat, amounts of extractable NO3-N, NH4-N and P in soil and soil moisture and bulk density were not significantly affected by tillage. The mean weight diameter of aggregates in surface soil was significantly greater under ZT than under the other systems. Wild buckwheat (Polygonum convolvulus L.) was more abundant under CT, but common groundsel (Senecio vulgaris L.), dandelion (Taraxacum officinale Weber), hemp nettle (Galeopsis tetrahit L.), field horsetail (Equisetum arvense L.) and smartweed (Polygonum scabrum Moench) tended to have higher populations under the ZT system. The populations of foxtail barley (Hordeum jubatum L.) wild rose (Rosa sp.), stinkweed (Thlaspi arvense L.) and wild oats (Avena fatua L.) showed no consistent effect of tillage. Tillage or preseeding application of glyphosate did not provide an effective control of all weed species. The spring tillage of the RT system improved crop yields and weed control relative to ZT, whereas the fall tillage of the CT system (in addition to spring tillage) reduced crop yields and had no significant effect on weed population relative to RT. The overall results showed that tillage intensity could be reduced to the level of RT without any adverse influence on crop yields, soil properties or weed populations. The RT system is also economical and environmentally desirable owing to lower tillage and herbicide requirements.

Cristian Paltineanu - One of the best experts on this subject based on the ideXlab platform.

  • Timing of phenological stages for apple and pear trees under Climate change in a temperate-Continental Climate
    International Journal of Biometeorology, 2020
    Co-Authors: Emil Chitu, Cristian Paltineanu
    Abstract:

    The study examines the consequences of Climate change in Malus (apple) and Pyrus (pear) on four phenological stages: bud swelling (code 51 BBCH Monograph), budburst (code 53), beginning of flowering (code 61), and end of flowering (code 69) in the temperate-Continental Climate of southern Romania. The hypothesis tested is how much the onset dates (TOD) of phenology stages moved earlier due to Climate change. Weather and phenological data were collected from 1969 to 2018 and were statistically processed. There was an increase in air temperature (T) during the first 5 months in the year, with a significant rise in March and April; significant linear relationships show an advance in TOD with the years elapsed. Inverse linear relationships were found between TOD, maximum ( T _max), mean ( T _mean), minimum ( T _min) temperature, and sunshine hours (Sh). The relationships between TOD and T _max were the strongest. The early stages of flowering phenology are advancing more strongly than later flowering stages. For apple, in the last 50 years, there was an advance of 13.8 days for stage 51, 14.8 days for stage 53, 10.7 days for stage 61, and only 7.3 days for stage 69; for pear trees, the advance was lower: 10 days for stage 51, 9 days for stage 53, 6.7 days for stage 61, and only 2.1 days for stage 69. These findings, which might be extrapolated to similar environments, have important consequences in fruit growing, like the occurrence of Climate accidents due to late frost, insect pollination, and application of pesticides and irrigation water.

  • Climate change impact on phenological stages of sweet and sour cherry trees in a Continental Climate environment
    Scientia Horticulturae, 2020
    Co-Authors: Cristian Paltineanu, Emil Chitu
    Abstract:

    Abstract This study presents the impact of Climate change on the first four phenological stages: bud swelling (code 51 BBCH Monograph), budburst (code 53), beginning of flowering (code 61), and end of flowering (code 69) of sweet cherry (Prunus avium L., Germersdorfer cultivar) and sour cherry (Prunus cerasus L., Crisana cultivar) trees, grafted on seedling, in a temperate-Continental Climate. We tested the hypothesis that the time to the onset of the phenological stages (TOPS) occurred earlier due to Climate change and analyzed the consequences for farmers. Weather and phenological data from 1970 to 2018 were statistically processed. There was a rise in air temperature (T) during January through May, with a significant increase in March and April. Inverse linear relationships were found between TOPS and time, as well as between TOPS and some Climate variables: maximum, mean and minimum T, and sunshine hours. There is an advance in the first three phenological stages, with stage 51 as the earliest. The impact is important in relation to insect pollination, pesticide application, and occurrence of Climate accidents due to late frost. Insect pollination does not always occur simultaneously with the flowering of trees in spring. Rain and cold temperatures can interfere with pollination. Application of pesticides in orchards should be adjusted according to the weather course. Farmers should consider additional pesticide treatments to hamper development of specific pests and diseases. They should adjust irrigation scheduling and perhaps harvesting time. These results might be useful for farmers in other countries with similar environments.