Increasing the energy of the initiating spark discharge in order to reduce and stabilize the delay time in a compact vacuum breaker

The similarity of the switching mechanisms of compact vacuum spark breakers and spark breakers with laser ignition is established at a comparable level of energy flux density in the ignition node–ionization of the residual gas by a stream of short-wave radiation and fast electrons from the cathode spot plasma or laser plasma. This mechanism allows you to effectively reduce the delay in triggering the spark gap by increasing the ignition energy. An experimental study of the advantages of using an ignition circuit with increased energy for controlling small-sized vacuum spark breakers is carried out. There is a steady decrease in the delay time of the spark gap and an increase in the level of delay stability. From the point of view of minimization and stability of the delay time of the spark gap, the energy investment in the formation of the initiating plasma occurs most effectively at the spark stage of the auxiliary discharge along the surface of the dielectric in the ignition node.

Anticipatory responses to drought by plants: What are the environmental cues?

This study is an attempt to reconcile the physics-driven variation in reference evapotranspiration (ET0) and possible sensory-driven anticipatory acclimation that contributes to tolerance of dry weather spells and drought by plants growing in open fields. We use an original data set measured at high temporal resolution. These data include the standard meteorological observations plus detailed observations of different bands of sunlight: UV-B, UV-A, photosynthetically active and global down-welling short-wave radiation, blue, red and far-red light from two growth seasons at Helsinki, Finland. We also report ET0 computed with the FAO formulation of the Penman-Monteith equation. We assessed the correlations among variables at different time scales and their performance as predictors of ET0. We conclude that all studied bands of sunlight are consistently good predictors of ET0. UV radiation is a specially good predictor of the daily course of ET0 while longer wavelengths function better in the prediction of day to day variation in ET0. In most cases sunlight bands that plants are known to sense through specific photoreceptors can explain more than 95% of the variation in ET0, making them as cues carrying information on the demand side of the water budget of vegetation. Sunlight as sensed by plants is consequently a good candidate as driver of anticipatory acclimation to likely future drought events.

Minimization of the delay time and its spread in a compact vacuum breaker

The similarity of the switching mechanisms of compact vacuum spark breakers and spark breakers with laser ignition is established at a comparable level of energy flux density in the ignition node–ionization of the residual gas by a stream of short-wave radiation and fast electrons from the cathode spot plasma or laser plasma. This mechanism allows you to effectively reduce the delay in triggering the spark gap by increasing the ignition energy. An experimental study of the advantages of using an ignition circuit with increased energy for controlling small-sized vacuum spark breakers is carried out. There is a steady decrease in the delay time of the spark gap and an increase in the level of delay stability. From the point of view of minimization and stability of the delay time of the spark gap, the energy investment in the formation of the initiating plasma occurs most effectively at the spark stage of the auxiliary discharge along the surface of the dielectric in the ignition node.

Introducing Ice Nucleating Particles functionality into the Unified Model and its impact on the Southern Ocean short-wave radiation biases

Insufficient reflection of short-wave radiation especially over the Southern Ocean region is still a leading issue in many present-day global climate models. One of the potential reasons for this observed bias is an inadequate representation of clouds. In a previous study, we modified the cloud micro-physics scheme in the Unified Model and showed that choosing a more realistic value for the capacitance or shape parameter of atmospheric ice-crystals, in better agreement with theory and observations, benefits the simulation of short-wave radiation over the Southern Ocean by brightening the clouds. However, attempts to modify the cloud phase by directly adjusting the micro-physics process rates like capacitance tend to affect both the hemispheres symmetrically whereas we seek to brighten only the high-latitude Southern Hemisphere clouds. In this study we implement a simple prognostic parametrisation whereby the heterogeneous ice nucleation temperature is made to vary three-dimensionally as a function of the mineral dust distribution in the model. As a result, those regions with less dust number density would have lower nucleation temperature compared to the default global value of −10 °C. By using mineral dust as an indicator for ice nucleating particles in the model, this parametrisation thus captures the impact of ice nucleating particles on the cloud distribution due to its general paucity over the Southern Ocean region. This approach thus improves the physics of the model with minimal complexity.

Variations in Short Wave Radiation and Ocean Temperature in the Tropical Indian Ocean

The purpose of this study was to know the results of the relation between short wave radiation (SWR) and sea temperature. This study used data of SWR and sea temperature from RAMA buoy which part of the data was obtained by the INA-PRIMA 2019. Besides, the SWR and Sea Temperature model data from ERA-5 and Copernicus were required to see these spatial and temporal variations. Diurnal analysis to determine the sea temperature responds to SWR parameters. While monthly analysis to see the variations of SWR and the sea temperature during Indian Ocean Dipole (IOD). The results show that there is a different response at sea temperature for each layer to the SWR parameter in diurnal. SWR can affect sea temperatures until 20 meters of depth. There is a time lag between 2 and 3 hours when the sun heats the sea until the sea surface temperature increases. The 20 meters of depth has a lag time until 4 hours. As for 40 to 80 meters of depth, the sea temperature was not longer responded by SWR, and the temperature is changed by the strength of these mixing.Warm pools are generally located in East Indian Ocean and the high SWR were very strong in West Indian Ocean along an anual.

Cloud effects on surface radiation balance at Helheim and Jakobshavn Glaciers (Greenland) using ground-based observations

<p>The surface radiation budget is an essential component of the total energy exchange between the atmosphere and the Earth’s surface. Measurements of radiative fluxes near/on ice surfaces are sparse in the polar regions, including on the Greenland Ice Sheet (GrIS), and the effects of cloud on radiative fluxes are still poorly studied. In this work, we assess the impacts of cloud on radiative fluxes using two metrics: the longwave-equivalent cloudiness, derived from long-wave radiation measurements, and the cloud transmittance factor, obtained from short-wave radiation. The metrics are applied to radiation data from two automatic weather stations located over the bare ground near the ice front of Helheim (HG) and Jakobshavn Isbræ (JI) on the GrIS. Comparisons of meteorological parameters, surface radiation fluxes, and cloud metrics show significant differences between the two sites. The cloud transmittance factor is higher at HG than at JI, and the incoming short-wave radiation in the summer at HG is 50.0 W m−2 larger than at JI. Cloud metrics derived at the two sites reveal   a high dependency on the wind direction. The total cloud radiative effect (CREnet) generally increases during melt season at the two stations due to long-wave CRE enhancement by cloud fraction.  CREnet decreases from May to June and increases afterward, due to the strengthened short-wave CRE. The annually averaged CREnet were 3.0 ± 7.4 W m-2 and 1.9 ± 15.1 W m−2 at JI and HG.  CREnet estimated from AWS indicates that clouds cool the JI and HG during melt season at different rates.</p>

Coupled water, vapor and heat flow in evaporation experiments under different boundary conditions

<p>Evaporation from bare soil is an important hydrological process which influences the water and energy budget at all scales. Modelling soil evaporation is complex because it involves coupled liquid, vapor and heat flow. Although high-quality experimental data and use of different boundary conditions is mandatory to validate theory and to discriminate between models, many controlled experiments are still restricted to single boundary conditions. We conducted laboratory bare-soil evaporation experiments with a sand and a silt loam with three atmospheric forcings, (i) wind, (ii) wind and short-wave radiation, and (iii) wind and intermittent short-wave radiation. The soil columns were instrumented with temperature sensors, mini-tensiometers, and relative humidity probes, and evaporation rates were measured gravimetrically. The evaporation experiments were then simulated with a coupled water, vapour and heat flow model. We show that the coupled model reproduces measured evaporation rates and soil state variables (pressure head and temperature) of the evaporation experiments very well. In particular, the onset of stage-two evaporation, characterized by a decrease in evaporation rate and an increase in soil temperature is predicted correctly. Notably, a soil surface resistance, which has been suggested in the literature as a necessary component of evaporation models, led to a gross underestimation of the evaporation rate and a mismatch of the transition to stage-2 evaporation for both soils, for all boundary conditions, and for different soil surface resistance models. This illustrates that the use of resistance factors in coupled water, vapor and heat flow modelling studies is not justified.</p>

Study of the sea ice impact on primary production in the Barents and Kara Seas in past and future climates

<p>A regional coupled eco-hydrodynamic model of the Barents and Kara Seas based on the MITgcm has been developed. The biogeochemical module is based on a 7-component model of pelagic biogeochemistry including the ocean carbon cycle. This regional model allows revealing and explaining the main mechanisms of the interaction between marine dynamic and biogeochemical processes in the Barents and Kara Seas under a changing climate. We present the main results of simulations for the past (1975-2005) and future (2035-2065) climate.</p><p>A clear relationship between the marginal ice zone area and primary production has been obtained, proving the importance of this zone in the functioning of the marine ecosystem. The interannual variability of the integrated primary production and the total sea ice area demonstrates an antiphase behavior, which means that the reduced sea ice cover area in the previous winter is one of the main reasons for the increase in primary production in the current year.</p><p>The model simulations demonstrate that, of all the external factors, sea ice area plays a primary role in the formation of primary production: in the overwhelming majority of cases, the contribution of the ice area prevails, and the pattern "more ice - less primary production" and vice versa is fulfilled in the Barents and Kara Seas. The effect of a decrease of incoming short-wave radiation becomes significant only when a significant decrease of the ice area occurs.</p><p>Compared to the period 1975-2005, the simulated total primary production in the Barents and Kara Seas is much higher for the period 2035-2065, while the sea ice area significantly decreases.</p><p>A regression dependence has been obtained for the total annual primary production as a function of sea ice area and incoming short-wave radiation. Its validity is verified for both past (dependent) and future (independent) climatic periods. It justifies the use of such simple statistical model for quick estimates of the primary production in the Barents and Kara Seas.</p><p>Acknowledgements: The research was performed in the framework of the state assignment of the Ministry of Science and Higher Education of Russia (theme No. 0128-2021-0014). This work used resources of the Deutsches Klimarechenzentrum (DKRZ) granted by its Scientific Steering Committee (WLA) under project ID ba1206.</p>

ABOUT THE CREATION OF AN LED LIGHT SOURCE WITH VARIABLE COLOR TEMPERATURE

The article is devoted to the development and research of an LED lamp of the A65 form factor and the type of E27 base with a choice of color temperature when the lamp is alternately connected to the supply network. The description of LEDs, driver, radiator, housing, base is given. Analysis of the results of measurements of lighting characteristics showed that the luminous flux and power consumption of the LED lamp amounted to 1004.1 lm and 12.5 W at a measured color temperature of 3056 K and 1059.8 lm and 12.37 W at 4120 K. Change in the color temperature of the lamp from 3056 K to 4120 K is characterized by an increase in the spectral density in the region of short-wave radiation with an increase in the proportion of blue, blue and violet colors. The shape of the lamp luminous intensity curve is close to the diffuse distribution. The change in color temperature is carried out by turning off and then turning on the lamp in the mains for no more than 5 seconds.