Nighttime Minimum Research Articles

The effect of urban form parameters on annual and diurnal cycles of land surface temperature with 30-meter hourly resolution

Understanding dynamic changes in urban land surface temperature (U-LST) is vital for improving urban thermal environment. Previous studies noted a close association between two/three-dimensional (2D/3D) urban form parameters (UFPs) and U-LST, but divergent conclusions emerged due to study scale and data spatiotemporal resolution. This study investigated the effect of 2D/3D UFPs on multi-temporal (hourly, diurnal, and annual) U-LSTs with 30-m spatial resolution, which is the first exploration of such dynamics at this fine scale. In addition, the influence of local climate zones (LCZs) was considered. Results showed that 2D/3D vegetation UFPs have the greatest summer cooling effect at 21:00, while 3D building UFP sky view factor (SVF) impacts minimum nighttime temperature more (5:00). The independently total explained variances (R2) of 2D UFPs (0.2–0.7) on seasonal average U-LSTs were higher than that of 3D UFPs (0.1–0.4) in most LCZs. LCZ 3 and LCZ 2 had the highest seasonal and daytime U-LST, respectively. Interestingly, SVF replaced normalized difference vegetation index as the dominant factor in LCZs 4–6 and LCZs A-C after summer. Findings of this study are useful for guiding urban planning, formulating urban heat island mitigation policies, and promoting sustainable development goals (SDGs 11, 13, 15) of cities and communities.

Assessment of Heat Exposure and Health Outcomes in Rural Populations of Western Kenya by Using Wearable Devices: Observational Case Study.

Climate change increasingly impacts health, particularly of rural populations in sub-Saharan Africa due to their limited resources for adaptation. Understanding these impacts remains a challenge, as continuous monitoring of vital signs in such populations is limited. Wearable devices (wearables) present a viable approach to studying these impacts on human health in real time. The aim of this study was to assess the feasibility and effectiveness of consumer-grade wearables in measuring the health impacts of weather exposure on physiological responses (including activity, heart rate, body shell temperature, and sleep) of rural populations in western Kenya and to identify the health impacts associated with the weather exposures. We conducted an observational case study in western Kenya by utilizing wearables over a 3-week period to continuously monitor various health metrics such as step count, sleep patterns, heart rate, and body shell temperature. Additionally, a local weather station provided detailed data on environmental conditions such as rainfall and heat, with measurements taken every 15 minutes. Our cohort comprised 83 participants (42 women and 41 men), with an average age of 33 years. We observed a positive correlation between step count and maximum wet bulb globe temperature (estimate 0.06, SE 0.02; P=.008). Although there was a negative correlation between minimum nighttime temperatures and heat index with sleep duration, these were not statistically significant. No significant correlations were found in other applied models. A cautionary heat index level was recorded on 194 (95.1%) of 204 days. Heavy rainfall (>20 mm/day) occurred on 16 (7.8%) out of 204 days. Despite 10 (21%) out of 47 devices failing, data completeness was high for sleep and step count (mean 82.6%, SD 21.3% and mean 86.1%, SD 18.9%, respectively), but low for heart rate (mean 7%, SD 14%), with adult women showing significantly higher data completeness for heart rate than men (2-sided t test: P=.003; Mann-Whitney U test: P=.001). Body shell temperature data achieved 36.2% (SD 24.5%) completeness. Our study provides a nuanced understanding of the health impacts of weather exposures in rural Kenya. Our study's application of wearables reveals a significant correlation between physical activity levels and high temperature stress, contrasting with other studies suggesting decreased activity in hotter conditions. This discrepancy invites further investigation into the unique socioenvironmental dynamics at play, particularly in sub-Saharan African contexts. Moreover, the nonsignificant trends observed in sleep disruption due to heat expose the need for localized climate change mitigation strategies, considering the vital role of sleep in health. These findings emphasize the need for context-specific research to inform policy and practice in regions susceptible to the adverse health effects of climate change.

Western Europe’s extreme July 2019 heatwave in a warmer world

Summertime heatwaves are extreme events with a large societal impact. Intensity, duration and spatial extent, all heatwave properties are projected to increase in a warming world, implying that summers that qualified as extreme in the past will become increasingly normal. In this paper we quantify how the changes play out for the July 2019 European heatwave that shattered temperature records throughout Western Europe. We combine a storyline approach with ensemble Pseudo Global Warming (PGW) and high-resolution dynamical downscaling. The downscaling is done with a regional climate model (RACMO2, 12 km resolution) and a convection-permitting model (HCLIM-AROME, 2.5 km resolution). Under PGW the maximum temperature during the heatwave rises 1.5 to 2.5 times faster than the global mean, implying that even at moderate warming levels the heatwave impact changes are tangible. Moreover, there is no sign that the increase in the maximum temperature levels off at higher warming levels, implying that at +4K above present-day temperatures could reach 50 ∘C. During heatwaves cities become islands of heat where daily maxima and night-time minima are up to 5 ∘C higher than in rural areas as we show in ultra-high resolution HCLIM-AROME simulations at 150 m resolution.

Electricity-carbon coupling retail package optimization considering low-carbon benefits of distributed renewable energy

Distributed renewable energy has developed rapidly in recent years, but its low-carbon value is usually ignored due to its limited individual capacity. It will be an important business for electricity retailers to aggregate these distributed renewable resources and make use of their carbon emission reduction benefits. Therefore, this paper proposes a business model for electricity retailers based on electricity-carbon coupling retail packages. Firstly, a framework of the business model is proposed to support distributed renewable energy transaction among the electricity retailer, prosumers, and consumers. Secondly, dynamic carbon evaluation mechanism-based electricity-carbon coupling retail packages are designed, which contain three types of generation packages for prosumers (e.g., fixed subsidy package, dynamic subsidy package and daytime generation package) and three types of consumption packages for consumers (e.g., daytime consumption package, nighttime consumption package and minimum consumption package). In addition, a single-leader and multi-followers Stackelberg game model is constructed to optimize the designed packages. Especially, the electricity retailer aims at maximizing its profit considering conditional value at risk (CVaR) as the leader. Meanwhile, prosumers and consumers respectively aim at maximizing their profit satisfaction and comprehensive satisfaction as followers. Finally, the particle swarm optimization (PSO) algorithm and CPLEX commercial solver are both used to obtain the model's Nash equilibrium (NE). Example analysis verifies the designed electricity-carbon coupling retail packages can utilize the low-carbon value of distributed renewable resources and improve the benefits and satisfaction of prosumers and consumers.

Energy- and yield-based performance evaluation of a phase change material–integrated single-span double-layered with a thermal screen greenhouse

Greenhouse technology emerged to ensure the optimum yield of the host crop —a prerequisite to achieving Sustainable Development Goals 7 and 2. To achieve this, supplemental energy is needed under extreme weather conditions at about half the operational cost. Researchers have focused and succeeded in reducing the energy demand using numerical methods with little focus on the impact of these methods on crop yield. A novel greenhouse system—phase change material–integrated single-span double-layered strawberry greenhouse with a thermal screen—is introduced herein. Furthermore, how the energy management method affects the yield of the host crop is explored. Moreover, the energy-saving potential and yield enhancement achieved by integrating PCMs and other passive thermal-management systems in a specific agricultural setting is investigated. TRNSYS 18 software is used to evaluate the effect of three passive variables on two performance indices. The passive variables are location: Daegu (DG), Seoul, and Jeju Island (JE); orientation: 90° (E-W), 45° (NE-SW), and 0° (N-S); and PCM type: “No-fill”, water, and Paraffin (ParC13–C24). The effect of thermal screen control was also studied on the localized optium configuration. Finally, economic analysis was conducted to ascertain the most sustainable configuration. The performance indices are the heating demand and strawberry yield. The results show that the location, orientation, and PCM usage inside the greenhouse greatly affect the greenhouse’s heating demand and crop yield. The configuration selected must be in such a way that the indoor nighttime temperature does not exceed 2 °C above the minimum nighttime optimum value of the host crop.

Pavement Temperature Forecasts Based on Model Output Statistics: Experiments for Highways in Jiangsu, China

Forecasts on transportation meteorology, such as pavement temperature, are becoming increasingly important in the face of global warming and frequent disruptions from extreme weather and climate events. In this study, we propose a pavement temperature forecast model based on stepwise regression—model output statistics (SRMOS) at the short-term timescale, using highways in Jiangsu, China, as examples. Experiments demonstrate that the SRMOS model effectively calibrates against the benchmark of the linear regression model based on surface air temperature (LRT). The SRMOS model shows a reduction in mean absolute errors by 0.7–1.6 °C, with larger magnitudes observed for larger biases in the LRT forecasts. Both forecasts exhibit higher accuracy in predicting minimum nighttime temperatures compared to maximum daytime temperatures. Additionally, it overall shows increasing biases from the north to the south, and the SRMOS superiority is greater over the south with larger initial LRT biases. Predictor importance analysis indicates that temperature, moisture, and larger-scale background are basically the key predictors in the SRMOS model for pavement temperature forecasts, of which the air temperature is the most crucial factor in the model’s construction. Although larger-scale circulation backgrounds are generally characterized by relatively low importance, their significance increases with longer lead times. The presented results demonstrate the considerable skill of the SRMOS model in predicting pavement temperatures, highlighting its potential in disaster prevention for extreme transportation meteorology events.

A comparative analysis of ambulatory blood pressure characteristics in acute stroke and non-stroke Indian patients.

The objective of this study is to identify 24-h blood pressure (BP) characteristics after acute stroke in Indian hospitalized patients. In total, 769 patients [284 women (36.9%)] admitted at a hospital in South India were analyzed. Of these, 364 patients (47.3%) had recently experienced stroke. All patients underwent ambulatory blood pressure measurement (ABPM) so that ABPM patterns and ABPM risk parameters of stroke and non-stroke patients could be compared. Additionally, to investigate the relationship between ABPM parameters and stroke, a stepwise logistic regression analysis was employed. Stroke patients had significantly higher BP than non-stroke patients (24-h ABP: 145.0 ± 22.1 vs. 133.7 ± 20.5 mmHg, P < 0.001), with similar dipping status. ABPM parameters mostly associated with stroke (all P < 0.001) were: nighttime [odds ratios (OR): 1.587, 95% confidence interval (95% CI): 1.341-1.885], 24-h (1.584, 1.34-1.881), minimum nighttime (1.582, 1.339-1.879), daytime (1.540, 1.304-1.827), and morning SBP (1.517, 1.287-1.797). Non-dipping status was relatively more common in stroke patients (79% vs. 71%, P < 0.05) but dipping percentage did not show a significant linear relationship with stroke. Several ABPM characteristics were strongly associated with stroke in Indian hospitalized patients. Specifically, minimum nighttime and average morning SBP may be considered as important and practical parameters for its relationship with stroke.

Trends in tropical nights and their effects on mortality in Switzerland across 50 years

Increasing temperatures and more frequent and severe heat waves in Switzerland are leading to a larger heat-related health burden. Additionally, high nighttime temperatures or tropical nights (TNs) also affect the well-being of the population. We aimed to assess the spatiotemporal patterns in the frequency and the exposed population to TNs, and its mortality effect in Switzerland. We identified the TNs (minimum nighttime temperature ≥ 20°C) in each district in Switzerland using population-weighted hourly temperature series (ERA5-Land reanalysis data set) between 1970–2019. We assessed the change in the frequency of TNs and the exposed population per district and decade through a spatiotemporal analysis. We then performed a case time series analysis to estimate the TN-mortality association (controlled for the daily mean temperature) by canton and for the main 8 cities using data on all-cause mortality at the district level between 1980–2018. We found an overall increase in the annual frequency of TN (from 90 to 2113 TNs per decade) and the population exposed (from 3.7 million to over 157 million population-TN per decade) in Switzerland between 1970–2019, mainly in the cities of Lausanne, Geneva, Basel, Lugano, and Zurich, and during the last two decades. The TN-mortality association was highly heterogeneous across cantons and cities. In particular, TNs were associated with an increase of 22–37% in the risk of mortality in the cantons of Vaud (Relative risk: 1.37 (95%CI:1.19–1.59)), Zurich (1.33 (0.99–1.79)), Lucerne (1.33 (0.95–1.87)) and Solothurn (1.22 (0.88–1.69)), while a negative association was observed in Ticino (0.51 (0.37–0.7)), Basel-Land (0.4 (0.24–0.65)) and Thurgau (0.65 (0.5–0.85)), and a null association in the remaining cantons. Our findings indicate that TNs are a relevant health hazard for a large part of the Swiss population leading to potentially larger impacts in the future due to climate change and increasing urbanization.

ОПЫТНО-АНАЛИТИЧЕСКОЕ ОПРЕДЕЛЕНИЕ КРИТИЧЕСКИХ ТЕМПЕРАТУРНЫХ ТОЧЕК ТЕПЛИЦЫ

In greenhouse, soil is the main heat accumulator, and its rational use is a very urgent task, which can be successfully solved only with full automation of the transfer of the missing thermal energy. To do this, it is enough to determine the following parameters in the greenhouse: the maximum daily temperatures of air and soil inside and outside, the distribution of temperature maxima during the day, the relative position and time of balancing the temperatures of the air and soil half-space in the greenhouse in the morning and in the evening, or the point of reversal of the heat flow. The temperature parameters were determined experimentally over a continuous 11 days, then approximated to third-order polynomial equations with a reliability of 0.92 ... 0.96, and analytical studies were carried out on them. The daily temperature maxima were calculated by equating the first derivatives to zero and solving the quadratic equation. The daily points of heat reversal to the soil and from the soil in time were determined by solving the system of equations for changing the temperature of the soil and the air half-space inside the greenhouse (points of intersection of the graphs). Similarly, from the system of equations, critical points were determined in the time of transition of the temperature of the air half-space inside the greenhouse to the negative zone (t=0ºC). The same method was used to calculate the optimal temperatures in the greenhouse or the moments in time of switching on and off the heat source, for which topt was introduced into the system of equations for each cultivated plant. A differentiated heating system for the greenhouse is proposed in terms of soil heat consumption, which consists in ensuring the minimum supply of additional heat during the daytime optimum and the maximum at nighttime minimum points.

New insights into the scientific configuration of a sheet heating system applied in Chinese solar greenhouse

• The shadow range on the north wall were analyzed though the perspective of solar radiation. • Theoretical basis for the solar collector size and installation position was proposed. • Daily average heat collection per unit collector area is 5.6 MJ/m 2 . • The control system can be regulated flexibly according to the indoor microclimate. • The solar water heating system is cost effective in terms of investment and energy saving. The traditional Chinese solar greenhouse (CSG) cannot meet the overwinter production of warm-season plants in the cold north of China. At present, a sheet heating system on the north wall is often used to solve the problem of low temperature in the CSG. However, there is a lack of a theoretical basis for the design of collectors in current research. To address this problem, a theoretical basis for the collector size and installation position of the system from the perspective of solar radiation was proposed in this study. A sheet heating system on the north wall was installed in a CSG in Beijing, which is a solar water recycling system (SWRS). To evaluate the thermal performance of the SWRS, field tests and theoretical verification were carried out. The results indicated that the minimum nighttime indoor temperature increased by 3.1 ℃ on average. The duration of nighttime indoor temperatures greater than 8.0 ℃ accounts for 80.0% in cold January. When the indoor temperature was the minimum, the indoor, north wall, north roof, south roof and ground temperatures increased by 3.4 °C, 2.0 °C, 1.8 °C, 1.0 °C and 1.9 °C, respectively. The indoor temperature could be maintained above 6.0 °C on continuous overcast days. The tomato yield increased by 34%, and the plant morphological parameters were better than those in the control greenhouse. The results of the economic analysis indicated that the SWRS is cost-effective in terms of investment and energy savings.

Impact of High Night Temperature on Yield and Pasting Properties of Flour in Early and Late-Maturing Wheat Genotypes.

The inexorable process of climate change in terms of the rise in minimum (nighttime) temperature delineates its huge impact on crop plants. It can affect the yield and quality of various crops. We investigated the effect of high night temperature (HNT) (+2.3 °C over ambient) from booting to physiological maturity on the yield parameters, grain growth rate (GGR), starch content, composition, and flour rheological properties in early (HI 1544, HI 1563) and late-maturing (HD 2932) wheat genotypes. The change in yield under HNT was highly correlated with grain number per plant (r = 0.740 ***) and hundred-grain weight (r = 0.628 **), although the reduction in grain weight was not significantly different. This was also reflected as an insignificant change in starch content (except in HI 1544). Under HNT, late-sown genotypes (HI 1563 and HD 2932) maintained high GGR compared to the timely sown (HI 1544) genotype during the early period of grain growth (5 to 10 days after anthesis), which declined during the later phase of grain development. The increased rheological properties under HNT can be attributed to a significant reduction in the amylose to amylopectin (AMY/AMP) ratio in early-maturity genotypes (HI 1544 and HI 1563). The AMY/AMP ratio was positively correlated to flour rheological parameters (except setback from peak) under HNT. Our study reports the HNT-induced change in the amylose/amylopectin ratio in early maturing wheat genotypes, which determines the stability of flour starches for specific end-use products.

Soil moisture and micrometeorological differences across reference and thinned stands during extremes of precipitation, southern Cascade Range

Modern forest management generally relies on thinning treatments to reduce fuels and mitigate the threat of catastrophic wildfire. They have also been proposed as a tool to augment downstream flows by reducing evapotranspiration. Warming climates are causing many forests to transition from snow-dominated to rain-dominated precipitation regimes—in which water stores are depleted earlier in the summer. However, there are relatively few studies of these systems that directly measure the hydrologic impacts of such treatments during and following snow-free winters. This work compares the below-canopy meteorological and subsurface hydrologic differences between two thinning prescriptions and an unaltered Control during periods of extreme drought and near-record precipitation (with little snow). The field site was within a coniferous forest in the rain-snow transition zone of the southern Cascades, near the Sierra Nevada Range of California. Both thinning-prescriptions had a modest and predictable impact on below-canopy meteorology, which included their causing lower nighttime minimum temperatures in the critical summer months and higher wind speeds. Relative to the Control, both treatments affected soil moisture storage by delaying its annual decline and increasing its minimum value by the end of the season. The onset of soil moisture depletion was strongly tied to the magnitude of winter precipitation. In dry years, it began much earlier within the dense Control stand than in the treated ones, and, without snow, soil moisture was not replenished in the late spring. During high precipitation years, the storage capacity was topped off for all three stands, which resulted in similar timing of moisture decline across them, later in the season. The two thinning prescriptions increased stores through the height of summer (in wet and drought years). Finally, the basal area increment (BAI) of the remaining trees rose in both, suggesting they used the excess moisture to support rapid growth.

Asymmetric Impacts of Diurnal Warming on Vegetation Carbon Sequestration of Marshes in the Qinghai Tibet Plateau

AbstractAs the world's Third Pole, the Qinghai‐Tibet Plateau has a large area of marshes, which plays an important role in global carbon cycle. The net primary productivity (NPP) of vegetation is a crucial index for measuring the carbon flux of marsh ecosystems. Understanding the change in marsh NPP and its response to climatic change is important for assessing carbon sequestration of marsh ecosystems. Based on MODIS NPP data and climate data from 2000 to 2020, this study analyzed the spatiotemporal change in marsh NPP and determined its relationship with climate factors on the Qinghai‐Tibet Plateau. The results showed that the average annual NPP of marshes on the Qinghai‐Tibet Plateau increased significantly by 11.70 ± 1.07 g C·m−2/10a during 2000–2020, with an average value of about 184.37 ± 11.12 g C·m−2. Spatially, the annual marsh NPP showed obviously increasing trend in the northeast but decreasing trend in the southwest regions. Daytime maximum and nighttime minimum temperatures had asymmetric effects on marsh NPP, with a larger positive effect of minimum temperature. Warmed minimum temperatures in winter and spring significantly increased the annual marsh NPP on the Qinghai‐Tibet Plateau. The increasing maximum and minimum temperatures in the summer obviously promoted the vegetation growth in marshes. Additionally, the increasing spring precipitation could significantly increase the marsh NPP. Our results highlight that the asymmetric impacts of daytime and nighttime temperatures on marsh vegetation should be adequately considered in predicting marsh carbon sequestration on the Qinghai‐Tibet Plateau, especially in the context of global asymmetric diurnal warming.

Data parallel processing in block streams for analysis of long-term series of ozone content in ground atmosphere

The article describes a new approach to the processing of long series of ozone monitoring data in the surface atmosphere called the Data Parallel Processing in Block Streams. The proposed method is based on splitting of a sequential series of initial data into blocks filled with surface ozone monitoring data for one day. Further, a chain is formed from such blocks, the length of which is determined by the total length of the monitoring process. Along this chain of blocks, parallel processing of the initial data is carried out, aimed at smoothing out fast fluctuations. The smoothed data is then used to determine the daily production of ozone due to photochemical reactions, its minimum nighttime levels, as well as the magnitude of nighttime maxima. The possibilities of the proposed approach are demonstrated using the analysis of surface ozone monitoring data in Moscow, Russia, in 2020. The prospects for further application of the developed method are discussed.

Impoundment increases methane emissions in Phragmites-invaded coastal wetlands.

Saline tidal wetlands are important sites of carbon sequestration and produce negligible methane (CH4 ) emissions due to regular inundation with sulfate-rich seawater. Yet, widespread management of coastal hydrology has restricted tidal exchange in vast areas of coastal wetlands. These ecosystems often undergo impoundment and freshening, which in turn cause vegetation shifts like invasion by Phragmites, that affect ecosystem carbon balance. Understanding controls and scaling of carbon exchange in these understudied ecosystems is critical for informing climate consequences of blue carbon restoration and/or management interventions. Here, we (1) examine how carbon fluxes vary across a salinity gradient (4-25 psu) in impounded and natural, tidally unrestricted Phragmites wetlands using static chambers and (2) probe drivers of carbon fluxes within an impounded coastal wetland using eddy covariance at the Herring River in Wellfleet, MA, United States. Freshening across the salinity gradient led to a 50-fold increase in CH4 emissions, but effects on carbon dioxide (CO2 ) were less pronounced with uptake generally enhanced in the fresher, impounded sites. The impounded wetland experienced little variation in water-table depth or salinity during the growing season and was a strong CO2 sink of -352 g CO2 -C m-2 year-1 offset by CH4 emission of 11.4g CH4 -C m-2 year-1 . Growing season CH4 flux was driven primarily by temperature. Methane flux exhibited a diurnal cycle with a night-time minimum that was not reflected in opaque chamber measurements. Therefore, we suggest accounting for the diurnal cycle of CH4 in Phragmites, for example by applying a scaling factor developed here of ~0.6 to mid-day chamber measurements. Taken together, these results suggest that although freshened, impounded wetlands can be strong carbon sinks, enhanced CH4 emission with freshening reduces net radiative balance. Restoration of tidal flow to impounded ecosystems could limit CH4 production and enhance their climate regulating benefits.

Low irradiance disrupts the internal O2 dynamics of seagrass (Thalassia testudinum) leading to shoot meristem H2S intrusion

Hypoxia and hydrogen sulfide (H2S) intrusion at night contribute to large-scale seagrass mortality events world-wide. Declining water quality has lowered irradiance and enhanced hypoxia in seagrass ecosystems, but linkages between low irradiance and seagrass internal pO2in situ are not well understood. We examined low irradiance effects on leaf and meristem pO2 dynamics of a dominant tropical seagrass, Thalassia testudinum, using microsensors over multiple diurnal cycles. Further, we determined how O2 dynamics affect H2S intrusion into shoot meristems under low irradiance. Sequential days of low irradiance disrupted internal leaf O2 status in three ways: i) causing a longer lag in morning O2 pressurization, ii) depressing maximum pO2 during the day, and iii) shortening the time where maximum pO2 was sustained into the afternoon. There was a close relationship between leaf and water column pO2 during the day (R2 = 0.93 ± 0.09); thus, internal O2 dynamics appear more dependent on water column pO2 under low irradiance. The nighttime minimum of leaf and meristem pO2 (1.2 and 0.4 kPa, respectively) were very low and the length of time the meristem sustained hypoxia (< 1.5 kPa pO2) at night was high (9:40 h:min). H2S intrusion into the meristem at night following 24–48 h of shading was persistent, likely the combined effect of limited internal O2 flow without saturating irradiances for photosynthesis, and a breakdown of the sediment oxic microshield. Under low irradiance, more frequent intrusions of H2S to the meristems increases the chances of large-scale seagrass mortality events at night.

Sweet Potato (Ipomoea Batatas) Biology and Importance in U.S. Agriculture

Sweet potato (Ipomoea batatas (L.) Lam) is a tuberous perennial grown as an annual throughout tropical to semi-tropical regions around the world. As a food crop, sweet potatoes are ranked seventh in the world, and the most widely grown root crop in the world. The growth cycle of sweet potatoes requires 3 to 5 months, with minimum nighttime air temperatures of 15°C necessary to optimize production. Sweet potato growth can be segregated into three distinct phases: establishment (0 to 4 weeks after transplanting); rapid growth (4 to 8 weeks after transplanting); and storage root development (8 to 16 weeks after transplanting). Worldwide, average yields are 14 metric tons per hectare, necessitating careful monitoring and replacement of soil nutrients. Sweet potatoes prefer well-drained soils, which are subject to nutrient deficiencies. Although established plants are somewhat drought tolerant, a total of 50cm of precipitation is optimal for production. Much of the world production is centered in Asia and Pacific islands, currently with the United States generating less than 4% of total production. U.S. production is focused in four states, predominantly led by North Carolina.

Performance of a new active solar heat storage–release system for Chinese assembled solar greenhouses used in high latitudes and cold regions

Various active solar heating systems have been developed to enhance the Chinese assembled solar greenhouse winter cultivation capacity by using renewable energy rather than traditional fossil fuel resources. These systems involve an efficient heat-collecting and transfer pattern, which solar energy can be converted into heat energy and flexibly utilized according to heating requirements, without unwarranted heating. To improve CASG thermal performance in high latitudes and cold regions, we modified the water-circulating solar heat collection and release system. The new structure was able to collect the solar radiation on the sheet during daytime to further generate heat through the magnetron sputtering plate. The collector also functions as a heating radiator during nighttime to protect crops from chilling injury in frigid weather. Field tests and economical analysis were performed to investigate the system’s thermal and energy-saving performance by analyzing several core parameters. Test results indicated that the average daily heat collection ratio of the system was 70.2%. The minimum nighttime indoor air temperature heated by the system was increased by 3.5 °C on average and maintained the temperatures above 9 °C after 2–3 cloudy days. The mean COP in heat collection and release phase were 8.2 and 2.4 over a period of 7 test days, respectively. The energy saving efficiency of the system was 44.1%. The novel system proposed in this study using thermal insulation structure and reasonable mass area ratio enables higher heat storage capacity and structure practicability. We demonstrated that the novel technology proposed in this study displayed energy saving characteristics. The new active solar heating system can be effectively used in high latitudes Chinese assembled solar greenhouse winter cultivation.

New insights of designing thermal insulation and heat storage of Chinese solar greenhouse in high latitudes and cold regions

The demand for the quality and yield requirements of crops in high latitudes and cold regions is increasing. The traditional structure design of the Chinese solar greenhouse (CSG) can't meet the needs of over-winter production of warm-season crops, the thermal insulation and heat storage capacity of the CSG need to be further improved. This paper proposed an innovative theory of designing the thermal insulation and heat storage of the CSG that divided into independent heat collection-release system, independent heat storage system and independent thermal insulation system. A novel CSG was designed and built in the Shenyang area, experimentally tested and analyzed the application performance in winter. The results showed that the minimum nighttime air temperature with the novel CSG was 10.1 °C on average during seven continuous days of the coldest temperatures and overcast weather. The maximum temperature difference between inside and outside the novel CSG increased to 38 °C in winter. The average daily heat collection ratio for the five coldest and overcast days was 73.4%. This paper can provide new sights and theoretical guidance for the design of the thermal insulation and heat storage of the CSG in high latitudes and cold regions.

Social Group Size and Shelter Availability Influence Individual Metabolic Traits in a Social Fish.

SynopsisGroup living is widespread among animal species and yields both costs and benefits. Presence of conspecifics can restrict or enhance the expression of individual behavior, and the recent social environment is thought to affect behavioral responses in later contexts, even when individuals are alone. However, little is known about how social group size influences the expression of individual physiological traits, including metabolic rates. There is some evidence that shoaling can reduce fish metabolic rates but this variable may be affected by habitat conditions such as shelter availability via density-dependent processes. We investigated how social group size and shelter availability influence Eurasian minnow (Phoxinus phoxinus) metabolic rates estimated by respirometry. Respirometry trials were conducted on fish in isolation before and after they were housed for 3 weeks in a social treatment consisting in a specific group size (n = 4 or 8) and shelter availability (presence or absence of plant shelter in the experimental tank). Plant shelter was placed over respirometers for half of the duration of the respirometry trials, allowing estimation of minimum daytime and nighttime metabolic rates in both conditions (in the presence or absence of plant shelter). Standard metabolic rate (SMR), maximum metabolic rate (MMR), and aerobic scope were also estimated over the entire trial. Minimum daytime and nighttime metabolic rates estimated while in presence of plant shelter were lower than when estimated in absence of plant shelter, both before and after individuals were housed in their social treatment. After the social treatment, SMRs were higher for fish that were held in groups of 4 as compared with those of fish held in groups of 8, while MMR showed no difference. Plant shelter availability during the social treatments did not influence SMR or MMR. Our results suggest that social group size may directly influence energy demands of individuals, highlighting the importance of understanding the role of group size on variations in physiological traits associated with energy expenditure.