Variation In Soil Temperature Research Articles

Evaluation and Analysis of Soil Temperature Data over Poyang Lake Basin, China

Soil temperature reflects the impact of local factors, such as the vegetation, soil, and atmosphere of a region. Therefore, it is important to understand the regional variation of soil temperature. However, given the lack of observations with adequate spatial and/or temporal coverage, it is often difficult to use observational data to study the regional variation. Based on the observational data from Nanchang and Ganzhou stations and ERA-Interim/Land reanalysis data, this study analyzed the spatiotemporal distribution characteristics of soil temperature over Poyang Lake Basin. Four soil depths were examined, 0–7, 7–28, 28–100, and 100–289 cm, recorded as ST1, ST2, ST3, and ST4, respectively. The results showed close correlations between observation data and reanalysis data at different depths. Reanalysis data could reproduce the main spatiotemporal distributions of soil temperature over the Poyang Lake Basin but generally underestimated their magnitudes. Temporally, there was a clear warming trend in the basin. Seasonally, the temperature increase was the most rapid in spring and the slowest in summer, except for ST4, which increased the fastest in spring and the slowest in winter. The temperature increase was faster for ST1 than the other depths. The warming trend was almost the same for ST2, ST3, and ST4. An abrupt change of annual soil temperature at all depths occurred in 1997, and annual soil temperatures at all depths were abnormally low in 1984. Spatially, annual soil temperature decreased with latitude, except for the summer ST1. Because of the high temperature and precipitation in summer, the ST1 values were higher around the lake and the river. The climatic trend of soil temperature generally increased from south to north, which was opposite to the distribution of soil temperature. These findings provide a basis for understanding and assessing the variation of soil temperature in the Poyang Lake Basin.

Investigating Influence of Metro Jet System Hydration Heat on Artificial Ground Freezing Using Numerical Analysis

With the development of urban subway system, intersection is sometimes inevitable during the construction of underground tunnels. When a tunnel to be excavated is underneath an existing subway station, the support wall of the station that lies on the way of the tunnel is often required to be partially dismantled to facilitate the construction of the tunnel. To ensure safety of the existing station and the tunnel, both metro jet system (MJS) using cement paste and artificial ground freezing (AGF) techniques can be applied and sometimes combined to stabilize the area under the influence of tunnel construction. However, when two techniques are combined, the hydration heat from the cement paste will bring an increase in the active freezing time. By taking advantage of an existing project, a preliminary numerical simulation is performed to evaluate the influence of hydration heat on a 100-day ground freezing process with considering the effect of ambient temperature, thermal insulation, and the timing of the initiation of the freezing after MJS treatment. Simulation results show that the active freezing time can be reduced by 53 and 3 days with thermal insulation at the end sections in summer and winter, respectively. Hydration heat leads to an increase of the active freezing time from 14 to 15 days, and the effect of timing for the initiation of artificial ground freezing is insignificant on the active freezing time. Subsequently, consistent with the construction plan and site condition, using the ambient temperature from the previous year, a numerical simulation is also performed to simulate the soil temperature variation during the releasing of hydration heat and the freezing followed. The simulation results show that 52-day active freezing time is required for the formation of a frozen soil wall which met the requirement for further tunneling.

Snowpack affects soil microclimate throughout the year

Variations in snow depth have complex effects on soil microclimate. Snow insulates soil and thus regulates, along with air temperature, the nature, and extent of soil freezing. There is great uncertainty about the main drivers of soil freezing, which have important effects on ecosystem carbon and nitrogen cycling processes and might change as climate warms and snowfall decreases as part of climate change. Here, we utilitze sites from a variety of elevations and aspects within the northern hardwood forest at the Hubbard Brook Experimental Forest (New Hampshire, USA) to investigate relationships between seasonal snowpack, soil freezing, and soil microclimate across this gradient using 8 years of bi-weekly snowpack and soil frost-depth measurements, and continuous soil climate monitoring. We utilize a time-integrated snowpack descriptor and find that snowpacks with lower seasonal snow water equivalents result in more soil temperature variation and deeper soil frost but have no effect on variation in soil moisture. Seasonal snow water equivalent of the snowpack influences the date of rapid soil warming in the spring, which in turn influences both summer soil moisture and an index of annual cumulative soil heat. These results show that snowpack dynamics, which are highly sensitive to changes in climate, have wide-ranging effects on soil microclimate year-round and thus could have important implications for ecosystem carbon and nitrogen cycling processes.

Are annual nitrous oxide fluxes sensitive to warming and increasing precipitation in the Gurbantunggut Desert?

AbstractTemperate desert soils are an important source of atmospheric nitrous oxide (N2O). However, it is uncertain how N2O emissions respond to warming, increased rainfall and nitrogen (N) addition in such soils. A multifactorial field manipulation study was carried out in the Gurbantunggut Desert, China's second largest desert, to investigate how these factors influence desert soil N2O emissions and to assess inter‐year variation. In our 3‐year study, under current climatic conditions, the annual flux of N2O in this temperate desert soil was 0.13 ± 0.02 kg N ha−1 yr−1, with the period of no plant growth contributing 43% of the annual emission. Surprisingly, there was no significant change in annual N2O flux under warming (+1°C) or increased precipitation (30%, +60 mm yr−1). In contrast, N2O emissions were significantly affected by extreme drought followed by precipitation. Additional N input, at 30 or 60 kg N ha−1 yr−1, greatly elevated annual N2O emission by 55–133%. The combined impact of N deposition and increasing rainfall on N2O emission was greater than that of any single factor, except for N deposition. This suggests that N2O emissions in this desert are driven primarily by soil available N content and are less sensitive to variations in soil temperature and moisture.

Spatial and temporal variability of soil N2 O and CH4 fluxes along a degradation gradient in a palm swamp peat forest in the Peruvian Amazon.

Mauritia flexuosa palm swamp, the prevailing Peruvian Amazon peatland ecosystem, is extensively threatened by degradation. The unsustainable practice of cutting whole palms for fruit extraction modifies forest's structure and composition and eventually alters peat‐derived greenhouse gas (GHG) emissions. We evaluated the spatiotemporal variability of soil N2O and CH4 fluxes and environmental controls along a palm swamp degradation gradient formed by one undegraded site (Intact), one moderately degraded site (mDeg) and one heavily degraded site (hDeg). Microscale variability differentiated hummocks supporting live or cut palms from surrounding hollows. Macroscale analysis considered structural changes in vegetation and soil microtopography as impacted by degradation. Variables were monitored monthly over 3 years to evaluate intra‐ and inter‐annual variability. Degradation induced microscale changes in N2O and CH4 emission trends and controls. Site‐scale average annual CH4 emissions were similar along the degradation gradient (225.6 ± 50.7, 160.5 ± 65.9 and 169.4 ± 20.7 kg C ha−1 year−1 at the Intact, mDeg and hDeg sites, respectively). Site‐scale average annual N2O emissions (kg N ha−1 year−1) were lower at the mDeg site (0.5 ± 0.1) than at the Intact (1.3 ± 0.6) and hDeg sites (1.1 ± 0.4), but the difference seemed linked to heterogeneous fluctuations in soil water‐filled pore space (WFPS) along the forest complex rather than to degradation. Monthly and annual emissions were mainly controlled by variations in WFPS, water table level (WT) and net nitrification for N2O; WT, air temperature and net nitrification for CH4. Site‐scale N2O emissions remained steady over years, whereas CH4 emissions rose exponentially with increased precipitation. While the minor impact of degradation on palm swamp peatland N2O and CH4 fluxes should be tested elsewhere, the evidenced large and variable CH4 emissions and significant N2O emissions call for improved modeling of GHG dynamics in tropical peatlands to test their response to climate changes.

Soil temperature change and its regional differences under different vegetation regions across China

AbstractChanges in soil temperature will exert an important influence on the management and utilization of vegetation and agricultural production, whereas the spatiotemporal variations in soil temperature under different vegetation regions across China remain largely unknown. The shallow soil temperatures (0–20 cm) during the growing season (May–September) from 1965 to 2014 across China were analysed, and the findings showed that the spatial distribution of shallow soil temperature was determined primarily by latitude in eastern China (east of 110°E), and by altitude in western China (west of 110°E) with some high (low) temperature centres. The vegetation regions with relatively low soil temperatures are mainly concentrated in high altitude and high latitude areas, which have relatively large differences in soil temperature at different depths and relatively high soil warming rates. Over the past 50 years, shallow soil temperatures increased greatly during the growing season at the site, vegetation region and nation scales, but the warming rate and its relationship with climate change varied greatly. The soil temperature variables were affected substantially by air temperature and precipitation in the subtropical forest and tropical forest regions but were affected primarily by air temperature in the other vegetation regions. This difference may be due to the spatial difference in precipitation amounts across China, which affected the soil temperature via soil moisture feedback. Further study indicated that the warming rate in shallow soil was higher in stations (vegetation regions) with less precipitation than in those with more precipitation.

Simulation of coupled transport of soil moisture and heat in a typical karst rocky desertification area, Yunnan Province, Southwest China.

Understanding the transport processes of soil moisture and heat is critical for vegetation restoration in karst rocky desertification areas where serious soil erosion and extensive exposure of carbonate rocks occur. Numerical simulation can provide an important approach to explore the transport processes of soil moisture and heat, but few studies employing this technique have been carried out in karst rocky desertification areas of southwest China. In this study, a model of coupled soil moisture and heat transport was established using HYDRUS-1D based on the high-resolution data of soil moisture, soil temperature, and meteorological parameters obtained throughout a year in a typical karst rocky desertification area in Yunnan province, southwest China. The modeling results reflect the rainfall-infiltration-evaporation processes in rocky desertification areas well. The frequently rainfall events in small intensity in the study site often induced great variations of soil moisture in the near-surface soil layer (< 1-cm depth). However, soil moisture in deep soil layer (> 10-cm depth) kept stable during light rainfall events, implying that the deep soil was only influenced by heavy rainfall events. The variations of soil temperature showed a high sinusoidal fitting trend. At the annual scale, variations of soil temperature were distinct apparent evident below the depth of 40 cm, but no evident daily variations were observed. The simulated fluxes of soil water showed that the vapor fluxes were lower than the liquid water fluxes by 3-6 orders of magnitude, suggesting the control of soil thermal gradients. Our results also indicate that the vapor flux has great significance for plant water utilization in the drought periods. The simulation errors are small for soil temperature but slightly more significant for the soil moisture in deep soil layer. This primary failure may result from the occurrence of preferential flows at the rock-soil interface, which needed to be further investigated in the future.

Bioclimatic gradients and soil property trends from northernmost mainland Norway to the Svalbard archipelago. Does the arctic biome extend into mainland Norway?

The boundary between the boreal and arctic biomes in northwest Europe has been a matter of debate for many years. Some authors consider that the boundary is marked by the northern limit of tree growth in the northernmost Norwegian mainland. In this study we have collected air and soil temperature data from 37 heath stands from northern Finnmark (71°N), the northernmost part of the Norwegian mainland, through Bear Island (74°N) in the Barents sea, to Adventsdalen (78)°N (in Spitsbergen) in Svalbard archipelago. In Finnmark, plots both south and north of the treeline were investigated. Vegetation and soil chemistry analyses were performed on the plots in Finnmark and Svalbard. Significant decreasing south-north trends in air and soil temperatures were observed from Finnmark to Spitsbergen. Soils in Finnmark were acidic and rich in organic matter, while those on Adventsdalen were basic and poor in organic matter. Vegetational analysis identified five communities: three in Finnmark and two on Adventsdalen. The communities in Finnmark had marked mutual similarities but were very different from those on Adventsdalen. No significant ecological differences between heaths south and north of the treeline in Finnmark were observed. Air and soil temperature variables in Finnmark were outside the recognized range for the arctic biome and inconsistent with the presence of permafrost both south and north of the treeline. A major difference between Finnmark and Spitsbergen was amount of soil frost and length of the growing season. Our results suggest that the boreal biome extends all the way to the north coast of mainland Norway; and previously used division of heaths in Finnmark into boreal, alpine and arctic biomes is not justified.

Heat Storage Capacity and Temporal-spatial Response in the Soil Temperature of Albic Soil Amended with Maize-derived Biochar for 2 Years

Under cold climate conditions, the temporal and spatial distribution of heat and the influencing factors in different layers of Albic soil remain unclear. Here, we aimed to clarify the influence of biochar on soil heat storage capacity and identify approaches to regulate temporal-spatial variations in Albic soil temperature. To this end, we studied thermal properties and temporal-spatial temperature variations in different soil layers (10 and 20 cm) amended with biochar at different concentrations (0, 10, 20, 30, 40 g·kg-1) in the key growth stages of soybeans through pot experiments for two years. We found that the daily mean soil temperature and accumulated soil temperature improved during the 2 years in both soil layers after biochar application. Compared with the control, the biochar treatments increased soil daily minimum temperature, decreased soil daily maximum temperature and soil temperature fluctuations, postponed the soil heating stage by 1 h, and caused a "warming effect" during the soil cooling stage. Furthermore, biochar treatment enhanced the thermal capacity of the Albic soil by 7.49% and 6.53% compared with the control in 2016 and 2017, respectively, whereas thermal conductivity and thermal diffusivity were decreased compared with the control. Biochar regulated the temporal-spatial response variation in temperature of the Albic soil as follows: biochar distributed heat in the Albic soil more uniformly over time by changing the soil temperature cycle and reducing the temperature difference, and heat tended to move downwards into the soil layers by increasing the heat capacity and reducing soil thermal conductivity and thermal diffusivity. Biochar changed the heat storage capacity of the Albic soil and temporal-spatial distribution of heat. These changes provide sufficient, timely, and effective heat supply for crop growth. Furthermore, biochar treatments had a significant and positive effect on soil physical properties and crop yield. In cold areas, these changes would help crops resist temperature changes caused by extreme weather and reduce the rate of cold damage. The results of this study have important practical relevance for enriching the basic scientific theory of biochar application.

Assessment of the Combined Effect of Temperature and Salinity on the Outputs of Soil Dielectric Sensors in Coconut Fiber

Dielectric sensors are useful instruments for measuring soil moisture and salinity. The soil moisture is determined by measuring the dielectric permittivity, while bulk electrical conductivity (EC) is measured directly. However, permittivity and bulk EC can be altered by many variables such as measurement frequency, soil texture, salinity, or temperature. Soil temperature variation is a crucial factor as there is much evidence showing that global warming is taking place. This work aims to assess how variations in the temperature and salinity of coconut fiber affect the output of EC5 (voltage) and GS3 (permittivity and bulk EC) Decagon sensors. The results showed that the effect of temperature and salinity on the output of the sensors can lead to substantial errors in moisture estimations. At low salinity values, permittivity readings decreased as temperature increased, while voltage readings were not affected, regardless of substrate moisture. The GS3 sensor underestimated the bulk EC when it is measured below 25 °C. The temperature dependence of the voltage of EC5 was not significant up to 10 dS m−1, and the permittivity of the GS3 was more affected by the interaction between temperature and salinity. The effect that salinity has on the permittivity of the GS3 sensor can be reduced if a permittivity–moisture calibration is performed with saline solutions, while the effect resulting from the interaction between temperature and salinity can be minimized using a regression model that considers such an interaction.

Removal of Total Petroleum Hydrocarbons from Contaminated Soil through Microwave Irradiation.

In this study, we investigated the removal mechanism of total petroleum hydrocarbons (TPH) from soil by microwave heating. TPH contaminated soil was investigated to determine the desorption behavior of five carbon number-based fractions of TPH. The applied operating microwave power density influenced the final temperature that was reached during heating. For low operating power density applications, microwave effectiveness was limited due to the soil’s dielectric properties, which exhibited a direct relationship with temperature variation. Soil particle distribution could be attributed to permeability, which significantly influenced the evaporation of contaminated soil during the microwave treatment. The results indicate that the activation energy was correlated with the influence of particle size. The removal efficiency of the coarse soil reached 91.1% at 15 min, whereas that of fine soil was low. A total of 30 min had passed, and a removal efficiency of 71.2% was found for the fine soil. Residual TPH concentration was decreased when irradiation time was increased with a removal rate dependent on soil temperature variation. The surface functional groups of the contaminated soil were influenced by microwave irradiation, and changes in the hydrocarbon fraction affected contaminant removal.

Evaluation of certain important biochemical parameters of four tropical earthworms in response to soil moisture and temperature variations

Evaluation of certain important biochemical parameters of four tropical earthworms in response to soil moisture and temperature variations

Soil contribution to CO2 fluxes in Chinampa ecosystems, Mexico

Since soil CO&lt;sub&gt;2&lt;/sub&gt; flux is a key component of ecosystem carbon balance, quantifying its contribution to the ecosystem carbon flux and understanding the factors that underlie its temporal variation is crucial for a better comprehension of ecosystem carbon dynamics under climate change and for optimal ecosystem use and management. Our objectives were to quantify the contributions of total soil CO&lt;sub&gt;2&lt;/sub&gt; efflux (&lt;em&gt;F&lt;/em&gt;&lt;sub&gt;S&lt;/sub&gt;) to ecosystem respiration (&lt;em&gt;R&lt;/em&gt;&lt;sub&gt;E&lt;/sub&gt;) and heterotrophic soil CO&lt;sub&gt;2&lt;/sub&gt; efflux (&lt;em&gt;F&lt;/em&gt;&lt;sub&gt;H&lt;/sub&gt;) to &lt;em&gt;F&lt;/em&gt;&lt;sub&gt;S&lt;/sub&gt; in two &lt;em&gt;chinampa&lt;/em&gt; ecosystems with different natural grass covers. We also aimed to identify the main environmental drivers of seasonal variability of these contributions. The CO&lt;sub&gt;2&lt;/sub&gt; fluxes were measured on each site about every 14 days from September 2008 to August 2009 in the Xochimilco Ecological Park in Mexico City using dark chamber techniques. For two studied sites, &lt;em&gt;R&lt;/em&gt;&lt;sub&gt;E&lt;/sub&gt;,&lt;em&gt; F&lt;/em&gt;&lt;sub&gt;S&lt;/sub&gt; and &lt;em&gt;F&lt;/em&gt;&lt;sub&gt;H&lt;/sub&gt; were estimated on average as 94.1 ± 8.5, 34.7 ± 3.5 and 16.5 ± 1.7 (± S.E.) mg C-CO&lt;sub&gt;2&lt;/sub&gt; m&lt;sup&gt;-2&lt;/sup&gt; h&lt;sup&gt;-1&lt;/sup&gt;, respectively. &amp;nbsp;On average over the study period and sites, the annual cumulative &lt;em&gt;R&lt;/em&gt;&lt;sub&gt;E&lt;/sub&gt;, &lt;em&gt;F&lt;/em&gt;&lt;sub&gt;S&lt;/sub&gt; and &lt;em&gt;F&lt;/em&gt;&lt;sub&gt;H&lt;/sub&gt; fluxes were 824 ± 74, 304 ± 31 and 145 ± 15 g C m&lt;sup&gt;-2&lt;/sup&gt; year, respectively. The &lt;em&gt;R&lt;/em&gt;&lt;sub&gt;E&lt;/sub&gt;, &lt;em&gt;F&lt;/em&gt;&lt;sub&gt;S&lt;/sub&gt; and &lt;em&gt;F&lt;/em&gt;&lt;sub&gt;H&lt;/sub&gt; varied between the winter and summer seasons; this variation was explained mostly by seasonal variations of soil temperature, soil water content and shoot plant biomass. Temperature sensitivity of CO&lt;sub&gt;2&lt;/sub&gt; fluxes depended on vegetation type and plant growth differences among the sites and decreased in the following order: &lt;em&gt;R&lt;/em&gt;&lt;sub&gt;E&lt;/sub&gt; &amp;gt; &lt;em&gt;R&lt;/em&gt;&lt;sub&gt;s&lt;/sub&gt; &amp;gt; &lt;em&gt;R&lt;/em&gt;&lt;sub&gt;H&lt;/sub&gt;. The contribution of &lt;em&gt;F&lt;/em&gt;&lt;sub&gt;S&lt;/sub&gt; to &lt;em&gt;R&lt;/em&gt;&lt;sub&gt;E&lt;/sub&gt; and &lt;em&gt;F&lt;/em&gt;&lt;sub&gt;H&lt;/sub&gt; to &lt;em&gt;F&lt;/em&gt;&lt;sub&gt;S&lt;/sub&gt; for the two studied sites and period averaged about 38% and 50%, respectively regardless of the site vegetation type, but the degree of &lt;em&gt;F&lt;/em&gt;&lt;sub&gt;S&lt;/sub&gt;/&lt;em&gt;R&lt;/em&gt;&lt;sub&gt;E&lt;/sub&gt; and &lt;em&gt;F&lt;/em&gt;&lt;sub&gt;H&lt;/sub&gt;/&lt;em&gt;F&lt;/em&gt;&lt;sub&gt;S&lt;/sub&gt; variability depended on the differences in seasonal dynamics of plant cover. The contribution of &lt;em&gt;F&lt;/em&gt;&lt;sub&gt;H &lt;/sub&gt;to &lt;em&gt;F&lt;/em&gt;&lt;sub&gt;S&lt;/sub&gt; varied from 37% in summer to 73% in winter at the site without a seasonal shift in dominant plant species, but &lt;em&gt;F&lt;/em&gt;&lt;sub&gt;H&lt;/sub&gt;/&lt;em&gt;F&lt;/em&gt;&lt;sub&gt;S&lt;/sub&gt; was close to constant during the year at the site with a seasonal change in dominant plant species. During the cold period, the contribution of &lt;em&gt;F&lt;/em&gt;&lt;sub&gt;H &lt;/sub&gt;to &lt;em&gt;F&lt;/em&gt;&lt;sub&gt;S&lt;/sub&gt; increased following plant growth decrease. The linear regression analysis showed that plant biomass was the dominant factor controlling the seasonal variation of &lt;em&gt;F&lt;/em&gt;&lt;sub&gt;H&lt;/sub&gt;/&lt;em&gt;F&lt;/em&gt;&lt;sub&gt;S&lt;/sub&gt; ratios, whereas the plant biomass dynamic followed the dynamics of soil water content, water table depth, and soil temperature. Our results suggest that seasonal variation of soil contribution to total fluxes from the &lt;em&gt;chinampa&lt;/em&gt; ecosystem is locally differentiated. These differences were related to differences in seasonal dynamics of cover productivity which has been associated with localization of soil water content. This finding has important implications for assessing the contribution of the chinampa ecosystem to the global carbon budget.

Determinación de profundidad óptima para intercambiadores de calor tierra-aire en Saltillo, Coahuila

Saltillo Coahuila, due to the lack of an adequate architectural design, some homes do not meet the thermal environment conditions required during the winter period, it is estimated that 471,725 habitants are affected by temperatures until - 3.4°C, which causes morbidity problems, so that the need for the use of electromechanical air conditioning systems with electrical energy consumption of high economic and environmental cost arises. The objective of the work was to study the feasibility of applying a geothermal heat exchanger for home heating. Periodic variation of soil temperature at different depths was studied to determine the optimum by experimentally validated equations. An ideal depth of 3 m was determined due to a variation of 25 y 30% and lower excavation cost compared to depths of 6, 9 and 12 m.

Mitigation of the Adverse Effects of the El Niño (El Niño, La Niña) Southern Oscillation (ENSO) Phenomenon and the Most Important Diseases in Avocado cv. Hass Crops.

Areas cultivated with Hass avocado crops in Colombia have growth rapidly. One of the major limitations is the avocado wilt complex disease (AWC) caused by biotic and abiotic factors which have increased under the El Niño southern oscillation ENSO phenomenon (El Niño, La Niña). The objective of this study was to evaluate different strategies for mitigating the adverse effects associated with the ENSO phenomenon and AWC in avocado crops. We evaluated native materials, mulches, and parameters associated with the production of seedlings and planting practices in the field. The response variables tested were plant development, incidence, severity, mortality, and microbial dynamics, among others. The results indicated that native genotypes of Persea americana had different levels of adaptability to drought and flooding conditions. These genotypes also showed some degree of resistance to Phytophthora cinnamomi and Verticillium sp. infection with several degrees of rootstock-scion incompatibility with the Hass cultivar. In addition, mulch reduced the variability of soil moisture and temperature in the soil profile. Adequate selection of genotypes and new tools for planting have decreased the susceptibility to adverse effects associated with the ENSO phenomenon and the incidence and mortality caused by diseases under drought and flooding conditions. This work presents alternatives to mitigate adverse effects of climate variability in avocado crops under tropical conditions.

Response of soil water content and temperature to rangeland desertification in an alpine region with seasonally frozen soil and plateau pika (Ochotona curzoniae) burrows

Variations in soil temperature and water content are important indicators of land desertification, and play a significant role in ecological environments in desert regions, thus could help in establishing effective measures to combat desertification. In this study, the changing characteristics of plateau pika (Ochotona curzoniae) burrows, soil water content, and temperature under three levels of desertification (slight, medium, and severe) were assessed. The number of pika burrows was investigated in quadrats with areas of 400 m2. The areas of pika burrow mounds were obtained by taking pictures vertically and measured by AutoCAD, 2007. Soil temperature and water content were monitored by soil temperature and moisture smart sensors installed at depths of 5, 10, 20, and 50 cm. Data were recorded at 10-min intervals by Hobo Data Loggers. The greatest number of pika burrows and the greatest area of pika burrow mounds were found in the medium desertified site, followed by the slightly desertified site, and no pika burrows were found in the severely desertified site. With increasing desertification degree, vegetation coverage and soil water content decreased. The onset dates of soil freeze and thaw in the severely desertified site were both earlier, and the duration of freezing days was shorter, than those in the slightly desertified site at each soil depth. The medium desertified site showed the earliest onset of soil freeze, latest onset of soil thaw, and longest duration of soil freezing days. The annual mean soil temperature was highest in the severely desertified site within 50-cm soil depth of the ground surface due to the loss of vegetation coverage and soil water content, and lowest in the medium desertified site within 20-cm soil depth due to the cooling effects of pika burrows. Desertification resulted in the loss of vegetation cover and reduced soil water content, leading to higher soil temperatures. However, the cooling effects of pika burrows could reduce soil temperatures. These findings provide insights into the impacts of rangeland desertification on soil environments, thereby helping in establishing effective measures to combat desertification.

Effect of the pipe material and burying depth on the thermal efficiency of earth-to-air heat exchangers

Abstract Aiming to provide the thermal comfort inside building houses in arid regions, an experimental investigation is performed regarding the effect of earth-to-air heat exchanger (EAHE) materials on the overall performances. A comparison is made between the efficiency of steel and PVC pipes. Furthermore, the variation of vertical soil temperature from the soil surface to 140 cm is determined. It is found from the comparison between EAHE made of PVC and steel that the pipe has a small effect on the outlet air temperature leaving the system. On the contrary, the pipe length has a big effect on the EAHE performance.

On the Performance of the Canadian Land Surface Scheme Driven by the ERA5 Reanalysis over the Canadian Boreal Forest

AbstractThe Canadian Land Surface Scheme (CLASS) has been applied over the years in coupled and uncoupled (offline) modes at local, regional, and global scales using various forcing datasets. In this study, CLASS is applied at a local scale in the offline configuration to evaluate its performance when driven by the ERA5 reanalysis. Simulated surface energy fluxes, as well as several other water balance components, are investigated at four sites across the Canadian boreal biome. The results from CLASS driven by ERA5 (CLASS-RNL) are compared with available in situ measurements, as well as with results from CLASS driven by observations (CLASS-CTL). Additional simulations are conducted to evaluate the effects of biases in the ERA5 precipitation, where CLASS is forced by ERA5 data, but with ERA5 precipitation being replaced by observed precipitation (CLASS-RNL-ObsP). The results show that simulated surface variables in CLASS-RNL are in good agreement with observations as well as with those simulated in CLASS-CTL. The CLASS-RNL captures well the observed annual cycles of the surface energy and water fluxes, as well as the year-to-year variation of snow depth, soil temperature, and soil moisture. A strong correlation is found between the observed and CLASS-RNL simulated snow depth and soil temperature. Biases in the ERA5 precipitation did not affect the simulation of soil state variables, whereas the simulated surface heat and water fluxes, as well as the snow depth, were significantly affected. For instance, the simulated runoff in CLASS-RNL is much higher than in CLASS-RNL-ObsP and CLASS-CTL at the most humid sites due to significant positive bias in ERA5 precipitation.

Investigating the Spatio-Temporal dynamics in the soil water storage in Alberta’s Agricultural region

Anomalous atmospheric conditions which, for the most part, manifest in the form of heavy precipitation events leading to the generation of pluvial or fluvial flooding in some years, or as extended extreme dry spells resulting in the development of severe drought conditions in other years has significant implications for subsurface moisture budgets in regional and local catchments in the Canadian Prairies. The myriad implications of these frequent and extended dry spells over Alberta’s Agricultural Region can be far reaching economically, socially and otherwise, thereby exerting substantial negative toll on agricultural productivity (crop cultivation, livestock husbandry, and pasture management) within the Province. Soil moisture dynamics both in spatial and temporal scales has critical implications for agricultural water management especially under semi-arid climate conditions that are typical of the local- and regional-scale catchments in southern Alberta. This study is focused on the assessment of the observations of the soil water storage, soil temperature and meteorological variables (precipitation and air temperature) acquired from 39 monitoring stations spanning a 12-year period with the principal objective of examining the spatial and temporal dynamics in the shallow and deep soil water storage processes across the study domain. This study revealed that the moisture anomalies in the deep soil moisture store exhibit the longest hydrologic memory relative to those in the shallow and intermediate soil moisture storages as well as those in the meteorological variables across the study domain. The anomalies computed for the soil moisture measurements undertaken in the deep soil moisture store revealed frequency features that are dominant at seasonal cycle (9-month) and at a higher periodicity of 32-month cycle. This low-frequency feature (32-month cycle) is evidently non-existent in the soil water storage measured at the shallower soil depths nor in the meteorological variables evaluated in this study. This implies that the low-frequency feature of the soil water storage wavelet spectra increases with increasing soil depth across the Agricultural Region; indicating that at deeper soil depths, the largest variances are shifted to lower frequencies. This observed dominant long-memory feature in the deep soil moisture store could have important implications for characterizing the development of temperature extremes as well as for the evaluation of the severity of the recurrent drought outbreaks over regional watersheds in Alberta and potentially for other Canadian Prairie catchments.

Soil temperature and agronomic implications in two regions of the State of São Paulo, Brazil

Plants can tolerate a wide range of soil temperature variations, but their development is affected when the soil undergoes higher or lower temperatures of certain extreme values. The aim of this study was to assess the soil temperature of two regions of the state of São Paulo, Brazil. Daily measurements of soil temperature were taken at two weather stations, one in the municipality of Adamantina (soil classified as Podzolic, Dark Red Latosol, Eutrophic, moderate A, of sandy/medium texture) and another in the municipality Monte Alegre do Sul (soil classified as Red Yellow Podzolic, of fine sandy-clayey texture) within a period of 365 days. The experimental design was completely randomized, with the two municipalities being the treatments, and 12 repetitions determined by monthly averages. The soil temperature at a 3-cm depth in Adamantina reached values above 40°C, values not observed in Monte Alegre do Sul. At a 12-cm depth, there were no differences between the municipalities. In Monte Alegre do Sul, the recorded soil temperatures proved suitable for crops, with better use of organic matter by the soil and greater stability of surface temperature throughout the day compared to Adamantina. In Adamantina, however, the use of agronomic technology is required to ensure greater stability of surface temperature. The temperature throughout the year in the soil surface layer in the Adamantina region in the afternoon was higher than in the Monte Alegre do Sul region, a fact that implies the need of differentiated agronomic technology depending on the cultivation location.