Potential Evaporation Estimates Research Articles

Reply to Comment on “Potential Evaporation and the Complementary Relationship” by Jozsef Szilagyi

AbstractWe appreciate Dr Szilagyi's interest in our article on potential evaporation and the complementary relationship (CR). For his first concern on the assumption of constant net radiation versus constant net solar radiation in the estimation of potential evaporation, here we show that the constant net solar radiation condition is more universally applicable both in observations and from a theoretical perspective. For his second concern on the CR model calibration, we clarify herein that no calibrations were used in our applications of the various CR models. Instead, the parameter values were all directly taken from previous studies to ensure a fair and practically meaningful inter‐model comparison.

Reply to Comment on “On the Estimation of Potential Evaporation Under Wet and Dry Conditions” by Jozsef Szilagyi

AbstractWe appreciate Dr. Szilagyi's interest in our work of recovering surface temperature and evaporation to a “hypothetical” saturated condition. Dr. Szilagyi criticized our approach by arguing that the recovered surface temperature is unphysically low. Here we reply to Dr. Szilagyi's concern by showing that our recovered surface temperature is not unphysically low and is physically attainable. In addition, our approach strictly follows the definition of potential evaporation by Wilfried Brutsaert (2015).

Comment on “On the Estimation of Potential Evaporation Under Wet and Dry Conditions” by Z. Tu and Y. Yang

AbstractIt is argued here that the wet‐surface temperature (Tws) estimation method employed by Tu and Yang for their potential evaporation estimates yields physically unreachable low values not only during dry, but frequently under wet environmental conditions as well. For these reasons it is claimed that the wet‐surface temperature estimation method of Szilagyi and Jozsa (2008, https://doi.org/10.1016/j.jhydrol.2008.03.008) may produce more realistic Tws values than the one by Yang and Roderick (2019, https://doi.org/10.1002/qj.3481) as employed by Tu and Yang (2022, https://doi.org/10.1029/2021WR031486).

Fewer Basins Will Follow Their Budyko Curves Under Global Warming and Fossil-Fueled Development.

The Budyko framework consists of a curvilinear relationship between the evaporative ratio (i.e., actual evaporation over precipitation) and the aridity index (i.e., potential evaporation over precipitation) and defines evaporation's water and energy limits. A basin's movement within the Budyko space illustrates its hydroclimatic change and helps identify the main drivers of change. On the one hand, long‐term aridity changes drive evaporative ratio changes, moving basins along their Budyko curves. On the other hand, historical human development can cause river basins to deviate from their curves. The question is if basins will deviate or follow their Budyko curves under the future effects of global warming and related human developments. To answer this, we quantify the movement in the Budyko space of 405 river basins from 1901–1950 to 2051–2100 based on the outputs of seven models from the Coupled Model Intercomparison Project ‐ Phase 6 (CMIP6). We account for the implications of using different potential evaporation models and study low‐ and high‐emissions scenarios. We find considerable differences of movement in Budyko space regarding direction and intensity when using the two estimates of potential evaporation. However, regardless of the potential evaporation estimate and the scenario used, most river basins will not follow their reference Budyko curves (>72%). Furthermore, the number of basins not following their curves increases under high greenhouse gas emissions and fossil‐fueled development SP585 and across dry and wet basin groups. We elaborate on the possible explanations for a large number of basins not following their Budyko curves.

Testing a maximum evaporation theory over saturated land: implications for potential evaporation estimation

Abstract. State-of-the-art evaporation models usually assume net radiation (Rn) and surface temperature (Ts; or near-surface air temperature) to be independent forcings on evaporation. However, Rn depends directly on Ts via outgoing longwave radiation, and this creates a physical coupling between Rn and Ts that extends to evaporation. In this study, we test a maximum evaporation theory originally developed for the global ocean over saturated land surfaces, which explicitly acknowledges the interactions between radiation, Ts, and evaporation. Similar to the ocean surface, we find that a maximum evaporation (LEmax) emerges over saturated land that represents a generic trade-off between a lower Rn and a higher evaporation fraction as Ts increases. Compared with flux site observations at the daily scale, we show that LEmax corresponds well to observed evaporation under non-water-limited conditions and that the Ts value at which LEmax occurs also corresponds with the observed Ts. Our results suggest that saturated land surfaces behave essentially the same as ocean surfaces at timescales longer than a day and further imply that the maximum evaporation concept is a natural attribute of saturated land surfaces, which can be the basis of a new approach to estimating evaporation.

On the Estimation of Potential Evaporation Under Wet and Dry Conditions

AbstractPotential evaporation (EP) is an important concept that has been extensively used in hydrology, climate, agriculture and many other relevant fields. However, EP estimates using conventional approaches generally do not conform with the underlying idea of EP, since meteorological forcing variables observed under real conditions are not necessarily equivalent to those over a hypothetical surface with an unlimited water supply. Here, we estimate EP using a recently developed ocean surface evaporation model (i.e., the maximum evaporation model) that explicitly acknowledges the inter‐dependence between evaporation, surface temperature (Ts) and radiation such that is able to recover radiation and Ts to a hypothetical wet surface. We first test the maximum evaporation model over land by validating its evaporation estimates with evaporation observations under unstressed conditions at 86 flux sites and found an overall good performance. We then apply the maximum evaporation model to the entire terrestrial surfaces under both wet and dry conditions to estimate EP. The mean annual (1979–2019) global land EP from the maximum evaporation model (EP_max) is 1,272 mm yr−1, which is 11.2% higher than that estimated using the widely adopted Priestley‐Taylor model (EP_PT). The difference between EP_max and EP_PT is negligible in humid regions or under wet conditions but becomes increasingly larger as the surface moisture availability decreases. This difference is primarily caused by increased net radiation (Rn) when restoring the dry surfaces to hypothetical wet surfaces, despite a lower Ts obtained under hypothetical wet conditions in the maximum evaporation model.

Calculating net radiation of freshwater reservoir to estimate spatial distribution of evaporation using satellite images

Evaporation over freshwater bodies is one of the main sources of water loss. However, evaporation estimation models using net radiation (Rn) over water bodies have not yet provided proper efficiency, the fact which has led to several attempts to improve such models using satellite images. Therefore, the purpose of this study is to introduce a model for estimation of Rn through using satellite images, and to utilize such model in evaporation calculation models in order to produce an evaporation map for freshwater bodies. In this regard, two reservoirs of Taleghan and Amirkabir dams in Iran were selected as the areas under study. Thirty-three Landsat satellite images from the years 2010 to 2018 along with the corresponding meteorological data were used in the implementations. A new simplified equation was introduced for calculating Rn and the subsequent estimation of potential evaporation over freshwater bodies using remote sensing images. Evaporation was generally estimated using FAO56-PM, Priestley-Taylor, Kimberly-Penman, and Hargreaves-Samani models, and the results were then compared with Pan evaporation data. The obtained results were also compared with the results of two energy balance models, including Surface Energy Balance System (SEBAL) and Mapping Evapotranspiration at high Resolution and with Internalized Calibration (METRIC). The results of this study indicated that Kimberly-Penman model with coefficient of determination (R2) of 0.76, Root Mean Square Error (RMSE) of 1.29 (mm), and Nash-Sutcliffe (NSE) of 0.65, and FAO56-PM model with R2 = 0.75, RMSE = 1.76 (mm), and NSE = 0.36 outperformed when compared to other similar methods. Moreover, the proposed model proved higher performance in estimating evaporation over freshwater bodies compared with SEBAL and METRIC models.

Interactions between snow cover and evaporation lead to higher sensitivity of streamflow to temperature

Estimates of potential evaporation often neglect the effects of snow cover on evaporation process. Here, we present a definition of potential evaporation that explicitly accounts for landscapes that are partially covered by snow. We show that, in the presence of snowpack, our evaporation estimates differ from conventional methods that assume evaporation from a free water surface. Specifically, we find that conventional methods overestimate potential evaporation as well as aridity, taken as the ratio of atmospheric water demand to supply, in landscapes where snowfall is significant. With dwindling snow-cover, actual aridity increases, which could explain the reduction in streamflow with decreasing snowfall. We suggest that streamflow, and hence water availability, is more sensitive to temperature changes in colder than in warmer regions.

A pan-African high-resolution drought index dataset

Abstract. Droughts in Africa cause severe problems, such as crop failure, food shortages, famine, epidemics and even mass migration. To minimize the effects of drought on water and food security on Africa, a high-resolution drought dataset is essential to establish robust drought hazard probabilities and to assess drought vulnerability considering a multi- and cross-sectional perspective that includes crops, hydrological systems, rangeland and environmental systems. Such assessments are essential for policymakers, their advisors and other stakeholders to respond to the pressing humanitarian issues caused by these environmental hazards. In this study, a high spatial resolution Standardized Precipitation-Evapotranspiration Index (SPEI) drought dataset is presented to support these assessments. We compute historical SPEI data based on Climate Hazards group InfraRed Precipitation with Station data (CHIRPS) precipitation estimates and Global Land Evaporation Amsterdam Model (GLEAM) potential evaporation estimates. The high-resolution SPEI dataset (SPEI-HR) presented here spans from 1981 to 2016 (36 years) with 5 km spatial resolution over the whole of Africa. To facilitate the diagnosis of droughts of different durations, accumulation periods from 1 to 48 months are provided. The quality of the resulting dataset was compared with coarse-resolution SPEI based on Climatic Research Unit (CRU) Time Series (TS) datasets, Normalized Difference Vegetation Index (NDVI) calculated from the Global Inventory Monitoring and Modeling System (GIMMS) project and root zone soil moisture modelled by GLEAM. Agreement found between coarse-resolution SPEI from CRU TS (SPEI-CRU) and the developed SPEI-HR provides confidence in the estimation of temporal and spatial variability of droughts in Africa with SPEI-HR. In addition, agreement of SPEI-HR versus NDVI and root zone soil moisture – with an average correlation coefficient (R) of 0.54 and 0.77, respectively – further implies that SPEI-HR can provide valuable information for the study of drought-related processes and societal impacts at sub-basin and district scales in Africa. The dataset is archived in Centre for Environmental Data Analysis (CEDA) via the following link: https://doi.org/10.5285/bbdfd09a04304158b366777eba0d2aeb (Peng et al., 2019a).

Impact of amplified evaporation due to lake expansion on the water budget across the inner Tibetan Plateau

AbstractOver the past decades, changing climate has exerted pronounced influences on the cryo‐hydrological environment on the Tibetan Plateau. One major manifestation is the widespread lake expansions over Tibetan endorheic basins. The enlarged lake water surface areas are expected to significantly alter land‐atmosphere water fluxes, which in return may pose feedbacks to the climate system and hydrological processes. The goal of this study is to investigate the potential influences of the recent lake expansions on amplifying the evaporation flux over the basins of inner Tibetan Plateau (ITP). We detected that the ITP lakes have experienced a net inundation increase of 4,542.3 km2 during 2000–2015, about 95.6% of which was contributed by lakes larger than 1 km2. We further estimated the land and water evaporations based on multi‐source, available actual evapotranspiration (ETa) and potential evapotranspiration data sets, and in situ evaporation records. The differences between land ETa and lake water evaporation were employed to represent the evaporation alternation over newly inundated basin (named “land‐to‐lake” hereafter) areas. The land ETa was estimated based on the average of three commonly used gridded data sets while the over‐lake evaporation was calculated by the empirical correction of potential evaporation estimates by spatial interpolation of pan evaporation. A conservative estimate using the pan coefficient of 0.6 indicates that the newly inundated lake area may have led to a potential evaporation increase of 3.08 ± 1.08 Gt/year on the ITP. The increased evaporation flux is close to half of the recent annual growth rate of lake water storage in the ITP. Despite unneglectable uncertainties, our estimates initiate an important assessment of how the recent lake expansion across the ITP has influenced the local land‐atmosphere interactions and the water cycle. Accounting this evaporation amplification is crucial to reduce the uncertainty in estimating basin‐scale water budgets and projecting the regional water balance.

Evaluating seasonal and regional calibration of temperature-based methods for estimating potential evaporation in Ontario

Development of appropriate water management strategies in the context of projected air temperature increases under a changing climate necessitates assessing how increases in atmospheric demand for water might constrain future water availability. This is most easily assessed using estimates of potential evaporation (PE). Most temperature-based methods for estimating PE have been calibrated in different landscapes in more southern locations using a singular calibration coefficient. This study assessed whether regionally calibrated temperature-based models improve estimates of PE in Ontario and whether further improvements could be made by adjusting coefficients monthly to address a marked seasonality in Ontario or spatially to address the province’s size and varied landscape. Monthly calibration coefficients were calculated for four temperature-based methods (Thornthwaite, Blaney–Criddle, Hamon and Hargreaves–Samani) using climate data and evaporation estimates from 18 pan evaporation stations in Ontario. Calibrated models were then evaluated against an additional 19 pan evaporation stations by comparing estimates of PE calculated using the adjusted and literature-derived coefficients with pan evaporation estimates. Finally, PE estimated using adjusted coefficients was compared to evaporation (E) estimated using a water balance approach for 64 watersheds across Ontario. As anticipated, the regional calibration process increased the accuracy of the PE estimates relative to those calculated using published model coefficients. Use of monthly model coefficients addressed the marked seasonality of evaporation in Ontario and resulted in improved PE estimates. Adjusted model coefficients varied spatially but the paucity of measurement stations precluded further regionalization. PE estimates improved using adjusted coefficients, varied less between models, and were highly correlated with water balance estimates of E. The Hargreaves–Samani model produced the best estimates of PE using unadjusted and adjusted coefficients and was most highly correlated with long-term water balance estimates of E.

National-scale analysis of low flow frequency: historical trends and potential future changes

The potential impact of climate change on hydrological extremes is of increasing concern across the globe. Here, a national-scale grid-based hydrological model is used to investigate historical trends and potential future changes in low flow frequency across Great Britain. The historical analyses use both observational data (1891–2015) and ensemble data from a regional climate model (1900–2006). The results show relatively few significant trends in historical low flows (2- or 20-year return period), whether based on 7- or 30-day annual minima. Significant negative trends seen in some limited parts of the country when using observational data are generally not seen when using climate model data. The future analyses use climate model ensemble data for both near future and far future time periods (2020–2049 and 2070–2099 respectively), which are compared to a baseline sub-period from the historical ensemble (1975–2004). The results show future reductions in low flows, which are generally larger in the south of the country, at the higher (20-year) return period, and for the later time period. Reductions are more limited if the estimates of future potential evaporation include the effect of increased carbon dioxide concentrations on stomatal resistance. Such reductions in river flow could have significant impacts on the aquatic environment and on agriculture, and present a challenge for water managers, especially as reductions in water supply are likely to occur alongside increases in demand.

Potential crop evapotranspiration and surface evaporation estimates via a gridded weather forcing dataset

Absent local weather stations, a gridded weather dataset can provide information useful for water management in irrigated areas including potential crop evapotranspiration calculations. In estimating crop irrigation requirements and surface evaporation in Utah, United States of America, methodology and software were developed using the ASCE Standardized Penman-Monteith Reference Evapotranspiration equation with input climate drivers from the North American Land Data Assimilation System (NLDAS) gridded weather forcing dataset and a digital elevation model. A simple procedure was devised to correct bias in NLDAS relative humidity and air temperature data based on comparison to weather data from ground stations. Potential evapotranspiration was calculated for 18 crops (including turfgrass), wetlands (large and narrow), and open water evaporation (deep and shallow) by multiplying crop coefficient curves to reference evapotranspiration with annual curve dates set by summation of Hargreaves evapotranspiration, cumulative growing degree days, or number of days. Net potential evapotranspiration was calculated by subtracting effective precipitation estimates from the Daymet gridded precipitation dataset. Analysis of the results showed that daily estimated potential crop evapotranspiration from the model compared well with estimates from electronic weather stations (1980–2014) and with independently calculated potential crop evapotranspiration in adjacent states. Designed for this study but open sourced for other applications, software entitled GridET encapsulated the GIS-based model that provided data download and management, calculation of reference and potential crop evapotranspiration, and viewing and analysis tools. Flexible features in GridET allows a user to specify grid resolution, evapotranspiration equations, cropping information, and additional datasets with the output being transferable to other GIS software.

Use of very high resolution climate model data for hydrological modelling: estimation of potential evaporation

Climate model data are increasingly used to drive hydrological models, to assess the possible impacts of climate change on river flows. Hydrological models often require potential evaporation (PE) from vegetation, alongside precipitation, but PE is not usually output by climate models so has to be estimated from other meteorological variables. Here, the Penman–Monteith formula is applied to estimate PE using data from a 12 km Regional Climate Model (RCM) and a nested very high resolution (1.5 km) RCM covering southern Britain. PE estimates from RCM runs driven by reanalysis boundary conditions are compared to observation-based PE data, to assess performance. The comparison shows that both the 1.5 and 12 km RCMs reproduce observation-based PE well, on daily and monthly time-steps, and enables choices to be made about application of the formula using the available data. Data from Current and Future RCM runs driven by boundary conditions from a Global Climate Model are then used to investigate potential future changes in PE, and how certain factors affect those changes. In particular, the importance of including changes in canopy resistance is demonstrated. PE projections are also shown to vary to some extent according to how aerosols are modelled in the RCMs.

Sensitivity of potential evaporation estimates to 100 years of climate variability

Abstract. Hydrological modeling frameworks require an accurate representation of evaporation fluxes for appropriate quantification of, e.g., the water balance, soil moisture budget, recharge and groundwater processes. Many frameworks have used the concept of potential evaporation, often estimated for different vegetation classes by multiplying the evaporation from a reference surface ("reference evaporation") by crop-specific scaling factors ("crop factors"). Though this two-step potential evaporation approach undoubtedly has practical advantages, the empirical nature of both reference evaporation methods and crop factors limits its usability in extrapolations under non-stationary climatic conditions. In this paper, rather than simply warning about the dangers of extrapolation, we quantify the sensitivity of potential evaporation estimates for different vegetation classes using the two-step approach when calibrated using a non-stationary climate. We used the past century's time series of observed climate, containing non-stationary signals of multi-decadal atmospheric oscillations, global warming, and global dimming/brightening, to evaluate the sensitivity of potential evaporation estimates to the choice and length of the calibration period. We show that using empirical coefficients outside their calibration range may lead to systematic differences between process-based and empirical reference evaporation methods, and systematic errors in estimated potential evaporation components. Quantification of errors provides a possibility to correct potential evaporation calculations and to rate them for their suitability to model climate conditions that differ significantly from the historical record, so-called no-analog climate conditions.

Potential evaporation estimation through an unstressed surface-energy balance and its sensitivity to climate change

Abstract. Potential evaporation (ETP) is a basic input for many hydrological and agronomic models, as well as a key variable in most actual evaporation estimations. It has been approached through several diffusive and energy balance methods, out of which the Penman–Monteith equation is recommended as the standard one. In order to deal with the diffusive approach, ETP must be estimated at a sub-diurnal frequency, as currently done in land surface models (LSMs). This study presents an improved method, developed in the ORCHIDEE LSM, which consists of estimating ETP through an unstressed surface-energy balance (USEB method). The results confirm the quality of the estimation which is currently implemented in the model (Milly, 1992). The ETP underlying the reference evaporation proposed by the Food and Agriculture Organization, FAO, (computed at a daily time step) has also been analysed and compared. First, a comparison for a reference period under current climate conditions shows that USEB and FAO's ETP estimations differ, especially in arid areas. However, they produce similar values when the FAO's assumption of neutral stability conditions is relaxed, by replacing FAO's aerodynamic resistance by that of the model's. Furthermore, if the vapour pressure deficit (VPD) estimated for the FAO's equation, is substituted by ORCHIDEE's VPD or its humidity gradient, the agreement between the daily mean estimates of ETP is further improved. In a second step, ETP's sensitivity to climate change is assessed by comparing trends in these formulations for the 21st century. It is found that the USEB method shows a higher sensitivity than the FAO's. Both VPD and the model's humidity gradient, as well as the aerodynamic resistance have been identified as key parameters in governing ETP trends. Finally, the sensitivity study is extended to two empirical approximations based on net radiation and mass transfer (Priestley–Taylor and Rohwer, respectively). The sensitivity of these ETP estimates is compared to the one provided by USEB to test if simplified equations are able to reproduce the impact of climate change on ETP.

Actual evaporation estimation from infrared measurement of soil surface temperature

Within the hydrological cycle, actual evaporation represents the second most important process in terms of volumes of water transported, second only to the precipitation phenomena. Several methods for the estimation of the Ea were proposed by researchers in scientific literature, but the estimation of the Ea from potential evapotranspiration often requires the knowledge of hard-to-find parameters (e.g.: vegetation morphology, vegetation cover, interception of rainfall by the canopy, evaporation from the canopy surface and uptake of water by plant roots) and many existing database are characterized by missing or incomplete information that leads to a rough estimation of the actual evaporation amount. Starting from the above considerations, the aim of this study is to develop and validate a method for the estimation of the Ea based on two steps: i) the potential evaporation estimation by using the meteorological data (i.e. Penman-Monteith); ii) application of a correction factor based on the infrared soil surface temperature measurements. The dataset used in this study were collected during two measurement campaigns conducted both in a plain testing site (Grugliasco, Italy), and in a mountain South-East facing slope (Cogne, Italy). During those periods, hourly measurement of air temperature, wind speed, infrared surface temperature, soil heat flux, and soil water content were collected. Results from the dataset collected in the two testing sites show a good agreement between the proposed method and reference methods used for the Ea estimation.

Evapotranspiration estimation methods in hydrological models

Actual evapotranspiration is a key process of hydrological cycle and a sole term that links land surface water balance and land surface energy balance. Evapotranspiration plays a key role in simulating hydrological effect of climate change, and a review of evapotranspira- tion estimation methods in hydrological models is of vital importance. This paper firstly summarizes the evapotranspiration estimation methods applied in hydrological models and then classifies them into the integrated converting methods and the classification gathering methods by their mechanism. Integrated converting methods are usually used in hydrological models and two differences exist among them: one is in the potential evaporation estimation methods, while the other in the function for defining relationship between potential evapora- tion and actual evapotranspiration. Due to the higher information requirements of the Pen- man-Monteith method and the existing data uncertainty, simplified empirical methods for calculating potential and actual evapotranspiration are widely used in hydrological models. Different evapotranspiration calculation methods are used depending on the complexity of the hydrological model, and importance and difficulty in the selection of the most suitable evapotranspiration methods is discussed. Finally, this paper points out the prospective de- velopment trends of the evapotranspiration estimating methods in hydrological modeling.

Potential evaporation estimation through an unstressed surface-energy balance and its sensitivity to climate change

Potential evaporation estimation through an unstressed surface-energy balance and its sensitivity to climate change

Density-Dependent Ecohydrological Effects of Piñon–Juniper Woody Canopy Cover on Soil Microclimate and Potential Soil Evaporation

Many rangeland processes are driven by microclimate and associated ecohydrological dynamics. Most rangelands occur in drylands where evapotranspiration normally dominates the water budget. In these water-limited environments plants can influence abiotic and biotic processes by modifying microclimate factors such as soil temperature and potential soil evaporation. Previous studies have assessed spatial variation in microclimate and associated ecohydrological attributes within an ecosystem (e.g., under vs. between woody canopies) or across ecosystems (e.g., with differing amounts of woody canopy cover), but generally lacking are assessments accounting systematically for both, particularly for evergreen woody plants. Building on recently quantified trends in near-ground solar radiation associated with a piñon–juniper gradient spanning 5% to 65% woody canopy cover, we evaluated trends in soil temperature and associated estimates of potential soil evaporation as a function of amount of woody canopy cover for sites overall and for associated canopy vs. intercanopy locations. Quantified soil temperature trends decreased linearly with increasing woody canopy cover for intercanopy as well as canopy patches, indicating the coalescing influence of individual canopies on their neighboring areas. Notably, intercanopy locations within high-density (65%) woody canopy cover could be as much as ∼10°C cooler than intercanopy locations within low-density (5%) cover. Corresponding potential soil evaporation rates in intercanopies within high-density woody canopy cover was less than half that for intercanopies within low density. Our results highlight ecohydrological consequences of density-dependent shading by evergreen woody plants on soil temperature and potential soil evaporation and enable managers to rapidly estimate and compare approximate site microclimates after assessing amounts of woody canopy cover. Such predictions of microclimate have general utility for improving management of rangelands because they are a fundamental driver of many key processes, whether related to understory forage and herbaceous species or to wildlife habitat quality for game or nongame species. Muchos procesos en los pastizales están definidos por microclimas y sus dinámicas ecohidrológicas asociadas. Muchos pastizales se localizan en zonas áridas donde la evapotranspiracio‘n normalmente es el flujo dominante del balance hídrico. En estos ambientes donde el agua es escasa, las plantas pueden influenciar procesos ecológicos, bióticos y abióticos, mediante la modificación de factores micro-climáticos, como temperatura del suelo el potencial de evaporación desde la superficie. Estudios previos han definido que la variación en microclimas y los atributos asociados con la eco-hidrología dentro de los ecosistemas (por ejemplo debajo del dosel vs. en espacios entre el dosel aé de dos árboles) o a través de los ecosistemas (por ejemplo con diferentes cantidades de cobertura de dosel). Sin embargo, se carece generalmente de la determinación sistemática de ambos, particularmente para las plantas arbustivas siempre verdes. Basándose en tendencias cuantificadas recientemente para la radiación solar cerca de suelo en un gradiente de pino-junípero abarcando una cubierta de 5% a 65% de cobertura de dosel, se evaluaron las tendencias en la temperatura del suelo y se desarrollaron estimaciones asociadas con el potencial de evaporación de suelo en función de la cantidad de cubierta arbórea tanto para sitios en general (en función de la cobertura), como para aquellos asociados con la cubierta contra sitios ubicados entre los árboles (no directamente debajo de las copas). Las temperaturas del suelo cuantificadas tendieron a decrecer linealmente con el incremento en la cobertura arbórea en los espacios entre árboles, asícomo los espacios cubiertos por los árboles, indicando la relación entre la influencia de las copas individuals sobre sus a‘reas vecinas. Notablemente, los espacios entre árboles dentro de lugares con altas densidades (65%) de cubierta arbórea pueden ser hasta 10uC más fríos que los espacios entre árboles dentro de una densidad baja de cobertura aérea (5%). Con respecto al potencial de las tasas de evaporación en los espacios entre árboles en las áreas con niveles altos de cubierta de dosel, resultó siendo menos de la mitad de la que ocurriría en espacios igualetne abiertos, pero localizados en zonas con baja cobertura de dosel arbóreo. Nuestros resultados resaltan los efectos eco-hidrológicos de la sombra producida por los árboles sobre la temperatura del suelo y el potencial de evaporación del suelo, y que dependen de la cantidad y densidad de árboles en el paisaje. Estos resultados permiten a los manejadores una rápida estimación y comparación del microclima en diversos sitios, después de determinar la cantidad de cubierta arbórea. Tales predicciones de microclimas tienen una utilidad general para mejorar el manejo de pastizales porque son fundamentales para muchos procesos esenciales, si se relacionan con pastos que se encuentran debajo de la cobertura arbórea, asícomo con las especies herbáceas o para la calidad del habitad de la vida silvestre de especies cinegéticas y no cinegéticas.