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1.
Application of possibility-probability distribution in assessing water resource risk in Yiwu city 总被引：1，自引：0，他引：1
The possibility-probability risk calculated using the interior-outer set model is referred to as fuzzy risk. A fuzzy expected
value of the possibility-probability distribution is a set with E
α(x) and [`(E)]a\bar E_\alpha (x) as its boundaries. The fuzzy expected values E
α(x) and [`(E)]a\bar E_\alpha (x) of a possibility-probability distribution represent the fuzzy risk values being calculated. Under such an α level, three
risk values can be calculated: conservative risk value, venture risk value and maximum probability risk value. As α adopts
all values throughout the set [0, 1], it is possible to obtain a series of risk values. Therefore, the fuzzy risk can be a
multi-valued risk or set-valued risk. Calculation of the fuzzy expected value of Yiwu city’s water resource risk has been
performed based on the interior-outer set model. We can get a conservative risk value (R
C
) of 800 mm for Yiwu city’s water resource risk, a venture risk value (R
V
) of 1020 mm, and a maximum probability risk value (R
M
) of 988 mm for the α = 0.1 level cut set. 相似文献
2.
3.
A self‐consistent model which describes transverse dune migration in equilibrium is introduced. It shows that an equilibrium expression for dune migration speed (c d) must take into account sand trapping efficiency (T E), and that T E is strongly related to the wind speedup over the windward surface. An expression for sand trapping efficiency (T E) is analytically derived from a microscale analysis of sand grain deposition on the slip face. Sand trapping efficiency (T E) is mainly determined by shear velocity on a level surface (u*(−∞)), and rapidly decreases as u*(−∞) increases. For each dune height (H), dune migration speed (c d) first increases, and then decreases monotonically after reaching the maximum, as the shear velocity on a level surface (u*(−∞)) increases. Dune migration speed (c d) is not inversely proportional to dune height (H). For low dunes, small sand trapping efficiency (T E) suppresses c d, whereas for high dunes, wind speedup and large T E resist the decrease of c d. Some field data show the same tendency. The dune‐to‐plane‐bed transition observed in subaqueous and venusian bedforms could be associated with the decrease of sand trapping efficiency (T E). Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
4.
ABSTRACTSourcing subsurface evaporation (Ess) into groundwater (Eg) and unsaturated zone (Eu) components has received little scientific attention so far, despite its importance in water management and agriculture. We propose a novel sourcing framework, with its implementation in dedicated post-processing software called SOURCE (used along with the HYDRUS1D model), to study evaporation sourcing dynamics, define quantitatively “shallow” and “deep” water table conditions and test the applicability of water table fluctuation (WTF) and “bucket” methods for estimation of Eg and Eu separately.For the “shallow” and “deep” water table we propose Eg?>?0.95Ess and Eg = 0 criteria, respectively. Assessment of the WTF method allowed sourcing of very small fluxes otherwise neglected by standard hydrological methods. Sourcing with SOURCE software was more accurate than the standard “bucket” method mainly because of greater flexibility in spatio-temporal discretization. This study emphasized the dry condition relevance of groundwater evaporation which should be analysed by applying coupled flow of heat, vapour and liquid water.
Editor D. Koutsoyiannis; Associate editor S. Kanae 相似文献
5.
We present a comparison of the observed behavior of the F region ionosphere over Millstone Hill during the geomagnetically quiet and storm period on 16/23 March, 1990, with numerical model calculations from the time-dependent mathematical model of the Earths ionosphere and plasmasphere. The effects of vibrationally excited N2(v) and O2(v) on the electron density and temperature are studied using the N2(v) and O2(v) Boltzmann and non-Boltzmann distribution assumptions. The deviations from the Boltzmann distribution for the first five vibrational levels of N2(v) and O2(v) were calculated. The present study suggests that these deviations are not significant at vibrational levels v = 1 and 2, and the calculated distributions of N2(v) and O2(v) are highly non-Boltzmann at vibrational levels v > 2. The N2(v) and O2(v) non-Boltzmann distribution assumption leads to the decrease of the calculated daytime NmF2 up to a factor of 1.44 (maximum value) in comparison with the N2(v) and O2(v) Boltzmann distribution assumption. The resulting effects of N2(v > 0) and O2(v) > 0) on the NmF2 is the decrease of the calculated daytime NmF2 up to a factor of 2.8 (maximum value) for Boltzmann populations of N2(v) and O2(v) and up to a factor of 3.5 (maximum value) for non-Boltzmann populations of N2(v) and O2(v). This decrease in electron density results in the increase of the calculated daytime electron temperature up to about 1040/1410 K (maximum value) at the F2 peak altitude giving closer agreement between the measured and modeled electron temperatures. Both the daytime and nighttime densities are not reproduced by the model without N2(v > 0) and O2(v > 0), and inclusion of vibrationally excited N2 and O2 brings the model and data into better agreement. The effects of vibrationally excited O2 and N2 on the electron density and temperature are most pronounced during daytime. 相似文献
6.
The estimation of evapotranspiration (E) in forested areas is required for various practical purposes (e.g. evaluation of drought risks) in Japan. This study developed a model that estimates monthly forest E in Japan with the input of monthly temperature (T). The model is based on the assumptions that E equals the equilibrium evaporation rate (Eeq) and that Eeq is approximated by a function of T. The model formulates E as E (mm month−1) = 3·48 T ( °C) + 32·3. The accuracy of the model was examined using monthly E data derived using short‐term water balance (WB) and micrometeorological (M) methods for 15 forest sites in Japan. The model estimated monthly E more accurately than did the Thornthwaite and Hamon equations according to regression analysis of the estimated E and E derived using the WB and M methods. Although the model tended to overestimate monthly E, the overestimation could be reduced by considering the effect of precipitation on E. As T data are commonly available all over Japan, the model would be a useful tool to estimate forest E in Japan. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
7.
Pan evaporation modelling and changing attribution analysis on the Tibetan Plateau (1970–2012) 
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下载免费PDF全文 Pan evaporation (Ep) is an important indicator of water and energy and the decline of Ep has been reported in many regions over the last decades. The climate and Ep are dependent on each other. In this study, the temporal trends of Ep and main Ep drivers, namely mean air temperature (Ta), wind speed (u), global solar radiation (Rs), net long‐wave radiation(Rnl) and vapour pressure deficit (D) from 1970 to 2012, were calculated on the basis of 26 meteorological stations on the Tibetan Plateau. The arithmetic average of Ep from 26 stations decreased with the rate of ?11.91 mm a?2; the trends of Rs, Rnl, Ta, u and D were ?1.434 w m?2 decade?1, 0.2511 w m?2 decade?1, 0.3590°C decade?1, ?0.2376 m s?1 decade?1 and 9.523 Pa decade?1, respectively. The diffuse irradiance is an essential parameter to model Ep and quantify the contribution of climatic factors to changing Ep. 60 724 observations of Rs and diffuse solar irradiance (Rd) from seven of the 26 stations were used to develop the correlation between the diffuse fraction (Rd/Rs), and the clearness index (Rs/Ro). On the basis of the estimation of the diffuse component of Rs and climatic data, we modified the PenPan model to estimate Chinese micro‐pan evaporation (Ep) and assess the attribution of Ep dynamics using partial derivatives. The results showed that there was a good agreement between the observed and calculated daily Ep values. The observed decrease in Ep was mostly due to declining wind speed (?13.7 mm a?2) with some contributions from decreasing solar irradiance (?3.1 mm a?2); and the increase of temperature had a large positive effect (4.55 mm a?2) in total whilst the increase of Rnl had insignificant effect (0.35 mm a?2) on Ep rates. The change of Ep is the net result of all the climatic variables. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
8.
P. Bencze 《Pure and Applied Geophysics》1969,75(1):167-174
Summary A yearly variation of the virtual height of sporadicE, reaching a maximum in the spring and a minimum in the autumn, has been recently found. This variation ofh' E
s is similar to the seasonal variation of the total amount of ozone. On the other hand, the seasonal variation of the virtual height of the lowest occurring sporadicE layer (l-type may be identified with the height variation of the boundary between homosphere and heterosphere. It may also be supposed that the latter is caused by the varying expansion of the homosphere. Since ozone strongly absorbs solar energy, the seasonal variation ofh' E
s is attributed to the expansion of the homosphere depending on the total amount of ozone.
Zusammenfassung Eine jahreszeitliche Änderung der scheinbaren Höhe der sporadischenE Schicht (h' E s) konnte festgestellt werden, die ein Maximum im Frühling und ein Minimum im Herbst zeigt. Diese Änderung vonh' E s ist der Änderung des totalen Ozonbetrages ähnlich. Andererseits kann man die jahreszeitliche Änderung der untersten sporadischenE Schicht (Typl) mit der Höhenänderung der Grenzfläche zwischen Homosphäre und Heterosphäre identifizieren. Es kann auch angenommen werden, dass die letztere durch die Expansion der Homosphäre hervorgerufen wird. Da ozon bekanntlich die Sonnenstrahlung sehr stark absorbiert, wird die jahreszeitliche Änderung vonh E s auf die vom totalen Ozonbetrag abhängigen Expansion der Homosphäre zurückgeführt.相似文献
9.
The effect of expansion ratio on the critical Reynolds number in single fracture flow with sudden expansion 下载免费PDF全文
下载免费PDF全文 Flow in a single fracture (SF) is an important research subject in groundwater hydrology, hydraulic engineering, radioactive nuclear waste repository and geotechnical engineering. An abruptly changing aperture is a unique type of SF. This study discusses the relation between the values of the critical Reynolds number (Rec) for the onset of symmetry breaking of flow and the expansion ratio (E) of SF, which is defined as the ratio between the outlet (D) and inlet (d) apertures. This study also investigates the effect of inlet aperture d on Rec for flow in an SF with abruptly changing apertures (SF‐ACA) using the finite volume method. Earlier numerical and experimental results showed that flow is symmetric in respect to the central plane of the SF‐ACA at small Reynolds number (Re) but becomes asymmetric when Re is sufficiently large. Our simulations show that the value of Rec decreases with the increasing E, and the relationship between the logarithm of Rec and E can be described accurately using either a quadratic polynomial function or a logarithmic function. However, the relationship of Rec and d for a given E value is vague, and Rec becomes even less sensitive to d when E increases. This study also reveals that the hydraulic gradient (J) and flow velocity (v) follow a super‐linear relationship that can be fitted almost perfectly by the Forchheimer equation. The inertial component (Ji) of J increases monotonically with Re, whereas the viscous component (Jv) of J decreases monotonically with Re. The Re value corresponding to equal inertial and viscous components of J (named as the transitional point Re) decreases when E increases, and such a transitional point Re should be closely related to the critical Reynolds number Rec, although a rigorous theoretical proof is not yet available. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
10.
We have performed a number of one-dimensional hybrid simulations (particle ions, massless electron fluid) of quasi-parallel collisionless shocks in order to investigate the injection and subsequent acceleration of part of the solar wind ions at the Earth’s bow shock. The shocks propagate into a medium containing magnetic fluctuations, which are initially superimposed on the background field, as well as generated or enhanced by the electromagnetic ion/ion beam instability between the solar wind and backstreaming ions. In order to study the mass (M) and charge (Q) dependence of the acceleration process He2+ is included self-consistently. The upstream differential intensity spectra of H+ and He2+ can be well represented by exponentials in energy. The e-folding energy Ec is a function of time: Ec increases with time. Furthermore the e-folding energy (normalized to the shock ramming energy Ep) increases with increasing Alfvén Mach number of the shock and with increasing fluctuation level of the initially superimposed turbulence. When backstreaming ions leave the shock after their first encounter they exhibit already a spectrum which extends to more than ten times the shock ramming energy and which is ordered in energy per charge. From the injection spectrum it is concluded that leakage of heated downstream particles does not contribute to ion injection. Acceleration models that permit thermal particles to scatter like the non-thermal population do not describe the correct physics. 相似文献
11.
12.
Shear flow instability is studied in the Earth’s magnetotail by treating plasma as compressible. A dispersion relation is derived from the linearized MHD equations using the oscillating boundary conditions at the inner central plasma sheet/outer central plasma sheet (OCPS) interface and OCPS/plasma-sheet boundary layer (PSBL) interface, whereas the surface-mode boundary condition is used at the PSBL/lobe interface. The growth rates and the real frequencies are obtained numerically for near-Earth (\midX\mid\sim10-15 RE) and far-Earth (\midX\mid\sim100 RE) magnetotail parameters. The periods and wavelengths of excited modes depend sensitively on the value of plasma-sheet half thickness, L, which is taken as L=5 RE for quiet time and L=1 RE for disturbed time. The plasma-sheet region is found to be stable for constant plasma flows unless MA3>1.25, where MA3 is the Alfvén Mach number in PSBL. For near-Earth magnetotail, the excited oscillations have periods of 2–20 min (quiet time) and 0.5-4 min (disturbed time) with typical transverse wavelengths of 2–30 RE and 0.5-6.5 RE, respectively; whereas for distant magnetotail, the analysis predicts the oscillation periods of \sim8-80 min for quiet periods and 2–16 min for disturbed periods. 相似文献
13.
Dependence of geomagnetic activity during magnetic storms on the solar wind parameters for different types of streams 总被引：1，自引：0，他引：1
The dependence of the maximal values of the |Dst| and AE geomagnetic indices observed during magnetic storms on the value of the interplanetary electric field (E
y
) was studied based on the catalog of the large-scale solar wind types created using the OMNI database for 1976–2000 [Yermolaev
et al., 2009]. An analysis was performed for eight categories of magnetic storms caused by different types of solar wind streams:
corotating interaction regions (CIR, 86 storms); magnetic clouds (MC, 43); Sheath before MCs (ShMC, 8); Ejecta (95); Sheath (ShE, 56); all ICME events (MC + Ejecta, 138); all compression regions Sheaths before MCs and Ejecta (ShMC + ShE, 64); and an indeterminate type of storm (IND, 75). It was shown that the |Dst| index value increases with increasing electric field E
y
for all eight types of streams. When electric fields are strong (E
y
> 11 mV m−1), the |Dst| index value becomes saturated within magnetic clouds MCs and possibly within all ICMEs (MC + Ejecta). The AE index value during magnetic storms is independent of the electric field value E
y
for almost all streams except magnetic clouds MCs and possibly the compressed (Sheath) region before them (ShMC). The AE index linearly increases within MC at small values of the electric field (E
y
< 11 mV m−1) and decrease when these fields are strong (E
y
> 11 mV m−1). Since the dynamic pressure (Pd) and IMF fluctuations (σB) correlate with the E
y
value in all solar wind types, both geomagnetic indices (|Dst| and AE) do not show an additional dependence on Pd and IMF δB. The nonlinear relationship between the intensities of the |Dst| and AE indices and the electric field E
y
component, observed within MCs and possibly all ICMEs during strong electric fields E
y
, agrees with modeling the magnetospheric-ionospheric current system of zone 1 under the conditions of the polar cap potential
saturation. 相似文献
14.
Khairi I. Grais 《Pure and Applied Geophysics》1969,74(1):78-82
Summary The darkening (S) of Illford Q2 photographic plates as ion detectors in mass spectrometer has been investigated. The dependence of the darkening (S) on the ion density (n=ions/mm2) i.e.S=S(n)E for constant energy (E)=z U ranging from 4U20 Kv of the impinging40A+1-,40A+2- and40A+3-ions whenS does not exceed the value 0.15 and the second relationn=n(z U)
S
for darkening 0.05S0.15 constructed from the above relationS=S(n)
E
has been determined. The darkening was found to increase with increasing ion-density which inturn decreases with the ionenergy. For40A+1-,40A+2-, and40A+3-ion of equal energy and ion-density the darkening effect was independent of the number of the charges carried by the argon ion. 相似文献
15.
We present a comparison of the electron density and temperature behaviour in the ionosphere and plasmasphere measured by the Millstone Hill incoherent-scatter radar and the instruments on board of the EXOS-D satellite with numerical model calculations from a time-dependent mathematical model of the Earths ionosphere and plasmasphere during the geomagnetically quiet and storm period on 20/30 January, 1993. We have evaluated the value of the additional heating rate that should be added to the normal photoelectron heating in the electron energy equation in the daytime plasmasphere region above 5000 km along the magnetic field line to explain the high electron temperature measured by the instruments on board of the EXOS-D satellite within the Millstone Hill magnetic field flux tube in the Northern Hemisphere. The additional heating brings the measured and modelled electron temperatures into agreement in the plasmasphere and into very large disagreement in the ionosphere if the classical electron heat flux along magnetic field line is used in the model. A new approach, based on a new effective electron thermal conductivity coefficient along the magnetic field line, is presented to model the electron temperature in the ionosphere and plasmasphere. This new approach leads to a heat flux which is less than that given by the classical Spitzer-Harm theory. The evaluated additional heating of electrons in the plasmasphere and the decrease of the thermal conductivity in the topside ionosphere and the greater part of the plasmasphere found for the first time here allow the model to accurately reproduce the electron temperatures observed by the instruments on board the EXOS-D satellite in the plasmasphere and the Millstone Hill incoherent-scatter radar in the ionosphere. The effects of the daytime additional plasmaspheric heating of electrons on the electron temperature and density are small at the F-region altitudes if the modified electron heat flux is used. The deviations from the Boltzmann distribution for the first five vibrational levels of N2(v) and O2(v) were calculated. The present study suggests that these deviations are not significant at the first vibrational levels of N2 and O2 and the second level of O2, and the calculated distributions of N2(v) and O2(v) are highly non-Boltzmann at vibrational levels v > 2. The resulting effect of N2(v > 0) and O2(v > 0) on NmF2 is the decrease of the calculated daytime NmF2 up to a factor of 1.5. The modelled electron temperature is very sensitive to the electron density, and this decrease in electron density results in the increase of the calculated daytime electron temperature up to about 580 K at the F2 peak altitude giving closer agreement between the measured and modelled electron temperatures. Both the daytime and night-time densities are not reproduced by the model without N2(v > 0) and O2(v > 0), and inclusion of vibrationally excited N2 and O2 brings the model and data into better agreement. 相似文献
16.
T. C. Sharma 《水文科学杂志》2013,58(1):79-92
Abstract Two entities of importance in hydrological droughts, viz. the longest duration, LT , and the largest magnitude, MT (in standardized terms) over a desired time period (which could also correspond to a specific return period) T, have been analysed for weekly flow sequences of Canadian rivers. Analysis has been carried out in terms of week-by-week standardized values of flow sequences, designated as SHI (standardized hydrological index). The SHI sequence is truncated at the median level for identification and evaluation of expected values of the above random variables, E(LT ) and E(MT ). SHI sequences tended to be strongly autocorrelated and are modelled as autoregressive order-1, order-2 or autoregressive moving average order-1,1. The drought model built on the theorem of extremes of random numbers of random variables was found to be less satisfactory for the prediction of E(LT ) and E(MT ) on a weekly basis. However, the model has worked well on a monthly (weakly Markovian) and an annual (random) basis. An alternative procedure based on a second-order Markov chain model provided satisfactory prediction of E(LT ). Parameters such as the mean, standard deviation (or coefficient of variation), and lag-1 serial correlation of the original weekly flow sequences (obeying a gamma probability distribution function) were used to estimate the simple and first-order drought probabilities through closed-form equations. Second-order probabilities have been estimated based on the original flow sequences as well as SHI sequences, utilizing a counting method. The E(MT ) can be predicted as a product of drought intensity (which obeys the truncated normal distribution) and E(LT ) (which is based on a mixture of first- and second-order Markov chains). Citation Sharma, T. C. & Panu, U. S. (2010) Analytical procedures for weekly hydrological droughts: a case of Canadian rivers. Hydrol. Sci. J. 55(1), 79–92. 相似文献
17.
It is shown that within the framework of the Kolmogorov model the “energy” of the pole E(t) = x
12 + x
22 can be interpreted as a Markovian process. The exact analytical expression has been obtained for the density of the conditional
probability of the quantity E(t) and the problem of the first passage time of the process E(t) has been analyzed. It was shown that the available data on the swing of the function E(t) are not at variance with the Kolmogorov model and a short-period drop of the amplitude of the Chandler wobble in the early
20th century fits this model at Q = 50–200 too; values of Q > 350 are less reasonable. 相似文献
18.
《水文科学杂志》2013,58(3):503-518
Abstract Two parameters of importance in hydrological droughts viz. the longest duration, LT and the largest severity, ST (in standardized form) over a desired return period, T years, have been analysed for monthly flow sequences of Canadian rivers. An important point in the analysis is that monthly sequences are non-stationary (periodic-stochastic) as against annual flows, which fulfil the conditions of stochastic stationarity. The parameters mean, μ, standard deviation, σ (or coefficient of variation), lag1 serial correlation, ρ, and skewness, γ (which is helpful in identifying the probability distribution function) of annual flow sequences, when used in the analytical relationships, are able to predict expected values of the longest duration, E(LT ) in years and the largest standardized severity, E(ST ). For monthly flow sequences, there are 12 sets of these parameters and thus the issue is how to involve these parameters to derive the estimates of E(LT ) and E(ST ). Moreover, the truncation level (i.e. the monthly mean value) varies from month to month. The analysis in this paper demonstrates that the drought analysis on an annual basis can be extended to monthly droughts simply by standardizing the flows for each month. Thus, the variable truncation levels corresponding to the mean monthly flows were transformed into one unified truncation level equal to zero. The runs of deficits in the standardized sequences are treated as drought episodes and thus the theory of runs forms an essential tool for analysis. Estimates of the above parameters (denoted as μav, σav, ρav, and γav) for use in the analytical relationships were obtained by averaging 12 monthly values for each parameter. The product- and L-moment ratio analyses indicated that the monthly flows in the Canadian rivers fit the gamma probability distribution reasonably well, which resulted in the satisfactory prediction of E(LT ). However, the prediction of E(ST ) tended to be more satisfactory with the assumption of a Markovian normal model and the relationship E(ST ) ≈ E(LT ) was observed to perform better. 相似文献
19.
Partitioning precipitation (P) between streamflow (Q) and actual evapotranspiration (Ea) on a basin scale is controlled by climate change in combination with catchment characteristics. Fu's formulation of the Budyko framework was used to estimate Q as a function of two meteorological variables, P and potential evaporation (Ep), and one adjustable parameter reflecting characteristics of catchment conditions (ω). Results show that ω reflects the impacts of catchment characteristics on the partitioning of P between Q and Ea for the different water yielding regions. As predicted, Q was more sensitive to P than to comparable changes in Ep for the whole of the Yellow River Basin (YRB), a water‐limited basin, while it was shown to be highly sensitive to changes in P, Ep, and ω in the low water yielding region (LWYR) of the basin, followed by YRB and the high water yielding region of the basin. The high sensitivity of Q to P, Ep, and ω in LWYR indicates that the management of catchments within these zones is critical to the management of overall basin flow, mitigating impacts of climate change on Q. The Budyko framework, incorporating the adjustable parameter ω, outlines interactions between Q, climate, and characteristics specific to different water yielding regions. It also provides a new approach in understanding hydrological process response to climate change. Due to the obscure physical attributes of ω, an explanation of the parameter using soil or vegetation characteristics will aid in the understanding of the eco‐hydrological behaviour of catchments and help to provide more detailed catchment management options for which to mitigate climate change with respect to concerns regarding agricultural water usage. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
20.
X. Jia T. S. Zha J. N. Gong B. Wu Y. Q. Zhang S. G. Qin G. P. Chen W. Feng S. Kellomäki H. Peltola 《水文研究》2016,30(6):972-985
During the last decade, the widely distributed shrublands in northern China have shown significant signs of recovery from desertification, the result of widespread conservation practices. However, to support the current efforts in conservation, more knowledge is needed on surface energy partitioning and its biophysical controls. Using eddy‐covariance measurements made over a semi‐arid shrubland in northwest China in 2012, we examined how surface energy‐balance components vary on diurnal and seasonal scales, and how biophysical factors control bulk surface parameters and energy exchange. Sensible heat flux (H) exceeded latent heat flux (λE) during most of the year, resulting in an annual Bowen ratio (β, i.e. H/λE) of 2.0. λE exceeded H only in mid‐summer when frequent rainfall co‐occurred with the seasonal peak in leaf area index (LAI). Evapotranspiration reached a daily maximum of 3.3 mm day?1, and summed to 283 mm yr?1. The evaporative fraction (EF, i.e. λE/Rn), Priestley–Taylor coefficient (α), surface conductance (gs) and decoupling coefficient (Ω) were all positively correlated with soil water content (SWC) and LAI. The direct enhancement of λE by high vapour pressure deficit (VPD) was buffered by a concurrent suppression of gs. The gs played a direct role in controlling EF and α by mediating the effects of LAI, SWC and VPD. Our results highlight the importance of adaptive plant responses to water scarcity in regulating ecosystem energy partitioning, and suggest an important role for revegetation in the reversal of desertification in semi‐arid areas. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献