[1] The net radiation available to drive surface-atmosphere exchange is strongly influenced by albedo and surface temperature. Tower-based microclimatic and eddy covariance measurements in typical Alaskan black spruce and tundra ecosystems before and immediately after fire indicated a 10% decrease in net radiation over the burned spruce stand but a 12% increase in net radiation over the burned ...

Previous studies in adrenalectomized (Adx) rats suggest that aldosterone may regulate ion transport in the ascending portion of Helen's loop. In order to examine directly the effect of adrenalectomy on transport, medullary thick ascending limb (Mtal) segments were isolated from Adx, Adx replaced with aldosterone (Adx + Ald, 0.5 micrograms X 100 g X body wt X d), and control Sprague-Dawley rats....

net photosynthesis rate (pn), stomatal conductance (gs) and transpiration rate (e) of anise hyssop were measured during the four cloudless days, in reference to diurnal fluctuations of leaf temperature (tleaf), leaf vapor pressure deficit (vpd leaf) and photosynthetic photon flux density (ppfd) in well watered (ww), stressed (s) and recovered (r) plants. an analysis of measured data showed that...

[1] Permafrost melting is occurring in areas of the boreal forest region where large amounts of carbon (C) are stored in organic soils. We measured soil respiration, net CO2 flux, and net CH4 flux during May–September 2003 and March 2004 in a black spruce lowland in interior Alaska to better understand how permafrost thaw in poorly drained landscapes affects land-atmosphere CO2 and CH4 exchange...

Interaction between synoptic eddy and lowfrequency flow (SELF) has been the subject of many studies. In this study, we further examine the interaction by introducing a transformed eddy-potential-vorticity (TEPV) flux that is obtained from eddy-potential-vorticity flux through a quasi-geostrophic potential-vorticity inversion. The main advantage of using the TEPV flux is that it combines the eff...

The evaluation of quality of the railway passenger service is an important way to know the quality of the railway passenger service. This paper firstly constructs an evaluation indicator system of the quality of the railway passenger service on the foundation of the related literatures, and constructs the multiple-attribute evaluation matrix and indicator weight vector based on the linguistic v...

There is a recurring question in solar physics regarding whether or not electric currents are neutralized in active regions (ARs). This question was recently revisited using three-dimensional (3D) magnetohydrodynamic (MHD) numerical simulations of magnetic flux emergence into the solar atmosphere. Such simulations showed that flux emergence can generate a substantial net current in ARs. Other s...

Two methods are developed to estimate net surface energy fluxes based upon satellite-derived reconstructions of radiative fluxes at the top of atmosphere and the atmospheric energy tendencies and transports from the ERA-Interim reanalysis. Method 1 applies the mass-adjusted energy divergence from ERA-Interim, while method 2 estimates energy divergence based upon the net energy difference at the...

The closed chamber technique is widely used to measure the exchange of methane (CH4) and carbon dioxide (CO2) from terrestrial ecosystems. There is, however, large uncertainty about which model should be used to calculate the gas flux from the measured gas concentrations. Due to experimental uncertainties the simple linear regression model (first-order polynomial) is often applied, even though ...

Isotopic net ecosystem exchange (isofluxes, or flux densities of CO2) can be combined with standard eddy covariance methods to partition net ecosystem exchange of carbon dioxide (F) into its component one-way fluxes, photosynthesis and respiration. At present, the approaches used to estimate isotopic fluxes are labor-intensive and dependent on several assumptions. To assess the relative utility...