Atmospheric absorption in the O2 Schumann-Runge band spectral range and photodissociation rates in the stratosphere and mesophere

A general analysis of the absorption of the Schumann-Runge bands of molecular oxygen has been made in order to compare the various experimental and theoretical results which have been obtained for an application to the O₂ atmospheric absorption and its photodissociation in the mesosphere and stratosphere. The different values of the oscillator strengths deduced from the laboratory absorption spectra and of the predissociation linewidths used for the calculation of the absorption have been compared.Calculations based on a Voight profile of the O₂ rotational lines have led to simple formulas for atmospheric applications taking into account that the total photodissociation rate in the stratosphere depends strongly on the absorption of solar radiation in the spectral range of the O₂ Herzberg continuum. Specific examples are given.     

General conservation equations for multi-phase systems: 3. Constitutive theory for porous media flow

Equations which describe single phase fluid flow and transport through an elastic porous media are obtained by applying constitutive theory to a set of general multiphase mass, momentum, energy, and entropy equations. Linearization of these equations yields a set of equations solvable upon specification of the material coefficients which arise. Further restriction of the flow to small velocities proves that Darcy's law is a special case of the general momentum balance.     

Secular resonance,solar spin down,and the orbit of Mercury

A mechanism capable of accounting for the large mean eccentricity (0.175) and inclination (7°.2) of Mercury is discussed. Provided the gravitational field of the rapidly rotating primordial Sun had a sufficiently large second degree harmonic (i.e., J₂ ? order 10^?3), subsequent solar spin down would drive the orbit of Mercury through two secular resonances with Venus, one involving the precession of the line of apsides, the other one involving the regression of the nodal line. Resonance passage generates contributions to the eccentricity and inclination that are proportional to the square root of the characteristic solar spin down time. We find that an initial solar rotation l period of $\text{P ? 5}\text{1}\text{2}\text{hr}$ guarantees passage through resonance and that a spin down time of $\text{τ = Ω|dΩ/dt|}{}^{\mathrm{?1}}$ of order 10⁶ years could have produced the observed eccentricity and inclination. Such a primordial rotation rate is comparable to the measured rotations of very young stars and the spin down time appears consistent with the time scale derived for magnetic braking of the Sun's rotation by an intense solar wind during a T-Tauri stage of solar evolution.     

Tidal evolution in close binary systems,III

In this paper we shall investigate the energy of close binary systems of constant momentum takng into consideration the first-order effects of rotation and tidal attraction of the components of finite size. The equations for the momentum and the energy of the system will be set up in Section 2, making use of terms including the effects of finite size of the components of finite degree of central condensation. In Section 3 perturbation theory is applied to these equations using the results of Kopal (1972b) as our initial values. In Section 4 we shall compare our results with the initial values and then discuss variations in our constants and the application to various real systems.     

Importance of water quality to nekton habitat use in a North Carolina Branch estuary

Nekton abundance and water quality were examined over 8 yr (1986–1993) in Isaac Creek, a small (2.5 km long), shallow (1–2 m), estuarine creek draining to Adams Creek (Neuse River system), North Carolina, United States. Water quality and nekton were sampled at 8 to 12 stations at 2–3 wk intervals from April to October (76 dates). The nekton assemblage, sampled by trawl, included 42 taxa but was dominated by 11 species (7 fish and 4 decapod crustaceans). Nekton and water quality (temperature, salinity, dissolved oxygen [DO], salinity gradient) data were grouped and analyzed by three (upper, middle, and lower) creek zones to determine if estimated abundance was correlated with water quality. Potentially stressful water quality conditions for salinity (<5 ppt), temperature (>30°C in morning), and DO (<2 mg 1⁻¹) mainly occurred in the upper and middle zones. The most frequent occurrence of potentially stressful conditions for salinity was in the spring and for dissolved oxygen and temperature in middle to late summer. The frequency of potentially stressful conditions increased during a 3-yr period following timber harvest of a large portion of the watershed. Canonical correspondence analysis (CCA) suggested little correlation between the top 11 species and water quality and indicated an assemblage with regular seasonal changes. Comparison of nekton use of the middle and upper zones of the creek for 3-yr pre- and post-harvest periods showed an increase in proportion of nekton caught in those zones, despite the higher frequency of potentially stressful water quality conditions. This observation suggests that a complex set of factors, including water quality, influence the pattern of nekton use in Isaac Creek.