Temperature lapse rate

Stability Type Potential Temperature Lapse Rate, (K/lOO m) AG/Az... 

The model tropopause is defined by a PV level of 3.5 pvu poleward of 20° latitude, and by a -2 K km 1 temperature lapse rate equatorward of 20° latitude. Consequently, in this study the troposphere is defined as the volume between the surface and the simulated tropopause. Because the model does not consider typical stratospheric chemical reactions explicitly, ozone concentrations are prescribed from 1-2 levels above the model tropopause up to the top of the model domain at 10 hPa. In both hemispheres we apply monthly and zonally averaged distributions from a 2D stratospheric chemistry model [31]. In the present version of the model, we use the simulated PV and the regression analysis of the MOZAIC data (Section 2) to prescribe ozone in the NH extratropical lower stratosphere, which improves the representation of ozone distributions influenced by synoptic scale disturbances [32, 33]. Furthermore, the present model contains updated reaction rates and photodissociation data [34]. 

The new clumped-isotope (A47) carbonate thermometer, expressed as A47, offers an independent and potentially very powerful approach to paleoelevation reconstruction. In contrast to the use of 8180 values, nothing need be known about the isotopic composition of water from which carbonate grew in order to estimate of temperature of carbonate formation from A47 values. Using assumed temperature lapse rates with elevation, paleoelevations can thereby be reconstructed. 

Paleoelevation models based on fossil floras use three different approaches 1) the use of floras to estimate temperature, which is used in combination with lapse rates to infer elevation 2) the use of floras to estimate enthalpy, which is used with gravitational acceleration to estimate elevation and 3) the use of stomatal frequency in leaves to indicate altitudinal changes in C02 partial pressure. This paper will focus on the first of these, the temperature-lapse rate method, which itself has three basically different approaches that differ in the way paleotemperatures can be estimated from fossil floras and in the methods by which lapse rates can be utilized in the calculations. The purpose of this paper is to provide a concise overview that summarizes... 

In the three different temperature-lapse rate methods for paleoaltimetry, Axelrod (e.g., Axelrod 1980, 1998a,b) relied on the NLR method for estimating temperature. Meyer (1986, 1992) estimated temperature primarily from characteristics of plant physiognomy (before the development of CLAMP) and secondarily from the climatic tolerances of particular genera. Wolfe (1994) and Gregory (1994 Gregory and Chase 1992 Gregory and McIntosh 1996) used CLAMP in their analyses. Besides these differences in the way that temperatures were estimated, each of these workers also used different types of lapse rates to estimate paleoelevation. 

Temperature. Temperature consistently decreases with altitude, although the specific temperature lapse rates are highly dependent on local geographical and climatic conditions. Humidity has a very prominent influence theoretically, lapse rates can vary from 10 °C/km in extremely dry conditions to 0 °C/km in extremely wet conditions, or can even be negative... 

C02 assimilation. The amount of C02 available for photosynthesis decreases with decreasing C02 partial pressure at higher elevations, but this effect is offset by the increase in diffusion speed at lower air pressure (Gale 1972, 1973). The lower temperature at higher altitudes, however, decreases diffusion speed, and therefore the temperature lapse rate of the particular mountain determines whether C02 availability decreases (dry-moist lapse rate) or stays relatively constant (very wet lapse rate) (Smith and Donahue 1991). The lower air pressure at altitude does not just decrease C02 partial pressure but also 02 partial pressure, which results in lower photorespiration rates and more efficient photosynthesis. When all these effects are modeled, photosynthetic rates generally decrease with altitude, unless the temperature lapse rate is very low (which could occur in extremely wet mountain ranges), but the photosynthetic limitation is much less than expected based on just the partial pressure decrease (Terashima et al. 1995 Smith and lohnson 2007). 

C02 decrease by adjusting the C02 mixing ratio (Woodward and Bazzaz 1988). These results strongly argue in favor of a central role of C02 partial pressure decreases with elevation on plant SD and SI. Under the relatively dry temperature lapse rates in California and New Zealand, therefore, the decrease in C02 partial pressure is expected to increase stomatal density and index, as observed in Q. kelloggii and N. solandri (Figs. 3, 4). 

Even if actual evaporation rates for the sites in this study are difficult to predict because of the dependence on the specific microclimatic conditions, we can infer general trends for the altitudinal transects in New Zealand and California. Both are located in temperate areas and have relatively dry temperature lapse rates (6 °C), and in California, cloudiness increases with altitude. Comparing these conditions to the modeled environments discussed above would suggest that evaporation is likely to decrease with altitude, or at least not increase significantly. The larger leaf size of the oak leaves may increase their evaporation rates relative to the smaller mountain beech leaves, but this remains speculative as no irradiation data available were available for either site. 

Leaf gas exchange rates are highly dependent on local climatic factors influencing C02 diffusion and evaporation rates, especially temperature lapse rates. The dependency of gas-exchange parameters on local climatic factors and leaf anatomy may account for the wide variability in leaf stomatal responses and stable isotope composition over elevation transects found in different species and different regions. 

Collect a modern training set from a reasonably similar geographical area (i.e. expecting comparable temperature lapse rates) to check if the taxon is indeed adjusting stomatal frequency to elevation and establish a calibration curve. 

Vertical wind profile and turbulence were measured using three Gill bivane anemometers installed at a tower 600 m upwind of the release point. The data from these sensors were not transferred from LLNL to WRI. On this same tower, five levels of platinum RTD sensors at heights of 1, 2, 4, 8, and 16 m were installed to measure the ambient temperature and temperature lapse rate. Eighteen (18) stations using two-axis cup-and-vane anemometers (Met-One) mounted 2 m above the ground were used to determine the characteristics of the wind field before, during and after each release. 

The basis for the prediction system is as follows. Convection cells of sufficient strength arise only if the lower atmosphere is (sufficiently) unstable. The criterion for this is that the adiabatic lapse rate (rate of decrease in temperature from the sea surface upward) exceeds some threshold, the value of which depends on the moisture content because of its consequence for possible cloud formation. In case the lapse rate is smaller than 5.5 to 7.5°C/km, the lower atmosphere is stable here 6.5C/km is used as a representative critical value. Between approximately 10°C/km and (say) 6.5°C/km, it is conditionally unstable (depending on the moisture content), and a temperature lapse rate larger than 10°C/km results in an unstable atmosphere. Prediction of the lapse rate and moisture content using multi-layered atmospheric models is part of routine weather forecast systems. This, therefore, also allows operational prediction of the occurrence of significant seiche events on a routine basis, just like common weather prediction. 

The joint frequency distribution in per cent of total time, of various class Intervals of wind speed at 200 feet and the temperature lapse rate from 3 fo t to 200 feet is shown in Table A-4. 

The temperature lapse rate is defined as the negative of the vertical temperature gradient, 9 r/9z. If the vertical temperature profile follows an adiabat, then T and 8T/dz = —RT/CpH therefore, RT/CpH is the adiabatic lapse rate in log-p... 

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