Parameterizations of the Daytime Friction Velocity, Temperature Scale, and Upslope Flow over Gently Inclined Terrain in Calm Synoptic Conditions

A set of new parameterizations for the friction velocity and temperature scale over gently sloped terrain and in calm synoptic conditions are theoretically derived. The friction velocity is found to be proportional to the product of the square root of the total accumulated heating in the boundary layer and the sinusoidal function of the slope angle, while the temperature scale is proportional to the product of the boundary layer depth, the sinusoidal function of the slope angle and the potential temperature gradient in the free atmosphere. Using the new friction velocity parameterization, together with a parameterization of eddy diffusivity and an initial potential temperature profile around sunrise, an improved parameterization for the thermally induced upslope flow profile is derived by solving the Prandtl equations. The upslope flow profile is found to be simply proportional to the friction velocity.

Topographic Indices and Yield Variability in a Rolling Landscape of Western Canada

Understanding the relationships between topographic indices and crop yield variability is important for soil manage- ment and crop production in rolling landscape. Two agricultural fields at Alvena and Hepburn, Saskatchewan, Canada were selected to examine how topographic indices were related to wheat yield under two topographic and weather conditions in the Canadian prairies. The landscapes of the two sites are classified as hummocky and the dominant soil type is an Aridic Ustoll. The relationships among yield, topography, soil, and weather were analyzed using wheat (Triticum aestivum L.) grain yield from Alvena in 2001 (dry year) and 2004 (wet year) and from Hepburn in 1998 (dry year). Topographic/soil indices included relative elevation, wetness index, upslope length, curvature, soil organic matter, and soil moisture storage before seeding. The results indicated that, in the dry years, the correlation coefficients between upslope length and grain yield were 0.79 for the typical rolling landscape (Alvena) in 2001 and 0.73 for shallow gentle rolling landscape (Hepburn) in 1998. In the wet year (2004), the relationships between yield and topographic/soil attributes were not as strong as in dry years. Therefore, upslope length was the best yield indicator for the two landscapes in dry years, whereas no topographic indices were highly correlated to crop yield in wet years. Those topographic indices seemed useful in identifying the yield variability and delineating the proper management zone.

The Formation of Lee Reversal Flow and Moisture Distribution Effect on the Characteristics of Precipitation

Moist flow over a bell-shaped mountain is investigated using the advanced regional prediction system (ARPS). Three closely related issues are addressed: the upslope precipitation mechanism, periodic evolution of precipitation associated with mountain waves, and lee precipitation induced by reversal flow. The results show that precipitation is strongly the moist distribution and terrain scale dependent. Beginning with the case of uniformly stratified flow over mountain, upslope precipitation and lee wave precipitation pattern are obtained. Most importantly, lee precipitation induced by reversal flow can be caused by layered flow over mountain, wherein lee reversal flow exerts a significant influence on the orographic precipitation.

De Winter syndrome and ST-segment elevation myocardial infarction can evolve into one another: Report of two cases

BACKGROUND The de Winter electrocardiography(ECG)pattern is a sign that implies proximal left anterior descending coronary artery occlusion in patients with chest pain.The previous view was that the de Winter ECG pattern is static.CASE SUMMARY A 65-year-old man presented with sudden chest pain at rest associated with diaphoresis for 55 min.The first ECG showed only T-wave inversion in III and aVF leads.Another ECG was performed at the 100th minute,showing upsloping ST segments depressed with tall and symmetrical T waves in the precordial leads;the J point was raised by 0.1 mV at the aVR lead.The patient was referred to our catheterization laboratory.A third ECG showed ST segment elevation by 0.2 mV in the I and aVL leads.The patient underwent emergency coronary angiography,which revealed complete proximal left anterior descending coronary(LAD)occlusion.The second patient presented with a 1-h history of sudden-onset,severe,substernal crushing chest pain.The first ECG showed STsegment elevation(0.1–1.7 mV)in I,aVL,and precordial leads.The patient was referred to the catheterization laboratory.On arrival,his symptoms alleviated,and ECG showed that the ST-segments had significantly fallen back.The third ECG showed a typical de Winter pattern.Coronary angiography revealed 99%stenosis of the middle LAD.CONCLUSION The de Winter ECG pattern is transient and dynamic,and it reflects proximal or mid-LAD subtotal occlusion rather than total occlusion.

THREE-DIMENSIONAL NUMERICAL SIMULATION OF THE MESOSCALE WIND STRUCTURE OVER SHANDONG PENINSULA

General features of 3-dimensional mesoscale wind and temperature structure over Shandong Peninsula are described in this paper.Results are achieved by numerical simulation with the 3- dimensional non-hydrostatic mesoscale model METRAS.For the onset and cessation time of sea- land breezes,the simulation results agree well with the statistical analyses of observational data available for the studied area.One interesting result is the 3 hour response time of wind field to the thermal change.Further statistic analysis based on the observational data is needed to make sure of this correlation.Important effects of coastal mountains on the wind structure are also exposed in detail by the model.Convergence and divergence centers resulting from the conjunction of sea-land breezes and complex terrain are clearly shown,which are not noticed before by conventional synoptic observation and theoretical analysis.

A THREE-DIMENSIONAL ELASTIC NESTED-GRID MESO-(β-γ) SCALE ATMOSPHERIC MODEL——PART Ⅱ:MODEL VALIDATION

By using the model developed in Part Ⅰ of the sister papers,simulations of severe storm,winter airflow and snowfall over a mountain,as well as mountain-valley winds and sea breeze are performed.Different functions of the model are verified through the computation and special emphasis is put on some important properties of the meso-(β-γ) systems frequently occurring.The simulation results of the cases are agreeable to field observations,conceptual models,and pre- vious numerical studies.It is shown that the model is applicable for the researches and prediction of various local and/or regional weather processes,and capable of describing their macro- and micro-structures,influences of orographic and underlying-surface forcing,and interaction between meso-β and meso-γ scales.In addition,the evolutional characteristics and mechanisms of the modeled processes are also analyzed.