Calculation of Airflow Over an Arbitrary Ridge Including Diabatic Heating and Cooling

Abstract

uses modified {L}ong's equation (i.e., nonlinear, 2-d, incompressible,constant {N} and {U}) and prescribed heating (i.e. effect of airflowupon heating neglected) at surface - iterative solution (integralssolved numerically): (1) specify inhomogeneous part of {L}ong's equation(caused by diabitc heating) (2) get homogeneous solution (for thestreamfunction) by specifying a distribution of "sources" on thelower boundary in order to fulfill the irregular lower boundary condition(!!!) (3) {U}se the streamfunction from (2) to recompute the (initiallyspecified) inhomogeneous part (4) iterate (2)-(3) till solutionsconverge - {RESULTS}: * simulated flow over broad ridge for comparisonof his method with previous research * with heated surface similarflow as with mountain, with upward motion (near the surface startingat the center of the heated region) * steep ridge causes warm airto fold under cold air (streamlines bend back- wards); since no turbulenceor instability mechanism included in his theory no wavebreaking (aswould happen in nature) can occur * asymmetric mountain: much strongerflow modification when gentler slope on upwind side * surface coolingamplifies wave above ridge, strong downslope winds penetrate fartherdownslope; heating weakens waves