TY - JOUR
T1 - Orographic flow response to variations in upstream humidity
AU - Reeves, Heather Dawn
AU - Rotunno, Richard
PY - 2008/11
Y1 - 2008/11
N2 - The effects of upstream relative humidity (RH) on low-level wind and precipitation patterns for lowspeed, statically stable flows over a mountain are investigated using idealized two- and three-dimensional numerical-simulation experiments in which RH is increased from 0% to 100%. For RH less than some critical threshold, the flow upstream becomes less decelerated as RH is increased; for RH greater than this threshold, the flow upstream becomes more decelerated as RH is increased. This increasing deceleration with RH is due to locally enhanced static stability resulting from enhanced condensation near the freezing level. Analyses from the simulations indicate that the lifted condensation level and the height of the freezing level are significant control parameters for the upstream-flow deceleration in the steady-state solutions. Dimensional analysis using these control parameters (as well as others) brings forth new nondimensional parameters that are shown to enter into analytic formulas for the orographic upstream-flow deceleration in a moist atmosphere.
AB - The effects of upstream relative humidity (RH) on low-level wind and precipitation patterns for lowspeed, statically stable flows over a mountain are investigated using idealized two- and three-dimensional numerical-simulation experiments in which RH is increased from 0% to 100%. For RH less than some critical threshold, the flow upstream becomes less decelerated as RH is increased; for RH greater than this threshold, the flow upstream becomes more decelerated as RH is increased. This increasing deceleration with RH is due to locally enhanced static stability resulting from enhanced condensation near the freezing level. Analyses from the simulations indicate that the lifted condensation level and the height of the freezing level are significant control parameters for the upstream-flow deceleration in the steady-state solutions. Dimensional analysis using these control parameters (as well as others) brings forth new nondimensional parameters that are shown to enter into analytic formulas for the orographic upstream-flow deceleration in a moist atmosphere.
UR - https://www.scopus.com/pages/publications/58049100190
U2 - 10.1175/2008JAS2762.1
DO - 10.1175/2008JAS2762.1
M3 - Article
AN - SCOPUS:58049100190
SN - 0022-4928
VL - 65
SP - 3557
EP - 3570
JO - Journal of the Atmospheric Sciences
JF - Journal of the Atmospheric Sciences
IS - 11
ER -