The role of unbalanced mesoscale circulations in dust storms

摘要: [1] In this study, two dust storms in northwestern Nevada (February 2002 and April 2004) are investigated through the use of Weather Research Forecasting (WRF) model simulations. The focus study is twofold: (1) Examination dynamic processes on meso-β scale for both cases, (2) analysis extreme upper-air cooling prior to storm formation development a nearly discontinuous gust front case that could not be validated an earlier synoptic-scale study. Results simulations suggest driving mechanism dynamics derives from breakdown subsequent balance between advection geostrophic wind total exit region polar jet. In process, deviation quasi-geostrophic (Q-G) creates plume ascent along right jet's region. cold pool generation mid-lower troposphere consequence adjustment sets up kinetic energy planetary boundary layer forward leaning (slope north south) under jet Surface heating coupled with frontal structure, rapid surface pressure falls (rises) occur initially (later) response diabatic (adiabatic) processes. adjustments at fast time scales, scales radically different those studies followed Q-G tenets Danielsen paradigm. results indicate features associated subgeostrophy curved aloft thermal imbalance (700–500 hPa) lead significant velocity divergence aloft. Mass/momentum strengthen baroclinic zone restoration accompanying resulted narrow rise strong low-level isallobaric winds. turbulent momentum ablation comes sequence