The Structure of A Pacific Narrow Cold Frontal Rainband

摘要: A NOAA P-3 instrumented aircraft observed an intense, fast-moving narrow cold frontal Farmhand as it approached the Pacific Northwest coast on 19 February 2001 during Coastal Jets Experiment. Pseudo-dual-Doppler analyses performed airborne Doppler radar data while system was well offshore indicated that a ribbon of very high reflectively convective cores characterized at low levels with echo tops to approximately 4-5 km. The NCFR exhibited gaps in its reflectively, probably result hydrodynamic instability all no advancing pool leading edge. In contrast some earlier studies rainbands, density current theory described motion overall front. character updraft structure associated heavy rainfall edge varied across gap region. vertical shear cross-frontal low-level ambient flow exerted strong influence character, consistent theoretical arguments developed for squall lines describing balance vorticity short regions south wind strongest updrafts and rain shafts more narrower, erect or even downshear tilted. North weakened less intense Dihedrals which tilted upshear broader band rainfall. Simulations using nonhydrostatic mesoscale nested grid model are used investigate regions, particularly induced pre-frontal shears Observations confirm results depends Downshear-tilted imply convection would weaken time relative segments north since inflow air be affected by passage through region before ascent, suggesting mechanism filling.