Land-based convection effects on formation of tropical cyclone Mekkhala (2008)
Bell, Michael M.
Elsberry, Russell L.
MetadataShow full item record
The effects of land-based convection on the formation of Tropical Storm Mekkhala (2008) off the west coast of the Philippines are investigated using the Weather Research and Forecasting Model with 4-km horizontal grid spacing. Five simulations with Thompson microphysics are utilized to select the control-land experiment that reasonably replicates the observed sea level pressure evolution. To demonstrate the contribution of the land-based convection, sensitivity experiments are performed by changing the land of the northern Philippines to water, and all five of these no-land experiments fail to develop Mekkhala. The Mekkhala tropical depression develops when an intense, well-organized land-based mesoscale convective system moves offshore from Luzon and interacts with an oceanic mesoscale system embedded in a strong monsoon westerly flow. Because of this interaction, a midtropospheric mesoscale convective vortex (MCV) organizes offshore from Luzon, where monsoon convection continues to contribute to low-level vorticity enhancement below the midlevel vortex center. In the no-land experiments, widespread oceanic convection induces a weaker midlevel vortex farther south in a strong vertical wind shear zone and subsequently farther east in a weaker monsoon vortex region. Thus, the monsoon convection–induced low-level vorticity remained separate from the midtropospheric MCV, which finally resulted in a failure of the low-level spinup. This study suggests that land-based convection can play an advantageous role in TC formation by influencing the intensity and the placement of the incipient midtropospheric MCV to be more favorable for TC low-level circulation development.
The article of record as published may be found at http://dx.doi.org/10.1175/MWR-D-16-0167.1
Showing items related by title, author, creator and subject.
DeLeon, Raymund P. (Monterey, California. Naval Postgraduate School, 2008-03);During July 2007, fields from both the NCEP GFS final analyses and ECMWF model of OW and SF analyses suggests the development of two distinct areas with sub-tropical intrusion from remnants of a decaying baroclinic system ...
Stone, Rebecca E. (Monterey, California. Naval Postgraduate School, 1999-06);The theory of oceanic convection and entrainment has been developed mainly in horizontally homogeneous regimes, yet large-scale spatial variability is known to control the sites and intensity of deep convection. Wintertime ...
Combining New Satellite Tools and Models to Examine Role of Mesoscale Interactions in Formation and Intensification of Tropical Cyclones Simpson, Joanne; Pierce, H.; Ritchie, L.; Liu, T.; Brueske, K.; Velden, C.; Halverson, J.; Einaudi, Franco (Technical Monitor) (2001-01);The objective of this research is to start filling the mesoscale gap to improve understanding and probability forecasts of formation and intensity variations of tropical cyclones. Sampling by aircraft equipped to measure ...