Spanish Plume Literature Review and Case Studies

The Spanish plume is a synoptic pattern associated with deep moist convective storms in western and central Europe. A large-amplitude trough or cut-off low in the jet stream extending to low latitudes produces a long fetch of southerly or southwesterly flow in the lower troposphere across the Iberian Peninsula and into Europe. The preconvective environment is traditionally characterized by an elevated mixed layer of hot dry air with steep lapse rates (i.e., the Spanish plume airstream) overtop a warm surface layer and capping inversion, resembling the loaded-gun convective sounding. A literature review of 102 peer-reviewed journal articles mentioning the Spanish plume is performed (of which 84 have only passing mentions). Some articles correctly employ the original definition of the Spanish plume airstream as the dry elevated mixed layer, whereas others incorrectly apply the term to the surface (sometimes humid) airstream. The origin of the airstream is variously described as the Iberian Peninsula, northern Africa, or both, often unevidenced. Some air in so-called Spanish plumes does not even cross Spain. Descriptions of convective storms in Spanish plume synoptic patterns also are largely unevidenced, with release of instability attributed to various synoptic-scale and mesoscale processes. This review reveals these and other issues with the literature on the Spanish plume, painting a sometimes unevidenced, inconsistent, unclear, and inaccurate picture. The goals are to recommend proper usage of the term Spanish plume and articulate future research questions, specifically related to quantifying interactions with terrain through diurnal sensible heat fluxes and orographic flow modification to produce favorable environments for convective storms.

This dataset contains the list of 102 journal articles used in this study and data from case studies of Spanish plume events.