Modelling coastal low-level wind-jets: does horizontal resolution matter?
2016 (English)In: Meteorology and atmospheric physics (Print), ISSN 0177-7971, E-ISSN 1436-5065, Vol. 128, no 2, 263-278 p.Article in journal (Refereed) Published
Atmospheric flows in coastal regions are impacted by land-sea temperature contrasts, complex terrain, shape of the coastline, among many things. Along the west coast of central North America, winds in the boundary layer are mainly from north or northwest, roughly parallel to the coastline. Frequently, the coastal low-level wind field is characterized by a sharp wind maximum along the coast in the lowest kilometer. This feature, commonly referred to as a Coastal Low-Level Jet (CLLJ), has significant impact on the climatology of the coastal region, influencing aviation, shipping, fishing and a number of other human activities along the littoral zone, and better understanding and forecasting of this is vital.
The purpose of this study is to elucidate the issue of proper resolution in a mesoscale numerical model to describe the physics of a CLLJ, and its impact on the upper ocean. The COAMPS® model is used for a summer event to determine the realism of the model results compared to observations, from an area of supercritical flow adjustment between Pt. Sur and Pt. Conception, California. Simulations at different model horizontal resolutions, from 54 km to 2 km are performed. While the model produces realistic results with increasing details at higher resolution, the results do not converge even at a resolution of only few kilometers and an objective analysis of model errors do not show an increased skill with increasing resolution. New methods may thus have to be developed to evaluate models at very high resolution. Based on all available information, a compromise resolution appears to be at least 6 km.
Place, publisher, year, edition, pages
2016. Vol. 128, no 2, 263-278 p.
low-level coastal jets, COAMPS, model resolution, scale dependence, mesoscale meteorology
Meteorology and Atmospheric Sciences
Research subject Atmospheric Sciences and Oceanography
IdentifiersURN: urn:nbn:se:su:diva-93148DOI: 10.1007/s00703-015-0413-1ISI: 000373304700009OAI: oai:DiVA.org:su-93148DiVA: diva2:645418