Mesoscale meteorology
Mesoscale meteorology is the study of weather systems and processes at scales smaller than synoptic-scale systems but larger than microscale and storm-scale. Horizontal dimensions generally range from around 5 kilometres (3 mi) to several hundred kilometers. Examples of mesoscale weather systems are sea breezes, squall lines, and mesoscale convective complexes.
Vertical velocity often equals or exceeds horizontal velocities in mesoscale meteorological systems due to nonhydrostatic processes such as buoyant acceleration of a rising thermal or acceleration through a narrow mountain pass.
Classification
The
It is anticipated that radar will provide useful information concerning the structure and behavior of that portion of the atmosphere which is not covered by either micro- or synoptic-meteorological studies. We have already observed with radar that precipitation formulations which are undoubtedly of significance occur on a scale too gross to be observed from a single station, yet too small to appear even on sectional synoptic charts. Phenomena of this size might well be designated as mesometeorological.
— M. G. H. Ligda, "Radar Storm Observation", Compendium of Meteorology (1951)[3]
Subclasses
Mesoscale meteorology broadly concerns meteorological phenomena larger than a few kilometers across but smaller than could be resolved by the observation networks used in the earliest standardized weather maps.[4] The mesoscale regime is often divided into these subclasses based on the size of associated weather systems:[5]
- Meso-alpha (meso-α) – 200–2000 km scale of phenomena like synoptic scale.[5]
- Meso-beta (meso-β) – 20–200 km scale of phenomena like
- Meso-gamma (meso-γ) – 2–20 km scale of phenomena like thunderstorm convection, complex terrain flows (at the edge to microscale, also known as storm-scale)
As a note, tropical and subtropical cyclones are classified by National Hurricane Center as synoptic scale rather than mesoscale.[7]
Dynamics
Mesoscale processes are characterized by having a relatively large
Large-scale
Mesoscale boundaries
As in synoptic frontal analysis, mesoscale analysis uses cold, warm, and occluded fronts on the mesoscale to help describe phenomena. On weather maps mesoscale fronts are depicted as smaller and with twice as many bumps or spikes as the synoptic variety. In the United States, opposition to the use of the mesoscale versions of fronts on weather analyses, has led to the use of an overarching symbol (a trough symbol) with a label of outflow boundary as the frontal notation.[10]
See also
- Microscale meteorology
- Misoscale meteorology
- POLYGON experiment
- Surface weather analysis
- Synoptic scale meteorology
References
- ^ ISBN 978-0-521-88942-1.
- ^ Fujita 1986, p. 23.
- ISBN 978-1-940033-70-9.
- ISBN 978-0-470-74213-6.
- ^ a b c Orlanski, I. (1975). "A rational subdivision of scales for atmospheric processes" (PDF). Bulletin of the American Meteorological Society. 56 (5): 527–530.
- ^ S2CID 257624656.
- ^ "Glossary of NHC Terms".
- ^ ISBN 978-0-12-382225-3.
- ^ ISBN 978-0-470-74213-6.
- ^ Roth, David. "Unified Surface Analysis Manual" (PDF). Hydrometeorological Prediction Center. Retrieved 2006-10-24.
- Fujita, T.T. (1986). "Mesoscale classifications: their history and their application to forecasting". In Ray, P.S. (ed.). Mesoscale Meteorology and Forecasting. Boston: American Meteorological Society. pp. 18–35.