The Lemon technique is a method used by meteorologists using weather radar to determine the relative strength of thunderstorm cells in a vertically sheared environment. It is named for Leslie R. Lemon, the co-creator of the current conceptual model of a supercell.[1] The Lemon technique is largely a continuation of work by Keith A. Browning, who first identified and named the supercell.[2][3][4]
The method focuses on updrafts and uses weather radar to measure quantities such as height (echo tops), reflectivity (such as morphology and gradient), and ___location to show features and trends described by Lemon.[5][6] These features include:
- Updraft tilt - The tilted updraft (vertical orientation) of the main updraft is an indication of the strength of the updraft, with nearly vertical tilts indicating stronger updrafts.
- Echo overhang - In intense thunderstorms, an area of very strong reflectivity atop the weak echo region and on the low-level inflow inside side of the storm.[7]
- Weak echo region (WER) - An area of markedly lower reflectivity, resulting from an increase in updraft strength.[8]
- Bounded weak echo region (BWER) - Another area of markedly lower reflectivity, now bounded by an area of high reflectivity. This is observed as a "hole" in reflectivity, and is caused by an updraft powerful enough to prevent ice and liquid from reaching the ground. This powerful updraft is often an indication of, or is facilitated by, a mesocyclone. A mesocyclone is not strictly necessary for BWER development. Storm rotation can be reliably detected by the Doppler velocities of a weather radar.[9]
- Descending reflectivity core
See also
editReferences
edit- ^ Lemon, Leslie R.; Charles A. Doswell III (September 1979). "Severe Thunderstorm Evolution and Mesocyclone Structure as Related to Tornadogenesis". Mon. Wea. Rev. 107 (9): 1184–97. Bibcode:1979MWRv..107.1184L. doi:10.1175/1520-0493(1979)107<1184:STEAMS>2.0.CO;2.
- ^ Browning, Keith A.; Frank H. Ludlam (April 1962). "Airflow in convective storms" (PDF). Quarterly Journal of the Royal Meteorological Society. 88 (376): 117–35. Bibcode:1962QJRMS..88..117B. doi:10.1002/qj.49708837602. Archived from the original (PDF) on 2012-03-07.; Browning, K. A.; Ludlam, F. H. (1962). "Airflow in convective storms". Quarterly Journal of the Royal Meteorological Society. 88 (378): 555. Bibcode:1962QJRMS..88..555B. doi:10.1002/qj.49708837819.
- ^ Browning, Keith A. (November 1964). "Airflow and Precipitation Trajectories Within Severe Local Storms Which Travel to the Right of the Winds". J. Atmos. Sci. 21 (6): 634–9. Bibcode:1964JAtS...21..634B. doi:10.1175/1520-0469(1964)021<0634:AAPTWS>2.0.CO;2. hdl:2027/mdp.39015095125533.
- ^ Browning, Keith (November 1965). "Some Inferences About the Updraft Within a Severe Local Storm". J. Atmos. Sci. (abstract). 22 (6): 669–77. Bibcode:1965JAtS...22..669B. doi:10.1175/1520-0469(1965)022<0669:SIATUW>2.0.CO;2. hdl:2027/mdp.39015095128867.
- ^ Lemon, Leslie R. (July 1977). New severe thunderstorm radar identification techniques and warning criteria: a preliminary report. Kansas City, MO: Techniques Development Unit, National Severe Storms Forecast Center.
- ^ Lemon, Leslie R. (April 1980). New Severe Thunderstorm Radar Identification Techniques and Warning Criteria. Kansas City, MO: Techniques Development Unit, National Severe Storms Forecast Center.
- ^ "AMS Glossary". Archived from the original on 2011-06-06. Retrieved 2007-12-16.
- ^ "AMS Glossary". Archived from the original on 2007-08-16. Retrieved 2007-12-16.
- ^ "AMS Glossary". Archived from the original on 2011-06-06. Retrieved 2007-12-16.