A numerical investigation of wind speed effects on lake-effect storms

Sousounis, Peter J.

doi:10.1007/bf00708966

Cited by 10 publications

(16 citation statements)

References 29 publications

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“…From 1.5 to 3.5 km, a stable layer was prescribed as a smooth transition to d/dz ϭ 8.0 K km Ϫ1 above 3.5 km. Similar profiles have often been observed upwind of lakes during LE events (e.g., Hjelmfelt and Braham 1983;Laird 1999) and used in prior idealized LE modeling investigations (e.g., Hjelmfelt 1990;Sousounis 1993;Rose 2000). Wind profiles were prescribed using a uniform speed and direction throughout the entire profile.…”

Section: Mesoscale Model and Model Setupsupporting

confidence: 65%

Model Simulations Examining the Relationship of Lake-Effect Morphology to Lake Shape, Wind Direction, and Wind Speed

2003

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Idealized model simulations with an isolated elliptical lake and prescribed winter lake-effect environmental conditions were used to examine the influences of lake shape, wind speed, and wind direction on the mesoscale morphology. This study presents the first systematic examination of variations in lake shape and the interplay between these three parameters. The array of 21 model simulations produced cases containing each of the three classic lake-effect morphologies (i.e., vortices, shoreline bands, and widespread coverage), and, in some instances, the mesoscale circulations were composed of coexisting morphologies located over the lake, near the downwind shoreline, or inland from the downwind shore. As with lake-effect circulations simulated over circular lakes, the ratio of wind speed (U) to maximum fetch distance (L) was found to be a valuable parameter for determining the morphology of a lake-effect circulation when variations of lake shape, wind speed, and wind direction were introduced. For a given elliptical lake and strong winds, a morphological transform from shoreline band toward widespread coverage accompanied changes in ambient flow direction from along to across the major lake axis. For simulations with weak winds over a lake with a large axis ratio, the morphology of the lake-effect circulation changed from vortex toward shoreline band with a change in wind direction from along to across the major lake axis. Weak winds across lakes with smaller axis ratios (i.e., 1:1 or 3:1) produced mesoscale vortices for each wind direction. Across the array of simulations, a shift in mesoscale lake-effect morphology from vortices to bands and bands toward widespread coverage was attended by an increase in U/L. Last, the elliptical-lake results suggest that the widths of the lakeeffect morphological transition zones in U/L parameter space, conditions favorable for the coexistence of multiple morphologies, were greater than for circular lakes.

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Section: Mesoscale Model and Model Setupsupporting

confidence: 65%

Model Simulations Examining the Relationship of Lake-Effect Morphology to Lake Shape, Wind Direction, and Wind Speed

2003

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“…Another form of lake effect precipitation occurs as lake effect snowfall. Lake effect snowfall in the Great Lakes region accounts for more than half of the region's annual total snowfall (Braham & Dungey, ; Liu & Moore, ; Sousounis, ). The average lake effect snowfall in Ontario Lake can make up as much as 70% of the total snowfall in autumn and winter (Veals & Steenburgh, ).…”

Section: Resultsmentioning

confidence: 99%

Observed and Simulated Lake Effect Precipitation Over the Tibetan Plateau: An Initial Study at Nam Co Lake

et al. 2018

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Thousands of lakes are located on the Tibetan Plateau. However, few studies examine the impacts of these lakes on local climate. To investigate lake effect precipitation over the plateau environment, we take Nam Co Lake as a case study, due to its large size and the availability of in situ observations. Using the Weather Research and Forecasting (WRF) model, the impacts of Nam Co Lake on downwind precipitation events (i.e., the generation and causes) are studied quantitatively. First, we compare meteorological station observations downwind of the lake with observations from other nearby stations. In total, four stations are located around Nam Co Lake in different directions, and these stations accurately represent the spatial distribution of observed precipitation. The largest amount of precipitation is observed at Nam Co station (downwind) in October, and this precipitation amount is more than twice that observed at the other three stations. Second, simulations are carried out using the WRF model, and the results show that WRF model accurately captures the precipitation events that occurred at Nam Co station in October 2006. Finally, the WRF_lake and WRF_nolake simulations, which do and do not include the lake, respectively, are carried out using the WRF model. Nam Co Lake caused an increase in precipitation of up to 70% downwind of the lake on 24 October 2006. The simulation results also show that the lake caused an increase in precipitation of up to 60% over the lake's area and downwind of the lake in October of 2006.

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“…To further investigate the advection-only hypothesis, we examined individually the relationships between U 850 and InPen 20 and between DZ CBL and InPen 20 . In addition to the inclusion of U 850 in the up-down model, boundary layer wind speed as a predictor of the inland extent of snowfall or lake-effect circulations is documented in Villani et al (2017) and is also implied in Niziol et al (1995) and in the numerical simulations of Sousounis (1993) and Laird et al (2003b). The 850-hPa wind speed is positively correlated with InPen 20 for our dataset (r 5 0.26), with a correlation coefficient similar to values obtained by Villani et al (2017) for measurements between inland extent and mean mixed layer wind speed.…”

Section: ) Advection-only Hypothesismentioning

confidence: 97%

Predicting the Inland Penetration of Long-Lake-Axis-Parallel Snowbands

Eipper

Young

Greybush

et al. 2018

Weather and Forecasting

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Predicting the inland penetration of lake-effect long-lake-axis-parallel (LLAP) snowbands is crucial to public safety because LLAP bands can produce hazardous weather well downwind of the parent lake. Accordingly, hypotheses for the variation in inland penetration of LLAP-band radar echoes (InPen) are formulated and tested. The hypothesis testing includes an examination of statistical relationships between environmental variables and InPen for 34 snapshots of LLAP bands observed during the Ontario Winter Lake-effect Systems (OWLeS) field campaign. Several previously proposed predictors of LLAP-band formation or InPen demonstrate weak correlations with InPen during OWLeS. A notable exception is convective boundary layer (CBL) depth, which is strongly correlated with InPen. In addition to CBL depth, InPen is strongly correlated with cold-air advection in the upper portion of the CBL, suggesting that boundary layer destabilization produced by vertically differential cold-air advection may be an important inland power source for preexisting LLAP bands. This power production is quantified through atmospheric energetics and the resulting variable, differential thermal advection power (DTAP), yields reasonably skillful predictions of InPen. Nevertheless, an InPen model developed using DTAP is outperformed by an empirical model combining CBL depth and potential temperature advection in the upper portion of the CBL. This two-variable model explains 76% of the observed InPen variance when tested on independent data. Finally, implications for operational forecasting of InPen are discussed.

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A numerical investigation of wind speed effects on lake-effect storms

Cited by 10 publications

References 29 publications

Model Simulations Examining the Relationship of Lake-Effect Morphology to Lake Shape, Wind Direction, and Wind Speed

Model Simulations Examining the Relationship of Lake-Effect Morphology to Lake Shape, Wind Direction, and Wind Speed

Observed and Simulated Lake Effect Precipitation Over the Tibetan Plateau: An Initial Study at Nam Co Lake

Predicting the Inland Penetration of Long-Lake-Axis-Parallel Snowbands

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