Mid-Tropospheric Flow Characteristics of Intense Precipitation Events in the Southeastern USA

2020 ◽  
Vol 11 (3) ◽  
pp. 10-23
Author(s):  
Walker Skeeter ◽  
Jason Senkbeil
Keyword(s):  
Large Scale ◽  
Flow Characteristics ◽  
Reanalysis Data ◽  
Southern Plains ◽  
Intense Precipitation ◽  
Precipitation Characteristics ◽  
And Cluster Analysis ◽  
Gis Methods ◽  
Manual Classification ◽  
Precipitation Events

This study evaluated 500mb and 850mb flow patterns as well as surface pressure and 72-hour precipitation characteristics of large areal scale intense precipitation events in the Southeastern United States from 1950-2016. This was attempted using a combination of statistical methods utilizing PCA and cluster analysis as well as a manual classification scheme based on synoptic-scale storm type and formation location. All large-scale events were able to fit within one of five manual classifications: tropical events, frontal events, and three mid-latitude cyclone types: those that formed over the Southeast/Gulf of Mexico, the southern plains, and the Midwest/northern plains. This research builds upon GIS methods of classifying flow characteristics utilizing reanalysis data and has the potential to aide forecasters in identifying setups conducive to large-scale intense precipitation events.

A novel method to identify subseasonal clustering episodes of extreme precipitation events and their contribution to large accumulations

2021 ◽  
Author(s):  
Jérôme Kopp ◽  
Pauline Rivoire ◽  
S. Mubashshir Ali ◽  
Yannick Barton ◽  
Olivia Martius
Keyword(s):  
Time Scales ◽  
Extreme Precipitation ◽  
Large Scale ◽  
Time Window ◽  
Heat Waves ◽  
Reanalysis Data ◽  
Data Set ◽  
Temporal Clustering ◽  
Extreme Precipitation Events ◽  
Precipitation Events

<p>Temporal clustering of extreme precipitation events on subseasonal time scales is a type of compound event, which can cause large precipitation accumulations and lead to floods. We present a novel count-based procedure to identify subseasonal clustering of extreme precipitation events. Furthermore, we introduce two metrics to characterise the frequency of subseasonal clustering episodes and their relevance for large precipitation accumulations. The advantage of this approach is that it does not require the investigated variable (here precipitation) to satisfy any specific statistical properties. Applying this methodology to the ERA5 reanalysis data set, we identify regions where subseasonal clustering of annual high precipitation percentiles occurs frequently and contributes substantially to large precipitation accumulations. Those regions are the east and northeast of the Asian continent (north of Yellow Sea, in the Chinese provinces of Hebei, Jilin and Liaoning; North and South Korea; Siberia and east of Mongolia), central Canada and south of California, Afghanistan, Pakistan, the southeast of the Iberian Peninsula, and the north of Argentina and south of Bolivia. Our method is robust with respect to the parameters used to define the extreme events (the percentile threshold and the run length) and the length of the subseasonal time window (here 2 – 4 weeks). The procedure could also be used to identify temporal clustering of other variables (e.g. heat waves) and can be applied on different time scales (e.g. for drought years). <span>For a complementary study on the subseasonal clustering of European extreme precipitation events and its relationship to large-scale atmospheric drivers, please refer to Barton et al.</span></p>

Response of Humidity and Clouds to Tropical Deep Convection

2009 ◽  
Vol 22 (9) ◽  
pp. 2389-2404 ◽  
Author(s):  
Mark D. Zelinka ◽  
Dennis L. Hartmann
Keyword(s):  
Large Scale ◽  
Deep Convection ◽  
Lower Troposphere ◽  
Upward Motion ◽  
Temporal Separation ◽  
Convective Event ◽  
Clear Sky ◽  
Intense Precipitation ◽  
Upper Level ◽  
Precipitation Events

Abstract Currently available satellite data can be used to track the response of clouds and humidity to intense precipitation events. A compositing technique centered in space and time on locations experiencing high rain rates is used to detail the characteristic evolution of several quantities measured from a suite of satellite instruments. Intense precipitation events in the convective tropics are preceded by an increase in low-level humidity. Optically thick cold clouds accompany the precipitation burst, which is followed by the development of spreading upper-level anvil clouds and an increase in upper-tropospheric humidity over a broader region than that occupied by the precipitation anomalies. The temporal separation between the convective event and the development of anvil clouds is about 3 h. The humidity increase at upper levels and the associated decrease in clear-sky longwave emission persist for many hours after the convective event. Large-scale vertical motions from reanalysis show a coherent evolution associated with precipitation events identified in an independent dataset: precipitation events begin with stronger upward motion anomalies in the lower troposphere, which then evolve toward stronger upward motion anomalies in the upper troposphere, in conjunction with the development of anvil clouds. Greater upper-tropospheric moistening and cloudiness are associated with larger-scale and better-organized convective systems, but even weaker, more isolated systems produce sustained upper-level humidity and clear-sky outgoing longwave radiation anomalies.

Precipitation scaling in the tropics with a convection-permitting model

2020 ◽  
Author(s):  
Daniel Argüeso ◽  
Alejandro Di Luca ◽  
Nicolas Jourdain ◽  
Romualdo Romero ◽  
Victor Homar
Keyword(s):  
Water Vapor ◽  
Large Scale ◽  
Potential Temperature ◽  
Lower Troposphere ◽  
Dew Point ◽  
Precipitation Extremes ◽  
Maritime Continent ◽  
Near Surface ◽  
Intense Precipitation ◽  
Precipitation Events

<p>The Maritime Continent is a major convective area and precipitation processes in the region pose great challenges to atmospheric models. A combination of large-scale drivers, such as the Madden-Julian Oscillation and ENSO, and fine-scale processes, such as orographically-forced precipitation, land-sea circulations and tropical convection, governs rainfall in the Maritime Continent. The use of convection-permitting models in the region has shown improved performance in the simulation of precipitation characteristics that are key for the region (i.e. diurnal cycle).</p><p>Most of the rainfall occurring over land is concentrated in the late afternoon and precipitation extremes often occur over short periods of time. The availability of water vapor in the lower troposphere and the high water-holding capacity of a warm atmosphere favors very intense precipitation events, according to the Clausius-Clapeyron relationship. In a warming climate, a full understanding of the so-called precipitation scaling with temperature is thus crucial. However, this potential generally requires the atmosphere be saturated and convection be initiated to become effective. Using a regional climate model operating at convection-permitting scales over 3 consecutive wet seasons, we investigate the response of intense precipitation to temperature.</p><p>In this presentation, we examine different approaches to relate precipitation extremes to near-surface temperature and dew-point temperature. We show that the relationship breaks at certain thresholds that are relatively uniform across islands. The region is well supplied with water vapor and the break is not explained by a deficit in water vapor, unlike previously proposed for other water-limited regions. We identify possible reasons for this behavior, such as the lack of environmental conditions that trigger convection. In this context, we explore the sensitivity of the modelling system to the convection representation (explicit vs. parameterized) and discuss the implications for future changes in intense precipitation events. Finally, we put forward the use of specific variables, such as temperature and equivalent potential temperature integrated in the vertical. These variables not only are coherent with the CC equation but also acknowledge the different warming rates near the surface and at higher tropospheric levels, where precipitating processes actually occur.</p>

scholarly journals Synoptic climatology of winter intense precipitation events along the Mediterranean coasts

2013 ◽  
Vol 13 (7) ◽  
pp. 1707-1722 ◽  
Author(s):  
M. Reale ◽  
P. Lionello
Keyword(s):  
Eastern Mediterranean ◽  
Reanalysis Data ◽  
Western Mediterranean ◽  
Teleconnection Pattern ◽  
Mediterranean Coast ◽  
Synoptic Climatology ◽  
Precipitation Event ◽  
Intense Precipitation ◽  
The Mediterranean ◽  
Precipitation Events

Abstract. The link between winter (December-January-February) precipitation events at 15 Mediterranean coastal locations and synoptic features (cyclones and Northern Hemisphere teleconnection patterns) is analyzed. A list of precipitation events has been produced; q percentile thresholds (Thq) and corresponding frequency Nq (for q equal to 25, 50, 90 and 98) have been considered. A negative trend has been detected in total precipitation and N50 at many locations, while no significant trend in N25, N90 and N98 has been found. The negative phase of the North Atlantic Oscillation (NAO) and the East Atlantic/West Russia pattern (EAWR) compete for exerting the largest influence on the frequency of the 25th, 50th and 90th percentiles, with EAWR and NAO exerting their largest influence in the central and western Mediterranean areas, respectively. All percentiles show a similar behavior except for the 98th percentile, which shows no convincing link to any teleconnection pattern. The cyclone tracks that are associated with precipitation events have been selected using the ERA-40 reanalysis data, and a strong link between intense precipitation and cyclones is shown for all stations. In general, the probability of detecting a cyclone within a distance of 20° from each station increases with the intensity of the precipitation event and decreases with the duration of a dry period. The origin and track of cyclones producing intense precipitation differ among different areas. When precipitation occurs in the northwestern Mediterranean, cyclones are generally either of Atlantic origin or secondary cyclones associated with the passage of major cyclones north of the Mediterranean Basin, while they are mostly generated inside the region itself for events at the eastern Mediterranean coast. An important fraction of intense events in the southern areas is produced by cyclones that are generated over northern Africa. The analysis of sea level pressure and geopotential height at 500 hPa highlights the important role of cyclone depth, circulation strength, surrounding synoptic condition, and of slow speed of the cyclone center for producing intense precipitation events.

scholarly journals North American extreme precipitation events and related large-scale meteorological patterns: a review of statistical methods, dynamics, modeling, and trends

2019 ◽  
Vol 53 (11) ◽  
pp. 6835-6875 ◽  
Author(s):  
Mathew Barlow ◽  
William J. Gutowski ◽  
John R. Gyakum ◽  
Richard W. Katz ◽  
Young-Kwon Lim ◽  
...  
Keyword(s):  
Extreme Precipitation ◽  
Large Scale ◽  
Climate Models ◽  
Early Stage ◽  
Reanalysis Data ◽  
Model Representation ◽  
Dynamics Modeling ◽  
Considerable Uncertainty ◽  
Extreme Precipitation Events ◽  
Precipitation Events

Abstract This paper surveys the current state of knowledge regarding large-scale meteorological patterns (LSMPs) associated with short-duration (less than 1 week) extreme precipitation events over North America. In contrast to teleconnections, which are typically defined based on the characteristic spatial variations of a meteorological field or on the remote circulation response to a known forcing, LSMPs are defined relative to the occurrence of a specific phenomenon—here, extreme precipitation—and with an emphasis on the synoptic scales that have a primary influence in individual events, have medium-range weather predictability, and are well-resolved in both weather and climate models. For the LSMP relationship with extreme precipitation, we consider the previous literature with respect to definitions and data, dynamical mechanisms, model representation, and climate change trends. There is considerable uncertainty in identifying extremes based on existing observational precipitation data and some limitations in analyzing the associated LSMPs in reanalysis data. Many different definitions of “extreme” are in use, making it difficult to directly compare different studies. Dynamically, several types of meteorological systems—extratropical cyclones, tropical cyclones, mesoscale convective systems, and mesohighs—and several mechanisms—fronts, atmospheric rivers, and orographic ascent—have been shown to be important aspects of extreme precipitation LSMPs. The extreme precipitation is often realized through mesoscale processes organized, enhanced, or triggered by the LSMP. Understanding of model representation, trends, and projections for LSMPs is at an early stage, although some promising analysis techniques have been identified and the LSMP perspective is useful for evaluating the model dynamics associated with extremes.

Searching for resemblance between large-scale sea level pressure patterns leading to “intense” precipitation events over Italy

2008 ◽  
Vol 95 (1-2) ◽  
pp. 183-196 ◽  
Author(s):  
N. Tartaglione ◽  
M. Maugeri ◽  
F. Dalan ◽  
M. Brunetti ◽  
T. Nanni ◽  
...  
Keyword(s):  
Sea Level ◽  
Large Scale ◽  
Sea Level Pressure ◽  
Level Pressure ◽  
Intense Precipitation ◽  
Precipitation Events

scholarly journals Intense Rainfall Events Affecting the La Plata Basin

2006 ◽  
Vol 7 (4) ◽  
pp. 769-787 ◽  
Author(s):  
Viviane B. S. Silva ◽  
Ernesto H. Berbery
Keyword(s):  
Large Scale ◽  
Amazon Basin ◽  
Level Structure ◽  
Intense Rainfall ◽  
Rainfall Events ◽  
La Plata ◽  
La Plata Basin ◽  
Intense Precipitation ◽  
Eta Model ◽  
Precipitation Events

Abstract The circulation features associated with intense precipitation events over the La Plata Basin (LPB) during the austral summers of 2001/02 and 2002/03 are investigated using the Eta Model runs generated at the University of Maryland. Based on the main mode of variability over LPB, two regions were selected: (i) the region of Brazil that is at the core of the South American summer monsoon system (SAMS) and (ii) the central region of LPB in southeastern South America (SESA). First, a comparison between the 24-h total precipitation in the Eta Model and the 24-h observed precipitation was made. Results show that the Eta Model captures well the temporal variability of precipitation events in both regions, although a positive bias is noticed over SAMS. Likewise, the model reproduces the distribution of precipitation rate over SESA, but not over SAMS. Nevertheless, the distribution of the moisture flux convergence intensity, which represents the dynamical forcing, is closer in shape to the observed precipitation distribution, suggesting that the model can be a useful tool in identifying the forcing for heavy precipitation events over both regions. Composites of atmospheric and surface variables were constructed for intense precipitation events during austral summer over both regions. Intense rainfall over the central La Plata Basin (SESA) is linked to an amplified upper-tropospheric midlatitude wave pattern in which rainfall occurs just east of an enhanced cyclonic circulation. Accompanying this circulation pattern, an enhanced low-level jet (LLJ) transports warm, moist air from the Amazon toward the region, contributing to an increase in the thermal contrast over SESA. The combined patterns of thermal and dynamical variables suggest that large-scale systems, like frontal systems, are important in producing intense rainfall events. The SAMS region events have a similar upper-level structure as in SESA, but they are longer lived. In this case, the moisture fluxes are determined by an eastward shift of the LLJ, but also directly from the Amazon Basin to the north. As expected, precipitation events produce large increases of simulated runoff. The largest impact is on the SESA region, affecting the streamflow of the Paraná, Paraguay, and Uruguay, the three main rivers of the LPB.

scholarly journals Second Phase Precipitation in As-Welded and Solution Annealed Alloy 22 Welds

2006 ◽  
Vol 128 (4) ◽  
pp. 644-647 ◽  
Author(s):  
Bassem S. El-Dasher ◽  
Sharon G. Torres
Keyword(s):  
Large Scale ◽  
Thick Plate ◽  
Electron Backscatter Diffraction ◽  
Second Phase ◽  
Solution Annealing ◽  
Annealed Alloy ◽  
Precipitation Characteristics ◽  
Alloy 22 ◽  
Tcp Phases ◽  
Backscatter Diffraction

The precipitation characteristics of tetrahedrally close-packed (TCP) phases during the welding and the subsequent solution annealing process of Alloy 22 1 1∕2in. thick plate double-U prototypical welds are investigated. Electron backscatter diffraction was used to provide large scale microstructural observation of the weld cross section, and scanning electron microscopy was used to map the location of the TCP phases. Analysis shows that TCP precipitation occurs congruent to the weld passes, with the solution annealing reducing the sizes of coarser precipitates.

scholarly journals Changes in Intense Precipitation over the Central United States

2012 ◽  
Vol 13 (1) ◽  
pp. 47-66 ◽  
Author(s):  
Pavel Ya. Groisman ◽  
Richard W. Knight ◽  
Thomas R. Karl
Keyword(s):  
United States ◽  
Extreme Precipitation ◽  
Heavy Precipitation ◽  
The Past ◽  
Extreme Precipitation Events ◽  
Intense Precipitation ◽  
Central United States ◽  
Extreme Rain ◽  
Rain Events ◽  
Precipitation Events

Abstract In examining intense precipitation over the central United States, the authors consider only days with precipitation when the daily total is above 12.7 mm and focus only on these days and multiday events constructed from such consecutive precipitation days. Analyses show that over the central United States, a statistically significant redistribution in the spectra of intense precipitation days/events during the past decades has occurred. Moderately heavy precipitation events (within a 12.7–25.4 mm day−1 range) became less frequent compared to days and events with precipitation totals above 25.4 mm. During the past 31 yr (compared to the 1948–78 period), significant increases occurred in the frequency of “very heavy” (the daily rain events above 76.2 mm) and extreme precipitation events (defined as daily and multiday rain events with totals above 154.9 mm or 6 in.), with up to 40% increases in the frequency of days and multiday extreme rain events. Tropical cyclones associated with extreme precipitation do not significantly contribute to the changes reported in this study. With time, the internal precipitation structure (e.g., mean and maximum hourly precipitation rates within each preselected range of daily or multiday event totals) did not noticeably change. Several possible causes of observed changes in intense precipitation over the central United States are discussed and/or tested.

Sign in / Sign up

Export Citation Format

Share Document