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(1 - 13 of 13)
- Title
- Bayesian Updating of Track-Forecast Uncertainty for Tropical Cyclones.
- Creator
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Kang, Nam-Young, Lim, Myeong-Soon, Elsner, James B., Shin, Dong-Hyun
- Abstract/Description
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The accuracy of track forecasts for tropical cyclones (TCs) is well studied, but less attention has been paid to the representation of track-forecast uncertainty. Here, Bayesian updating is employed on the radius of the 70% probability circle using 72-h operational forecasts with comparisons made to the classical approach based on the empirical cumulative density (ECD). Despite an intuitive and efficient way of treating track errors, the ECD approach is statistically less informative than...
Show moreThe accuracy of track forecasts for tropical cyclones (TCs) is well studied, but less attention has been paid to the representation of track-forecast uncertainty. Here, Bayesian updating is employed on the radius of the 70% probability circle using 72-h operational forecasts with comparisons made to the classical approach based on the empirical cumulative density (ECD). Despite an intuitive and efficient way of treating track errors, the ECD approach is statistically less informative than Bayesian updating. Built on a solid statistical foundation, Bayesian updating is shown to be a useful technique that can serve as a substitute for the classical approach in representing operational TC track-forecast uncertainty.
Show less - Date Issued
- 2016-04
- Identifier
- FSU_libsubv1_wos_000376216300016, 10.1175/WAF-D-15-0140.1
- Format
- Citation
- Title
- Climate Mechanism for Stronger Typhoons in a Warmer World.
- Creator
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Kang, Nam-Young, Elsner, James B.
- Abstract/Description
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Violent typhoons continue to have catastrophic impacts on economies and welfare, but how they are responding to global warming has yet to be fully understood. Here, an empirical framework is used to explain physically why observations support a tight connection between increasing ocean warmth and the increasing intensity of supertyphoons in the western North Pacific. It is shown that the energy needed for deep convection is on the rise with greater heat and moisture in the lower tropical...
Show moreViolent typhoons continue to have catastrophic impacts on economies and welfare, but how they are responding to global warming has yet to be fully understood. Here, an empirical framework is used to explain physically why observations support a tight connection between increasing ocean warmth and the increasing intensity of supertyphoons in the western North Pacific. It is shown that the energy needed for deep convection is on the rise with greater heat and moisture in the lower tropical troposphere but that this energy remains untapped when air pressure is high. Accordingly, tropical cyclone formation is becoming less common, but those that do form are likely to reach extreme intensities from the discharge of stored energy. These thermodynamic changes to the environment most significantly influence the upper portion of extreme typhoon intensities, indicating that supertyphoons are likely to be stronger at the expense of overall tropical cyclone occurrences in the western North Pacific.
Show less - Date Issued
- 2016-02
- Identifier
- FSU_libsubv1_wos_000369285500001, 10.1175/JCLI-D-15-0585.1
- Format
- Citation
- Title
- Clouds and temperature drive dynamic changes in tropical flower production.
- Creator
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Pau, Stephanie, Wolkovich, Elizabeth, Cook, Benjamin, Nytch, Christopher J., Regetz, James, Zimmerman, Jess, Wright, S.
- Abstract/Description
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Tropical forests are incredibly dynamic, showing rapid and longer-term changes in growth, mortality and net primary productivity. Tropical species may be highly sensitive to temperature increases associated with climate change because of their narrow thermal tolerances. However, at the ecosystem scale the competing effects of temperature, light and precipitation on tropical forest productivity have been difficult to assess. Here we quantify cloudiness over the past several decades to...
Show moreTropical forests are incredibly dynamic, showing rapid and longer-term changes in growth, mortality and net primary productivity. Tropical species may be highly sensitive to temperature increases associated with climate change because of their narrow thermal tolerances. However, at the ecosystem scale the competing effects of temperature, light and precipitation on tropical forest productivity have been difficult to assess. Here we quantify cloudiness over the past several decades to investigate how clouds, together with temperature and precipitation, affect flower production in two contrasting tropical forests. Our results show that temperature, rather than clouds, is critically important to tropical forest flower production. Warmer temperatures increased flower production over seasonal, interannual and longer timescales, contrary to recent evidence that some tropical forests are already near their temperature threshold. Clouds were primarily important seasonally, and limited production in a seasonally dry forest but enhanced production in an ever-wet forest. A long-term increase in flower production at the seasonally dry forest is not driven by clouds and instead may be tied to increasing temperatures. These relationships show that tropical forest productivity, which is not widely thought to be controlled by temperature, is indeed sensitive to small temperature changes (1–4°C) across multiple timescales.
Show less - Date Issued
- 2013
- Identifier
- FSU_migr_geo_faculty_publications-0001, 10.1038/nclimate1934
- Format
- Set of related objects
- Title
- The Combined Risk Of Extreme Tropical Cyclone Winds And Storm Surges Along The Us Gulf Of Mexico Coast.
- Creator
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Trepanier, J. C., Yuan, J., Jagger, T. H.
- Abstract/Description
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Tropical cyclones, with their nearshore high wind speeds and deep storm surges, frequently strike the United States Gulf of Mexico coastline influencing millions of people and disrupting offshore economic activities. The combined risk of occurrence of tropical cyclone nearshore wind speeds and storm surges is assessed at 22 coastal cities throughout the United States Gulf of Mexico. The models used are extreme value copulas fitted with margins defined by the generalized Pareto distribution or...
Show moreTropical cyclones, with their nearshore high wind speeds and deep storm surges, frequently strike the United States Gulf of Mexico coastline influencing millions of people and disrupting offshore economic activities. The combined risk of occurrence of tropical cyclone nearshore wind speeds and storm surges is assessed at 22 coastal cities throughout the United States Gulf of Mexico. The models used are extreme value copulas fitted with margins defined by the generalized Pareto distribution or combinations of Weibull, gamma, lognormal, or normal distributions. The statistical relationships between the nearshore wind speed and storm surge are provided for each coastal city prior to the copula model runs using Spearman's rank correlations. The strongest significant relationship between the nearshore wind speed and storm surge exists at Shell Beach, LA ( = 0.67), followed by South Padre Island, TX ( = 0.64). The extreme value Archimedean copula models for each city then provide return periods for specific nearshore wind speed and storm surge pairs. Of the 22 cities considered, Bay St. Louis, MS, has the shortest return period for a tropical cyclone with at least a 50ms(-1) nearshore wind speed and a 3m surge (19.5years, 17.1-23.5). The 90% confidence intervals are created by recalculating the return periods for a fixed set of wind speeds and surge levels using 100 samples of the model parameters. The results of this study can be utilized by policy managers and government officials concerned with coastal populations and economic activity in the Gulf of Mexico. Synopsis Using a branch of extreme statistics, the combined risk of tropical cyclone wind speeds and storm surges is estimated at 22 cities along the U.S. Gulf of Mexico coastline in Texas, Louisiana, Mississippi, Alabama, and Florida. The city with the shortest return time for a Category 3 hurricane (50ms(-1)) with a 3m surge is Bay St. Louis, Mississippi. This city can expect a storm of this magnitude every 19years, on average. Shell Beach, Louisiana, has the second highest return frequency for this type of event (about 28years). This information can be used by emergency managers and policy makers to better allocate resources for protective measures against tropical cyclones along the coast.
Show less - Date Issued
- 2017-03-27
- Identifier
- FSU_libsubv1_wos_000399655200008, 10.1002/2016JD026180
- Format
- Citation
- Title
- Daily Tornado Frequency Distributions in the United States.
- Creator
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Elsner, James, Widen, Holly, Chavas, Daniel, Jagger, Thomas
- Abstract/Description
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The authors examine daily tornado counts in the United States over the period 1994–2012 and find strong evidence for a power-law relationship in the distribution frequency. The scaling exponent is estimated at 1.64 (0.019 s.e.) giving a per tornado-day probability of 0.014% (return period of 71 years) that a tornado day produces 145 tornadoes as was observed on 27 April 2011. They also find that the total number of tornadoes by damage category on days with at least one violent tornado follows...
Show moreThe authors examine daily tornado counts in the United States over the period 1994–2012 and find strong evidence for a power-law relationship in the distribution frequency. The scaling exponent is estimated at 1.64 (0.019 s.e.) giving a per tornado-day probability of 0.014% (return period of 71 years) that a tornado day produces 145 tornadoes as was observed on 27 April 2011. They also find that the total number of tornadoes by damage category on days with at least one violent tornado follows an exponential rule. On average, the daily number of tornadoes in the next lowest damage category is approximately twice the number in the current category. These findings are important and timely for tornado hazard models and for seasonal and sub-seasonal forecasts of tornado activity.
Show less - Date Issued
- 2014-02-27
- Identifier
- FSU_libsubv1_scholarship_submission_1475085241, 10.1088/1748-9326/9/2/024018
- Format
- Citation
- Title
- Population And Energy Elasticity Of Tornado Casualties.
- Creator
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Fricker, Tyler, Elsner, James B., Jagger, Thomas H.
- Abstract/Description
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Tornadoes are capable of catastrophic destruction and mass casualties, but there are yet no estimates of how sensitive the number of casualties are to changes in the number of people in harm's way or to changes in tornado energy. Here the relationship between tornado casualties (deaths and injuries), population, and energy dissipation is quantified using the economic concept of elasticity. Records of casualties from individual tornadoes over the period 2007-2015 are fit to a regression model....
Show moreTornadoes are capable of catastrophic destruction and mass casualties, but there are yet no estimates of how sensitive the number of casualties are to changes in the number of people in harm's way or to changes in tornado energy. Here the relationship between tornado casualties (deaths and injuries), population, and energy dissipation is quantified using the economic concept of elasticity. Records of casualties from individual tornadoes over the period 2007-2015 are fit to a regression model. The coefficient on the population term (population elasticity) indicates that a doubling in population increases the casualty rate by 21% [(17, 24)%, 95% credible interval]. The coefficient on the energy term (energy elasticity) indicates that a doubling in energy dissipation leads to a 33% [(30, 35)%, 95% credible interval] increase in the casualty rate. The difference in elasticity values show that on average, changes in energy dissipation have been relatively more important in explaining tornado casualties than changes in population. Assuming no changes in warning effectiveness or mitigation efforts, these elasticity estimates can be used to project changes in casualties given the known population trends and possible trends in tornado activity.
Show less - Date Issued
- 2017-04-28
- Identifier
- FSU_libsubv1_wos_000401847500058, 10.1002/2017GL073093
- Format
- Citation
- Title
- Quantifying the sensitivity of maximum, limiting, and potential tropical cyclone intensity to SST: Observations versus the FSU/COAPS global climate model.
- Creator
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Strazzo, Sarah, Elsner, James B., Larow, Tim
- Abstract/Description
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Previous research quantified the sensitivity of limiting intensity to SST for observed tropical cyclones (TCs) and for TCs generated by two global climate models (GCMs). On average, a 1° C increase in sea surface temperature (SST) is associated with a 7.9 m s−1 increase in the statistical upper limit of observed intensity. Conversely, a 1°C increase in SST does not significantly affect the limiting intensity of GCM-generated TCs. The study presented here builds on previous research in two...
Show morePrevious research quantified the sensitivity of limiting intensity to SST for observed tropical cyclones (TCs) and for TCs generated by two global climate models (GCMs). On average, a 1° C increase in sea surface temperature (SST) is associated with a 7.9 m s−1 increase in the statistical upper limit of observed intensity. Conversely, a 1°C increase in SST does not significantly affect the limiting intensity of GCM-generated TCs. The study presented here builds on previous research in two ways: (1) A comparison is made between the statistically defined limiting intensity and the physically defined potential intensity, and (2) a test is performed on the ability of a ∼0.94° resolution GCM to reproduce the observed statistical relationship between potential intensity and SST. Data from NASA's Modern Era Reanalysis are used to approximate the observed sensitivity of potential intensity to SST for the 1982-2008 time period. Results indicate that the sensitivity of potential intensity to SST is not statistically different from the sensitivity of observed maximum or limiting intensity to SST. This result links the statistically defined sensitivity to the physically based theory of hurricanes. Potential intensity is also estimated from the FSU/COAPS GCM. Although the FSU/COAPS model does not capture the observed sensitivity of TC maximum or limiting intensity to SST, the model reproduces the observed sensitivity of potential intensity to SST. The model generates suitable atmospheric conditions for the development of strong TCs, however strong TCs do not develop, possibly as a result of insufficient resolution. [ABSTRACT FROM AUTHOR]
Show less - Date Issued
- 2015-04-23
- Identifier
- FSU_libsubv1_scholarship_submission_1474986340, 10.1002/2015MS000432
- Format
- Citation
- Title
- The Relationship between Elevation Roughness and Tornado Activity: A Spatial Statistical Model Fit to Data from the Central Great Plains.
- Creator
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Elsner, James B., Fricker, Tyler, Widen, Holly M., Castillo, Carla M., Humphreys, John, Jung, Jihoon, Rahman, Shoumik, Richard, Amanda, Jagger, Thomas H., Bhatrasataponkul,...
Show moreElsner, James B., Fricker, Tyler, Widen, Holly M., Castillo, Carla M., Humphreys, John, Jung, Jihoon, Rahman, Shoumik, Richard, Amanda, Jagger, Thomas H., Bhatrasataponkul, Tachanat, Gredzens, Christian, Dixon, P. Grady
Show less - Abstract/Description
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The statistical relationship between elevation roughness and tornado activity is quantified using a spatial model that controls for the effect of population on the availability of reports. Across a large portion of the central Great Plains the model shows that areas with uniform elevation tend to have more tornadoes on average than areas with variable elevation. The effect amounts to a 2.3% [(1.6%, 3.0%) = 95% credible interval] increase in the rate of a tornado occurrence per meter of...
Show moreThe statistical relationship between elevation roughness and tornado activity is quantified using a spatial model that controls for the effect of population on the availability of reports. Across a large portion of the central Great Plains the model shows that areas with uniform elevation tend to have more tornadoes on average than areas with variable elevation. The effect amounts to a 2.3% [(1.6%, 3.0%) = 95% credible interval] increase in the rate of a tornado occurrence per meter of decrease in elevation roughness, defined as the highest minus the lowest elevation locally. The effect remains unchanged if the model is fit to the data starting with the year 1995. The effect strengthens for the set of intense tornadoes and is stronger using an alternative definition of roughness. The elevation-roughness effect appears to be strongest over Kansas, but it is statistically significant over a broad domain that extends from Texas to South Dakota. The research is important for developing a local climatological description of tornado occurrence rates across the tornado-prone region of the Great Plains.
Show less - Date Issued
- 2016-04
- Identifier
- FSU_libsubv1_wos_000372839700002, 10.1175/JAMC-D-15-0225.1
- Format
- Citation
- Title
- Remote sensing of dominant species for quantifying ecosystem services.
- Creator
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Pau, Stephanie, Dee, Laura E.
- Abstract/Description
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Remote sensing (RS) is a powerful tool to measure and monitor Essential Biodiversity Variables (EBVs) and their environmental drivers. Despite this potential, stronger integration between remote sensing experts and the ecological community could better support biodiversity initiatives. Here we highlight opportunities to harness remote sensing technology to better understand biodiversity patterns, ecological processes and the consequences for ecosystem services (ESs). We argue that tracking...
Show moreRemote sensing (RS) is a powerful tool to measure and monitor Essential Biodiversity Variables (EBVs) and their environmental drivers. Despite this potential, stronger integration between remote sensing experts and the ecological community could better support biodiversity initiatives. Here we highlight opportunities to harness remote sensing technology to better understand biodiversity patterns, ecological processes and the consequences for ecosystem services (ESs). We argue that tracking many EBVs using remote sensing should prioritize the monitoring of dominant species, a scalable property across multiple EBV classes, for several reasons. First, a few dominant species in an ecological community disproportionately contribute to the satellite spectral signature. Second, a focus on dominance would enable a stronger links to ecological research, as dominance reflects the ecological community context (i.e. relative abundance of coexisting species). For example dominant species should be especially important contributors to many ecosystem functions and services that rely on abundance or biomass, such as carbon storage or nutrient cycling, because of their greater representation in a community. Furthermore, global change impacts on communities may be reflected in changing dominance structure before the losses of species, thus tracking dominance provides an early-warning sign of community change for EBVs. Finally, focusing on dominant species should improve understanding of spatial and temporal dynamics of dominance-driven ESs through RS mapping. Given the importance of dominant species to ecological communities and ESs, monitoring dominance under changing environmental conditions and human impacts should be a global priority.
Show less - Date Issued
- 2016-08-02
- Identifier
- FSU_libsubv1_scholarship_submission_1518816337_47def662, 10.1002/rse2.23
- Format
- Citation
- Title
- Root Functional Diversity Of Native And Nonnative C-3 And C-4 Grass Species In Hawai'i.
- Creator
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Angelo, Courtney L., Pau, Stephanie
- Abstract/Description
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C-3 and C-4 plants are often reported to differ in functional traits and resource-use strategies, whereas nonnative plants may differ from native plants in functional traits, leading to different resource-use strategies that facilitate their invasion. In this study, we compared root functional traits of native and nonnative C-3 and C-4 grasses with the prediction that different resource acquisition strategies would be observed among these groups. We examined five root functional traits [mean...
Show moreC-3 and C-4 plants are often reported to differ in functional traits and resource-use strategies, whereas nonnative plants may differ from native plants in functional traits, leading to different resource-use strategies that facilitate their invasion. In this study, we compared root functional traits of native and nonnative C-3 and C-4 grasses with the prediction that different resource acquisition strategies would be observed among these groups. We examined five root functional traits [mean diameter, specific root length, root tissue density, fine root percentage (diameter <0.2 mm), and root length density] among natural communities of C-3 and C-4 grass species along an elevation gradient in Hawai'i to classify resource-use strategies. We also examined how root functional traits were related to environmental characteristics (mean annual, seasonal, and July soil moisture; mean annual precipitation and temperature; and soil nitrogen percentage) along this elevation gradient. Root traits corresponded broadly to differences in photosynthetic pathway [C-3 versus C-4 (P < .05)]. However, significant variation occurred within the C-3 functional group (P < .05), whereas all C-4 species had similar root functional traits. Grass assemblages were associated with differences in seasonal soil moisture, but root traits did not sort consistently along any environmental gradient. Principal component and cluster analyses of root functional traits showed that nonnative C-3 species tended to be resource acquisitive whereas the native C-3 species was resource conservative, similar to native and nonnative C-4 species. Evaluating functional traits of native versus nonnative species will provide a better understanding of invasion dynamics and suggest possible restoration and conservation strategies in grassland communities where native species still persist.
Show less - Date Issued
- 2017-04
- Identifier
- FSU_libsubv1_wos_000399267300002, 10.2984/71.2.2
- Format
- Citation
- Title
- Spatial Variation In The Quality Of American Community Survey Estimates.
- Creator
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Folch, David C., Arribas-Bel, Daniel, Koschinsky, Julia, Spielman, Seth E.
- Abstract/Description
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Social science research, public and private sector decisions, and allocations of federal resources often rely on data from the American Community Survey (ACS). However, this critical data source has high uncertainty in some of its most frequently used estimates. Using 2006-2010 ACS median household income estimates at the census tract scale as a test case, we explore spatial and nonspatial patterns in ACS estimate quality. We find that spatial patterns of uncertainty in the northern United...
Show moreSocial science research, public and private sector decisions, and allocations of federal resources often rely on data from the American Community Survey (ACS). However, this critical data source has high uncertainty in some of its most frequently used estimates. Using 2006-2010 ACS median household income estimates at the census tract scale as a test case, we explore spatial and nonspatial patterns in ACS estimate quality. We find that spatial patterns of uncertainty in the northern United States differ from those in the southern United States, and they are also different in suburbs than in urban cores. In both cases, uncertainty is lower in the former than the latter. In addition, uncertainty is higher in areas with lower incomes. We use a series of multivariate spatial regression models to describe the patterns of association between uncertainty in estimates and economic, demographic, and geographic factors, controlling for the number of responses. We find that these demographic and geographic patterns in estimate quality persist even after we account for the number of responses. Our results indicate that data quality varies across places, making cross-sectional analysis both within and across regions less reliable. Finally, we present advice for data users and potential solutions to the challenges identified.
Show less - Date Issued
- 2016-10
- Identifier
- FSU_libsubv1_wos_000385144600012, 10.1007/s13524-016-0499-1
- Format
- Citation
- Title
- The Relationship between Elevation Roughness and Tornado Activity.
- Creator
-
Elsner, James B., Fricker, Tyler, Widen, Holly M., Castillo, Carla M., Humphreys, John, Jung, Jihoon, Rahman, Shoumik, Richard, Amanda, Jagger, Thomas H., Bhatrasataponkul,...
Show moreElsner, James B., Fricker, Tyler, Widen, Holly M., Castillo, Carla M., Humphreys, John, Jung, Jihoon, Rahman, Shoumik, Richard, Amanda, Jagger, Thomas H., Bhatrasataponkul, Tachanat, Gredzens, Christian, Dixon, P. Grady
Show less - Abstract/Description
-
The statistical relationship between elevation roughness and tornado activity is quantified using a spatial model that controls for the effect of population on the availability of reports. Across a large portion of the central Great Plains the model shows that areas with uniform elevation tend to have more tornadoes on average than areas with variable elevation. The effect amounts to a 2.3% [(1.6%, 3.0%) = 95% credible interval] increase in the rate of a tornado occurrence per meter of...
Show moreThe statistical relationship between elevation roughness and tornado activity is quantified using a spatial model that controls for the effect of population on the availability of reports. Across a large portion of the central Great Plains the model shows that areas with uniform elevation tend to have more tornadoes on average than areas with variable elevation. The effect amounts to a 2.3% [(1.6%, 3.0%) = 95% credible interval] increase in the rate of a tornado occurrence per meter of decrease in elevation roughness, defined as the highest minus the lowest elevation locally. The effect remains unchanged if the model is fit to the data starting with the year 1995. The effect strengthens for the set of intense tornadoes and is stronger using an alternative definition of roughness. The elevation-roughness effect appears to be strongest over Kansas, but it is statistically significant over a broad domain that extends from Texas to South Dakota. The research is important for developing a local climatological description of tornado occurrence rates across the tornado-prone region of the Great Plains.
Show less - Date Issued
- 2016-04
- Identifier
- FSU_libsubv1_wos_000372839700002, 10.1175/JAMC-D-15-0225.1
- Format
- Citation
- Title
- Tornado Intensity Estimated from Damage Path Dimensions.
- Creator
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Elsner, James, Jagger, Thomas
- Abstract/Description
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The Newcastle/Moore and El Reno tornadoes of May 2013 are recent reminders of the destructive power of tornadoes. A direct estimate of a tornado's power is difficult and dangerous to get. An indirect estimate on a categorical scale is available from a post-storm survery of the damage. Wind speed bounds are attached to the scale, but the scale is not adequate for analyzing trends in tornado intensity separate from trends in tornado frequency. Here tornado intensity on a continuum is estimated...
Show moreThe Newcastle/Moore and El Reno tornadoes of May 2013 are recent reminders of the destructive power of tornadoes. A direct estimate of a tornado's power is difficult and dangerous to get. An indirect estimate on a categorical scale is available from a post-storm survery of the damage. Wind speed bounds are attached to the scale, but the scale is not adequate for analyzing trends in tornado intensity separate from trends in tornado frequency. Here tornado intensity on a continuum is estimated from damage path length and width, which are measured on continuous scales and correlated to the EF rating. The wind speeds on the EF scale are treated as interval censored data and regressed onto the path dimensions and fatalities. The regression model indicates a 25% increase in expected intensity over a threshold intensity of 29 m s−1 for a 100 km increase in path length and a 17% increase in expected intensity for a one km increase in path width. The model shows a 43% increase in the expected intensity when fatalities are observed controlling for path dimensions. The estimated wind speeds correlate at a level of .77 (.34, .93) [95% confidence interval] with a small sample of wind speeds estimated independently from a doppler radar calibration. The estimated wind speeds allow analyses to be done on the tornado database that are not possible with the categorical scale. The modeled intensities can be used in climatology and in environmental and engineering applications. Research is needed to understand the upward trends in path length and width.
Show less - Date Issued
- 2014-09-17
- Identifier
- FSU_libsubv1_scholarship_submission_1475155297, 10.1371/journal.pone.0107571
- Format
- Citation
