Corene J. Matyas

Effects of Extreme Climate Events on Tea (Camellia sinensis) Functional Quality Validate Indigenous Farmer Knowledge and Sensory Preferences in Tropical China

Climate change is impacting agro-ecosystems, crops, and farmer livelihoods in communities worldwide. While it is well understood that more frequent and intense climate events in many areas are resulting in a decline in crop yields, the impact on crop quality is less acknowledged, yet it is critical for food systems that benefit both farmers and consumers through high-quality products. This study examines tea (Camellia sinensis; Theaceae), the worlds most widely consumed beverage after water, as a study system to measure effects of seasonal precipitation variability on crop functional quality and associated farmer knowledge, preferences, and livelihoods. Sampling was conducted in a major tea producing area of China during an extreme drought through the onset of the East Asian Monsoon in order to capture effects of extreme climate events that are likely to become more frequent with climate change. Compared to the spring drought, tea growth during the monsoon period was up to 50% higher. Concurrently, concentrations of catechin and methylxanthine secondary metabolites, major compounds that determine tea functional quality, were up to 50% lower during the monsoon while total phenolic concentrations and antioxidant activity increased. The inverse relationship between tea growth and concentrations of individual secondary metabolites suggests a dilution effect of precipitation on tea quality. The decrease in concentrations of tea secondary metabolites was accompanied by reduced farmer preference on the basis of sensory characteristics as well as a decline of up to 50% in household income from tea sales. Farmer surveys indicate a high degree of agreement regarding climate patterns and the effects of precipitation on tea yields and quality. Extrapolating findings from this seasonal study to long-term climate scenario projections suggests that farmers and consumers face variable implications with forecasted precipitation scenarios and calls for research on management practices to facilitate climate adaptation for sustainable crop production.

Quantifying the Shapes of U.S. Landfalling Tropical Cyclone Rain Shields

Abstract Tropical cyclones (TCs) produce complex rainfall patterns that are difficult to predict due to atmospheric and land surface forcings. This study utilizes geographic information systems to spatially analyze radar returns and calculate several metrics that quantify the shapes of TC rain shields. Three stepwise discriminant analyses are performed to determine which of the shape metrics distinguish among TCs categorized by: intensity, distance traveled inland, and orientation of terrain encountered. Results confirm that TC rain shields often assume noncircular shapes. Utilizing shape indices to model rain shields could help produce TC rainfall forecasts that are more spatially accurate.

Cognitive and affective responses of Florida tourists after exposure to hurricane warning messages

Tourists are particularly vulnerable to natural disasters such as hurricanes since they might be less informed and prepared than residents of disaster-prone areas. Thus, understanding how the traits of a tropical cyclone as well as specific characteristics of tourists influence affective and cognitive responses to a hurricane warning message is a critical component in disaster planning. Using scenarios that presented tropical cyclones with different relevant characteristics (such as category at landfall), tourists’ knowledge, experience with hurricanes, trip traits, and the location of the survey (coastal or inland), this study contributes to the literature on sociological issues related to natural disasters. The findings suggest that risk perceptions and fear are influenced differently by the traits of the hurricanes and tourists’ knowledge and experience. Risk is strongly influenced by the projected category of the hurricane at landfall, while fear is not as sensitive to this extremely relevant trait of cyclones. The results also suggest that the influence of risk and fear on evacuation likelihood is strong and positive. This study shows the value of studying cognitive and affective responses to uncertain events.

A Spatial Analysis of Radar Reflectivity Regions within Hurricane Charley (2004)

Regions of 35-dBZ radar reflectivity returns are examined within a landfalling hurricane to determine whether these regions are composed of stratiform, convective, or transition-type precipitation. After calculating spatial attributes of the reflectivity regions such as elongation and edge roughness within a GIS, discriminant analysis is performed to determine whether the 35-dBZ regions are more similar to 40-dBZ regions of convective precipitation or to 30-dBZ regions of stratiform precipitation. Results show that within the outer region rainbands of Hurricane Charley (2004) a sharp horizontal reflectivity gradient exists, indicating that 35-dBZ regions are similar in shape to adjacent convective regions of 40-dBZ reflectivity values. Within the interior region, the 35-dBZ regions are identified as transition regions similar to those found within mesoscale convective complexes rather than being strictly stratiform or convective in nature. The rain rates produced by the reflectivity regions are examined using rain gauge and radar estimates. In 32% of cases, the 35-dBZ regions produced rain rates in excess of 10 mm h 21 , exceeding both the radarestimatedrain rates and the 8.4 mm h 21 rain rate ascribedto 35-dBZregionsby the tropicalZ–Rrelationship. Thus, 35-dBZ regions surrounding the convective cores of additional landfalling TCs should be examined to determine whether they also represent transition-type rainfall regions capable of producing convective rainfall rates exceeding 10 mm h 21 .

Tropical cyclones in the North American Regional Reanalysis: An assessment of spatial biases in location, intensity, and structure

Long-term reanalysis data sets, such as the North American Regional Reanalysis (NARR) and Climate Forecast System Reanalysis (CFSR), are data-rich resources for weather and climate research. However, investigations into tropical cyclone (TC) structures are lacking. This study examines position, intensity, and structure of U.S. landfalling TCs in these data sets during 1998–2012. TC positions are determined using three dynamic and thermodynamic parameters. In NARR, positions are problematic near the domain boundary but show statistically significant improvements compared with CFSR in regions over the U.S. and near its coastlines. TC intensity is universally underestimated in both data sets, yet the pressure-wind relationship is reasonably maintained. NARR and CFSR intensities are highly correlated (r = 0.93), suggesting that these data sets are limited in a similar fashion in their generation of intensity and that advanced data assimilation techniques are unable to overcome the shortcomings of low resolutions. To investigate TC structure, a 10-storm composite is constructed using the most intense model TCs at peak intensity. Both models develop robust warm cores (T′ ~ 6–7 K), but the radius of maximum winds (>100 km) is too broad compared with storms in nature. Secondary circulation features in NARR are more realistic, particularly the shallow inflow layer, vertical motion in the inner core, and confined outflow in the upper troposphere. Results indicate that, over the U.S. and near its coastline, NARR positions and structure are competitive with or slightly improved upon CFSR. Away from the domain boundary, NARR is a suitable resource for evaluating TC positions and certain aspects of the secondary circulation.

Comparing the Rainfall Patterns Produced by Hurricanes Frances (2004) and Jeanne (2004) over Florida

During 2004, Hurricanes Frances and Jeanne produced heavy rainfall across Florida. Although making landfall at the same location and moving along similar tracks, these storms produced different rainfall patterns. We employ a GIS to analyze rain gauge and radar-estimated rainfall data spatially, and we determine which physical mechanisms caused the asymmetrical rain swaths produced by each storm. We find that due to a moist environment and weakening vertical wind shear, the rain fields of Frances covered a large area. Strong convection in several outer rainbands and slow forward velocity yielded high rainfall totals. Although Jeanne contained more convective rainfall than Frances, vertical wind shear, a faster forward velocity, and existence within a relatively dry environment caused rainfall totals to be lower. The techniques employed in this study could be applied to a larger number of landfalling tropical cyclones to better understand where high rain totals occur under different combinations of environmental conditions.

Extreme weather and economic well-being in rural Mozambique

Societies dependent on rain-fed agriculture are highly vulnerable to weather extremes; thus, linkages between rainfall variability and economic well-being merit close attention. The hypothesis of this paper is that rainfall patterns impact changes in income within our study region of central and northern Mozambique. Utilizing satellite-based estimates of rainfall analyzed within a GIS, we establish a 12-year rainfall climatology and calculate monthly rainfall anomalies for 419 villages during three growing seasons. We also approximate storm-total rainfall from tropical cyclones entering the Mozambique Channel. Hierarchical cluster analysis groups the villages according to the monthly rainfall anomalies and rainfall received from Cyclones Delfina and Japhet. Then, using data from the National Agricultural Survey of Mozambique conducted in 2002 and 2005, we relate rainfall and change in income through the calculation of Pearson’s correlation coefficients and independent-samples t tests using village-groups produced by the cluster analysis. We find that no season closely approximates the 12-year climatology and that rainfall varied among the three seasons. Although most villages experience income declines, those affected by Delfina exhibit the worst economic performance, indicating that heavy rainfall from some tropical cyclones can have long-lasting negative effects on income. Additionally, receiving above-normal rainfall may hinder economic well-being more than below-normal rainfall. Our study identifies patterns in sub-national rainfall variability and economic well-being that enable a more detailed understanding of weather-related effects on socio-economic outcomes.

Conditions associated with large rain-field areas for tropical cyclones landfalling over Florida

To adequately warn the public about the potential for heavy rainfall, it is important to understand the conditions associated with large rain fields as tropical cyclones (TCs) move over land. This study examines rain-field areas during 29 landfalls over Florida utilizing data from the Tropical Rainfall Measuring Mission’s 3B42 product. A GIS was used to calculate the areas of regions delineated by 5 mm h−1 rain rates occurring within 48 h pre- or post-landfall. Thirteen conditions were evaluated, including intensity, motion, vertical wind shear, cause of demise, month, and time of day. After dividing observations into groups for each condition, Mann–Whitney U and Kruskal–Wallis tests determined that statistically significant differences existed among the groups for 11 conditions. The largest rain fields belonged to TCs that occurred in October or November, followed by those that were hurricanes and/or were intensifying at landfall. TCs nearing the end of an extratropical transition as well as those observed at 1100 Eastern Daylight Time also had relatively large areas of moderate-to-high rain rates. TCs meeting these conditions should be monitored closely as they move towards and over Florida due to their potential for widespread moderate-to-heavy rainfall, which may begin prior to the arrival of the fastest winds.

A Geospatial Analysis of Convective Rainfall Regions Within Tropical Cyclones After Landfall

In this article, the author utilizes a GIS to spatially analyze radar reflectivity returns during the 24 hours following 43 tropical cyclone (TC) landfalls. The positions of convective rainfall regions and their areal extent are then examined according to storm intensity, motion, vertical wind shear, time until extratropical transition, time after landfall, and distance from the coastline. As forward velocity increases in conjunction with an extratropical transition, these regions move outward, shift from the right side to the front of the TC, and grow in size. A similar radial shift, but with a decrease in areal extent, occurs as TCs weaken. Further quantification of the shapes of these regions could yield a more spatially accurate assessment of where TCs may produce high rainfall totals.

A Shape Metric Methodology for Studying the Evolving Geometries of Synoptic-Scale Precipitation Patterns in Tropical Cyclones

A tropical cyclone (TC) is a cyclonic weather system with compact, centrally organized precipitation. As a TC transitions from a symmetric warm-core cyclone to an extratropical system, or as the TC dissipates, the weather system loses its characteristic central, symmetric qualities. In this article, we demonstrate a shape metric methodology that can be used to assess the overall evolution of and the spatiotemporal positions of significant changes to synoptic-scale precipitation structure. We first illustrate this methodology using three-hourly North American Regional Reanalysis (NARR) accumulated precipitation in Hurricane Katrina (2005) and then extend the analysis to all 2004 to 2015 U.S. landfalling TCs. To quantify the shape of the precipitation pattern, we construct a binary image by limiting the search radius to a distance of 600 km from the TC center and applying a minimum threshold based on the 90th percentile of precipitation observed within the search radius. Using the fundamental geographic concept of compactness, we formulate a suite of shape metrics that encompass the characteristic geometries of TCs moving into the midlatitudes: asymmetry, fragmentation, and dispersiveness. As we demonstrate with Hurricane Katrina, a moving Mann–Whitney U test reveals significant shape changes during the TC life cycle. These evolutionary periods correspond to structural changes observed by National Hurricane Center forecasters. Extending the analysis to all 2004 to 2015 storms, we observe increasing (decreasing) compactness in the eastern and central (western) Gulf of Mexico. Dispersiveness increases prior to landfall in most cases; however, asymmetry and fragmentation increase more commonly in western (vs. eastern) Gulf landfalls.