Increasing tropical cyclone intensity and potential intensity in the subtropical Atlantic around Bermuda from an ocean heat content perspective 1955- 2019

We investigate tropical cyclone (TC) activity and intensity within a 100km radius of Bermuda between 1955 and 2019. The results show a more easterly genesis over time and significant increasing trends in tropical cyclone intensity (maximum wind speed (Vmax)) with a decadal Vmax median value increase of 30kts from 33 to 63kts (r=0.94, p=0.02), together with significant increasing August, September, October (ASO) sea surface temperature (SST) of 1.1°C (0.17°C per decade) r= 0.4 (p<0.01) and increasing average ocean temperature between 0.5–0.7°C (0.08-0.1°C per decade) r=0.3(p<0.01) in the depth range 0-300m. The strongest correlation is found between TC intensity and ocean temperature averaged through the top 50m ocean layer (T50m ) r=0.37 (p<0.01). We show how tropical cyclone potential intensity estimates are closer to actual intensity by using T50m as opposed to SST using the Bermuda Atlantic Timeseries Hydrostation S dataset. We modify the widely used sea surface temperature potential intensity index by using T50m to provide a closer estimate of the observed minimum sea level pressure (MSLP), and associated Vmax than by using SST, creating a T50m potential intensity (T50m_PI) index. The average MSLP difference is reduced by 12mb and proportional (r=0.74, p<0.01) to the SST/(T50m ) temperature difference. We also suggest the index could be used over a wider area of the subtropical/tropical Atlantic where there is a shallow mixed layer depth

Exceptional atmospheric conditions in June 2023 generated a northwest European marine heatwave which contributed to breaking land temperature records

The Northwest European shelf experienced unprecedented surface temperature anomalies in June 2023 (anomalies up to 5 °C locally, north of Ireland). Here, we show the shelf average underwent its longest recorded category II marine heatwave (16 days). With state-of-the-art observation and modelling capabilities, we show the marine heatwave developed quickly due to strong atmospheric forcing (high level of sunshine, weak winds, tropical air) and weak wave activity under anticyclonic weather regimes. Once formed, this shallow marine heatwave fed back on the weather: over the sea it reduced cloud cover and over land it contributed to breaking June mean temperature records and to enhanced convective rainfall through stronger, warmer and moister sea breezes. This marine heatwave was intensified by the last 20-year warming trend in sea surface temperatures. Such sea surface temperatures are projected to become commonplace by the middle of the century under a high greenhouse gas emission scenario

The Recent Atlantic Cold Anomaly: Causes, Consequences, and Related Phenomena

Cold ocean temperature anomalies have been observed in the mid- to high-latitude North Atlantic on interannual to centennial timescales. Most notably, a large region of persistently low surface temperatures accompanied by a sharp reduction in ocean heat content was evident in the subpolar gyre from the winter of 2013-2014 to 2016, and the presence of this feature at a time of pervasive warming elsewhere has stimulated considerable debate. Here, we review the role of air-sea interaction and ocean processes in generating this cold anomaly and place it in a longer-term context. We also discuss the potential impacts of surface temperature anomalies for the atmosphere, including the North Atlantic Oscillation and European heat waves; contrast the behavior of the Atlantic with the extreme warm surface event that occurred in the North Pacific over a similar timescale; and consider the possibility that these events represent a response to a change in atmospheric planetary wave forcing.</p

Recent changes in the North Atlantic circulation simulated with eddy-permitting and eddy-resolving ocean models

Three eddy-permitting (1/4°) versions and one eddy-resolving (1/12°) version of the OCCAM ocean model are used to simulate the World Ocean circulation since 1985. The first eddy-permitting simulation has been used extensively in previous studies, and provides a point of reference. A second, improved, eddy-permitting simulation is forced in the same manner as the eddy-resolving simulation, with a dataset based on a blend of NCEP re-analysis and satellite data. The third eddy-permitting simulation is forced with a different dataset, based on the ERA-40 re-analysis data. Inter-comparison of these simulations in the North Atlantic clarifies the relative importance of resolution and choice of forcing dataset, for simulating the mean state and recent variability of the basin-scale circulation in that region. Differences between the first and second eddy-permitting simulations additionally reveal an erroneous influence of sea ice on surface salinity, dense water formation, and the meridional overturning circulation. Simulations are further evaluated in terms of long-term mean ocean heat transport at selected latitudes (for which hydrographic estimates are available) and sea surface temperature errors (relative to observations). By these criteria, closest agreement with observations is obtained for the eddy-resolving simulation. In this simulation, there is also a weak decadal variation in mid-latitudes, with heat transport strongest, by around 0.2 PW, in the mid-1990s. In two of the eddy-permitting simulations, by contrast, heat transport weakens through the study period, by up to 0.4 PW in mid-latitudes. The most notable changes of heat transport in all simulations are linked to a weakening of the subpolar gyre, rather than changes in the meridional overturning circulation. It is concluded that recent changes in the structure of mid-latitude heat transport in the North Atlantic are more accurately represented if eddies are explicitly resolved.<br/

Climate-induced storminess forces major increases in future storm surge hazard in the South China Sea region

Coastal floods, driven by extreme sea levels, are one of the most dangerous natural hazards. The people at highest risk are those living in low-lying coastal areas exposed to tropical-cyclone-forced storm surges. Here we apply a novel modelling framework to estimate past and/or present and future storm-surge-level and extreme-sea-level probabilities along the coastlines of southern China, Vietnam, Cambodia, Thailand, and Malaysia. A regional hydrodynamic model is configured to simulate 10 000 years of synthetic tropical cyclone activity, representative of a past/present (1980–2017) and high-emission-scenario future (2015–2050) period. Results show that extreme storm surges, and therefore total water levels, will increase substantially in the coming decades, driven by an increase in the frequency of intense tropical cyclones. Storm surges along the southern Chinese and northern and southern Vietnamese coastlines increase by up to 1 m, significantly larger than expected changes in mean sea-level rise over the same period. The length of coastline that is presently exposed to storm surge levels of 2.5 m or greater will more than double by 2050. Sections of Cambodian, Thai, and Malaysian coastlines are projected to experience storm surges (at higher return periods) in the future, not previously seen, due to a southward shift in tropical cyclone tracks. Given these findings, coastal flood management and adaptation in these areas should be reviewed for their resilience against future extreme sea levels

Assessing the Effects of Recent Immigration on Serious Property Crime in Austin, Texas

In this article the authors examine the impact of recent immigration on rates of serious property crime across communities in Austin, Texas. The greater Austin foreign-born population has increased by more than 580 percent since 1980, and Austin is considered a "preemerging" immigrant gateway city to the United States. The changing population dynamics in Austin provide an excellent opportunity to study the effect of recent immigration on crime in a target destination for recent immigrants. Although interest in the relationship between violent crime and immigration to new locales is evidenced by recent studies that show less favorable outcomes for Latinos in new destinations, little attention has been directed to the relationship of recent immigration with serious property crime in new destinations. Negative binomial regression models with corrections for spatial autocorrelation indicate that recent immigration is not associated with an increased rate of burglary, larceny, or motor vehicle theft once important structural predictors of crime are controlled for. © 2013 by Pacific Sociological Association. All rights reserved