Hurricanes

Soundscape ecology is an emerging field in both terrestrial and aquatic ecosystems, and provides a powerful approach for assessing habitat quality and the ecological response of sound-producing species to natural and anthropogenic perturbations. Little is known of how underwater soundscapes respond during and after severe episodic disturbances, such as hurricanes. This study addresses the impacts of Hurricane Irma on the coral reef sounds-cape at two spur-and-groove fore-reef sites within the Florida Keys USA, using passive acoustic data collected before and during the storm at Western Dry Rocks (WDR) and before, during and after the storm at Eastern Sambo (ESB). As the storm passed, the cumulative acoustic exposure near the seabed at these sites was comparable to a small vessel operating continuously overhead for 1-2 weeks. Before the storm, sound pressure levels (SPLs) showed a distinct pattern of low frequency diel variation and increased high frequency sound during crepuscular periods. The low frequency band was partitioned in two groups representative of soniferous reef fish, whereas the high frequency band represented snapping shrimp sound production. Daily daytime patterns in low-frequency sound production largely persisted in the weeks following the hurricane. Crepuscular sound production by snapping shrimp was maintained post-hurricane with only a small shift (~1.5dB) in the level of daytime vs nighttime sound production for this high frequency band. This study suggests that on short time scales, temporal patterns in the coral reef soundscape were relatively resilient to acoustic energy exposure during the storm, as well as changes in the benthic habitat and environmental conditions resulting from hurricane damage.

Hurricane Sandy was exceptional in many ways – its rare track, its extratropical transition just prior to landfall and associated late secondary intensification, and the extensive damage it caused to a major coastal metropolitan area from both storm surge and wind. Fortuitously, understanding the fine structure of this storm during its landfall on New Jersey is aided considerably by two key resources: (1) the pair of resilient mesonets, the New Jersey Weather and Climate Network and the Delaware Environmental Observing System, that continued to log surface observations throughout the storm and (2) a 500 meter resolution, 4 billion grid point, Weather Research and Forecasting (WRF) simulation that was run on the Cray XE6 “Blue Waters” at the National Center for Supercomputing Applications (NCSA).

The 96 hour WRF simulation (Johnsen et al. 2013) was initialized at 12Z on October 26, 2012 and 224 Gigabytes of output were archived every half-hour for a total of 43 Terabytes. During 36 hours spanning landfall time of 00Z on October 30, WRF winds representing 10 meter elevations were compared with winds observed by New Jersey (njweather.org) and Delaware (deos.udel.edu) mesonets and on nearby ASOS stations and marine platforms. Other data, such as WSR-88D radar, rawinsonde soundings, satellite imagery and reconnaissance flight observations, were studied along with prior simulations (Galarneau et al. 2013) to gain insights regarding the low-level 3-D wind field structure.

Until near landfall time, the simulation’s storm center track and timing are exceptionally accurate, especially in view of its initialization time at 84 hours before landfall. By two hours before landfall the simulation begins to turn the storm center slightly left of the actual track and by an hour after landfall its translation speed slows considerably compared to observations. On average, WRF wind speeds are 2% lower than measured on ocean buoys and 35-45% higher than measured at land stations, whose wind speeds were adjusted for anemometer heights but not for land surface roughness.

Although WRF wind fields exhibit exceptionally detailed mesoscale features over water, finer scale wind field structures are much less obvious over land. Similarly, WRF wind speed time series for almost all land-based stations exhibit a rather mundane rise and fall during Sandy’s traversal of New Jersey, while the mesonet time series are much more feature-rich on the time scale of hours. These land-water differences along with WRF wind speeds that are 35-45% higher than measured at land stations might be attributed to limitations of WRF’s boundary layer parameterization scheme for this region’s terrain. The latter will be investigated further, possibly by using a large eddy simulation (LES) boundary layer scheme.

Together, the fine-resolution observations and WRF simulation enabled the identification and investigation of storm structures that may have contributed to the wind speed characteristics observed across the landfall region. These structures include low level jets, warm and cool surface air surges, and roll vortices. This experience exemplifies the value of the 500 meter resolution WRF simulation in interpreting and understanding the range of features that are exhibited in the mesonet and supplementary observations.

China has relied on seawalls for storm protection along its coasts for decades. In contrast, the storm protection functions of coastal wetlands are often ignored by decision makers in China. We examined 127 historical storms with consequent economic loss to China from 1989 to 2016 and estimated the value of coastal wetlands with controlling for seawalls for storm protection. A regression model with the natural log of damage per unit gross domestic product in the storm swath as the dependent variable and explanatory variables including the length of existing seawalls in the storm swath and the natural logs of wind speed, storm duration and wetland area in the storm swath was highly significant and explained 59.2% of the variation in relative damages. Results show that a gain of 1 km 2 of wetlands corresponds to an average CNY 83.90 million (median = CNY 11.87 million) decrease in storm damage from specific storms. Coastal wetlands are gifts of nature and self-maintaining so they have zero construction and maintenance costs. They also provide many other valuable ecosystem services that hard sea-walls do not.

Some years ago, Matt Visser asked the following interesting questions: How much of modern cosmology is really cosmography? How much of modern cosmology is independent of the Einstein equations? (Independent of the Friedmann equations?) These questions are becoming increasingly germane — as the models cosmologists use for the stress-energy content of the universe become increasingly baroque. Therefore, in this paper we will discuss a novel Newtonian cosmology model with vortex, which offers wide implications from solar system, galaxy modeling up to large scale structures of the Universe. The basic starting point is very simple: It has been known for long time that most of the existing cosmology models have singularity problem. Cosmological singularity has been a consequence of excessive symmetry of flow, such as "Hubble's law." More realistic one is suggested, based on Newtonian cosmology model but here we include the vortical-rotational effect of the whole Universe. We review an Ermakov-type equation obtained by Nurgaliev, and solve the equation numerically with Mathematica. A potential application is also considered, namely for understanding tornado dynamics using 3D Navier-Stokes equations. It is our hope that the new proposed method can be verified with observations, in order to open new possibilities of more realistic nonlinear cosmology models.