Increased Wave Activity Research Articles

Studying infrasound propagation in the middle atmosphere with ICON and UA-ICON: comparison with the IFS and ground-based remote sensing

Infrasound signals are used to monitor various anthropogenic and natural sources. In particular, infrasound is one of the four verification technologies used by the International Monitoring System (IMS) of the Comprehensive Test-Ban Treaty organisation (CTBTO). To determine accurate source locations and energies, an accurate model of wind and temperature up to the lower thermosphere is necessary, hence operational NWP products are of great importance for routine infrasound monitoring activities. However, many of these models focus on tropospheric conditions, and the middle atmosphere (MA) is not well represented. UA-ICON is an upper atmosphere version of the ICON model that provides modelled atmospheric parameters up to 150 km. First, to assess ICON and IFS operational analysis products, comparisons to lidar observations are made. The main differences between both products were analysed with respect to winds and temperatures in the MA. Second, UA-ICON simulations outputs were compared to ICON and IFS fields to demonstrate the increased wave activity above ~30 km with UA-ICON. The added value of UA-ICON with respect to ICON and IFS for infrasound propagation simulations is discussed. The comparisons between the instrumental observations and the models will be presented, as well as comparisons between modelled and measured infrasound propagation.

Identifying and Constraining Marsh-Type Transitions in Response to Increasing Erosion over the Past Century

Marsh environments, characterized by their flora and fauna, change laterally in response to shoreline erosion, water levels and inundation, and anthropogenic activities. The Grand Bay coastal system (USA) has undergone multiple large-scale geomorphic and hydrologic changes resulting in altered sediment supply, depositional patterns, and degraded barrier islands, leaving wetland salt marshes vulnerable to increased wave activity. Two shore-perpendicular transect sites, one along a low-activity shoreline and the other in a high activity area of the same bay-marsh complex, were sampled to investigate how the marshes within 50 m of the modern shoreline have responded to different levels of increased wave activity over the past century. Surface sediments graded finer and more organic with increased distance from the shoreline while cores generally exhibited a coarsening upwards grain-size trend; all cores contained multiple large sedimentological shifts. 210Pb-based mass accumulation rates over the last two decades were greater than the long-term (centurial) average at each site with the fastest accumulation rates of 7.81 ± 1.58 and 7.79 ± 1.63 kg/m2/year at the sites nearest the shoreline. A shoreline change analysis of three time-slices (1848–2017, 1957–2017, 2016–2017) shows increased erosion at both sites since 1848 with modern rates of −0.95 and −0.88 m/year. Downcore sedimentology, mass accumulation rates, and shoreline change rates paired with foraminiferal biofacies and identification of local estuarine indicator species, Paratrochammina simplissima, aided in identifying paleo marsh types, their relative proximity to the shoreline, and sediment provenance. The high-energy marsh site transitioned from middle marsh to low marsh in the 1960s, and the low-energy marsh site transitioned later, at the end of the twentieth and early twenty-first century, due to its more protected location. Marsh type transition corresponds chronologically with the coarsening upwards grain-size trend observed and the degradation of Grand Batture Island; since its submergence, signatures of multiple storm event have been preserved downcore.

Influence of Salinity on the Survival Rate of Fertilized Chum Salmon (Oncorhynchus keta) Eggs

Chum salmon (Oncorhynchus keta) exhibit a remarkable ability to adapt to changes in salinity during their life cycle. However, the fertilized egg stages are sensitive to salinity, affecting ontogeny and hatching. This study investigated the effect of salinity (0, 1, 3, and 5 PSU) on the survival of two developmental stages (<1 day after fertilization and <1 day after the eyed-egg stage) of fertilized eggs. Based on the experimental results, we assessed the spawning ground environment using the in situ salinity data of the Namdae River from 1997 to 2002, where the largest number of salmon in Korea migrate to spawn. Survival of the <1-day-old fertilized eggs decreased sharply at 3 PSU or more, and all eggs died at 5 PSU. Hatching of the eyed-egg stage occurred under all environmental conditions. After 2010, the salinity of the layer of water in contact with the sediment in the lower reaches of the river increased (>6.9 PSU) with the frequency of high waves. Overall, the function of the lower river in spawning and hatching is weakening. This study enhances our understanding of the effects of climate change, including increased wave activity, on salmon spawning grounds.

The Bessarabian (Sarmatian) reef buildup between the village of Tyulenovo and Cape Shabla (Northeastern Bulgaria) as climatic and paleoecological indicator

The Bessarabian (Sarmatian) limestones composed mainly of endemic foraminifera Nubicularia novorossica are studied in detail in three sections between the village of Tyulenovo and Cape Shabla (Northeastern Bulgaria). An important reef buildup found in the upper levels of the sections allows to reconstruct the climatic and paleoenvironmental conditions. The most prominent changes are а shift from subtropical to drier climate and increased wave activity. This led to a decrease in the amount of Nubicularia novorossica and an increase in encrusting organisms such as encrusting nubicularia, bryozoans and red algae, which protected the newly formed sediments from destruction by the strong wave disturbance. The occurrence of less favorable climatic conditions is also evidenced by the presence of microbial micrite masses in the reef limestones.

Effects of Rossby Waves Breaking and Atmospheric Blocking Formation on the Extreme Forest Fire and Floods in Eastern Siberia 2019

In 2019, the southern region of Eastern Siberia (located between 45° N and 60° N) experienced heavy floods, while the northern region (between 60° N and 75° N) saw intense forest fires that lasted for almost the entire summer, from 25 June to 12 August. To investigate the causes of these natural disasters, we analyzed the large-scale features of atmospheric circulation, specifically the Rossby wave breaking and atmospheric blocking events. In the summer of 2019, two types of Rossby wave breaking were observed: a cyclonic type, with a wave breaking over Siberia from the east (110° E–115° E), and an anticyclonic type, with a wave breaking over Siberia from the west (75° E–90° E). The sequence of the Rossby wave breaking and extreme weather events in summer, 2019 are as follows: 24–26 June (cyclonic type, extreme precipitation, flood), 28–29 June and 1–2 July (anticyclonic type, forest fires), 14–17 July (both types of breaking, forest fires), 25–28 July (cyclonic type, extreme precipitation, flood), 2 and 7 August (anticyclonic type, forest fires). Rossby wave breaking occurred three times, resulting in the formation and maintenance of atmospheric blocking over Eastern Siberia: 26 June–3 July, 12–21 July and 4–10 August. In general, the scenario of the summer events was as follows: cyclonic Rossby wave breaking over the southern part of Eastern Siberia (45° N–60° N) caused extreme precipitation (floods) and led to low gradients of potential vorticity and potential temperature in the west and east of Lake Baikal. The increased wave activity flux from the Europe–North Atlantic sector caused the anticyclonic-type Rossby wave breaking to occur west of the area of a low potential vorticity gradient and north of 60° N. This, in turn, contributed to the maintenance of blocking anticyclones in the north of Eastern Siberia, which led to the intensification and expansion of the area of forest fires. These events were preceded by an increase in the amplitude of the quasi-stationary wave structure over the North Atlantic and Europe during the first half of June.

Wave propagation in the marginal ice zone: connections and feedback mechanisms within the air-ice-ocean system.

The propagation of ocean surface waves within the marginal ice zone (MIZ) is a defining phenomenon of this dynamic zone. Over decades of study, a variety of methods have been developed to observe and model wave propagation in the MIZ, with a common focus of determining the attenuation of waves with increasing distance into the MIZ. More recently, studies have begun to explore the consequences of wave attenuation and the coupled processes in the air–ice–ocean–land system. Understanding these coupled processes and effects is essential for accurate high-latitude forecasts. As waves attenuate, their momentum and energy are transferred to the sea ice and upper ocean. This may compact or expand the MIZ, depending on the conditions, while simultaneously modulating the wind work on the system. Wave attenuation is also a key process in coastal dynamics, where land–fast ice has historically protected both natural coasts and coastal infrastructure. With observed trends of increasing wave activity and retreating seasonal ice coverage, the propagation of waves within the MIZ is increasingly important to regional and global climate trends.This article is part of the theme issue ‘Theory, modelling and observations of marginal ice zone dynamics: multidisciplinary perspectives and outlooks’.

Wave–sea-ice interactions in a brittle rheological framework

Abstract. As sea ice extent decreases in the Arctic, surface ocean waves have more time and space to develop and grow, exposing the marginal ice zone (MIZ) to more frequent and more energetic wave events. Waves can fragment the ice cover over tens of kilometres, and the prospect of increasing wave activity has sparked recent interest in the interactions between wave-induced sea ice fragmentation and lateral melting. The impact of this fragmentation on sea ice dynamics, however, remains mostly unknown, although it is thought that fragmented sea ice experiences less resistance to deformation than pack ice. Here, we introduce a new coupled framework involving the spectral wave model WAVEWATCH III and the sea ice model neXtSIM, which includes a Maxwell elasto-brittle rheology. This rheological framework enables the model to efficiently track and keep a “memory” of the level of sea ice damage. We propose that the level of sea ice damage increases when wave-induced fragmentation occurs. We used this coupled modelling system to investigate the potential impact of such a local mechanism on sea ice kinematics. Focusing on the Barents Sea, we found that the internal stress decrease of sea ice resulting from its fragmentation by waves resulted in a more dynamical MIZ, particularly in areas where sea ice is compact. Sea ice drift is enhanced for both on-ice and off-ice wind conditions. Our results stress the importance of considering wave–sea-ice interactions for forecast applications. They also suggest that waves likely modulate the area of sea ice that is advected away from the pack by the ocean, potentially contributing to the observed past, current and future sea ice cover decline in the Arctic.

On the coagulated pancake ice formation: Observation in the refreezing Chukchi Sea and comparison to the Antarctic consolidated pancake ice

Emergence of pancake ice in the western Arctic Ocean is understood to be an effect of the increasing wave activity. During the 2018 R/V Mirai field campaign in the refreezing Chukchi Sea, we obtained observational evidence of sea ice formation that resembled the pancake cycle—frazil/pancake/consolidated pancake ice—first discovered and known to be ubiquitous in the Antarctic. Apparently, R/V Mirai encountered a sequence of environmental conditions that were conducive to producing coagulated pancake ice, of which the formation process was relatable to the Antarctic consolidated pancake ice. We investigate how pancake ice form in two different environments: the Antarctic marginal ice zone (MIZ) is adjacent to the vigorous Antarctic Circumpolar region whereas the western Arctic Ocean is surrounded by sea ice and land. We found that a key distinction between the two regimes is that rafting is less likely in the western Arctic Ocean due to its wave climate, meaning the coagulated pancake ice is thinner than the Antarctic consolidated pancake ice. As the sea ice extent declines, thinner coagulated pancake ice may dominate the refreezing ocean, which affects the melting and possibly the broader Arctic climate.

Future wintertime meridional wind trends through the lens of subseasonal teleconnections

Abstract. Large-scale atmospheric circulation is expected to change considerably in the upcoming decades, and with it the interaction between Rossby waves and the jet stream. A common feature of midlatitude wintertime variability is upper-tropospheric quasi-stationary number 5 wave packets, which often propagate zonally along the jet. These are collectively referred to as the circumglobal teleconnection pattern (CTP). Their likeness seemingly emerges as a robust signal in future meridional wind trend projections in the Northern Hemisphere, which take the form of a zonal wave encompassing the midlatitudes. We attempt to elucidate this link across timescales (daily, monthly, and climatological), focusing on wave propagation in the jet waveguide in reanalysis and a 36-member ensemble of CMIP5 models. Using empirical orthogonal function (EOF) analysis on 300 hPa subseasonal V anomalies, we first establish the ensemble's skill in capturing the pattern. Then, by investigating EOF phase space, we characterize the CTP's behavior in present-day climatology and how it is projected to change. Under RCP8.5 forcing, most models develop a gradual preference for monthly-mean waves with certain longitudinal phases. The ensemble is thus divided into subgroups based on region of increased wave activity. For each model, this region corresponds to a more pronounced local trend, which helps explain the ensemble projection spread. Additionally, in two test-case models, this coincides with an increasing number of preferably phased wave packets at the synoptic scale. Some signs suggest that differences in CTP dynamics might stem from mean flow interaction, while no evidence was found for the role of tropical diabatic forcing. Thus, we conclude that this climate change response, seemingly a single large-scale wave, is actually comprised of several regional effects which are related to shifts in CTP phase distributions. The strong dynamical disagreement in the ensemble then manifests as significantly different circulation trends, which in turn might affect projected local temperature and precipitation patterns.

A Study of False Alarms of a Major Sudden Stratospheric Warming by Real-Time Subseasonal-to-Seasonal Forecasts for the 2017/2018 Northern Winter

This study investigates false alarms of a major sudden stratospheric warming (MSSW) by real-time subseasonal-to-seasonal forecast data of the European Centre for Medium-Range Weather Forecasts system for the 2017/2018 Northern Hemisphere winter season. The analysis reveals two false alarm cases in the season, one in early December and the other in early February. Each case is characterized by ensembles of which a considerable part of the members (MSSW members) show an MSSW, that is, reversal of the zonal mean zonal wind in the extratropical stratosphere on similar calendar dates. Ensemble forecasts that are initialized earlier or later basically lack an MSSW, demonstrating clear intraseasonal variability in the frequency of forecasted MSSWs. For each false alarm case, the MSSW member mean field shows equatorward displacement of the polar vortex around the onset date. For both cases, the MSSW members accompany stronger wave activity in the lower stratosphere than other non-MSSW members and reanalysis data. They are further associated with higher geopotential height than the non-MSSW members, in the upper troposphere over northeastern Canada and Greenland before the first case, and lower height over northeastern Eurasia before the second case. These are located over the ridge and trough, respectively, of the climatological planetary wave of zonal wave number one, and are consistent with the increased wave activity.

Why Are Stratospheric Sudden Warmings Sudden (and Intermittent)?

Abstract This paper examines the role of wave–mean flow interaction in the onset and suddenness of stratospheric sudden warmings (SSWs). Evidence is presented that SSWs are, on average, a threshold behavior of finite-amplitude Rossby waves arising from the competition between an increasing wave activity A and a decreasing zonal-mean zonal wind u¯. The competition puts a limit to the wave activity flux that a stationary Rossby wave can transmit upward. A rapid, spontaneous vortex breakdown occurs once the upwelling wave activity flux reaches the limit, or equivalently, once u¯ drops below a certain fraction of uREF, a wave-free, reference-state wind inverted from the zonalized quasigeostrophic potential vorticity. This fraction is 0.5 in theory and about 0.3 in reanalyses. We propose r≡u¯/uREF as a local, instantaneous measure of the proximity to vortex breakdown (i.e., preconditioning). The ratio r generally stays above the threshold during strong-vortex winters until a pronounced final warming, whereas during weak-vortex winters it approaches the threshold early in the season, culminating in a precipitous drop in midwinter as SSWs form. The essence of the threshold behavior is captured by a semiempirical 1D model of SSWs, similar to the “traffic jam” model of Nakamura and Huang for atmospheric blocking. This model predicts salient features of SSWs including rapid vortex breakdown and downward migration of the wave activity/zonal wind anomalies, with analytical expressions for the respective time scales. The model’s response to a variety of transient wave forcing and damping is discussed.

Non-pollen palynomorphs as indicators of palaeoenvironmental changes: a case study from Lake Chokrak (the Crimean Peninsula)

The paper presents the first study of the non-pollen palynomorphs assemblages of the upper Holocene sediments of hypersaline Lake Chokrak. As has been previously shown, the Crimean saline lakes tend to have low variety and frequencies of non-pollen palynomorphs (Mudie et al., 2011). The upper samples from Lake Chokrak have yielded high pollen frequencies, as well as a relatively diverse assemblage of NPPs, including acritarchs, dinoflagellate cysts, microforaminiferal linings, fungal spores, eggs of Artemia salina, ostracod jaws and arthropod parts. Acritarchs are represented mostly by Sigmopollis sp., which are abundant in all the studied samples, and by occasional Micrhystridium sp. and Pseudoschizaea circula. Among the fungal spores, Podospora, Delitschia and Sporormiella have been identified, indicating a former settlement. Three species of dinoflagellate cysts have been identified, Lingulodinium machaerophorum, Impagidinium caspiense and Spiniferites cf. crusiformis. These species are found in brackish/marine environments and do not tolerate high water salinity. They could have been transported to the lake by overflowing marine waters over the sand barrier between the lake and the Sea of Azov. Therefore, their appearance in the lake sediments may indicate possible sea-level changes and/or increased wave activity. So far, within the analysed top 2 m of the core, we can distinguish five intervals where dinocysts and microforaminiferal linings are present, possibly indicating increased marine influence,separated by four intervals where few or no brackish species have been found. Impagidinium caspiense is a dominant species among the dinocysts in all the samples, except the surface sample, where L. machaerophorum is much more abundant. This could indicate the increased salinity and/or higher nutrient loading to the Sea of Azov during the XX century. The allochthonous nature of dinocysts and some other NPPs in the Lake Chokrak sediments can play an important role in reconstructing level changes of the Sea of Azov and depositional environment of the lake, as well as contribute to the interpretation of pollen data.

Extreme drought in the recent two decades in northern China resulting from Eurasian warming

The analysis of 55-year daily precipitation data reveals prolonging in consecutive dry-day (CDD) and extreme summertime droughts in northern China since the 1990s. Anomalous CDD corresponds to a persistent anticyclone anomaly, that has a significant correlation with enhancing in Eurasian forced waves including Eurasian teleconnection (EU) pattern and Silk Road pattern (SRP), which have response to the upward wave activity flux over the key region (40°N–70°N, 0°E–60°E) and other regions along the EU and SRP over Eurasia. Those are the partly significant forcing sources converting energy for the forced wave. It is hypothesized that increasing Eurasian heating is more notable with global warming, and it leads to increasing atmospheric baroclinicity in the lower troposphere, further for increasing wave activity flux, that is responsible for the enhancing EU and SRP, and finally contributes to enhancing anticyclone anomaly over northern China. These anomalous circulations may result in prolonging CDD and persistent summertime drought under anthropogenic warming as projected by global climate models.

Delta progradation in Greenland driven by increasing glacial mass loss.

Climate changes are pronounced in Arctic regions and increase the vulnerability of the Arctic coastal zone. For example, increases in melting of the Greenland Ice Sheet and reductions in sea ice and permafrost distribution are likely to alter coastal morphodynamics. The deltas of Greenland are largely unaffected by human activity, but increased freshwater runoff and sediment fluxes may increase the size of the deltas, whereas increased wave activity in ice-free periods could reduce their size, with the net impact being unclear until now. Here we show that southwestern Greenland deltas were largely stable from the 1940s to 1980s, but prograded (that is, sediment deposition extended the delta into the sea) in a warming Arctic from the 1980s to 2010s. Our results are based on the areal changes of 121 deltas since the 1940s, assessed using newly discovered aerial photographs and remotely sensed imagery. We find that delta progradation was driven by high freshwater runoff from the Greenland Ice Sheet coinciding with periods of open water. Progradation was controlled by the local initial environmental conditions (that is, accumulated air temperatures above 0 °C per year, freshwater runoff and sea ice in the 1980s) rather than by local changes in these conditions from the 1980s to 2010s at each delta. This is in contrast to a dominantly eroding trend of Arctic sedimentary coasts along the coastal plains of Alaska, Siberia and western Canada, and to the spatially variable patterns of erosion and accretion along the large deltas of the main rivers in the Arctic. Our results improve the understanding of Arctic coastal evolution in a changing climate, and reveal the impacts on coastal areas of increasing ice mass loss and the associated freshwater runoff and lengthening of open-water periods.

A 500 year climate catch: Pelagic fish scales and paleoproductivity in the Santa Barbara Basin from the Medieval Climate Anomaly to the Little Ice Age (AD 1000–1500)

Based upon observations from the 20th century, populations of lower trophic level, short-lived fish species are thought to be controlled by large scale ocean–atmosphere circulation shifts. Here, we provide a new 500 year reconstruction of northern anchovy and Pacific sardine fish scale deposition rates (SDRs) and relative abundance from Santa Barbara Basin (SBB), through the transition from the Medieval Climate Anomaly into the Little Ice Age (AD 1000–1500). Three intervals of high anchovy biomass (high SDRs) were coincident with increased upwelling diatom abundance in SBB and cool/negative Pacific Decadal Oscillation (PDO) events at 1130–1160, 1280–1310 and 1410–1450. Intervals of absent or low SDR of both sardine and anchovy in SBB sediments occurred in association with increased wave activity (benthic diatoms), California Current diatoms, and the relative dominance of sardine over anchovy. Thus although ocean–atmosphere circulation shifts such as the PDO appear to play a role in shifting the dominance of anchovy over sardine, the biomass of sardines as indicated by SDRs has a more complicated response to environmental change.

The impact of polar stratospheric ozone loss on Southern Hemisphere stratospheric circulation and climate

Abstract. The impact of polar stratospheric ozone loss resulting from chlorine activation on polar stratospheric clouds is examined using a pair of model integrations run with the fully coupled chemistry climate model UM-UKCA. Suppressing chlorine activation through heterogeneous reactions is found to produce modelled ozone differences consistent with observed ozone differences between the present and pre-ozone hole period. Statistically significant high-latitude Southern Hemisphere (SH) ozone loss begins in August and peaks in October–November, with > 75% of ozone destroyed at 50 hPa. Associated with this ozone destruction is a > 12 K decrease of the lower polar stratospheric temperatures and an increase of > 6 K in the upper stratosphere. The heating components of this temperature change are diagnosed and it is found that the temperature dipole is the result of decreased short-wave heating in the lower stratosphere and increased dynamical heating in the upper stratosphere. The cooling of the polar lower stratosphere leads, through thermal wind balance, to an acceleration of the polar vortex and delays its breakdown by ~ 2 weeks. A link between lower stratospheric zonal wind speed, the vertical component of the Eliassen–Palm (EP) flux, Fz and the residual mean vertical circulation, w*, is identified. In November and December, increased westerly winds and a delay in the breakup of the polar vortex lead to increases in Fz, indicating increased wave activity entering the stratosphere and propagating to higher altitudes. The resulting increase in wave breaking, diagnosed by decreases to the EP flux divergence, drives enhanced downwelling over the polar cap. Many of the stratospheric signals modelled in this study propagate down to the troposphere, and lead to significant surface changes in December.

Wind-wave Climate Projections for the Indian Ocean from Satellite Observations

The oceans play a key role in climate change and their impact has profound implications on the marine ecosystem and multitude activities around the globe. The effects due to climate change can have long-term repercussion. The latest report on the Intergovernmental Panel on Climate Change had identified the importance of wind-wave climate and its key role in global climate models. The present study investigates the impact of climate change on variability of maximum significant wave height and wind speeds over the Indian Ocean basin. The study is based on analysis from the daily observation of satellite altimeter measured wind and waves derived from eight satellite missions covering a period of 21 years from 1992 until 2012. The results signify that the Southern Ocean belt encompassing latitudinal belts between 40°S – 55°S experienced the highest variability due to impact from climate change. Both wind and wave activity has shown an increasing trend in the Southern Ocean, and this rise is more conspicuous in the current decade. The implications from increased wave activity in the Southern Ocean results in swell field that can influence the local wind-generated waves in the North Indian Ocean basin. The wind-wave activity in certain sectors of the tropical North Indian Ocean also increased from impact of climate change.

Wave power variability and trends across the North Pacific

Multiyear climate variations influence North Pacific storm intensity and resultant variations in wave energy levels. The timing of these decadal fluctuations and strong El Niño's have had a strong influence on long‐term trends. Here we investigate variations in the North Pacific wave power, PW, determined from WAVEWATCH III (WW3) wave model significant wave height, Hs, and peak period data forced by NRA‐1 winds spanning the 1948–2008 epoch. Over the entire hindcast, upward trends in Hs and PW, especially in winter, are observed over much of the North Pacific, strongly influenced by an apparent storm intensification after the mid‐1970s regime shift. Heightened PW is concentrated in particular regions of the basin, and is associated with increased wave activity during the warm phase of the Pacific Decadal Oscillation (PDO). Wave power events, PE, defined as episodes when Hs exceeded the 90th percentile threshold for at least 12 h, exhibit significant upward trends along much of the U.S. Pacific coast during winter months. Importantly, the hindcast exhibits a recent decrease in PW across much of the North Pacific, in contrast to the long‐term increase of PW and Hs. This recent decrease is associated with the prevalent PDO cool phase that developed after the late 1990s. Variability and intensification of coastal PW and PE have important practical implications for shoreline and beach erosion, coastal wetlands inundation, storm‐surge flooding, and coastal planning. These considerations will become increasingly important as sea level rises.

Satellite Observations Monitor Outages From Superstorm Sandy

In late October 2012, Hurricane Sandy traveled across Jamaica, Cuba, and the Bahamas, then progressed northward along the eastern seaboard of the United States, resulting in numerous tropical storm warnings along the coasts of Florida and North Carolina. As the storm approached the Mid‐Atlantic region, interaction with an upper‐level low drew the cyclone inland, with the center passing just north of Atlantic City, N. J. In what media reports dubbed a “superstorm,” Sandy produced hurricane‐force winds, significant coastal storm surge, torrential rain, inland flooding, and extensive damage over a vast area. Further west of the cyclone center, strong winds increased wave activity throughout the Great Lakes, and heavy snowfall occurred across portions of Tennessee, Kentucky, and West Virginia. As of early November, more than 100 fatalities had been attributed to Sandy in the northeastern United States, with total economic losses of up to $50 billion [New York Times, 2012, and Walsh and Schwartz, 2012].

Spontaneous calcium waves in Bergman glia increase with age and hypoxia and may reduce tissue oxygen.

Glial calcium (Ca(2+)) waves constitute a means to spread signals between glial cells and to neighboring neurons and blood vessels. These waves occur spontaneously in Bergmann glia (BG) of the mouse cerebellar cortex in vivo. Here, we tested three hypotheses: (1) aging and reduced blood oxygen saturation alters wave activity; (2) glial Ca(2+) waves change cerebral oxygen metabolism; and (3) neuronal and glial wave activity is correlated. We used two-photon microscopy in the cerebellar cortexes of adult (8- to 15-week-old) and aging (48- to 80-week-old) ketamine-anesthetized mice after bolus loading with OGB-1/AM and SR101. We report that the occurrence of spontaneous waves is 20 times more frequent in the cerebellar cortex of aging as compared with adult mice, which correlated with a reduction in resting brain oxygen tension. In adult mice, spontaneous glial wave activity increased on reducing resting brain oxygen tension, and ATP-evoked glial waves reduced the tissue O(2) tension. Finally, although spontaneous Purkinje cell (PC) activity was not associated with increased glia wave activity, spontaneous glial waves did affect intracellular Ca(2+) activity in PCs. The increased wave activity during aging, as well as low resting brain oxygen tension, suggests a relationship between glial waves, brain energy homeostasis, and pathology.