Reliability of sea level dating using Th/U method for mollusks from the west coast of the red sea and from the atlantic coast of the Moroccan high atlas

From 1979 through 2009, 81 records of long-distance vagrancy in the Long-billed Murrelet (Brachyramphus perdix) in North America south of Alaska were examined to assess body condition and survival after first observation. Sixty-one records were of live birds, of which 38 (62.3%) were discovered at sea along the west coast of North America, 18 (29.5%) were encountered inland, and 5 (8.2%) were encountered along the Atlantic coast. Fifteen of the 20 individuals salvaged (19 adults, 1 juvenile) were discovered on lake shores (75.0%) and the other 5 (25.0%) on marine coasts; 85.0% were dead when initially found (15 dead, 2 shot), and 3 (15.0%) were moribund (2 died within one day, 1 later released). Of 10 sexed individuals, 5 were adult males, 4 were adult females, and 1 was a juvenile female. Eight of 10 murrelets observed foraging were diving on lakes, but 2 others surfaced with fish; two species of common freshwater fish were removed from stomachs of 2 birds shot by hunters. Most birds (72.1%, n = 61) disappeared after one observation, which suggests survival and moving on; one bird stayed at the same location for at least 25 days before disappearing. Dead or dying Long-billed Murrelets found on shorelines of fresh water may have been too emaciated to regain lost mass after arrival—they weighed less than those shot, presumably because they were not able to locate prey or too weak to capture it. Survival for weeks or longer on freshwater stopover sites better explains how Long-billed Murrelets move across North America, with some reaching the Atlantic Ocean. Long-surviving vagrants may establish a new breeding population of Long-billed Murrelet on the west coast of North America.

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Large-Scale Sea Level Response to Atmospheric Forcing along the West Coast of North America, Summer 1973

Journal of Physical Oceanography ◽

10.1175/1520-0485(1984)014<0864:lsslrt>2.0.co;2 ◽

1984 ◽

Vol 14 (5) ◽

pp. 864-886 ◽

Cited By ~ 45

Author(s):

George R. Halliwell ◽

J. S. Allen

Keyword(s):

North America ◽

Sea Level ◽

West Coast ◽

Large Scale ◽

Atmospheric Forcing ◽

The West

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87:6062 Intraseasonal oscillations in sea level along the west coast of the Americas

Deep Sea Research Part B Oceanographic Literature Review ◽

10.1016/0198-0254(87)90525-5 ◽

1987 ◽

Vol 34 (11) ◽

pp. 921

Keyword(s):

Sea Level ◽

West Coast ◽

The West ◽

Intraseasonal Oscillations

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Importance of wind variations and intersecting waveguides near Sri Lanka for the intraseasonal sea level variability along the west coast of India

10.5194/egusphere-egu2020-19919 ◽

2020 ◽

Author(s):

Iyyappan Suresh ◽

Jerome Vialard ◽

Matthieu Lengaigne ◽

Takeshi Izumo ◽

Muraleedharan Pillathu Moolayil

Keyword(s):

Sri Lanka ◽

Indian Ocean ◽

Sea Level ◽

Bay Of Bengal ◽

West Coast ◽

Equatorial Indian Ocean ◽

Direct Connection ◽

Local Wind ◽

The West ◽

Eastern Equatorial Indian Ocean

Remote wind forcing plays a strong role in the Northern Indian Ocean, where oceanic anomalies can travel long distances within the coastal waveguide. Previous studies for instance emphasized that remote equatorial forcing is the main driver of the sea level and currents intraseasonal variability along the west coast of India (WCI). Until now, the main pathway for this connection between the equatorial and coastal waveguides was thought to occur in the eastern equatorial Indian Ocean, through coastal Kelvin waves that propagate around the Bay of Bengal rim and then around Sri Lanka to the WCI. Using a linear, continuously stratified ocean model, the present study demonstrates that two other mechanisms in fact dominate. First, the equatorial waveguide also intersects the coastal waveguide at the southern tip of India and Sri Lanka, creating a direct connection between the equator and WCI. Rossby waves reflected from the eastern equatorial Indian Ocean boundary indeed have a sufficiently wide meridional scale to induce a pressure signal at the Sri Lankan coast, which eventually propagates to the WCI as a coastal Kelvin wave. Second, local wind variations in the vicinity of Sri Lanka generate strong intraseasonal signals, which also propagate to the WCI along the same path. Sensitivity experiments indicate that these two new mechanisms (direct equatorial connection and local wind variations near Sri Lanka) dominate the WCI intraseasonal sea level variability, with the &#8220;classical&#8221; pathway around the Bay of Bengal only coming next. Other contributions (Bay of Bengal forcing, local WCI forcing) are much weaker.We further show that the direct connection between the equatorial waveguide and WCI is negligible at seasonal timescale, but not at interannual timescales where it contributes to the occurrence of anoxic events. By providing an improved understanding of the mechanisms that control the WCI thermocline and oxycline variability, our results could have socio-economic implications for regional fisheries and ecosystems.

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Interactions of extreme river flows and sea levels for coastal flooding

10.5194/egusphere-egu2020-22494 ◽

2020 ◽

Author(s):

Peter Robins ◽

Lisa Harrison ◽

Mariam Elnahrawi ◽

Matt Lewis ◽

Tom Coulthard ◽

...

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

West Coast ◽

Flood Risk ◽

Coastal Flooding ◽

Relative Timing ◽

The West ◽

Sea Levels ◽

Flooding Hazards ◽

Fluvial Response

Coastal flooding worldwide causes the vast majority of natural disasters; for the UK costing &#163;2.2 billion/year. Fluvial and surge-tide extremes can occur synchronously resulting in combination flooding hazards in estuaries, intensifying the flood risk beyond fluvial-only or surge-only events. Worse, this flood risk has the potential to increase further in the future as the frequency and/or intensity of these drivers change, combined with projected sea-level rise. Yet, the sensitivity of contrasting estuaries to combination and compound flooding hazards at sub-daily scales &#8211; now and in the future &#8211; is unclear. Here, we investigate the dependence between fluvial and surge interactions at sub-daily scales for contrasting catchment and estuary types (Humber vs. Dyfi, UK), using 50+ years of data: 15-min fluvial flows and hourly sea levels. Additionally, we simulate intra-estuary (<50&#160;m resolution) sensitivities to combination flooding hazards based on: (1) realistic extreme events (worst-on-record); (2) realistic events with shifted timings of the drivers to maximise flooding; and (3) modified drivers representing projected climate change.For well-documented flooding events, we show significant correlation between skew surge and peak fluvial flow, for the Dyfi (small catchment and estuary with a fast fluvial response on the west coast of Britain), with a higher dependence during autumn/winter months. In contrast, we show no dependence for the Humber (large catchment and estuary with a slow fluvial response on the east coast of Britain). Cross-correlation results, however, did show correlation with a time lag (~10 hours). For the Dyfi, flood extent was sensitive to the relative timing of the fluvial and surge-tide drivers. In contrast, the relative timing of these drivers did not affect flooding in the Humber. However, extreme fluvial flows in the Humber actually reduced water levels in the outer estuary, compared with a surge-only event. Projected future changes in these drivers by 2100 are likely to increase combination flooding hazards: sea-level rise scenarios predicted substantial and widespread flooding in both estuaries. However, similar increases in storm surge resulted in a greater seawater influx, altering the character of the flooding. Projected changes in fluvial volumes were the weakest driver of estuarine flooding. On the west coast of Britain containing many small/steep catchments, combination flooding hazards from fluvial and surges extremes occurring together is likely. Moreover, high-resolution data and hydrodynamic modelling are necessary to resolve the impact and inform flood mitigation methodology.

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