Sperm whales exhibit variation in echolocation tactics with depth and sea state but not naval sonar exposures

2021 ◽  
Author(s):  
Saana Isojunno ◽  
Alexander M. von Benda‐Beckmann ◽  
Paul J. Wensveen ◽  
Petter H. Kvadsheim ◽  
Frans‐Peter A. Lam ◽  
...  
Keyword(s):  
Sperm Whales ◽  
Sea State

Distribution and relative abundance of sperm whales in the Mediterranean Sea

2002 ◽  
Vol 243 ◽  
pp. 281-293 ◽  
Author(s):  
A Gannier ◽  
V Drouot ◽  
JC Goold
Keyword(s):  
Mediterranean Sea ◽  
Relative Abundance ◽  
Sperm Whales ◽  
The Mediterranean

Male Nipples in Blue and Fin Whales and Their Absence in Sperm Whales

2005 ◽  
Vol 31 (1) ◽  
pp. 124-132
Author(s):  
Robert Clarke
Keyword(s):  
Sperm Whales ◽  
Fin Whales

Calculation of magnetic flow noise inside an enclosure in a sea-state

1998 ◽  
Author(s):  
Mark Hyman ◽  
Iskender Sahin ◽  
Thai Nguyen
Keyword(s):  
Sea State ◽  
Magnetic Flow ◽  
Flow Noise

GPS Surface Reflection for Ionosphere and Sea State Determination

2001 ◽  
Author(s):  
Stephen J. Katzberg ◽  
Lloyd A. Linstrom
Keyword(s):  
Sea State ◽  
Surface Reflection ◽  
State Determination

Notes on the Right and Sperm Whales

1873 ◽  
Vol 7 (1) ◽  
pp. 1-4 ◽  
Author(s):  
N. S. Shaler
Keyword(s):  
Sperm Whales ◽  
The Right

First record of Norwegian killer whales attacking and feeding on a harbour porpoise

2015 ◽  
Vol 8 ◽  
Author(s):  
A. Mel Cosentino
Keyword(s):  
North Atlantic ◽  
Marine Mammals ◽  
First Record ◽  
Harbour Porpoise ◽  
Sperm Whales ◽  
Killer Whales ◽  
Strait Of Gibraltar ◽  
Cetacean Species ◽  
The North ◽  
Northern Bottlenose Whales

Orcinus orcais a cosmopolitan species and the most widely distributed marine mammal. Its diet includes over 140 species of fish, cephalopods, sea birds and marine mammals. However, many populations are specialised on certain specific prey items. Three genetically distinct populations have been described in the North Atlantic. Population A (that includes the Icelandic and Norwegian sub-populations) is believed to be piscivorous, as is population C, which includes fish-eating killer whales from the Strait of Gibraltar. In contrast, population B feeds on both fish and marine mammals. Norwegian killer whales follow the Norwegian spring spawning herring stock. The only description in the literature of Norwegian killer whales feeding on another cetacean species is a predation event on northern bottlenose whales in 1968. Daily land-based surveys targeting sperm whales were conducted from the Andenes lighthouse using BigEyes®binoculars (25×, 80 mm). The location of animals at sea was approximated through the use of an internal reticule system and a graduated wheel. On 24 June 2012 at 3:12 am, an opportunistic sighting of 11 killer whales was made off Andenes harbour. The whales hunted and fed on a harbour porpoise. Despite these species having overlapping distributions in Norwegian waters, this is the first predatory event reported in the literature.

scholarly journals An Analytical Method for Dynamic Wave-Related Errors of Interferometric SAR Ocean Altimetry under Multiple Sea States

2021 ◽  
Vol 13 (5) ◽  
pp. 986
Author(s):  
Yao Chen ◽  
Mo Huang ◽  
Yuanyuan Zhang ◽  
Changyuan Wang ◽  
Tao Duan
Keyword(s):  
Electromagnetic Scattering ◽  
Analytical Method ◽  
Wave Spectrum ◽  
High Accuracy ◽  
Sea State ◽  
Error Budget ◽  
Ocean Topography ◽  
Mean Square Errors ◽  
Dynamic Wave ◽  
Wide Swath

The spaceborne interferometric synthetic aperture radar (InSAR) is expected to measure the sea surface height (SSH) with high accuracy over a wide swath. Since centimeter-level accuracy is required to monitor the ocean sub-mesoscale dynamics, the high accuracy implies that the altimetric errors should be totally understood and strictly controlled. However, for the dynamic waves, they move randomly all the time, and this will lead to significant altimetric errors. This study proposes an analytical method for the dynamic wave-related errors of InSAR SSH measurement based on the wave spectrum and electromagnetic scattering model. Additionally, the mechanisms of the dynamic wave-related errors of InSAR altimetry are analyzed, and the detailed numerical model is derived. The proposed analytical method is validated with NASA’s Surface Water and Ocean Topography (SWOT) project error budget, and the Root-Mean-Square Errors (RMSEs) are in good agreement (0.2486 and 0.2470 cm on a 0.5 km2 grid, respectively). Instead of analysis for a typical project, the proposed method can be applied to different radar parameters under multiple sea states. The RMSEs of Ka-band under low sea state, moderate sea state, and high sea state are 0.2670, 1.3154, and 6.6361 cm, respectively. Moreover, the RMSEs of X-band and Ku-band are also simulated and presented. The experimental results demonstrate that the dynamic wave-related errors of InSAR altimetry are not sensitive to the frequencies but are sensitive to the sea states. The error compensation method is necessary for moderate and higher sea states for centimetric accuracy requirements. This can provide feasible suggestions on system design and error budget for the future interferometric wide-swath altimeter.

High-performance altimeter Doppler processing for measuring sea level height under varying sea state conditions

2021 ◽  
Author(s):  
T. Moreau ◽  
E. Cadier ◽  
F. Boy ◽  
J. Aublanc ◽  
P. Rieu ◽  
...  
Keyword(s):  
Sea Level ◽  
High Performance ◽  
Sea State ◽  
Level Height

scholarly journals How Good Is the STW Sensor? An Account from a Larger Shipping Company

2021 ◽  
Vol 9 (5) ◽  
pp. 465
Author(s):  
Angelos Ikonomakis ◽  
Ulrik Dam Nielsen ◽  
Klaus Kähler Holst ◽  
Jesper Dietz ◽  
Roberto Galeazzi
Keyword(s):  
High Frequency ◽  
Additional Data ◽  
Empirical Method ◽  
Influential Factor ◽  
Sensor Data ◽  
Sea State ◽  
Shipping Company ◽  
Frequency Sensor ◽  
Semi Empirical

This paper examines the statistical properties and the quality of the speed through water (STW) measurement based on data extracted from almost 200 container ships of Maersk Line’s fleet for 3 years of operation. The analysis uses high-frequency sensor data along with additional data sources derived from external providers. The interest of the study has its background in the accuracy of STW measurement as the most important parameter in the assessment of a ship’s performance analysis. The paper contains a thorough analysis of the measurements assumed to be related with the STW error, along with a descriptive decomposition of the main variables by sea region including sea state, vessel class, vessel IMO number and manufacturer of the speed-log installed in each ship. The paper suggests a semi-empirical method using a threshold to identify potential error in a ship’s STW measurement. The study revealed that the sea region is the most influential factor for the STW accuracy and that 26% of the ships of the dataset’s fleet warrant further investigation.

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