PREDICTION OF IN‐SITU ACOUSTIC AND ELASTIC PROPERTIES OF MARINE SEDIMENTS

Geophysics ◽  
1971 ◽  
Vol 36 (2) ◽  
pp. 266-284 ◽  
Author(s):  
Edwin L. Hamilton
Keyword(s):  
Marine Sediments ◽  
Elastic Moduli ◽  
Environmental Control ◽  
Compressional Wave ◽  
Sediment Surface ◽  
Empirical Relationships ◽  
The North ◽  
Sediment Data ◽  
The North Pacific

This is one of several interrelated reports concerning sound velocity, elasticity, and related properties of marine sediments from several major environments in the North Pacific and adjacent areas. Previous reports were concerned with methods, measured properties (e.g., compressional‐wave velocity, density, porosity), environmental control, empirical relationships, elastic models for saturated, porous marine sediments, and the computation of elastic moduli. These measured and computed properties were referred to 1 atmosphere pressure and 23°C; all samples were from the sediment surface (0 to 30 cm). This report is concerned with the correction of laboratory values to in‐situ values, and the prediction of in‐situ values in the absence of any sediment data.

scholarly journals In situ observation of atmospheric oxygen and carbon dioxide in the North Pacific using a cargo ship

2018 ◽  
Vol 18 (13) ◽  
pp. 9283-9295 ◽  
Author(s):  
Yu Hoshina ◽  
Yasunori Tohjima ◽  
Keiichi Katsumata ◽  
Toshinobu Machida ◽  
Shin-ichiro Nakaoka
Keyword(s):  
Carbon Dioxide ◽  
Mole Fraction ◽  
North Pacific ◽  
Atmospheric Oxygen ◽  
The United States ◽  
In Situ Observation ◽  
Airflow Rate ◽  
The North ◽  
The North Pacific

Abstract. Atmospheric oxygen (O2) and carbon dioxide (CO2) variations in the North Pacific were measured aboard a cargo ship, the New Century 2 (NC2), while it cruised between Japan and the United States between December 2015 and November 2016. A fuel cell analyzer and a nondispersive infrared analyzer were used for the measurement of O2 and CO2, respectively. To achieve parts-per-million precision for the O2 measurements, we precisely controlled the flow rates of the sample and reference air introduced into the analyzers and the outlet pressure. A relatively low airflow rate (10 cm3 min−1) was adopted to reduce the consumption rate of the reference gases. In the laboratory, the system achieved measurement precisions of 3.8 per meg for δ(O2 ∕ N2), which is commonly used to express atmospheric O2 variation, and 0.1 ppm for the CO2 mole fraction. After the in situ observation started aboard NC2, we found that the ship's motion caused false wavy variations in the O2 signal with an amplitude of more than several tens of ppm and a period of about 20 s. Although we have not resolved the problem at this stage, hourly averaging considerably suppressed the variation associated with ship motion. Comparison between the in situ observation and flask sampling of air samples aboard NC2 showed that the averaged differences (in situ–flask) and the standard deviations (±1σ) are −2.8 ± 9.4 per meg for δ(O2 ∕ N2) and −0.02 ± 0.33 ppm for the CO2 mole fraction. We compared 1 year of in situ data for atmospheric potential oxygen (APO; O2 +1.1×CO2) obtained from the broad middle-latitude region (140∘ E–130∘ W, 29∘ N–45∘ N) with previous flask sampling data from the North Pacific. This comparison showed that longitudinal differences in the seasonal amplitude of APO, ranging from 51 to 73 per meg, were smaller than the latitudinal differences.

scholarly journals Satellite views of global phytoplankton community distributions using an empirical algorithm and a numerical model

2013 ◽  
Vol 10 (1) ◽  
pp. 1083-1109 ◽  
Author(s):  
C. S. Rousseaux ◽  
T. Hirata ◽  
W. W. Gregg
Keyword(s):  
Seasonal Variation ◽  
Data Base ◽  
Observation Data ◽  
Independent Observation ◽  
In Situ Data ◽  
The North ◽  
Model Versus ◽  
Mean Differences ◽  
The North Pacific

Abstract. We compared the functional response of a biogeochemical data assimilation model versus an empirical satellite-derived algorithm in describing the variation of four phytoplankton (diatoms, cyanobacteria, coccolithophores and chlorophytes) groups globally and in 12 major oceanographic basins. Global mean differences of all groups were within ~ 15% of an independent observation data base for both approaches except for satellite-derived chlorophytes. Diatoms and cyanobacteria concentrations were significantly (p < 0.05) correlated with the independent observation data base for both methods. Coccolithophore concentrations were only correlated with the in situ data for the model approach and the chlorophyte concentration was only significantly correlated to the in situ data for the satellite-derived approach. Using monthly means from 1998–2007, the seasonal variation from the satellite-derived approach and model were significantly correlated in 11 regions for diatoms and in 9 for coccolithophores but only in 3 and 2 regions for cyanobacteria and chlorophytes. Most disagreement on the seasonal variation of phytoplankton composition occurred in the North Pacific and Antarctic where, except for diatoms, no significant correlation could be found between the monthly mean concentrations derived from both approaches. In these two regions there was also an overestimate of diatom concentration by the model of ~ 60% whereas the satellite-derived approach was closer to in situ data (8–26% underestimate). Chlorophytes were the group for which both approaches differed most and that was furthest from the in situ data. These results highlight the strengths and weaknesses of both approaches and allow us to make some suggestions to improve our approaches to understanding phytoplankton dynamics and distribution.

scholarly journals In situ measurements of capelin (Mallotus villosus) target strength in the North Pacific Ocean

2008 ◽  
Vol 66 (2) ◽  
pp. 258-263 ◽  
Author(s):  
Michael A. Guttormsen ◽  
Christopher D. Wilson
Keyword(s):  
Pacific Ocean ◽  
North Pacific ◽  
North Pacific Ocean ◽  
In Situ Measurements ◽  
Target Strength ◽  
Mallotus Villosus ◽  
The North ◽  
Capelin Mallotus Villosus ◽  
The North Pacific

Abstract Guttormsen, M. A. and Wilson, C. D. 2009. In situ measurements of capelin (Mallotus villosus) target strength in the North Pacific Ocean. – ICES Journal of Marine Science, 66: 258–263. In situ measurements of capelin (Mallotus villosus) target strength (TS) were collected during summer 2001–2003 near Kodiak Island in the Gulf of Alaska, using a calibrated EK500 echosounder with 38 and 120 kHz split-beam transducers. Targets were detected over dispersed, night-time aggregations using standard acoustic methods, then filtered using a quality-control algorithm to reject invalid targets. The 38 kHz-based, fitted model estimate was TS = 20 log10L− 70.3 (r2 = 0.30), where L is total length of fish. Compared with other studies, the TS-fitted model at 38 kHz was similar to that calculated from swimbladder morphology measurements from St Lawrence estuary capelin (TS = 20 log10L− 69.3), but resulted in greater estimates than models based on in situ measurements of capelin TS in the Barents Sea (TS = 19.1 log10L−74.0) and northern Atlantic Ocean (TS = 20 log10L − 73.1). The large intraspecific variability exhibited in the fitted TS – L models for this species suggests the use of TS measurements from the geographic region where the data were collected.

scholarly journals In Situ Diazotroph Population Dynamics Under Different Resource Ratios in the North Pacific Subtropical Gyre

2018 ◽  
Vol 9 ◽  
Author(s):  
Kendra A. Turk-Kubo ◽  
Paige Connell ◽  
David Caron ◽  
Mary E. Hogan ◽  
Hanna M. Farnelid ◽  
...  
Keyword(s):  
Population Dynamics ◽  
North Pacific ◽  
Subtropical Gyre ◽  
North Pacific Subtropical Gyre ◽  
The North ◽  
The North Pacific ◽  
Resource Ratios
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