Gulf Stream velocity structure through combined inversion of hydrographic and acoustic doppler data

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1987.Microfiche copy available in Archives and Science.Bibliography: leaves 64-65.by Stephen D. Pierce.M.S

Equatorward jets and poleward undercurrents along the eastern boundary of the mid-latitude north Pacific

We sharpen our view of an eastern boundary current region during the upwelling season through the analysis of several data sets. We focus on the mesoscale flow field off of northern California, observed during the Coastal Transition Zone (CTZ) experiment of 1988. First, we estimate tidal currents in the region by least-squares harmonic analysis of both shipboard acoustic Doppler current profiler (ADCP) and moored data. The tide is predominantly M2 and varies from 1-4 cm/s across the region, consistent with previous tidal studies. Next, we use detided ADCP together with conductivity-temperature-depth data to infer absolute geostrophic velocities during each of the five surveys in July-August 1988. Referencing geostrophy with the ADCP reveals a stronger equatorward jet than previously reported; southward volume transport from 0-500 m through a 200 km onshore-offshore line is as high as 8.0 Sv, with a mean over the five surveys of 6.3 +- 1.3 Sv. The jet was about 50 km wide, with core velocities > 0.6 m/s. During a two-week period in July 1988, horizontal velocity shears were sufficient to shift the effective local inertial frequency 10% higher on the cold (inshore) side and 5% lower on the warm (offshore) side of the jet. Observed near-inertial currents have amplified energy in the region with lower effective inertial frequency, consistent with theoretical predictions. Next, the basic instability mechanism leading to a meandering CTZ jet is analyzed using a linear quasi-geostrophic model applied to observed basic state velocity profiles. The jet is subject to both barotropic and baroclinic instability processes, and meander wavelengths of 260-265 km are the fastest growing. Growth periods of 7-11 days and along-jet phase speeds of 4-8 km/d are predicted. Finally, the poleward undercurrent which was observed during the 1988 CTZ experiment is also investigated with a series of shipboard ADCP sections collected from 33-51N during July-August 1995. Subsurface poleward flow occurred in 91% of the sections, with a mean undercurrent core velocity of 17 +- 1 cm/s and transport in a 140-325 m layer of 0.9 +- 0.1 Sv. One portion of the undercurrent is continuous over a 440 km length.Keywords: physical oceanography, eastern boundary curren

Performance of Solid-State Sensors for Continuous, Real-Time Measurement of Soil CO\u3csub\u3e2\u3c/sub\u3e Concentrations

Recent advances in sensor technology provide a robust capability for continuous measurement of soil gases. The performance of solid-state CO2 sensors (Model GMM220 series, Vaisala, Inc., Helsinki, Finland) was evaluated in laboratory, greenhouse, and irrigated winter wheat (Triticum aestivum L.). In ambient CO2 concentration, the GMM222 sensor averaged 427 ± 8.3 μL L−1. Under variable CO2 concentrations, the sensor was slightly lower than concentrations measured with an infrared gas analyzer (IRGA). In greenhouse pots planted with triticale (Triticale hexaploide Lart.) and an agricultural field of irrigated winter wheat, soil CO2 concentration exceeded the 10,000 μL L−1 limit of the GMM222. Alternatively, the GMM221 sensor, designed to measure between 0 and 20,000 μL L−1, showed soil CO2 concentrations were between 14,000 and 16,000 μL L−1. The GMM222 accurately measures real-time soil CO2 concentrations under field conditions that were within the sensor detection limit. However, periods of high biological soil activity require the GMM221 sensor with a higher detection limit

Asymmetry in Resting Alpha Activity: Effects of Handedness

Frontal electroencephalographic (EEG) alpha band power during rest shows increased right, and/or decreased left, hemisphere activity under conditions of state or trait withdrawal-associated effect. Non-right-handers (NRH) are more likely to have mental illnesses and dispositions that involve such withdrawal-related effect. The aim of the study was to examine whether NRH might be characterized by increased right, relative to left, hemisphere activity during rest. Methods: The present research investigated that hypothesis by examining resting EEG alpha power in consistently-right-handed (CRH) and NRH individuals. Results: In support of the hypothesis, NRH demonstrated decreased right hemisphere alpha power, and therefore increased right hemisphere activity, during rest, compared to CRH.Conclusions: The study demonstrates further support for an association between increased right hemisphere activity and negative affect via an association between such EEG activity and NRH

Acoustic doppler current profiler observations during the Coastal Ocean Advances in Shelf Transport (COAST) Survey III : R/V Wecoma cruise W0301B, 19 January - 9 February 2003

We present velocity observations from a shipboard acoustic Doppler current profiler (ADCP) on R/V Wecoma during cruise W0301b (19 January - 3 February 2003). The cruise was a component (Survey III) of the Coastal Ocean Advances in Shelf Transport (COAST) experiment. The ADCP was an RD Instruments hull-mounted 153-kHz narrowband unit. Data were collected nearly continuously using an ensemble averaging interval of 1 min and a vertical bin length of 8 m. This implies an inherent short-term random uncertainty of 2 cm/s for each data point; this uncertainty is reduced with additional space or time averaging. To reference the velocities to earth coordinates, we used P-code GPS navigation in combination with the ship’s gyrocompass. Bottom-tracking was enabled when the bottom depth was less than about 400 m. Our processing methods are generally standard ones, primarily making using of the CODAS software package as described at http://ilikai.soest.hawaii.edu/sadcp. Overall ADCP data quality for the cruise was excellent. To produce the vector maps here, we applied 5 km spatial averaging. For the sections, we contoured using a two-pass Barnes method with horizontal (vertical) smoothing of 5 km (24 m) and 2.5 km (12 m) for the first and second passes. An online version of this report is available at http://damp.coas.oregonstate.edu/coast/adcp. In addition, the complete data set and all processing details are available from the NODC Joint Archive for Shipboard ADCP: http://ilikai.soest.hawaii.edu/sadcp. A cruise narrative is included in the companion Seasoar data report at http://damp.coas.oregonstate.edu/coast/seasoar. This work was funded by National Science Foundation grant OCE-9907854

Acoustic doppler current profiler observations during the Coastal Ocean Advances in Shelf Transport (COAST) Survey II : R/V Wecoma cruise W0108A, 6-25 August 2001

We present velocity observations from a shipboard acoustic Doppler current profiler (ADCP) on R/V Wecoma during cruise W0108a (6-25 August 2001). The cruise was a component (Survey II) of the Coastal Ocean Advances in Shelf Transport (COAST) experiment. The ADCP was an RD Instruments hull-mounted 153-kHz narrowband unit. Data were collected nearly continuously using an ensemble averaging interval of 1 min and a vertical bin length of 8 m. This implies an inherent short-term random uncertainty of 2 cm/s for each data point; this uncertainty is reduced with additional space or time averaging. To reference the velocities to earth coordinates, we used GPS navigation in combination with the ship's gyrocompass and a GPS attitude system. Our processing methods are generally standard ones, primarily making using of the CODAS software package as described at http://ilikai.soest.hawaii.edu/sadcp. Overall ADCP data quality for the cruise was excellent. To produce the vector maps here, we applied 5 km spatial averaging. For the sections, we contoured using a two-pass Barnes method with horizontal (vertical) smoothing of 5 km (24 m) and 2.5 km (12 m) for the first and second passes. An online version of this report is available at http://damp.coas.oregonstate.edu/coast/adcp. In addition, the complete data set and all processing details are available from the NODC Joint Archive for Shipboard ADCP: http://ilikai.soest.hawaii.edu/sadcp. A cruise narrative is included in the companion Seasoar data report at http://damp.coas.oregonstate.edu/coast/seasoar. This work was funded by National Science Foundation grant OCE-9907854

Dispersion in the open ocean seasonal pycnocline at scales of 1-10 km and 1-6 days

Author Posting. © American Meteorological Society, 2020. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 50(2), (2020): 415-437, doi:10.1175/JPO-D-19-0019.1.Results are presented from two dye release experiments conducted in the seasonal thermocline of the Sargasso Sea, one in a region of low horizontal strain rate (~10−6 s−1), the second in a region of intermediate horizontal strain rate (~10−5 s−1). Both experiments lasted ~6 days, covering spatial scales of 1–10 and 1–50 km for the low and intermediate strain rate regimes, respectively. Diapycnal diffusivities estimated from the two experiments were κz = (2–5) × 10−6 m2 s−1, while isopycnal diffusivities were κH = (0.2–3) m2 s−1, with the range in κH being less a reflection of site-to-site variability, and more due to uncertainties in the background strain rate acting on the patch combined with uncertain time dependence. The Site I (low strain) experiment exhibited minimal stretching, elongating to approximately 10 km over 6 days while maintaining a width of ~5 km, and with a notable vertical tilt in the meridional direction. By contrast, the Site II (intermediate strain) experiment exhibited significant stretching, elongating to more than 50 km in length and advecting more than 150 km while still maintaining a width of order 3–5 km. Early surveys from both experiments showed patchy distributions indicative of small-scale stirring at scales of order a few hundred meters. Later surveys show relatively smooth, coherent distributions with only occasional patchiness, suggestive of a diffusive rather than stirring process at the scales of the now larger patches. Together the two experiments provide important clues as to the rates and underlying processes driving diapycnal and isopycnal mixing at these scales.Results are presented from two dye release experiments conducted in the seasonal thermocline of the Sargasso Sea, one in a region of low horizontal strain rate (~10−6 s−1), the second in a region of intermediate horizontal strain rate (~10−5 s−1). Both experiments lasted ~6 days, covering spatial scales of 1–10 and 1–50 km for the low and intermediate strain rate regimes, respectively. Diapycnal diffusivities estimated from the two experiments were κz = (2–5) × 10−6 m2 s−1, while isopycnal diffusivities were κH = (0.2–3) m2 s−1, with the range in κH being less a reflection of site-to-site variability, and more due to uncertainties in the background strain rate acting on the patch combined with uncertain time dependence. The Site I (low strain) experiment exhibited minimal stretching, elongating to approximately 10 km over 6 days while maintaining a width of ~5 km, and with a notable vertical tilt in the meridional direction. By contrast, the Site II (intermediate strain) experiment exhibited significant stretching, elongating to more than 50 km in length and advecting more than 150 km while still maintaining a width of order 3–5 km. Early surveys from both experiments showed patchy distributions indicative of small-scale stirring at scales of order a few hundred meters. Later surveys show relatively smooth, coherent distributions with only occasional patchiness, suggestive of a diffusive rather than stirring process at the scales of the now larger patches. Together the two experiments provide important clues as to the rates and underlying processes driving diapycnal and isopycnal mixing at these scales.2020-08-0

Age-Stratified QTL Genome Scan Analyses for Anthropometric Measures

With the availability of longitudinal data, age-specific (stratified) or age-adjusted genetic analyses have the potential to localize different putative trait influencing loci. If age does not influence the locus-specific penetrance function within the range examined, age-stratified analyses will tend to yield comparable results for an individual trait. However, age-stratified results should vary across age strata when the locus-specific penetrance function is age dependent. In this paper, age-stratified and age-adjusted quantitative trait loci (QTL) linkage analyses were contrasted for height, weight, body mass index (BMI), and systolic blood pressure on a subset of the Framingham Heart Study. The strata comprised individuals with data present in each of three age groups: 31–49, 50–60, 61–79. Genome-wide QTL analyses were performed using SOLAR. Over all ages, a linkage signal for height was detected on chromosome 14q11.2 near marker GATA74E02A (LOD for ages 31–49 = 2.38, LOD for ages 50–60 = 1.84, LOD for ages 61–79 = 2.45). Evidence of linkage to BMI in the 31–49 age group was found on chromosome 3q22 (GATA3C02, LOD = 2.89, p = 0.0003) at the same location as the signal for weight (LOD = 3.10, p = 0.0002). Linkage was also supported on chromosome 1p22.1 for BMI (LOD = 2.21, p = 0.0014) and weight (LOD = 2.47, p = 0.0007) in the 31–49 age group. Our age-stratified results suggest that QTL that are expressed over long periods of time and affecting multiple, correlated traits may be identified using genome scan and variance-component methodology to help detect early and/or late gene expression