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result(s) for
"Beck, John G."
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A comparison of differential rotation measurements – (Invited Review)
2000
Observers have long measured solar rotation with different techniques and obtained different results. This paper compares differential rotation measurements from four techniques: Doppler shift, Doppler feature tracking, magnetic feature tracking, and p-mode splittings. The different rotation rates measured by the first three techniques are interpreted as rotation rates of solar phenomena which depend on the properties and depth of that which is measured. This interpretation is supported by comparison with rotation measurements obtained from p-mode splittings except for Doppler features. The rotation rate of the plasma corresponds to the surface rate obtained by inversions; the rates of magnetic features correspond to the rotation rate at various depths within the convection zone. Supergranulation rotates at a rate greater than the maximum rotation rate within the convection zone, suggesting that supergranules are not simple convection cells anchored at a particular depth.[PUBLICATION ABSTRACT]
Journal Article
Analysis of Supergranule Sizes and Velocities Using Solar Dynamics Observatory (SDO)/Helioseismic Magnetic Imager (HMI) and Solar and Heliospheric Observatory (SOHO)/Michelson Doppler Imager (MDI) Dopplergrams
by
Beck, John G.
,
Lee, Shannon
,
Williams, Peter E.
in
Astrophysics and Astroparticles
,
Atmospheric Sciences
,
Flow velocity
2014
Co-temporal Doppler images from
Solar and Heliospheric Observatory
(SOHO)/
Michelson Doppler Imager
(MDI) and
Solar Dynamics Observatory
(SDO)/
Helioseismic Magnetic Imager
(HMI) have been analyzed to extract quantitative information about global properties of the spatial and temporal characteristics of solar supergranulation. Preliminary comparisons show that supergranules appear to be smaller and have stronger horizontal velocity flows within HMI data than was measured with MDI. There appears to be no difference in their evolutionary timescales. Supergranule sizes and velocities were analyzed over a ten-day time period at a 15-minute cadence. While the averages of the time-series retain the aforementioned differences, fluctuations of these parameters first observed in MDI data were seen in both MDI and HMI time-series, exhibiting a strong cross-correlation. This verifies that these fluctuations are not instrumental, but are solar in origin. The observed discrepancies between the averaged values from the two sets of data are a consequence of instrument resolution. The lower spatial resolution of MDI results in larger observed structures with lower velocities than is seen in HMI. While these results offer a further constraint on the physical nature of supergranules, they also provide a level of calibration between the two instruments.
Journal Article
Supergranulation rotation
2000
Simple convection models estimate the depth of supergranulation at approximately 7500 km which suggests that supergranules would rotate at the rate of the plasma in the outer 1% of the solar radius. The supergranulation rotation obtained from MDI dopplergrams shows that supergranules rotate faster than the outer 5% of the convection zone and show zonal flows matching results from inversions of f-mode splittings. Additionally, the rotation rate depends on the size scale of the features.[PUBLICATION ABSTRACT]
Journal Article
Analysis of Supergranule Sizes and Velocities Using Solar Dynamics Observatory (SDO)/Helioseismic Magnetic Imager (HMI) and Solar and Heliospheric Observatory (SOHO)/Michelson Doppler Imager (MDI) Dopplergrams
2013
Co-temporal Doppler images from Solar and Heliospheric Observatory (SOHO)/ Michelson Doppler Imager (MDI) and Solar Dynamics Observatory (SDO)/Helioseismic Magnetic Imager (HMI) have been analyzed to extract quantitative information about global properties of the spatial and temporal characteristics of solar supergranulation. Preliminary comparisons show that supergranules appear to be smaller and have stronger horizontal velocity flows within HMI data than was measured with MDI. There appears to be no difference in their evolutionary timescales. Supergranule sizes and velocities were analyzed over a ten-day time period at a 15-minute cadence. While the averages of the time-series retain the aforementioned differences, fluctuations of these parameters first observed in MDI data were seen in both MDI and HMI time-series, exhibiting a strong cross-correlation. This verifies that these fluctuations are not instrumental, but are solar in origin. The observed discrepancies between the averaged values from the two sets of data are a consequence of instrument resolution. The lower spatial resolution of MDI results in larger observed structures with lower velocities than is seen in HMI. While these results offer a further constraint on the physical nature of supergranules, they also provide a level of calibration between the two instruments.
Journal Article
Analysis of Supergranule Sizes and Velocities Using Solar Dynamics Observatory (SDO)/Helioseismic Magnetic Imager (HMI) and Solar and Heliospheric Observatory (SOHO)/Michelson Doppler Imager (MDI) Dopplergrams
2013
Co-temporal Doppler images from Solar and Heliospheric Observatory (SOHO)/ Michelson Doppler Imager (MDI) and Solar Dynamics Observatory (SDO)/Helioseismic Magnetic Imager (HMI) have been analyzed to extract quantitative information about global properties of the spatial and temporal characteristics of solar supergranulation. Preliminary comparisons show that supergranules appear to be smaller and have stronger horizontal velocity flows within HMI data than was measured with MDI. There appears to be no difference in their evolutionary timescales. Supergranule sizes and velocities were analyzed over a ten-day time period at a 15-minute cadence. While the averages of the time-series retain the aforementioned differences, fluctuations of these parameters first observed in MDI data were seen in both MDI and HMI time-series, exhibiting a strong cross-correlation. This verifies that these fluctuations are not instrumental, but are solar in origin. The observed discrepancies between the averaged values from the two sets of data are a consequence of instrument resolution. The lower spatial resolution of MDI results in larger observed structures with lower velocities than is seen in HMI. While these results offer a further constraint on the physical nature of supergranules, they also provide a level of calibration between the two instruments.
Journal Article
Year-2000 customer risk assessment
1999
While it is safe to say that the typical asset-based borrower does not have a Y2K problem of the magnitude of most large corporations, asset-based borrowers also have limited capital resources. One asset-based finance field examination unit has crafted a Y2K audit program consisting of a series of probing questions regarding a borrower's or prospect's understanding of the Y2K problem and their preparation for dealing with it. The objective is to determine whether the customer has sufficient awareness of the issue and has established a process to become Y2K-compliant.
Journal Article
Respirator Physiology Research: Answers in Search of the Question
by
Beck, John G.
,
Harber, Philip
,
Brown, Carol L.
in
Adaptation, Physiological
,
Heart Rate
,
Humans
1991
Adverse effects of respirators have been the focus of considerable research over the past decade. Individual research projects have generally focused on one specifíc category of effects: ventilatory, respiratory control, work limitation, subjective discomfort, psychologic effects, thermal loading, and cardiovascular changes. Most were studied in experimental laboratory situations rather than in actual worksites. Very little attention has been given to compliance with use and actual effectiveness in preserving health. Inasmuch as many types of effects have been demonstrated, there is a need to carefully define which type(s) of effects is/are most important for respirator design selection and worker medical certification in particular situations. In general, respirators should be assessed for their effect on all relevant variables.
Journal Article
Faded glory : an industry (life insurance) in transition (repeal of Sections 818c and 820 of Tax Code and its unfortunate results)
1990
After World War II, the US life insurance industry was a market where easy money abounded, which drew reinsurers from Europe, which increased competition, which led to price wars. To protect profits, insurers began abusing the US Tax Code, until the 1984 Congress repealed the provisions of which insurers had taken advantage. Many companies then turned to universal life, but the assumptions underlying this shift (mortality savings and interest- crediting gains) never panned out. Many companies, now are going back to whole life, but in an alteredenvironment, with banks involved in insurance marketing and a national health care system on the horizon.
Journal Article
Died
by
Beck, John G
,
Harn, A
1864
...--At New Bedford, ... on Saturday, Augusto, JOHN AFT, in the ... year of ...
Newspaper Article
Evaluation of 18 Satellite- and Model-Based Soil Moisture Products Using in Situ Measurements From 826 Sensors
by
Sheffield, Justin
,
Beck, Hylke E.
,
Kimball, John S.
in
Brightness temperature
,
Calibration
,
Data assimilation
2021
Information about the spatiotemporal variability of soil moisture is critical for many purposes, including monitoring of hydrologic extremes, irrigation scheduling, and prediction of agricultural yields. We evaluated the temporal dynamics of 18 state-of-the-art (quasi-)global near-surface soil moisture products, including six based on satellite retrievals, six based on models without satellite data assimilation (referred to hereafter as “open-loop” models), and six based on models that assimilate satellite soil moisture or brightness temperature data. Seven of the products are introduced for the first time in this study: one multi-sensor merged satellite product called MeMo (Merged soil Moisture) and six estimates from the HBV (Hydrologiska Byråns Vattenbalansavdelning) model with three precipitation inputs (ERA5, IMERG, and MSWEP) with and without assimilation of SMAPL3E satellite retrievals, respectively. As reference, we used in situ soil moisture measurements between 2015 and 2019 at 5 cm depth from 826 sensors, located primarily in the USA and Europe. The 3-hourly Pearson correlation (R) was chosen as the primary performance metric. We found that application of the Soil Wetness Index (SWI) smoothing filter resulted in improved performance for all satellite products. The best-to-worst performance ranking of the four single-sensor satellite products was SMAPL3ESWI, SMOSSWI, AMSR2SWI, and ASCATSWI, with the L-band-based SMAPL3ESWI (median R of 0.72) outperforming the others at 50 % of the sites. Among the two multi-sensor satellite products (MeMo and ESA-CCISWI), MeMo performed better on average (median R of 0.72 versus 0.67), probably due to the inclusion of SMAPL3ESWI. The best-to-worst performance ranking of the six open-loop models was HBV-MSWEP, HBV-ERA5, ERA5-Land, HBV-IMERG, VIC-PGF, and GLDAS-Noah. This ranking largely reflects the quality of the precipitation forcing. HBV-MSWEP (median R of 0.78) performed best not just among the open-loop models but among all products. The calibration of HBV improved the median R by +0.12 on average compared to random parameters, highlighting the importance of model calibration. The best-to-worst performance ranking of the six models with satellite data assimilation was HBV-MSWEP+SMAPL3E, HBV-ERA5+SMAPL3E, GLEAM, SMAPL4, HBV-IMERG+SMAPL3E, and ERA5. The assimilation of SMAPL3E retrievals into HBV-IMERG improved the median R by +0.06, suggesting that data assimilation yields significant benefits at the global scale.
Journal Article