scholarly journals Cross-Calibrations of the HY-2B Altimeter Using Jason-3 Satellite During the Period of April 2019–September 2020

2021 ◽  
Vol 9 ◽  
Author(s):  
Jianbo Wang ◽  
Huan Xu ◽  
Lei Yang ◽  
Qingjun Song ◽  
Chaofei Ma
Keyword(s):  
Satellite Altimeter ◽  
Sea Level Anomalies ◽  
Global Quality ◽  
Sea State Bias ◽  
Crossover Analysis ◽  
Wave Heights ◽  
Sea Surface Heights ◽  
Global Oceans ◽  
Assessment Results

In 2018, the Haiyang-2B (HY-2B) satellite altimeter was sent to orbit as a follow-up mission of the HY-2A satellite altimeter. The performance of the HY-2B system over the global oceans is considered to be critical. However, its performance is not fully known at the present time. In the present study, the first global quality assessment of the HY-2B Geophysical Data Record (GDR) was presented using comparison and crossover analysis processes of the main parameters and sea level anomalies (SLAs) with Jason-3 GDR data. This study’s assessment results demonstrated that the editing proportion of unqualified data for the HY-2B was 2.67%, which was at a similar level as the Jason-3 (2.86%). In addition, this study’s assessment results of the HY-2B key parameters (mainly the backscatter coefficients, significant wave heights, sea state bias, wet troposphere delays, and ionosphere delays) showed good agreement with the Jason-3, and there were no abnormal trends observed. The mean and standard deviations (STDs) were determined to be (0.21 ± 6.70) cm and (−3.4 ± 6.25) cm for the SLA differences at the self-crossover points of the HY-2B and dual-crossover points between the HY-2B and Jason-3 satellites, respectively. In addition, the SLA crossover analysis results indicated that the accuracy of the sea surface heights for the HY-2B was close to that of the Jason-3 satellite. The spatial distributions of the SLA differences showed no significant errors in the geographic characteristics. The SLA measurements were assessed using a wavenumber spectra method. The obtained results suggested that the power spectrum of the SLAs of the HY-2B satellite followed the regular patterns of the traditional Jason-3 altimeter. Furthermore, based on the spectrum analysis results, it was revealed that the noise level of the HY-2B was lower than that of the Jason-3, indicating a good overall performance of the HY-2B.

scholarly journals Multicore structures and the splitting and merging of eddies in global oceans from satellite altimeter data

2018 ◽  
Author(s):  
Wei Cui ◽  
Wei Wang ◽  
Jie Zhang ◽  
Jungang Yang
Keyword(s):  
Intermediate Stage ◽  
Altimeter Data ◽  
Western Boundary ◽  
Mean Flow ◽  
Sea Level Anomalies ◽  
Strong Current ◽  
A Cell ◽  
Circumpolar Current ◽  
Overlap Ratio ◽  
Global Oceans

Abstract. This study investigated the statistics of eddy splitting and merging in the global oceans based on 23 years’ altimetry data. Multicore structures were identified using an improved threshold-free closed-contour algorithm of sea surface height. Splitting and merging events were discerned from continuous time series maps of sea level anomalies. Multicore structures represent an intermediate stage in the process of eddy evolution, similar to the generation of multiple nuclei in a cell as a preparatory phase for cell division. Generally, splitting or merging events can change substantially (by a factor of two or more) the eddy scale, amplitude, and eddy kinetic energy. Specifically, merging (splitting) generally causes an increase (decrease) of eddy properties. Multicore eddies were found to tend to split into two eddies with different intensities. Similarly, eddy merging is not an interaction of two equal-intensity eddies, and that it tends to manifest as a strong eddy merging with a weaker one. A hybrid tracking strategy based on the eddy overlap ratio, considering both multicore and single-core eddies, was used to confirm splitting and merging events globally. The census revealed that eddy splitting and merging do not always occur most frequently in eddy-rich regions, e.g., their frequencies of occurrence in the Antarctic Circumpolar Current and western boundary currents were found obviously higher than mid-latitude regions (20°–35°) north and south. Eddy splitting and merging are caused primarily by an unstable configuration of multicore structures due to obvious current– or eddy–topography interaction, strong current variation, and eddy–mean flow interaction.

scholarly journals Case-crossover analysis of short-term particulate matter exposures and stroke in the health professionals follow-up study

2019 ◽  
Vol 124 ◽  
pp. 153-160 ◽  
Author(s):  
Jared A. Fisher ◽  
Robin C. Puett ◽  
Francine Laden ◽  
Gregory A. Wellenius ◽  
Amir Sapkota ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Health Professionals ◽  
Short Term ◽  
Follow Up Study ◽  
Case Crossover ◽  
Crossover Analysis

Directional correction of modeled sea and swell wave heights using satellite altimeter data

2018 ◽  
Vol 131 ◽  
pp. 103-114 ◽  
Author(s):  
João Albuquerque ◽  
Jose A.A. Antolínez ◽  
Ana Rueda ◽  
Fernando J. Méndez ◽  
Giovanni Coco
Keyword(s):  
Altimeter Data ◽  
Satellite Altimeter ◽  
Wave Heights ◽  
Satellite Altimeter Data

scholarly journals On the Use of Satellite Altimeter Data in Argo Quality Control

2009 ◽  
Vol 26 (2) ◽  
pp. 395-402 ◽  
Author(s):  
Stephanie Guinehut ◽  
Christine Coatanoan ◽  
Anne-Lise Dhomps ◽  
Pierre-Yves Le Traon ◽  
Gilles Larnicol
Keyword(s):  
Time Series ◽  
Quality Control ◽  
Real Time ◽  
Altimeter Data ◽  
Satellite Altimeter ◽  
Sea Level Anomalies ◽  
The Impact ◽  
Satellite Altimeter Data ◽  
Made In

Abstract Satellite altimeter measurements are used to check the quality of the Argo profiling floats time series. The method compares collocated sea level anomalies from altimeter measurements and dynamic height anomalies calculated from Argo temperature and salinity profiles for each Argo float time series. Different kinds of anomalies (sensor drift, bias, spikes, etc.) have been identified on some real-time but also delayed-mode Argo floats. About 4% of the floats should probably not be used until they are carefully checked and reprocessed by the principal investigators (PIs). The method appears to be very complementary to the existing quality control checks performed in real time or delayed mode. It could also be used to quantify the impact of the adjustments made in delayed mode on the pressure, temperature, and salinity fields.

scholarly journals Disability and Symptom Burden Among the Very Old: Comparison of Survivors and Decedents

2020 ◽  
Vol 4 (Supplement_1) ◽  
pp. 230-231
Author(s):  
Xinran Liu ◽  
Steven Albert
Keyword(s):  
Symptom Burden ◽  
Time Of Death ◽  
Very Old ◽  
Global Quality ◽  
Global Quality Of Life ◽  
Severity Of Disability ◽  
Disability Prevalence ◽  
Loss Of Appetite

Abstract How does disability and symptom burden among the very old differ between those who die and those who do not die over 12 months? We explored patterns of disability and symptom burden in the Health ABC cohort study, which involved quarterly phone interviews in 2011-14 (years 15-17). A proxy completed the interview when the proband was unable to participate. We identified a sample of 291 decedents with at least 1-year of follow-up before death and matched a 1:1 sample of survivors at the time of death by race, sex, and age (within ±3 years). 252 decedents (age 90.0±3.03, 65.1% Black, 52.4% female) and 288 survivors (age 90.1±3.03, 64.9% Black, 52.4% female) with at least 3 quarterly interviews were included for analysis. Decedents had a higher proportion of proxy-reported interviews compared to survivors (40.9%vs16.0%, P<0.01). Disability prevalence among decedents was significantly higher (P<0.01) compared to survivors (using an assisted walking device, 62.3%vs37.4%; difficulty getting in/out of bed, 32.0%vs19.4%; difficulty bath/shower, 28.9%vs10.0%; difficulty dressing, 19.0%vs8.7%). Decedents and survivors differed significantly (P<0.05) in self-reported number of symptoms (2.35vs1.78), severity of disability due to shortness of breath (4.09vs2.04), constipation (3.97vs1.74), and difficulty concentrating (1.98vs1.25). Decedents also had a significant higher score (P<0.01) on self-reported loss of appetite (2.24vs1.91) and worse global quality of life rating (3.04vs2.64), compared to survivors. The patterns were similar in proxy-reported group and in the group with a combination of self-and proxy-reported interviews. Even in very late old age, disability and symptom burden increase with the approach of death.

scholarly journals Air pollution exposure and risk of spontaneous abortion in the Nurses’ Health Study II

2019 ◽  
Vol 34 (9) ◽  
pp. 1809-1817 ◽  
Author(s):  
Audrey J Gaskins ◽  
Jaime E Hart ◽  
Jorge E Chavarro ◽  
Stacey A Missmer ◽  
Janet W Rich-Edwards ◽  
...  
Keyword(s):  
Air Pollution ◽  
Spontaneous Abortion ◽  
Pregnancy Outcomes ◽  
Ambient Air ◽  
Ambient Air Pollution ◽  
Health Study ◽  
Case Crossover ◽  
Increased Risk ◽  
Crossover Analysis

Abstract STUDY QUESTION Is there an association between air pollution exposures and the risk of spontaneous abortion (SAB)? SUMMARY ANSWER Higher exposure to particulate matter (PM) air pollution above and beyond a woman’s average exposure may be associated with greater risk of SAB, particularly among women experiencing at least one SAB during follow-up. WHAT IS KNOWN ALREADY There is sufficient biologic plausibility to suggest that air pollution adversely affects early pregnancy outcomes, particularly pregnancy loss; however, the evidence is limited. STUDY DESIGN, SIZE, DURATION Our prospective cohort study included 19 309 women in the Nurses’ Health Study II who contributed a total of 35 025 pregnancies between 1990 and 2008. We also conducted a case-crossover analysis among 3585 women (11 212 pregnancies) with at least one SAB and one live birth during follow-up. PARTICIPANTS/MATERIALS, SETTING, METHODS Proximity to major roadways and exposure to PM <10 microns (PM10), 2.5–10 microns (PM2.5–10) and <2.5 microns (PM2.5) were determined for residential addresses between 1989 and 2007. Pregnancy outcomes were self-reported biannually throughout follow-up and comprehensively in 2009. Multivariable log-binomial regression models with generalized estimating equations were used to estimate the risk ratios and 95% CIs of SAB. Conditional logistic regression was used for the case-crossover analysis. MAIN RESULTS AND THE ROLE OF CHANCE During the 19 years of follow-up, 6599 SABs (18.8% of pregnancies) were reported. In the main analysis, living closer to a major roadway and average exposure to PM10, PM10–2.5 or PM2.5 in the 1 or 2 years prior to pregnancy were not associated with an increased risk of SAB. However, small positive associations between PM exposures and SAB were observed when restricting the analysis to women experiencing at least one SAB during follow-up. In the case-crossover analysis, an increase in PM10 (per 3.9 μg/m3), PM2.5–10 (per 2.3 μg/m3) and PM2.5 (per 2.0 μg/m3) in the year prior to pregnancy was associated with 1.12 (95% CI 1.06, 1.19), 1.09 (95% CI 1.03, 1.14) and 1.10 (95% CI 1.04, 1.17) higher odds of SAB, respectively. LIMITATIONS, REASONS FOR CAUTION We did not have information on the month or day of SAB, which precluded our ability to examine specific windows of susceptibility or acute exposures. We also used ambient air pollution exposures as a proxy for personal exposure, potentially leading to exposure misclassification. WIDER IMPLICATIONS OF THE FINDINGS In our case-crossover analysis (but not in the entire cohort) we observed positive associations between exposure to all size fractions of PM exposure and risk of SAB. This may suggest that changes in PM exposure confer greater risk of SAB or that women with a history of SAB are a particularly vulnerable subgroup. STUDY FUNDING/COMPETING INTEREST(S) The authors are supported by the following NIH grants UM1CA176726, R00ES026648 and P30ES000002. The authors have no actual or potential competing financial interests to disclose.

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