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Author Deng, J.; Wu, Z.; Zhang, M.; Huang, N.E.; Wang, S.; Qiao, F.
Title Using Holo-Hilbert spectral analysis to quantify the modulation of Dansgaard-Oeschger events by obliquity Type $loc['typeJournal Article']
Year 2018 Publication Quaternary Science Reviews Abbreviated Journal Quaternary Science Reviews
Volume 192 Issue Pages 282-299
Keywords Pleistocene; Paleoclimatology; Greenland; Antarctica; Data treatment; Data analysis; Dansgaard-oeschger (DO) events; Obliquity forcing; Phase preference; Holo-hilbert spectral analysis; Amplitude modulation; EMPIRICAL MODE DECOMPOSITION; GREENLAND ICE-CORE; NONSTATIONARY TIME-SERIES; ABRUPT CLIMATE-CHANGE; LAST GLACIAL PERIOD; NORTH-ATLANTIC; MILLENNIAL-SCALE; RECORDS; VARIABILITY; CYCLE
Abstract Astronomical forcing (obliquity and precession) has been thought to modulate Dansgaard-Oeschger (DO) events, yet the detailed quantification of such modulations has not been examined. In this study, we apply the novel Holo-Hilbert Spectral Analysis (HHSA) to five polar ice core records, quantifying astronomical forcing's time-varying amplitude modulation of DO events and identifying the preferred obliquity phases for large amplitude modulations. The unique advantages of HHSA over the widely used windowed Fourier spectral analysis for quantifying astronomical forcing's nonlinear modulations of DO events is first demonstrated with a synthetic data that closely resembles DO events recorded in Greenland ice cores (NGRIP, GRIP, and GISP2 cores on GICC05 modelext timescale). The analysis of paleoclimatic proxies show that statistically significantly more frequent DO events, with larger amplitude modulation in the Greenland region, tend to occur in the decreasing phase of obliquity, especially from its mean value to its minimum value. In the eastern Antarctic, although statistically significantly more DO events tend to occur in the decreasing obliquity phase in general, the preferred phase of obliquity for large amplitude modulation on DO events is a segment of the increasing phase near the maximum obliquity, implying that the physical mechanisms of DO events may be different for the two polar regions. Additionally, by using cross-spectrum and magnitude-squared analyses, Greenland DO mode at a timescale of about 1400 years leads the Antarctic DO mode at the same timescale by about 1000 years. (C) 2018 Elsevier Ltd. All rights reserved.
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Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0277-3791 ISBN Medium
Area Expedition Conference
Funding Approved $loc['no']
Call Number COAPS @ user @ Serial 971
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Author Kelly, T.B.; Goericke, R.; Kahru, M.; Song, H.; Stukel, M.R.
Title CCE II: Spatial and interannual variability in export efficiency and the biological pump in an eastern boundary current upwelling system with substantial lateral advection Type $loc['typeJournal Article']
Year 2018 Publication Deep Sea Research Part I: Oceanographic Research Papers Abbreviated Journal Deep Sea Research Part I: Oceanographic Research Papers
Volume 140 Issue Pages 14-25
Keywords CALIFORNIA CURRENT ECOSYSTEM; OCEAN CARBON-CYCLE; COASTAL WATERS; FRONTAL ZONE; TIME-SERIES; FLUX; SINKING; SEA; PACIFIC; ZOOPLANKTON
Abstract Estimating interannual variability in carbon export is a key goal of many marine biogeochemical studies. However, due to variations in export mechanisms between regions, generalized models used to estimate global patterns in export often fail when used for intra-regional analysis. We present here a region-specific model of export production for the California Current Ecosystem (CCE) parameterized using intensive Lagrangian process studies conducted during El Niño-Southern Oscillation (ENSO) warm and neutral phases by the CCE Long-Term Ecological Research (LTER) program. We find that, contrary to expectations from prominent global algorithms, export efficiency (e-ratio = export / primary productivity) is positively correlated with temperature and negatively correlated with net primary productivity (NPP). We attribute these results to the substantial horizontal advection found within the region, and verify this assumption by using a Lagrangian particle tracking model to estimate water mass age. We further suggest that sinking particles in the CCE are comprised of a recently-produced, rapidly-sinking component (likely mesozooplankton fecal pellets) and a longer-lived, slowly-sinking component that is likely advected long distances prior to export. We determine a new algorithm for estimating particle export in the CCE from NPP (Export = 0.08 · NPP + 72 mg C m-2 d-1). We apply this algorithm to a two-decade long time series of NPP in the CCE to estimate spatial and interannual variability across multiple ENSO phases. Reduced export during the warm anomaly of 2014-2015 and El Niño 2015-2016 resulted primarily from decreased export in the coastal upwelling region of the CCE; the oligotrophic offshore region exhibited comparatively low seasonal and interannual variability in flux. The model resolves intra-regional patterns of in situ export measurements, and provides a valuable contrast to global export models.
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Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0967-0637 ISBN Medium
Area Expedition Conference
Funding Approved $loc['no']
Call Number COAPS @ rl18 @ Serial 984
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Author Kelly, T.B.; Goericke, R.; Kahru, M.; Song, H.; Stukel, M.R.
Title CCE II: Spatial and interannual variability in export efficiency and the biological pump in an eastern boundary current upwelling system with substantial lateral advection Type $loc['typeJournal Article']
Year 2018 Publication Deep Sea Research Part I: Oceanographic Research Papers Abbreviated Journal Deep Sea Research Part I: Oceanographic Research Papers
Volume 140 Issue Pages 14-25
Keywords california current ecosystem; coastal waters; flux; frontal zone; ocean carbon-cycle; oceanography; pacific; sea; sinking; time-series; Zooplankton
Abstract
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Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0967-0637 ISBN Medium
Area Expedition Conference
Funding Approved $loc['no']
Call Number COAPS @ user @ Serial 1022
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Author Liu, M.; Lin, J.; Wang, Y.; Sun, Y.; Zheng, B.; Shao, J.; Chen, L.; Zheng, Y.; Chen, J.; Fu, T.-M.; Yan, Y.; Zhang, Q.; Wu, Z.
Title Spatiotemporal variability of NO2 and PM2.5 over Eastern China: observational and model analyses with a novel statistical method Type $loc['typeJournal Article']
Year 2018 Publication Atmospheric Chemistry and Physics Abbreviated Journal Atmos. Chem. Phys.
Volume 18 Issue 17 Pages 12933-12952
Keywords TROPOSPHERIC NITROGEN-DIOXIDE; PROVINCIAL CAPITAL CITIES; CRITERIA AIR-POLLUTANTS; BOUNDARY-LAYER; NORTH CHINA; HILBERT SPECTRUM; UNITED-STATES; TIME-SERIES; OZONE; EMISSIONS
Abstract Eastern China (27-41 degrees N, 110-123 degrees E) is heavily polluted by nitrogen dioxide (NO2), particulate matter with aerodynamic diameter below 2.5 mu m (PM2.5), and other air pollutants. These pollutants vary on a variety of temporal and spatial scales, with many temporal scales that are nonperiodic and nonstationary, challenging proper quantitative characterization and visualization. This study uses a newly compiled EOF-EEMD analysis visualization package to evaluate the spatiotemporal variability of ground-level NO2, PM2.5, and their associations with meteorological processes over Eastern China in fall-winter 2013. Applying the package to observed hourly pollutant data reveals a primary spatial pattern representing Eastern China synchronous variation in time, which is dominated by diurnal variability with a much weaker day-to-day signal. A secondary spatial mode, representing north-south opposing changes in time with no constant period, is characterized by wind-related dilution or a buildup of pollutants from one day to another.

We further evaluate simulations of nested GEOS-Chem v9-02 and WRF/CMAQ v5.0.1 in capturing the spatiotemporal variability of pollutants. GEOS-Chem underestimates NO2 by about 17 mu g m(-3) and PM2.5 by 35 mu g m(-3 )on average over fall-winter 2013. It reproduces the diurnal variability for both pollutants. For the day-to-day variation, GEOS-Chem reproduces the observed north-south contrasting mode for both pollutants but not the Eastern China synchronous mode (especially for NO2). The model errors are due to a first model layer too thick (about 130 m) to capture the near-surface vertical gradient, deficiencies in the nighttime nitrogen chemistry in the first layer, and missing secondary organic aerosols and anthropogenic dust. CMAQ overestimates the diurnal cycle of pollutants due to too-weak boundary layer mixing, especially in the nighttime, and overestimates NO2 by about 30 mu g m(-3) and PM2.5 by 60 mu g m(-3). For the day-to-day variability, CMAQ reproduces the observed Eastern China synchronous mode but not the north-south opposing mode of NO2. Both models capture the day-to-day variability of PM2.5 better than that of NO2. These results shed light on model improvement. The EOF-EEMD package is freely available for noncommercial uses.
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Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1680-7324 ISBN Medium
Area Expedition Conference
Funding Approved $loc['no']
Call Number COAPS @ user @ Serial 946
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Author Zhang, M.; Wu, Z.; Qiao, F.
Title Deep Atlantic Ocean Warming Facilitated by the Deep Western Boundary Current and Equatorial Kelvin Waves Type $loc['typeJournal Article']
Year 2018 Publication Journal of Climate Abbreviated Journal J. Climate
Volume 31 Issue 20 Pages 8541-8555
Keywords Ocean; Atlantic Ocean; Heating; Kelvin waves; Ocean circulation; Oceanic variability; EMPIRICAL MODE DECOMPOSITION; NONSTATIONARY TIME-SERIES; NORTH-ATLANTIC; CLIMATE-CHANGE; HEAT-CONTENT; HIATUS; VARIABILITY; CIRCULATION; TEMPERATURE; PACIFIC
Abstract Increased heat storage in deep oceans has been proposed to account for the slowdown of global surface warming since the end of the twentieth century. How the imbalanced heat at the surface has been redistributed to deep oceans remains to be elucidated. Here, the evolution of deep Atlantic Ocean heat storage since 1950 on multidecadal or longer time scales is revealed. The anomalous heat in the deep Labrador Sea was transported southward by the shallower core of the deep western boundary current (DWBC). Upon reaching the equator around 1980, this heat transport route bifurcated into two, with one continuing southward along the DWBC and the other extending eastward along a narrow strip (about 4 degrees width) centered at the equator. In the 1990s and 2000s, meridional diffusion helped to spread warming in the tropics, making the eastward equatorial warming extension have a narrow head and wider tail. The deep Atlantic Ocean warming since 1950 had overlapping variability of approximately 60 years. The results suggest that the current basinwide Atlantic Ocean warming at depths of 1000-2000 m can be traced back to the subsurface warming in the Labrador Sea in the 1950s. An inference from these results is that the increased heat storage in the twenty-first century in the deep Atlantic Ocean is unlikely to partly account for the atmospheric radiative imbalance during the last two decades and to serve as an explanation for the current warming hiatus.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0894-8755 ISBN Medium
Area Expedition Conference
Funding Approved $loc['no']
Call Number COAPS @ user @ Serial 950
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