scholarly journals Persistent homology of time-dependent functional networks constructed from coupled time series

2017 ◽  
Vol 27 (4) ◽  
pp. 047410 ◽  
Author(s):  
Bernadette J. Stolz ◽  
Heather A. Harrington ◽  
Mason A. Porter
Keyword(s):  
Time Series ◽  
Persistent Homology ◽  
Time Dependent ◽  
Functional Networks

scholarly journals Onboard Radio Frequency Interference as the Origin of Inter-Satellite Biases for Microwave Humidity Sounders

2019 ◽  
Vol 11 (7) ◽  
pp. 866 ◽  
Author(s):  
Imke Hans ◽  
Martin Burgdorf ◽  
Stefan A. Buehler
Keyword(s):  
Time Series ◽  
Radio Frequency ◽  
Time Dependent ◽  
Radio Frequency Interference ◽  
Climate Variables ◽  
Compelling Evidence ◽  
Climate Data ◽  
The Earth ◽  
Correction Scheme

Understanding the causes of inter-satellite biases in climate data records from observations of the Earth is crucial for constructing a consistent time series of the essential climate variables. In this article, we analyse the strong scan- and time-dependent biases observed for the microwave humidity sounders on board the NOAA-16 and NOAA-19 satellites. We find compelling evidence that radio frequency interference (RFI) is the cause of the biases. We also devise a correction scheme for the raw count signals for the instruments to mitigate the effect of RFI. Our results show that the RFI-corrected, recalibrated data exhibit distinctly reduced biases and provide consistent time series.

scholarly journals On the Characterization and Forecasting of Ground Displacements of Ocean-Reclaimed Lands

2020 ◽  
Vol 12 (18) ◽  
pp. 2971
Author(s):  
Jingzhao Ding ◽  
Qing Zhao ◽  
Maochuan Tang ◽  
Fabiana Calò ◽  
Virginia Zamparelli ◽  
...  
Keyword(s):  
Time Series ◽  
Ground Deformation ◽  
Proper Time ◽  
Global Climate ◽  
Time Dependent ◽  
Ground Displacement ◽  
Data Set ◽  
Future Evolution ◽  
Adopted Model ◽  
Sar Data

In this work, we study ground deformation of ocean-reclaimed platforms as retrieved from interferometric synthetic aperture radar (InSAR) analyses. We investigate, in particular, the suitability and accuracy of some time-dependent models used to characterize and foresee the present and future evolution of ground deformation of the coastal lands. Previous investigations, carried out by the authors of this paper and other scholars, related to the zone of the ocean-reclaimed lands of Shanghai, have already shown that ocean-reclaimed lands are subject to subside (i.e., the ground is subject to settling down due to soil consolidation and compression), and the temporal evolution of that deformation follows a certain predictable model. Specifically, two time-gapped SAR datasets composed of the images collected by the ENVISAT ASAR (ENV) from 2007 to 2010 and the COSMO-SkyMed (CSK) sensors, available from 2013 to 2016, were used to generate long-term ground displacement time-series using a proper time-dependent geotechnical model. In this work, we use a third SAR data set consisting of Radarsat-2 (RST-2) acquisitions collected from 2012 to 2016 to further corroborate the validity of that model. As a result, we verified with the new RST-2 data, partially covering the gap between the ENV and CSK acquisitions, that the adopted model fits the data and that the model is suitable to perform future projections. Furthermore, we extended these analyses to the area of Pearl River Delta (PRD) and the city of Shenzhen, China. Our study aims to investigate the suitability of different time-dependent ground deformation models relying on the different geophysical conditions in the two areas of Shanghai and Shenzhen, China. To this aim, three sets of SAR data, collected by the ENV platform (from both ascending and descending orbits) and the Sentinel-1A (S1A) sensor (on ascending orbits), were used to obtain the ground displacement time-series of the Shenzhen city and its surrounding region. Multi-orbit InSAR data products were also combined to discriminate the up–down (subsidence) ground deformation time-series of the coherent points, which are then used to estimate the parameters of the models adopted to foresee the future evolution of the land-reclaimed ground consolidation procedure. The exploitation of the obtained geospatial data and products are helpful for the continuous monitoring of coastal environments and the evaluation of the socio-economical impacts of human activities and global climate change.

Oxidative stress and DNA damage in utero and embryo implantation of mice exposed to carbon disulfide at peri-implantation

2013 ◽  
Vol 33 (4) ◽  
pp. 424-434 ◽  
Author(s):  
L Yang ◽  
B Zhang ◽  
Y Yuan ◽  
C Li ◽  
Z Wang
Keyword(s):  
Oxidative Stress ◽  
Time Series ◽  
Dna Damage ◽  
Carbon Disulfide ◽  
Embryo Implantation ◽  
Reproductive Toxicity ◽  
Mouse Embryos ◽  
Time Dependent ◽  
Strong Negative Correlation ◽  
Endometrial Cells

Carbon disulfide (CS2) has reproductive toxicity but the mechanism remains unclear. The aim of the present study was to investigate the effect of oxidative stress and DNA damage on embryo implantation of mice exposed to CS2 at peri-implantation. CS2 exposure was on gestational day 3 (GD3), GD4, GD5 and GD6, separately, and the number of embryonic day 9 (E9) mouse embryos was obtained. DNA damage of endometrial cells, oxidative stress and 8-hydroxy-2′-deoxyguanosine (8-OH-dG) level in uterus tissues were tested with time series at different end points after exposure. The number of E9 mouse embryos significantly decreased in all CS2 exposure groups, especially on GD4 exposure. The rates of embryo implantation decreased by 43.05%, 63.74%, 60.45% and 47.26% for CS2 exposure on GD3, GD4, GD5 and GD6, respectively. Oxidative stress significantly increased within 24 h and reached the top level at 18 h after exposure. The same time-dependent trend was observed no matter when the exposure happened at peri-implantation. 8-OH-dG significantly increased at 18 h and 24 h after exposure by 893.8% and 647.4%, respectively, when compared with the control. The indexes of DNA damage significantly increased at 6 h after exposure, which appeared earlier than the changes of oxidative stress and 8-OH-dG. Besides, both oxidative stress and DNA damage showed a strong negative correlation with the number of E9 mouse embryos. The present study illustrated that CS2 directly induced DNA damage in endometrial cells and enhanced the action through oxidative stress, both of which were responsible for CS2-induced embryo loss.

Seasonal to multi-annual speedup and slowdown of Greenland outlet glaciers inferred from time-dependent remote sensing observations

2020 ◽  
Author(s):  
Lizz Ultee ◽  
Bryan Riel ◽  
Brent Minchew
Keyword(s):  
Time Series ◽  
Flow Velocity ◽  
Ice Sheet ◽  
Surface Air Temperature ◽  
Greenland Ice Sheet ◽  
Time Dependent ◽  
Surface Velocity ◽  
Short Term ◽  
Ice Flow

<p>The rate of ice flux from the Greenland Ice Sheet to the ocean depends on the ice flow velocity through outlet glaciers. Ice flow velocity, in turn, evolves in response to multiple geographic and environmental forcings at different timescales. For example, velocity may vary daily in response to ocean tides, seasonally in response to surface air temperature, and multi-annually in response to long-term trends in climate. The satellite observations processed as part of the NASA MEaSUREs Greenland Ice Sheet Velocity Map allow us to analyse variations in ice surface velocity at multiple timescales. Here, we decompose short-term and long-term signals in time-dependent velocity fields for Greenland outlet glaciers based on the methods of Riel et al. (2018). Patterns found in short-term signals can constrain basal sliding relations and ice rheology, while the longer-term signals hint at decadal in/stability of outlet glaciers. We present example velocity time series for outlets including Sermeq Kujalleq (Jakobshavn Isbrae) and Helheim Glacier, and we highlight features indicative of dynamic drawdown or advective restabilization. Finally, we comment on the capabilities of a time series analysis software under development for glaciological applications.</p>

scholarly journals First intercalibration of column-averaged methane from the Total Carbon Column Observing Network and the Network for the Detection of Atmospheric Composition Change

2012 ◽  
Vol 5 (1) ◽  
pp. 1355-1379
Author(s):  
F. Forster ◽  
R. Sussmann ◽  
M. Rettinger ◽  
N. M. Deutscher ◽  
D. W. T. Griffith ◽  
...  
Keyword(s):  
Time Series ◽  
Near Infrared ◽  
Calibration Factor ◽  
Time Dependent ◽  
Total Carbon ◽  
Atmospheric Composition ◽  
Composition Change ◽  
Data Set ◽  
The Difference ◽  
Difference Time

Abstract. We present the intercalibration of dry-air column-averaged mole fractions of methane (XCH4) retrieved from solar FTIR measurements of the Network for the Detection of Atmospheric Composition Change (NDACC) in the mid-infrared (MIR) versus near-infrared (NIR) soundings from the Total Carbon Column Observing Network (TCCON). The study uses multi-annual quasi-coincident MIR and NIR measurements from the stations Garmisch, Germany (47.48° N, 11.06° E, 743 m a.s.l.) and Wollongong, Australia (34.41° S, 150.88° E, 30 m a.s.l.). Direct comparison of the retrieved MIR and NIR time series shows a phase shift in XCH4 seasonality, i.e. a significant time-dependent bias leading to a standard deviation (stdv) of the difference time series (NIR-MIR) of 8.4 ppb. After eliminating differences in a prioris by using ACTM-simulated profiles as a common prior, the seasonalities of the (corrected) MIR and NIR time series agree within the noise (stdv = 5.2 ppb for the difference time series). The difference time series (NIR-MIR) do not show a significant trend. Therefore it is possible to use a simple scaling factor for the intercalibration without a time-dependent linear or seasonal component. Using the Garmisch and Wollongong data together, we obtain an overall calibration factor MIR/NIR = 0.9926(18). The individual calibration factors per station are 0.9940(14) for Garmisch and 0.9893(40) for Wollongong. They agree within their error bars with the overall calibration factor which can therefore be used for both stations. Our results suggest that after applying the proposed intercalibration concept to all stations performing both NIR and MIR measurements, it should be possible to obtain one refined overall intercalibration factor for the two networks. This would allow to set up a harmonized NDACC and TCCON XCH4 data set which can be exploited for joint trend studies, satellite validation, or the inverse modeling of sources and sinks.

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