Sensitivity of segmentation of GNSS IWV time series and trend estimates to data properties

2021 ◽  
Author(s):  
Khanh Ninh Nguyen ◽  
Annarosa Quarello ◽  
Olivier Bock ◽  
Emilie Lebarbier
Keyword(s):  
Time Series ◽  
Processing Method ◽  
Change Points ◽  
Data Sets ◽  
Segmentation Method ◽  
Data Processing Method ◽  
Integrated Water Vapour ◽  
The Difference ◽  
Gnss Measurements ◽  
The Impact

<p>Homogenization is an important step to improve the quality of long-term observational data sets and estimate climatic trends. In this work, we use the GNSSseg/GNSSfast segmentation packages that were developed by Quarello et al., 2020, for the detection of abrupt changes in the mean of Integrated Water Vapour (IWV) data derived from GNSS measurements. The method works on the difference of the IWV time series (GNSS – reference) in order to cancel out the common climatic variations and enhance the discontinuities due to the inhomogeneities in the GNSS series. This segmentation method accounts for changes in the variance on fixed intervals (monthly) and a periodic bias (annual) due to representativeness differences between GNSS and the reference (in our case, a global atmospheric reanalysis). <br>The goal of this study is to analyze the sensitivity of the segmentation method to the data properties, particularly the GNSS data processing method. Two reprocessed GNSS solutions are considered: IGS repro1, covering the period 1995-2010, and CODE REPRO2015 + OPER, covering the period 1994-2018. Next, the impact of the length of time series and missing data are investigated. Finally, the use of two different reference series is considered (ERA-Interim and ERA5 reanalyses).<br>The segmentation results are screened for outliers (multiple detections occurring within a distance of 80 days) and validated with respect to known equipment changes (from GNSS metadata). The impact of the data properties is analyzed by comparing the number and position of detected change-points and the fraction of validated change-points. The influence of the variance of the IWV difference series and the magnitude of the periodic bias is examined. Finally, the results are compared in terms of estimated linear trends taking the detected change-points into account.<br>From the multiple comparisons, we found that about 30 % of change points are similar when the GNSS processing method changed, while 60 % are similar when the CODE series is shortened to match the length of the repro1 series. These tests highlight that the segmentation results are processing-dependent and are affected by the length of the series. The impact of the data properties on the IWV trends and associated uncertainties are also quantified. Besides, it is important to note that the best segmentation result is found when the ERA5 reanalysis is used as a reference.</p>

scholarly journals Sensitivity of Change-Point Detection and Trend Estimates to GNSS IWV Time Series Properties

Atmosphere ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 1102
Author(s):  
Khanh Ninh Nguyen ◽  
Annarosa Quarello ◽  
Olivier Bock ◽  
Emilie Lebarbier
Keyword(s):  
Time Series ◽  
A Priori ◽  
Change Point Detection ◽  
Change Points ◽  
Data Sets ◽  
Auxiliary Data ◽  
Data Processing Method ◽  
Point Detection ◽  
Gnss Data ◽  
Higher Sensitivity

This study investigates the sensitivity of the GNSSseg segmentation method to change in: GNSS data processing method, length of time series (17 to 25 years), auxiliary data used in the integrated water vapor (IWV) conversion, and reference time series used in the segmentation (ERA-Interim versus ERA5). Two GNSS data sets (IGS repro1 and CODE REPRO2015), representative of the first and second IGS reprocessing, were compared. Significant differences were found in the number and positions of detected change-points due to different a priori ZHD models, antenna/radome calibrations, and mapping functions. The more recent models used in the CODE solution have reduced noise and allow the segmentation to detect smaller offsets. Similarly, the more recent reanalysis ERA5 has reduced representativeness errors, improved quality compared to ERA-Interim, and achieves higher sensitivity of the segmentation. Only 45–50% of the detected change-points are similar between the two GNSS data sets or between the two reanalyses, compared to 70–80% when the length of the time series or the auxiliary data are changed. About 35% of the change-points are validated with respect to metadata. The uncertainty in the homogenized trends is estimated to be around 0.01–0.02 kg m−2 year−1.

scholarly journals The Impact of OECD Countries’ Macroeconomic Factors on Turkey’s Foreign Trade

2017 ◽  
Vol 8 (1) ◽  
pp. 24
Author(s):  
Elif Guneren Genc ◽  
Ozlem Deniz Basar
Keyword(s):  
Time Series ◽  
Panel Data ◽  
Urban Population ◽  
Economic Structure ◽  
Oecd Countries ◽  
Data Sets ◽  
Macroeconomic Factors ◽  
Macroeconomic Time Series ◽  
Per Capita ◽  
The Impact

The purpose of this study is to investigate the makroeconomic effects of OECD countries, having a major economic share in the regional communities, in the scope of complex economic structure, and accordingly, to determine the effects of those on Turkey's exports and imports. For this purpose, Turkey’s bilateral export and import volumes with OECD countries for the period of 1996 to 2014 were modelled by using these countries’ macroeconomic time series variables and panel data sets. It was revealed at the end of the study that the most determinant macroeconomic factors concerning the increase in Turkey’s import is the increase in per capita GNP in these countries. This variable is seen to be followed by these countries’ urban population, export indices and the export increases of Turkey for these countries respectively.

scholarly journals Two decades of satellite observations of AOD over mainland China using ATSR-2, AATSR and MODIS/Terra: data set evaluation and large-scale patterns

2018 ◽  
Vol 18 (3) ◽  
pp. 1573-1592 ◽  
Author(s):  
Gerrit de Leeuw ◽  
Larisa Sogacheva ◽  
Edith Rodriguez ◽  
Konstantinos Kourtidis ◽  
Aristeidis K. Georgoulias ◽  
...  
Keyword(s):  
Time Series ◽  
European Space Agency ◽  
Mainland China ◽  
Satellite Observations ◽  
Data Sets ◽  
Data Set ◽  
Modis Aod ◽  
The Difference ◽  
Along Track ◽  
Aerosol Properties

Abstract. The retrieval of aerosol properties from satellite observations provides their spatial distribution over a wide area in cloud-free conditions. As such, they complement ground-based measurements by providing information over sparsely instrumented areas, albeit that significant differences may exist in both the type of information obtained and the temporal information from satellite and ground-based observations. In this paper, information from different types of satellite-based instruments is used to provide a 3-D climatology of aerosol properties over mainland China, i.e., vertical profiles of extinction coefficients from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP), a lidar flying aboard the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite and the column-integrated extinction (aerosol optical depth – AOD) available from three radiometers: the European Space Agency (ESA)'s Along-Track Scanning Radiometer version 2 (ATSR-2), Advanced Along-Track Scanning Radiometer (AATSR) (together referred to as ATSR) and NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Terra satellite, together spanning the period 1995–2015. AOD data are retrieved from ATSR using the ATSR dual view (ADV) v2.31 algorithm, while for MODIS Collection 6 (C6) the AOD data set is used that was obtained from merging the AODs obtained from the dark target (DT) and deep blue (DB) algorithms, further referred to as the DTDB merged AOD product. These data sets are validated and differences are compared using Aerosol Robotic Network (AERONET) version 2 L2.0 AOD data as reference. The results show that, over China, ATSR slightly underestimates the AOD and MODIS slightly overestimates the AOD. Consequently, ATSR AOD is overall lower than that from MODIS, and the difference increases with increasing AOD. The comparison also shows that neither of the ATSR and MODIS AOD data sets is better than the other one everywhere. However, ATSR ADV has limitations over bright surfaces which the MODIS DB was designed for. To allow for comparison of MODIS C6 results with previous analyses where MODIS Collection 5.1 (C5.1) data were used, also the difference between the C6 and C5.1 merged DTDB data sets from MODIS/Terra over China is briefly discussed. The AOD data sets show strong seasonal differences and the seasonal features vary with latitude and longitude across China. Two-decadal AOD time series, averaged over all of mainland China, are presented and briefly discussed. Using the 17 years of ATSR data as the basis and MODIS/Terra to follow the temporal evolution in recent years when the environmental satellite Envisat was lost requires a comparison of the data sets for the overlapping period to show their complementarity. ATSR precedes the MODIS time series between 1995 and 2000 and shows a distinct increase in the AOD over this period. The two data series show similar variations during the overlapping period between 2000 and 2011, with minima and maxima in the same years. MODIS extends this time series beyond the end of the Envisat period in 2012, showing decreasing AOD.

scholarly journals KEBUTUHAN GURU PENDIDIKAN AGAMA ISLAM DI SEKOLAH

2018 ◽  
Vol 16 (2) ◽  
Author(s):  
Suprapto Suprapto
Keyword(s):  
High School ◽  
Junior High School ◽  
Qualitative Method ◽  
Descriptive Analysis ◽  
Study Groups ◽  
Processing Method ◽  
Optimum Level ◽  
Vocational High School ◽  
Data Processing Method ◽  
The Impact

AbstractIslam Education (PAI) at schools has not achieved the optimum level, due to the shortage of the PAI teacher. The number of the PAI teacher in Nusa Tenggara Barat (NTB) Province is currently not comparable with the number of students, because: (i) the impact of moratorium policy of the PAI teacher’s recruitment (pengangkatan guru), (ii) the teachers are retiring, and (iii) unscattered number of the PAI teacher. This research used qualitative method, supported by quantitative data. Data collection was conducted through observation, questionnaire, interview, and documentary. Meanwhile, data processing method was editing, coding, tabulating, and interpretation through qualitative and descriptive analysis. Research found that: 1) The shortage of the PAI teachers in NTB, for level SD (Elementary School), SMP (Junior High School), SMA (Senior High School), and SMK (Vocational High School); 2) The Ministry of Religious Affairs - District/City is facing the problem to organize the PAI  teacher at schools, due to the recruitment and payroll system of the Education Board (Dinas Pendidikan); 3) The deployment of the PAI teacher has not followed the system of surplus and shortage analysis, based on education unit within the number of study groups; 4) The PAI teacher’s supervision at schools through Teachers Working Group (Kelompok Kerja Guru, KKG) and Lesson-Teacher Meeting (Musyawarah Guru Mata Pelajaran, MGMP). This research recommends that: 1) The demand of the PAI teacher at schools can be fulfilled by recruiting temporary teacher (guru honorer), done by schools and Education Board, by giving additional teaching duties for the PAI teacher who has not achieved minimum 24 hours; 2) The PAI teacher’s recruitment, deployment and supervision have to be fully authorized by The Ministry of Religious Affairs; 3) The surplus and shortage analysis of the PAI teacher is needed in Level Education Board (Dinas Pendidikan), The Ministry of Religious Affairs – District/City, and Education unit, and 4) The Ministry of Religious Affairs through Directorate of Islam Education (Direktorat Pendidikan Agama Islam) should allocate operational budget for proper KKG/MGMP actitivities of PAI.Abstrak Penyelenggaraan Pendidikan Agama Islam (PAI) di sekolah belum optimal karena kurangnya jumlah guru pendidikan agama Islam. Jumlah guru pendidikan agama Islam di provinsi Nusa Tenggara Barat saat ini tidak sebanding dengan jumlah siswa sebagai akibat kebijakan moratorium pengangkatan guru PAI, ada yang pensiun dan tidak meratanya sebaran guru PAI. Metode penelitian ini adalah kualitatif yang didukung oleh data kuantitatif. Pengumpulan data melalui teknik observasi, angket, wawancara dan dokumenter. Adapun teknik pengolahan data yang digunakan adalah editing, coding, tabulating dan interpretation data dengan menggunakan analisis deskriptif kualitatif. Temuan penelitian: 1) Jumlah guru PAI di provinsi Nusa Tenggara Barat pada jenjang SD, SMP, SMA dan SMK masih mengalami kekurangan; 2) Kementerian Agama Kabupaten/Kota mengalami kesulitan dalam mengkoordinasikan guru PAI di sekolah karena pengangkatan dan penggajian oleh Dinas Pendidikan; 3) Penempatan guru PAI belum berdasarkan kepada sistem analisis kelebihan dan kekurangan guru PAI berdasarkan satuan pendidikan sesuai jumlah rombongan belajar; 4) Pembinaan guru PAI di sekolah melalui Kelompok Kerja Guru (KKG) dan Musyawarah Guru Mata Pelajaran (MGMP). Penelitian ini merekomendasikan: 1) Pemenuhan guru PAI di sekolah dapat dilakukan melalui pengangkatan guru honorer oleh sekolah dan melalui Dinas Pendidikan, dengan memberikan tugas tambahan mengajar bagi guru PAI yang belum memenuhi jumlah minimal 24 jam; 2) Pengangkatan, penempatan dan pembinaan guru PAI seharusnya menjadi kewenangan penuh Kementerian Agama; 3) Perlunya sistem analisis kelebihan dan kekurangan guru PAI di tingkat Dinas Pendidikan, Kementerian Agama Kabupaten/Kota dan Satuan Pendidikan dan 4) Kementerian Agama melalui Direktorat Pendidikan Agama Islam perlu menganggarkan dana operasional kegiatan KKG/MGMP PAI yang memadai.

scholarly journals The SPARC water vapour assessment II: Comparison of stratospheric and lower mesospheric water vapour time series observed from satellites

2018 ◽  
Author(s):  
Farahnaz Khosrawi ◽  
Stefan Lossow ◽  
Gabriele P. Stiller ◽  
Karen H. Rosenlof ◽  
Joachim Urban ◽  
...  
Keyword(s):  
Time Series ◽  
Water Vapour ◽  
Data Sets ◽  
Data Set ◽  
The Future ◽  
Modelling Studies ◽  
The Difference ◽  
The Tropics ◽  
The Antarctic ◽  
Satellite Instruments

Abstract. Time series of stratospheric and lower mesospheric water vapour using 33 data sets from 15 different satellite instruments were compared in the framework of the second SPARC (Stratosphere-troposphere Processes And their Role in Climate) water vapour assessment (WAVAS-II). This comparison aimed to provide a comprehensive overview of the typical uncertainties in the observational database that can be considered in the future in observational and modelling studies addressing e.g stratospheric water vapour trends. The time series comparisons are presented for the three latitude bands, the Antarctic (80°–70° S), the tropics (15° S–15° N) and the northern hemisphere mid-latitudes (50° N–60° N) at four different altitudes (0.1, 3, 10 and 80 hPa) covering the stratosphere and lower mesosphere. The combined temporal coverage of observations from the 15 satellite instruments allowed considering the time period 1986–2014. In addition to the qualitative comparison of the time series, the agreement of the data sets is assessed quantitatively in the form of the spread (i.e. the difference between the maximum and minimum volume mixing ratio among the data sets), the (Pearson) correlation coefficient and the drift (i.e. linear changes of the difference between time series over time). Generally, good agreement between the time series was found in the middle stratosphere while larger differences were found in the lower mesosphere and near the tropopause. Concerning the latitude bands, the largest differences were found in the Antarctic while the best agreement was found for the tropics. From our assessment we find that all data sets can be considered in the future in observational and modelling studies addressing e.g. stratospheric and lower mesospheric water vapour variability and trends when data set specific characteristics (e.g. a drift) and restrictions (e.g. temporal and spatial coverage) are taken into account.

Distance Measures for Surgical Process Models

2013 ◽  
Vol 52 (05) ◽  
pp. 422-431 ◽  
Author(s):  
U. Bühligen ◽  
T. Neumuth ◽  
S. Schumann
Keyword(s):  
Graph Matching ◽  
Surgical Techniques ◽  
Process Models ◽  
Distance Measures ◽  
Levenshtein Distance ◽  
Data Sets ◽  
Distance Measurements ◽  
Surgical Interventions ◽  
The Difference ◽  
The Impact

SummaryBackground: The development of new resources, such as surgical techniques and approaches, results in continuous modification of surgery. To assess these modifications, it is necessary to use measures that quantify the impact of resources on surgical processes.Objectives: The objective of this work is to introduce and evaluate distance measurements that are able to represent differences in the courses of surgical interventions as processes.Methods: Hence, we present four different distance measures for surgical processes: the Jaccard distance, Levenshtein distance, Adjacency distance, and Graph matching distance. These measures are formally introduced and evaluated by applying them to clinical data sets from laparoscopic training in pediatric surgery.Results: We analyzed the distances of 450 surgical processes using these four measures with a focus on the difference in surgical processes performed by novices and by experienced surgeons. The Levenshtein and Adjacency distances were best suited to measure distances between surgical processes.Conclusion: The measurement of distances between surgical processes is necessary to estimate the benefit of new surgical techniques and strategies.

scholarly journals The SPARC water vapour assessment II: comparison of stratospheric and lower mesospheric water vapour time series observed from satellites

2018 ◽  
Vol 11 (7) ◽  
pp. 4435-4463 ◽  
Author(s):  
Farahnaz Khosrawi ◽  
Stefan Lossow ◽  
Gabriele P. Stiller ◽  
Karen H. Rosenlof ◽  
Joachim Urban ◽  
...  
Keyword(s):  
Time Series ◽  
Water Vapour ◽  
Data Sets ◽  
Data Set ◽  
Spatial Coverage ◽  
Modelling Studies ◽  
The Difference ◽  
The Tropics ◽  
The Antarctic ◽  
Satellite Instruments

Abstract. Time series of stratospheric and lower mesospheric water vapour using 33 data sets from 15 different satellite instruments were compared in the framework of the second SPARC (Stratosphere-troposphere Processes And their Role in Climate) water vapour assessment (WAVAS-II). This comparison aimed to provide a comprehensive overview of the typical uncertainties in the observational database that can be considered in the future in observational and modelling studies, e.g addressing stratospheric water vapour trends. The time series comparisons are presented for the three latitude bands, the Antarctic (80∘–70∘ S), the tropics (15∘ S–15∘ N) and the Northern Hemisphere mid-latitudes (50∘–60∘ N) at four different altitudes (0.1, 3, 10 and 80 hPa) covering the stratosphere and lower mesosphere. The combined temporal coverage of observations from the 15 satellite instruments allowed the consideration of the time period 1986–2014. In addition to the qualitative comparison of the time series, the agreement of the data sets is assessed quantitatively in the form of the spread (i.e. the difference between the maximum and minimum volume mixing ratios among the data sets), the (Pearson) correlation coefficient and the drift (i.e. linear changes of the difference between time series over time). Generally, good agreement between the time series was found in the middle stratosphere while larger differences were found in the lower mesosphere and near the tropopause. Concerning the latitude bands, the largest differences were found in the Antarctic while the best agreement was found for the tropics. From our assessment we find that most data sets can be considered in future observational and modelling studies, e.g. addressing stratospheric and lower mesospheric water vapour variability and trends, if data set specific characteristics (e.g. drift) and restrictions (e.g. temporal and spatial coverage) are taken into account.

New Data Processing Method Research on GLONASS

2014 ◽  
Vol 599-601 ◽  
pp. 1580-1583
Author(s):  
Zhao Jun Liu
Keyword(s):  
Data Processing ◽  
Phase Difference ◽  
Carrier Phase ◽  
Processing Method ◽  
Relative Deviation ◽  
Data Processing Method ◽  
Receiver Clock ◽  
System Data ◽  
Gps Data Processing ◽  
The Impact

Because GLONASS and GPS are different in system, data processing of GLONASS carrier phase difference is quite different from that of GPS, requiring special methods. Based on eliminating the impact of the relative deviation of receiver clock, a new mathematical model of GLONASS phase difference is introduced in this article. This new model can make full use of existing GPS data processing technology to complete GLONASS data processing work conveniently.

scholarly journals Analysis Of Form Coefficient For Measuring Gross Tonnage Of Wooden Ship Based On Domestic Meansurment Method Of Indonesia

2021 ◽  
Vol 3 (2) ◽  
pp. 165-171
Author(s):  
Habibi Amal ◽  
Syamsul Asri ◽  
Andi Ardianti ◽  
Suandar Baso
Keyword(s):  
Measurement Method ◽  
Processing Method ◽  
Volume Factor ◽  
Size And Shape ◽  
Data Processing Method ◽  
Measurement Results ◽  
Mathematical Equations ◽  
The Difference ◽  
Actual Size

Most of the traditional wooden boats in Sinjai and Bone Districts were measured using the domestic measurement method, ship owners with sizes <GT 7 and <GT 30 refused to verify their vessels. Ship owners feel disadvantaged in terms of policies, permits, landing fees, subsidized fuel rations and so on. This study aims to determine the characteristics of the size and shape of traditional wooden ships, analyze and compare the results of the calculation of the gross tonnage (GT) of the ship which is calculated based on the actual size and shape of the ship (real body) with the ship calculated using domestic measurement methods and compiling mathematical equations in determining the value of the ship volume factor based on the main size to calculate the GT. The data processing method was carried out by using the Slovin technique with a population of 49 ship data for the determination of the minimum sample and then entered into the interval class. The results showed that the traditional wooden ships in Sinjai and Bone Regencies have geometric characteristics that are not much different from one another, but the main sizes are quite varied. The larger the main size of the ship, the greater the difference in GT calculations when using the volume factor value based on the domestic measurement method compared to using the volume factor value generated by real body calculations. The formula for the volume factor value (Cb or f) = 0.238 Log ((LBH)1/3) + 0.5134 can be used to determine the volume factor, especially for ships operating in the Sinjai and Bone Regencies as well as an initial reference for measurements by measuring experts ship so that moderate measurement results are obtained.

scholarly journals Ударное и "задержанное" повреждение поверхности керамики ZnS-CVD

2019 ◽  
Vol 45 (22) ◽  
pp. 39
Author(s):  
И.П. Щербаков ◽  
А.А. Дунаев ◽  
А.Б. Синани ◽  
А.Е. Чмель
Keyword(s):  
Time Series ◽  
Crack Nucleation ◽  
Chemical Vapor ◽  
Active Phase ◽  
Dislocation Motion ◽  
Energy Yield ◽  
Time Domains ◽  
Weak Points ◽  
The Difference ◽  
The Impact

Impact and impeded damage of ZnS-CVD ceramics surface I.P. Shcherbakov, A.A. Dunaev, A.B. Sinani, A.E. Chmel Localized damage of the surface of ductile ZnS ceramics synthesized by the chemical vapor deposition (CVD) method was performed by either impact of a pointed striker or by the impeded indenting of a Vickers pyramid. In both cases, the time series of acoustic emission pulses were recorded. The duration of the impact-induced sound emission was of 0.3-0.5 ms, while the indenting-produced active phase of emission was of 3-5 ms in length. The primary emission followed by the irradiation of weak acoustic signals during 80-100 ms. The statistical analysis of the time series showed the exponential (poissonian) energy distribution in impact-induced pulses, while in indented specimens, the distribution function followed a power law of the Gutenberg-Richter type. Considering that dislocation clusters serve as weak points for the crack nucleation, the difference in the mode of energy yield was explained by varying temporal pattern characteristics of the strain-stimulated dislocation motion in different time domains.

Sign in / Sign up

Export Citation Format

Share Document