scholarly journals Discontinuities in the Ozone Concentration Time Series from MERRA 2 Reanalysis

Atmosphere ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 812 ◽  
Author(s):  
Peter Krizan ◽  
Michal Kozubek ◽  
Jan Lastovicka
Keyword(s):  
Time Series ◽  
Trend Analysis ◽  
Ozone Concentration ◽  
Homogeneity Test ◽  
Concentration Data ◽  
Trend Analyses ◽  
Earth Observing System ◽  
Concentration Time ◽  
Concentration Time Series ◽  
Modern Era

Artificial discontinuities in time series are a great problem for trend analysis because they influence the values of the trend and its significance. The aim of this paper is to investigate their occurrence in the Modern-Era Retrospective analysis for Research and Applications, version 2 (MERRA 2) ozone concentration data. It is the first step toward the utilization of the MERRA 2 ozone data for trend analysis. We use the Pettitt homogeneity test to search for discontinuities in the ozone time series. We showed the data above 4 hPa are not suitable for trend analyses due to the unrealistic patterns in an average ozone concentration and due to the frequent occurrence of significant discontinuities. Below this layer in the stratosphere, their number is much smaller, and mostly, they are insignificant, and the patterns of the average ozone concentration are explainable. In the troposphere, the number of discontinuities increases, but they are insignificant. The transition from Solar Backscatter Ultraviolet Radiometer (SBUV) to Earth Observing System (EOS) Aura data in 2004 is visible only above 1 hPa, where the data are not suitable for trend analyses due to other reasons. We can conclude the MERRA 2 ozone concentration data can be used in trend analysis with caution only below 4 hPa.

Application of nonparametric trend analysis to concentration time series

2020 ◽  
Author(s):  
Artur Kohler
Keyword(s):  
Time Series ◽  
Hazardous Substances ◽  
Anthropogenic Activity ◽  
Actual State ◽  
Temporal Behavior ◽  
Concentration Data ◽  
Concentration Time ◽  
Concentration Time Series ◽  
Repeated Sampling ◽  
Non Parametric

<p>Groundwater contamination resulted from chemical releases related to anthropogenic activity often proves to be a persistent feature of the affected groundwater regime.  The affected volume (i.e. where the concentration of hazardous substances exceeds a certain threshold) is a complex and dynamic entity commonly called “contaminant plume”.  The plume can be described as a spatially dependent concentration pattern with temporal behavior.  Persistent plumes are regularly monitored, concentration data gained by repeated sampling of monitoring points and laboratory analyses of the samples are used to assess the actual state of the plume.  The change of the concentrations at certain points of the plume facilitates the assessment of the temporal behavior of the plume.  Repeated sampling of the monitoring points provides concentration time series.</p><p>Concentration time series are evaluated for trends.  Methods include parametric (regression using least squares) and non-parametric methods.  Mann-Kendall statistic is a commonly used, well known non parametric method.</p><p>When using Mann-Kendall statistics consecutive concentration data are compared to each other, their cumulative relation defines Mann-Kendall statistic ‘S’.  However, when comparing concentration data laboratory uncertainties are usually neglected.  Allowing for laboratory uncertainties, rises the question of what concentrations are considered equal, less or more than other concentrations.  In addition aggravating concentration data will change the previous equal – more - less status of two concentrations, thus changing the Mann-Kendall statistics value, which sometimes results in differences in trend significance.</p>

Occurrence of discontinuities in the ozone concentration data from three reanalyses

2020 ◽  
Author(s):  
Peter Krizan
Keyword(s):  
Vertical Distribution ◽  
Data Quality ◽  
Ozone Concentration ◽  
Frequent Occurrence ◽  
Homogeneity Test ◽  
Concentration Data ◽  
Trend Analyses ◽  
Ozone Data ◽  
Before And After ◽  
The Vertical Distribution

<p>The aim of this presentation is to compare the occurrence of discontinuities in the ozone concentration data from the MERRA-2, ERA-5 and JRA-55 reanalyse, with the help of the Pettitt homogeneity test. We distinguish between the significant and insignificant discontinuities, according to the relation between the dispersion and the average ozone values before and after the discontinuity.    This occurrence is important for trend analyses, because the presence of discontinuities influences the values of trends and their significance. Discontinuities arise from the changing in the assimilation procedure, introducing new observation to the reanalyse, and changing of data quality. We search for their spatial, temporal and geographical occurrence. There are differences among these reanalyses. In the case of the MERRA-2 data, the transition from SBUV to EOS Aura data in 2004 has great impact on discontinuity behaviour. The frequent occurrence of discontinuities is seen in the uppermost model layers. The uppermost MERRA-2 layer is 0.1 hPa, while for ERA-5 this layer is 1 hPa. So there are differences in the vertical distribution of discontinuities among the reanalyses. The ozone data with the strong occurrence of the significant discontinuities is not suitable for trend analyses.   </p>

Scaling characteristics in ozone concentration time series (OCTS)

Chemosphere ◽  
2006 ◽  
Vol 62 (6) ◽  
pp. 934-946 ◽  
Author(s):  
Chung-Kung Lee ◽  
Lain-Chuen Juang ◽  
Cheng-Cai Wang ◽  
Yu-Ying Liao ◽  
Chung-Chin Yu ◽  
...  
Keyword(s):  
Time Series ◽  
Ozone Concentration ◽  
Concentration Time ◽  
Concentration Time Series

Analysis and generation of groundwater concentration time series

2018 ◽  
Vol 111 ◽  
pp. 20-30 ◽  
Author(s):  
Maria Crăciun ◽  
Călin Vamoş ◽  
Nicolae Suciu
Keyword(s):  
Time Series ◽  
Concentration Time ◽  
Concentration Time Series

scholarly journals Cluster analysis of WIBS single-particle bioaerosol data

2013 ◽  
Vol 6 (2) ◽  
pp. 337-347 ◽  
Author(s):  
N. H. Robinson ◽  
J. D. Allan ◽  
J. A. Huffman ◽  
P. H. Kaye ◽  
V. E. Foot ◽  
...  
Keyword(s):  
Time Series ◽  
Cluster Analysis ◽  
Single Particle ◽  
Fungal Spores ◽  
Polystyrene Latex ◽  
Data Sets ◽  
Forest Site ◽  
Fluorescence Measurements ◽  
Concentration Time ◽  
Concentration Time Series

Abstract. Hierarchical agglomerative cluster analysis was performed on single-particle multi-spatial data sets comprising optical diameter, asymmetry and three different fluorescence measurements, gathered using two dual Wideband Integrated Bioaerosol Sensors (WIBSs). The technique is demonstrated on measurements of various fluorescent and non-fluorescent polystyrene latex spheres (PSL) before being applied to two separate contemporaneous ambient WIBS data sets recorded in a forest site in Colorado, USA, as part of the BEACHON-RoMBAS project. Cluster analysis results between both data sets are consistent. Clusters are tentatively interpreted by comparison of concentration time series and cluster average measurement values to the published literature (of which there is a paucity) to represent the following: non-fluorescent accumulation mode aerosol; bacterial agglomerates; and fungal spores. To our knowledge, this is the first time cluster analysis has been applied to long-term online primary biological aerosol particle (PBAP) measurements. The novel application of this clustering technique provides a means for routinely reducing WIBS data to discrete concentration time series which are more easily interpretable, without the need for any a priori assumptions concerning the expected aerosol types. It can reduce the level of subjectivity compared to the more standard analysis approaches, which are typically performed by simple inspection of various ensemble data products. It also has the advantage of potentially resolving less populous or subtly different particle types. This technique is likely to become more robust in the future as fluorescence-based aerosol instrumentation measurement precision, dynamic range and the number of available metrics are improved.

Occurrence of discontinuities in the ozone concentration data from three reanalyses

2020 ◽  
Author(s):  
Peter Krizan ◽  
Michal Kozubek ◽  
Jan Lastovicka
Keyword(s):  
Time Evolution ◽  
Southern Hemisphere ◽  
Ozone Concentration ◽  
Temporal Structure ◽  
The Other ◽  
Trace Gas ◽  
Homogeneity Test ◽  
Concentration Data ◽  
Ozone Data ◽  
Ozone Trend

Abstract. Ozone is a very important trace gas in the stratosphere and thus we need to know its time evolution over the globe. The ground based measurements are rare, especially in the Southern Hemisphere. Satellite ozone data have broader coverage, but they are not available from everywhere. On the other hand, the reanalyse data have regular spatial and temporal structure, which is very good for trend analyses. But there are discontinuities in these data.These discontinuities may influence the result of trend studies. The aim of this paper is to detect the discontinuity occurrence (DO) in the following reanalyses: MERRA-2, ERA-5 and JRA-55 with the help of the Pettitt homogeneity test at all common layers above 500 hPa. The discontinuities are sorted according to their size to the significant and the insignificant ones; the former can affect the ozone trend studies. It was shown that DO for the significant discontinuities is the smallest in JRA-55. In the upper model layers, the discontinuity occurrence is the highest. The other area of high DO is the troposphere.

Sign in / Sign up

Export Citation Format

Share Document