Validation of satellite OClO products from S5P/TROPOMI and MetopA and B/GOME2 

2021 ◽  
Author(s):  
Gaia Pinardi ◽  
Michel Van Roozendael ◽  
François Hendrick ◽  
Andreas Meier ◽  
Andreas Richter ◽  
...  
Keyword(s):  
Time Series ◽  
Chlorine Dioxide ◽  
Ozone Depletion ◽  
Correlation Coefficients ◽  
Polar Regions ◽  
Data Record ◽  
Fixed Reference ◽  
Selection Of

<p>Chlorine dioxide is an indicator for chlorine activation in the stratosphere, of importance for understanding spring-time ozone depletion processes in the polar regions of both hemispheres. Within the EUMETSAT AC SAF working group, chlorine dioxide (OClO) was retrieved from the GOME-2 instruments on MetOp-A and MetOp-B platforms, respectively over the time periods 2007-2016 and 2012-2016. Moreover, recent work performed as part of the S5p+ Innovation programme has led to the creation of an additional dataset derived from the TROPOMI instrument, extending the OClO time series in 2018-2020.</p><p>This study analyses the quality of both OClO slant column (SCD) datasets by comparing them to ground-based DOAS zenith-sky measurements at a selection of 8 stations in Arctic and Antarctic regions: Eureka (80°N), Ny Alesund (79°N), Kiruna (68°N), Harestua (60°N), Marambio (64°S), Belgrano (78°S), Neumayer (71°S) and Arrival Heights (78°S). To allow for comparison with satellite data, ground-based OClO spectral analyses are performed using yearly fixed reference spectra recorded at low SZA in the absence of chlorine activation. Furthermore, an additional bias-correction is applied in post-processing to generate a consistent long-term OClO data record covering the 2007-2020 period.</p><p>Daily comparisons of satellite and ground-based SCD data pairs corresponding to similar SZA conditions are performed, assuming similar stratospheric light paths in satellite nadir and ground-based zenith-sky geometries. Daily mean OClO SCD time-series show that satellite and ground-based observations agree well at all stations in terms of short-term variability and seasonal variation. Linear regression plots show a correlation coefficient R of about 0.97, a slope of 0.9 and an intercept of less than 1x10<sup>13</sup> molec/cm² for TROPOMI, while for GOME-2 results are more noisy and tend to be biased low, with correlation coefficients between 0.76 and 0.88, slopes between 0.65 and 0.74 and intercepts up to 2.4 x10<sup>13 </sup>molec/cm².</p>

scholarly journals The Passive Microwave Neural Network Precipitation Retrieval Algorithm for Climate Applications (PNPR-CLIM): Design and Verification

2021 ◽  
Vol 13 (9) ◽  
pp. 1701
Author(s):  
Leonardo Bagaglini ◽  
Paolo Sanò ◽  
Daniele Casella ◽  
Elsa Cattani ◽  
Giulia Panegrossi
Keyword(s):  
Neural Network ◽  
Passive Microwave ◽  
Retrieval Algorithm ◽  
Climate Data ◽  
High Quality ◽  
Data Record ◽  
Global Precipitation ◽  
Climate Data Record

This paper describes the Passive microwave Neural network Precipitation Retrieval algorithm for climate applications (PNPR-CLIM), developed with funding from the Copernicus Climate Change Service (C3S), implemented by ECMWF on behalf of the European Union. The algorithm has been designed and developed to exploit the two cross-track scanning microwave radiometers, AMSU-B and MHS, towards the creation of a long-term (2000–2017) global precipitation climate data record (CDR) for the ECMWF Climate Data Store (CDS). The algorithm has been trained on an observational dataset built from one year of MHS and GPM-CO Dual-frequency Precipitation Radar (DPR) coincident observations. The dataset includes the Fundamental Climate Data Record (FCDR) of AMSU-B and MHS brightness temperatures, provided by the Fidelity and Uncertainty in Climate data records from Earth Observation (FIDUCEO) project, and the DPR-based surface precipitation rate estimates used as reference. The combined use of high quality, calibrated and harmonized long-term input data (provided by the FIDUCEO microwave brightness temperature Fundamental Climate Data Record) with the exploitation of the potential of neural networks (ability to learn and generalize) has made it possible to limit the use of ancillary model-derived environmental variables, thus reducing the model uncertainties’ influence on the PNPR-CLIM, which could compromise the accuracy of the estimates. The PNPR-CLIM estimated precipitation distribution is in good agreement with independent DPR-based estimates. A multiscale assessment of the algorithm’s performance is presented against high quality regional ground-based radar products and global precipitation datasets. The regional and global three-year (2015–2017) verification analysis shows that, despite the simplicity of the algorithm in terms of input variables and processing performance, the quality of PNPR-CLIM outperforms NASA GPROF in terms of rainfall detection, while in terms of rainfall quantification they are comparable. The global analysis evidences weaknesses at higher latitudes and in the winter at mid latitudes, mainly linked to the poorer quality of the precipitation retrieval in cold/dry conditions.

scholarly journals Ice processes and growth history on Arctic and sub-Arctic lakes using ERS-1 SAR data

Polar Record ◽  
1995 ◽  
Vol 31 (177) ◽  
pp. 115-128 ◽  
Author(s):  
K. Morris ◽  
M. O. Jeffries ◽  
W. F. Weeks
Keyword(s):  
Arctic Lakes ◽  
Polar Regions ◽  
Lake Ice ◽  
Sar Images ◽  
The North ◽  
Growth History ◽  
North Slope Of Alaska ◽  
Term Monitoring ◽  
Selection Of

AbstractA survey of ice growth and decay processes on a selection of shallow and deep sub-Arctic and Arctic lakes was conducted using radiometrically calibrated ERS-1 SAR images. Time series of radar backscatter data were compiled for selected sites on the lakes during the period of ice cover (September to June) for the years 1991–92 and 1992–93. A variety of lake-ice processes could be observed, and significant changes in backscatter occurred from the time of initial ice formation in autumn until the onset of the spring thaw. Backscatter also varied according to the location and depth of the lakes. The spatial and temporal changes in backscatter were most constant and predictable at the shallow lakes on the North Slope of Alaska. As a consequence, they represent the most promising sites for long-term monitoring and the detection of changes related to global warming and its effects on the polar regions.

Comparison of Tropospheric Zenith Wet Delay from VLBI and GNSS Estimations

2021 ◽  
Author(s):  
Vicky Jia Liu ◽  
Maaria Nordman ◽  
Nataliya Zubko
Keyword(s):  
Time Series ◽  
Seasonal Variations ◽  
Elevation Angle ◽  
Correlation Coefficients ◽  
Satellite System ◽  
Tropospheric Delay ◽  
Polar Regions ◽  
Long Baseline ◽  
Zenith Wet Delay ◽  
Space Geodetic Techniques

<p>Tropospheric delay is one of the major error sources for space geodetic techniques such as Very Long Baseline Interferometry (VLBI) and Global Navigation Satellite System (GNSS). In this study, we compared the agreement of tropospheric zenith wet delay (ZWD) seasonal variations derived from VLBI and GNSS observations at 8 stations that are located at all around the globe. We have analysed time series of 8 years, starting in 2012 until end of 2019. Results show that VLBI_ZWD present clear seasonal variations which depend on the location of each station, in the tropics the variability is more pronounced than in mid-latitudes or polar regions. Furthermore, the VLBI_ZWD also shows a reasonably good agreement with seasonal fit model. When comparing zenith wet delays derived from co-located GNSS and VLBI stations at  cut-off elevation angle, they agree quite well, which is proved by the high correlation coefficients, varying from 0.6 up to 0.95. The biases between the techniques are in mm level and standard errors of the whole time series are in few centimetres.</p>

scholarly journals Estimation of Burned Area in the Northeastern Siberian Boreal Forest from a Long-Term Data Record (LTDR) 1982–2015 Time Series

2018 ◽  
Vol 10 (6) ◽  
pp. 940 ◽  
Author(s):  
José García-Lázaro ◽  
José Moreno-Ruiz ◽  
David Riaño ◽  
Manuel Arbelo
Keyword(s):  
Time Series ◽  
Boreal Forest ◽  
Burned Area ◽  
Data Record ◽  
Term Data

scholarly journals Automatic Curve Extraction for Digitizing Rainfall Strip Charts

2011 ◽  
Vol 28 (7) ◽  
pp. 891-906 ◽  
Author(s):  
H. E. van Piggelen ◽  
T. Brandsma ◽  
H. Manders ◽  
J. F. Lichtenauer
Keyword(s):  
Time Series ◽  
Batch Process ◽  
Rainfall Time Series ◽  
Graphical Interface ◽  
The Core ◽  
Cumulative Rainfall ◽  
Color Detection ◽  
Meta Information

Abstract A method has been developed that largely automates the labor-intensive extraction work for large amounts of rainfall strip charts and paper rolls. The method consists of the following five basic steps: 1) scanning the charts and rolls to high-resolution digital images, 2) manually and visually registering relevant meta information from charts and rolls and preprocessing rolls to locate day transitions, 3) applying automatic curve extraction software in a batch process to determine the coordinates of cumulative rainfall lines on the images, 4) postprocessing the curves that were not correctly determined in step 3, and 5) aggregating the cumulative rainfall in pixel coordinates to the desired time resolution. The core of the method is in step 3. Here a color detection procedure is introduced that automatically separates the background of the charts and rolls from the grid and subsequently the rainfall curve. The rainfall curve is detected by minimization of a cost function. In total, 321 station years of locations in the Netherlands have successfully been digitized and transformed to long-term rainfall time series with 5-min resolution. In about 30% of the cases, semiautomatic postprocessing of the results was needed using a purpose-built graphical interface application. This percentage, however, strongly depends on the quality of the recorded curves and the charts and rolls. Although developed for rainfall, the method can be applied to other elements as well.

CURRENT BEST PRACTICES AND BIOBANKING RECOMMENDATIONS

2019 ◽  
Vol 64 (12) ◽  
pp. 769-776 ◽  
Author(s):  
Y. V. Doludin ◽  
A. L. Borisova ◽  
M. S. Pokrovskaya ◽  
O. V. Stefanyuk ◽  
O. V. Sivakova ◽  
...  
Keyword(s):  
Best Practices ◽  
Preanalytical Phase ◽  
Wide Range ◽  
Research Problems ◽  
Processing And Storage ◽  
And Storage ◽  
Quality Of Research ◽  
Selection Of

The biobank is a structure established with the goal of long-term responsible storage of biological samples and the associated data for their further use in scientific and clinical research. The objectives of biobanking are the creation of unified recommendations on: the planning of premises and the selection of equipment for storage; development of management methods and staff training; standardization of methods for the collection, shipping, processing and storage of biomaterial of various origins, as well as methods for quality control and validation of the applied methods; creation and use of databases of information accompanying biospecimens. The lack of common standards for conducting the preanalytical phase has been the cause of low accuracy and poor reproducibility of research results. To date, a large number of guidelines and best practices have been published that provide an answer to a wide range of problems in organizing the biobanking process. The article provides an overview of the most famous biobanking guidelines that can be used to solve various research problems. Biobanking in Russia is actively developing. Since 1996 there is a work on the legislative regulation of biobanking activities, as a result of which a number of regulatory documents have been issued. An important stage in the development of biobanking in Russia was the establishment of the “National Association of Biobanks and Biobanking Specialists” (NASBio) in 2018, which included representatives of medical and research institutions, commercial firms, and qualified specialists in the field of biobanking. One of the key tasks of NASBio is the adaptation and implementation of the best biobanking practices in Russian research institutes and centers. The use of modern guidelines and best practices on biobanking will lead to an increase in the quality of research and publications.

scholarly journals Dietary assessment methods for micronutrient intake in elderly people: a systematic review

2009 ◽  
Vol 102 (S1) ◽  
pp. S118-S149 ◽  
Author(s):  
Adriana Ortiz-Andrellucchi ◽  
Almudena Sánchez-Villegas ◽  
Jorge Doreste-Alonso ◽  
Jeanne de Vries ◽  
Lisette de Groot ◽  
...  
Keyword(s):  
Elderly People ◽  
Dietary Assessment ◽  
Correlation Coefficients ◽  
Reference Method ◽  
Assessment Method ◽  
Short Term ◽  
Dietary Assessment Methods ◽  
Micronutrient Intake

The European micronutrient recommendations aligned (EURRECA) Network of Excellence seeks to establish clear guidelines for assessing the validity of reported micronutrient intakes among vulnerable population groups. A systematic literature review identified studies validating the methodology used in elderly people for measuring usual dietary micronutrient intake. The quality of each validation study selected was assessed using a EURRECA-developed scoring system. The validation studies were categorised according to whether the reference method applied reflected short-term intake ( < 7 d), long-term intake ( ≥ 7 d) or used biomarkers (BM). A correlation coefficient for each micronutrient was calculated from the mean of the correlation coefficients from each study weighted by the quality of the study. Thirty-three papers were selected, which included the validation of twenty-five different FFQ, six diet histories (DH), one 24-h recall (24HR) and a videotaped dietary assessment method. A total of five publications analysed BM, which were used to validate four FFQ, and one 24HR, presenting very good correlations only for vitamin E. The analysis of weighted correlation coefficients classified by FFQ or DH showed that most of the micronutrients had higher correlations when the DH was used as the dietary method. Comparing only FFQ results showed very good correlations for measuring short-term intakes of riboflavin and thiamin and long-term intakes of P and Mg. When frequency methods are used for assessing micronutrient intake, the inclusion of dietary supplements improves their reliability for most micronutrients.

scholarly journals Neural Network Classifiers for Local Wind Prediction

2004 ◽  
Vol 43 (5) ◽  
pp. 727-738 ◽  
Author(s):  
Ralf Kretzschmar ◽  
Pierre Eckert ◽  
Daniel Cattani ◽  
Fritz Eggimann
Keyword(s):  
Neural Network ◽  
Time Series ◽  
Performance Measure ◽  
Lead Times ◽  
Wind Gust ◽  
Model Data ◽  
The Neural Network ◽  
Neural Network Classifiers ◽  
Selection Of

Abstract This paper evaluates the quality of neural network classifiers for wind speed and wind gust prediction with prediction lead times between +1 and +24 h. The predictions were realized based on local time series and model data. The selection of appropriate input features was initiated by time series analysis and completed by empirical comparison of neural network classifiers trained on several choices of input features. The selected input features involved day time, yearday, features from a single wind observation device at the site of interest, and features derived from model data. The quality of the resulting classifiers was benchmarked against persistence for two different sites in Switzerland. The neural network classifiers exhibited superior quality when compared with persistence judged on a specific performance measure, hit and false-alarm rates.

scholarly journals Search for evidence of trend slow-down in the long-term TOMS/SBUV total ozone data record: the importance of instrument drift uncertainty

2006 ◽  
Vol 6 (12) ◽  
pp. 4057-4065 ◽  
Author(s):  
R. S. Stolarski ◽  
S. M. Frith
Keyword(s):  
Time Series ◽  
Total Ozone ◽  
Rate Of Change ◽  
Data Set ◽  
Ozone Data ◽  
Data Record ◽  
Cusum Analysis ◽  
Statistical Time ◽  
Drift Uncertainty

Abstract. We have developed a merged ozone data set (MOD) for the period October 1978 through June 2006 combining total ozone measurements (Version 8 retrieval) from the TOMS (Nimbus 7, Earth Probe) and SBUV/SBUV2 (Nimbus 7, NOAA 9/11/16) series of satellite instruments. We use the MOD data set to search for evidence of ozone recovery in response to the observed leveling off of chlorine and bromine compounds in the stratosphere. A crucial step in any time series analysis is the evaluation of uncertainties. In addition to the standard statistical time series uncertainties, we evaluate the possible instrument drift uncertainty for the MOD data set. We combine these two sources of uncertainty and apply them to a cumulative sum of residuals (CUSUM) analysis for trend slow-down. For the extra-polar mean between 60° S and 60° N, the apparent slow-down in trend is found to be clearly significant if instrument uncertainties are ignored. When instrument uncertainties are added, the slow-down becomes marginally significant at the 2σ level. For the mid-latitudes of the northern hemisphere (30° to 60° N) the trend slow-down is highly significant at the 2σ level, while in the southern hemisphere the trend slow-down has yet to meet the 2σ significance criterion. The rate of change of chlorine/bromine compounds is similar in both hemispheres, and we expect the ozone response to be similar in both hemispheres as well. The asymmetry in the trend slow-down between hemispheres likely reflects the influence of dynamical variability, and thus a clearly statistically significant response of total ozone to the leveling off of chlorine and bromine in the stratosphere is not yet indicated.

Long-term changes in the discharge regime in Finland

2010 ◽  
Vol 41 (3-4) ◽  
pp. 253-268 ◽  
Author(s):  
Johanna Korhonen ◽  
Esko Kuusisto
Keyword(s):  
Time Series ◽  
Peak Flow ◽  
Trend Test ◽  
Regulated Rivers ◽  
Annual Peak ◽  
Discharge Regime ◽  
Long Term Trends ◽  
Individual Time Series ◽  
Selection Of

This paper presents characteristics of the discharge regime, long-term trends and variability in Finland. A selection of long-term discharge records including both unregulated and regulated rivers and lake outlets were analysed up to the year 2004. In addition to individual time series, monthly and annual discharges from the territory of Finland were calculated for the period 1912–2004. The observed drought and flood periods are also discussed, as well as the connection between discharge regime and climate. Moreover, the periodicity of the time series is examined for a couple of sites. The Mann–Kendall trend test was applied to assess changes in annual, monthly and seasonal mean discharges, maximum and minimum flows and, in addition, the date of the annual peak flow. The trend analysis revealed no changes in mean annual flow in general, but the seasonal distribution of streamflow has changed. Winter and spring mean monthly discharges have increased at most of the observation sites. The spring peak has moved to an earlier date at over one-third of the sites. However, the magnitudes of spring high flow have not changed. Autumn flow did not show trends in general. Minimum flows have increased at about half of the unregulated sites.

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