Comparison of methods for filling in gaps in monthly rainfall series in arid regions

2021 ◽  
Author(s):  
Zeinab Abu Romman ◽  
Jawad Al‐bakri ◽  
Mustafa Al Kuisi
Keyword(s):  
Arid Regions ◽  
Monthly Rainfall ◽  
Rainfall Series ◽  
Comparison Of Methods

scholarly journals An approach to quality analysis, gap filling and homogeneity of monthly rainfall series

2021 ◽  
Vol 29 ◽  
pp. 157-168
Author(s):  
Janaina Cassiano dos Santos ◽  
Gustavo Bastos Lyra ◽  
Marcel Carvalho Abreu ◽  
Daniel Carlos de Menezes
Keyword(s):  
Linear Regression ◽  
Rio De Janeiro ◽  
The State ◽  
Monthly Rainfall ◽  
Rainfall Series ◽  
Quality Analysis ◽  
Linear Regression Method ◽  
Simple Linear Regression ◽  
Gap Filling ◽  
Unsupervised Approaches

The aim of this work was to propose a method for the consistency of climatic series of monthly rainfall using a supervised and unsupervised approach. The methodology was applied for the series (1961-2010) of rainfall from weather stations located in the State of Rio de Janeiro (RJ) and in the borders with the states of São Paulo, Minas Gerais and Espírito Santo with the State of Rio de Janeiro. The data were submitted to quality analysis (physical and climatic limit and, space-time tendency) and gap filling, based on simple linear regression analysis, associated with the prediction band (p < 0.05 or 0.01), in addition to the Z-score (3, 4 or 5). Next, homogeneity analysis was applied to the continuous series, using the method of cumulative residuals. The coefficients of determination (r²) between the assessed series and the reference series were greater than 0.70 for gap filling both for the supervised and unsupervised approaches. In the analysis of data homogeneity, supervised and unsupervised approaches were effective in selecting homogeneous series, in which five out of the nine final stations were homogeneous (p > 0.9). In the other series, the homogeneity break points were identified and the simple linear regression method was applied for their homogenization. The proposed method was effective to consist of the rainfall series and allows the use of these data in climate studies.

scholarly journals A 305-year continuous monthly rainfall series for the island of Ireland (1711–2016)

2018 ◽  
Vol 14 (3) ◽  
pp. 413-440 ◽  
Author(s):  
Conor Murphy ◽  
Ciaran Broderick ◽  
Timothy P. Burt ◽  
Mary Curley ◽  
Catriona Duffy ◽  
...  
Keyword(s):  
Decadal Variability ◽  
Rainfall Variability ◽  
Summer Precipitation ◽  
Recent Decade ◽  
Monthly Rainfall ◽  
Rainfall Series ◽  
Continuous Series ◽  
Temperature Record ◽  
The North

Abstract. A continuous 305-year (1711–2016) monthly rainfall series (IoI_1711) is created for the Island of Ireland. The post 1850 series draws on an existing quality assured rainfall network for Ireland, while pre-1850 values come from instrumental and documentary series compiled, but not published by the UK Met Office. The series is evaluated by comparison with independent long-term observations and reconstructions of precipitation, temperature and circulation indices from across the British–Irish Isles. Strong decadal consistency of IoI_1711 with other long-term observations is evident throughout the annual, boreal spring and autumn series. Annually, the most recent decade (2006–2015) is found to be the wettest in over 300 years. The winter series is probably too dry between the 1740s and 1780s, but strong consistency with other long-term observations strengthens confidence from 1790 onwards. The IoI_1711 series has remarkably wet winters during the 1730s, concurrent with a period of strong westerly airflow, glacial advance throughout Scandinavia and near unprecedented warmth in the Central England Temperature record – all consistent with a strongly positive phase of the North Atlantic Oscillation. Unusually wet summers occurred in the 1750s, consistent with proxy (tree-ring) reconstructions of summer precipitation in the region. Our analysis shows that inter-decadal variability of precipitation is much larger than previously thought, while relationships with key modes of climate variability are time-variant. The IoI_1711 series reveals statistically significant multi-centennial trends in winter (increasing) and summer (decreasing) seasonal precipitation. However, given uncertainties in the early winter record, the former finding should be regarded as tentative. The derived record, one of the longest continuous series in Europe, offers valuable insights for understanding multi-decadal and centennial rainfall variability in Ireland, and provides a firm basis for benchmarking other long-term records and reconstructions of past climate. Correlation of Irish rainfall with other parts of Europe increases the utility of the series for understanding historical climate in further regions.

scholarly journals Supplementary material to "A 305-year continuous monthly rainfall series for the Island of Ireland (1711–2016)"

2017 ◽  
Author(s):  
Conor Murphy ◽  
Ciaran Broderick ◽  
Timothy P. Burt ◽  
Mary Curley ◽  
Catriona Duffy ◽  
...  
Keyword(s):  
Monthly Rainfall ◽  
Rainfall Series ◽  
Supplementary Material

HOMOGENEITY ANALYSIS OF RAINFALL IN KELANTAN, MALAYSIA

2015 ◽  
Vol 76 (15) ◽  
Author(s):  
Ng Jing Lin ◽  
Samsuzana Abd Aziz ◽  
Huang Yuk Feng ◽  
Aimrun Wayayok ◽  
Md Rowshon Kamal
Keyword(s):  
River Basin ◽  
Monthly Rainfall ◽  
Rainfall Series ◽  
Rainfall Data ◽  
Seasonal Rainfall ◽  
Homogeneity Test ◽  
Ratio Test ◽  
Homogeneity Analysis ◽  
Standard Normal Homogeneity Test ◽  
Kelantan River Basin

Good quality of rainfall data is required for the hydrological studies, water resources planning and sustainable environmental management. Consequently, the assessment of the homogeneity of rainfall data at different region is becoming increasing popular in the past few decades. In this study, the homogeneity analysis of rainfall data was carried out in Kelantan River Basin, Malaysia. The methods, namely standard normal homogeneity test (SHNT), Buishand range test, Pettitt test and von Neumann ratio test were applied to the monthly, yearly and seasonal data. The historical rainfall data from 10 rainfall stations covering the study period from 28 to 60 years were selected. The four tests were applied to 120 monthly series, 10 yearly series and 40 seasonal series. ‘Useful’, ‘doubtful’ and ‘suspect’ were used to classify the results of the four tests. The results showed that 94.17% of the monthly rainfall series, 70% of yearly rainfall series and 97.5% of seasonal rainfall series are labelled ‘useful’. There is 5% of monthly rainfall series, 30% of yearly rainfall series and 1% of seasonal rainfall series are classified as ‘doubtful’. Meanwhile, there is only 0.83% of monthly rainfall series and no yearly rainfall series and seasonal rainfall series detected in the class ‘suspect’. Overall, the percentage of inhomogeneity detected in the monthly, yearly and seasonal rainfall data series of Kelantan River Basin is very small, thus most of the data is suitable to be used for further hydrological and variability analysis.

scholarly journals Reconstruction of rainfall in Zafra (southwest Spain) from 1750 to 1840 from documentary sources

2011 ◽  
Vol 7 (6) ◽  
pp. 3895-3918 ◽  
Author(s):  
M. I. Fernández-Fernández ◽  
M. C. Gallego ◽  
F. Domínguez-Castro ◽  
J. M. Vaquero ◽  
J. M. Moreno González ◽  
...  
Keyword(s):  
North Atlantic ◽  
Extreme Values ◽  
Correlation Coefficients ◽  
Monthly Rainfall ◽  
Rainfall Series ◽  
Reconstruction Method ◽  
The North ◽  
Rainfall Index ◽  
The North Atlantic Oscillation ◽  
High Resolution Reconstruction

Abstract. This work presents the first high-resolution reconstruction of rainfall in southwestern Spain during the period 1750–1840. The weather descriptions used are weekly reports describing the most relevant events that occurred in the Duchy of Feria. An index was defined to characterise the weekly rainfall. Monthly indices were obtained by summing the corresponding weekly indices, obtaining cumulative monthly rainfall indices. The reconstruction method consisted of establishing a linear correlation between the monthly rainfall index and monthly instrumental data (1960–1990). The correlation coefficients were greater than 0.80 for all months. The rainfall reconstruction showed major variability similar to natural variability. The reconstructed rainfall series in Zafra was compared with the rainfall series of Cadiz, Gibraltar and Lisbon for the period 1750–1840, with all four series found to have a similar pattern. The influence of the North Atlantic Oscillation (NAO) on the winter rainfall reconstruction was found to behave similarly to that of modern times. Other studies described are of the SLP values over the entire North Atlantic in the months with extreme values of rainfall, and unusual meteorological events (hail, frost, storms and snowfall) in the reports of the Duchy of Feria.

scholarly journals A 305-year continuous monthly rainfall series for the Island of Ireland (1711–2016)

2017 ◽  
Author(s):  
Conor Murphy ◽  
Ciaran Broderick ◽  
Timothy P. Burt ◽  
Mary Curley ◽  
Catriona Duffy ◽  
...  
Keyword(s):  
Rainfall Variability ◽  
Summer Precipitation ◽  
Recent Decade ◽  
Monthly Rainfall ◽  
Rainfall Series ◽  
Annual Rainfall ◽  
Temperature Record ◽  
Annual Series ◽  
The North

Abstract. A continuous 305-year (1711–2016) monthly rainfall series is created for the Island of Ireland. Two overlapping data sources are employed: i) a previously unpublished UK Meteorological Office note containing annual rainfall anomalies and corresponding proportional monthly totals based on weather diaries and early observational records for the period 1711–1977 and; ii) a long-term, homogenised monthly rainfall series for the island of Ireland for the period 1850–2016. Using estimates of long-term average precipitation from the homogenised series to merge these sources, the new 305-year record is constructed and insights drawn about notable extremes, climate variability and change. The consistency of the resulting series was evaluated by comparison with independent long-term observations and reconstructions of precipitation, temperature and circulation indices from across the British-Irish Isles. Strong decadal consistency is evident throughout the record amongst all series in spring, summer and autumn. The winter series is probably too dry from the 1740s to the 1780s, but strong consistency with other records strengthens confidence from 1790 onwards. The new Island of Ireland series reveals remarkably wet winters during the 1730s, concurrent with a period of strong westerly airflow, glacial advance throughout Scandinavia and near unprecedented warmth in the Central England Temperature record – all consistent with the strong phase of the North Atlantic Oscillation. The driest winter decade in the series coincides with the Laki eruption of 1783–1784. Unusually wet summers occurred in the 1750s, consistent with proxy (tree-ring) reconstructions of summer precipitation in the region. In the annual series, the most recent decade (2006–2015) is found to be the wettest in over 300 years. The new series reveals statistically significant (0.05 level) multi-centennial trends in winter (increasing) and summer (decreasing) seasonal precipitation. However, given uncertainties in the early winter record, the former should be treated as tentative. Importantly, we show that the years 1940 to present – the period with the most widely available digitised records – is unrepresentative of long-term changes in all seasons. Although there are recognized uncertainties in the early record, the derived series offers valuable insights for understanding multi-decadal and centennial rainfall variability in Ireland, and provides a firm basis for benchmarking other long-term records and future reconstructions.

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