Statistical analysis of long-term trends in UK effective rainfall: implications for deep-seated landsliding

2020 ◽  
Vol 53 (4) ◽  
pp. 587-597
Author(s):  
E.M. Lee
Keyword(s):  
Time Series ◽  
Statistical Test ◽  
Positive Trend ◽  
Effective Rainfall ◽  
Significant Spatial Variation ◽  
Long Term Trends ◽  
Temperature Records ◽  
Parametric Statistical Test ◽  
The Uk

Rainfall and its impact on the water content of a slope are known to be important controls on landslide activity in the UK. This paper presents an analysis of long-term monthly rainfall and temperature records from selected stations throughout the UK, including the application of a non-parametric statistical test to evaluate the significance of any trends in these time series. The results indicate that there is significant spatial variation in the long-term trends. A positive trend of increasing effective rainfall (precipitation minus evapotranspiration) is present at some (but not all) Scottish stations (Eskdalemuir, Lerwick, Paisley, Stornoway and Tiree), but is not present across the rest of the UK.

scholarly journals Is the Last Years Abrupt Warming in the National Observatory of Athens Records a Climate Change Manifestation?

2013 ◽  
Vol 9 (2) ◽  
pp. 107-116
Keyword(s):  
Time Series ◽  
Air Temperature ◽  
Eastern Mediterranean ◽  
National Observatory ◽  
Urban Effect ◽  
Long Term Trends ◽  
Temperature Records ◽  
The 19Th Century ◽  
Temperature Time

Instrumental data time series show an average global warming of approximately 0.90C over the last century. Eastern Mediterranean air temperature follows the northern hemisphere (NH) secular trend till 1970s, while the NH warming of the last 30 years is not noticeable in the eastern Mediterranean till 1990s. National Observatory of Athens (NOA) meteorological time series start from the last decades of the 19th Century, therefore are at first suitable for detection of long term trends in the region. In this study we investigate whether the abrupt increase of the NOA air temperature time series, which appears during the last few years, is the finger-print of the broader scale climatic change or it is a discontinuity in the record of urban effect or of station’s problems origin. It is shown that NOA air temperature records display a statistically significant discontinuity attributable to change of the station thermometers on 1995 and therefore NOA records must be treated with caution for long term air temperature trends detection.

scholarly journals Changepoint Detection in Climate Time Series with Long-Term Trends

2013 ◽  
Vol 26 (14) ◽  
pp. 4994-5006 ◽  
Author(s):  
Colin Gallagher ◽  
Robert Lund ◽  
Michael Robbins
Keyword(s):  
Time Series ◽  
Mean Shift ◽  
Asymptotic Properties ◽  
Erroneous Conclusion ◽  
Test Application ◽  
Long Term Trends ◽  
Temperature Records ◽  
Climate Time Series ◽  
Two Temperature

Abstract Climate time series often have artificial shifts induced by instrumentation changes, station relocations, observer changes, etc. Climate time series also often exhibit long-term trends. Much of the recent literature has focused on identifying the structural breakpoint time(s) of climate time series—the so-called changepoint problem. Unfortunately, application of rudimentary mean-shift changepoint tests to scenarios with trends often leads to the erroneous conclusion that a mean shift occurred near the series' center. This paper examines this problem in detail, constructing some simple homogeneity tests for series with trends. The asymptotic distribution of the proposed statistic is derived; en route, an attempt is made to unify the asymptotic properties of the changepoint methods used in today's climate literature. The tests presented here are linked to the ubiquitous t test. Application is made to two temperature records: 1) the continental United States record and 2) a local record from Jacksonville, Illinois.

scholarly journals Maps, trends, and temperature sensitivities—phenological information from and for decreasing numbers of volunteer observers

2021 ◽  
Author(s):  
Ye Yuan ◽  
Stefan Härer ◽  
Tobias Ottenheym ◽  
Gourav Misra ◽  
Alissa Lüpke ◽  
...  
Keyword(s):  
Climate Change ◽  
Time Series ◽  
Strong Decrease ◽  
Temperature Changes ◽  
Interpolation Accuracy ◽  
Observation Network ◽  
Shiny App ◽  
Long Term Trends ◽  
Autumn And Winter

AbstractPhenology serves as a major indicator of ongoing climate change. Long-term phenological observations are critically important for tracking and communicating these changes. The phenological observation network across Germany is operated by the National Meteorological Service with a major contribution from volunteering activities. However, the number of observers has strongly decreased for the last decades, possibly resulting in increasing uncertainties when extracting reliable phenological information from map interpolation. We studied uncertainties in interpolated maps from decreasing phenological records, by comparing long-term trends based on grid-based interpolated and station-wise observed time series, as well as their correlations with temperature. Interpolated maps in spring were characterized by the largest spatial variabilities across Bavaria, Germany, with respective lowest interpolated uncertainties. Long-term phenological trends for both interpolations and observations exhibited mean advances of −0.2 to −0.3 days year−1 for spring and summer, while late autumn and winter showed a delay of around 0.1 days year−1. Throughout the year, temperature sensitivities were consistently stronger for interpolated time series than observations. Such a better representation of regional phenology by interpolation was equally supported by satellite-derived phenological indices. Nevertheless, simulation of observer numbers indicated that a decline to less than 40% leads to a strong decrease in interpolation accuracy. To better understand the risk of declining phenological observations and to motivate volunteer observers, a Shiny app is proposed to visualize spatial and temporal phenological patterns across Bavaria and their links to climate change–induced temperature changes.

Mercury trends and cycling in northern Wisconsin related to atmospheric and hydrologic processes

2019 ◽  
Vol 76 (5) ◽  
pp. 831-846 ◽  
Author(s):  
C.J. Watras ◽  
D. Grande ◽  
A.W. Latzka ◽  
L.S. Tate
Keyword(s):  
Time Series ◽  
Water Cycle ◽  
Water Levels ◽  
Hydrologic Processes ◽  
Littoral Sediments ◽  
Long Term Trends ◽  
Acid Base Status ◽  
Explanatory Mechanism ◽  
Regional Water

Atmospheric deposition is the principal source of mercury (Hg) to remote northern landscapes, but its fate depends on multiple factors and internal feedbacks. Here we document long-term trends and cycles of Hg in the air, precipitation, surface water, and fish of northern Wisconsin that span the past three decades, and we investigate relationships to atmospheric processes and other variables, especially the regional water cycle. Consistent with declining emission inventories, there was evidence of declining trends in these time series, but the time series for Hg in some lakes and most fish were dominated by a near-decadal oscillation that tracked the regional oscillation of water levels. Concentrations of important solutes (SO4, dissolved organic carbon) and the acid–base status of lake water also tracked water levels in ways that cannot be attributed to simple dilution or concentration. The explanatory mechanism is analogous to the “reservoir effect” wherein littoral sediments are periodically exposed and reflooded, altering the internal cycles of sulfur, carbon, and mercury. These climatically driven, near-decadal oscillations confound short or sparse time series and complicate relationships among Hg emissions, deposition, and bioaccumulation.

Warming is Driving Decreases in Snow Fractions While Runoff Efficiency Remains Mostly Unchanged in Snow-Covered Areas of the Western United States

2018 ◽  
Vol 19 (5) ◽  
pp. 803-814 ◽  
Author(s):  
Gregory J. McCabe ◽  
David M. Wolock ◽  
Melissa Valentin
Keyword(s):  
United States ◽  
Time Series ◽  
Winter Precipitation ◽  
Western United States ◽  
Balance Model ◽  
Winter Temperatures ◽  
Long Term Trends ◽  
Monthly Water Balance ◽  
Surface Water Supply

Abstract Winter snowfall and accumulation is an important component of the surface water supply in the western United States. In these areas, increasing winter temperatures T associated with global warming can influence the amount of winter precipitation P that falls as snow S. In this study we examine long-term trends in the fraction of winter P that falls as S (Sfrac) for 175 hydrologic units (HUs) in snow-covered areas of the western United States for the period 1951–2014. Because S is a substantial contributor to runoff R across most of the western United States, we also examine long-term trends in water-year runoff efficiency [computed as water-year R/water-year P (Reff)] for the same 175 HUs. In that most S records are short in length, we use model-simulated S and R from a monthly water balance model. Results for Sfrac indicate long-term negative trends for most of the 175 HUs, with negative trends for 139 (~79%) of the HUs being statistically significant at a 95% confidence level (p = 0.05). Additionally, results indicate that the long-term negative trends in Sfrac have been largely driven by increases in T. In contrast, time series of Reff for the 175 HUs indicate a mix of positive and negative long-term trends, with few trends being statistically significant (at p = 0.05). Although there has been a notable shift in the timing of R to earlier in the year for most HUs, there have not been substantial decreases in water-year R for the 175 HUs.

11. The United Kingdom: Towards a Parting of the Ways

2020 ◽  
pp. 257-279
Author(s):  
Anand Menon ◽  
Luigi Scazzieri
Keyword(s):  
European Union ◽  
Public Opinion ◽  
Institutional Development ◽  
The European Union ◽  
Integration Process ◽  
The United Kingdom ◽  
History Of ◽  
Long Term Trends ◽  
The Uk

This chapter examines the history of the United Kingdom’s relationship with the European integration process. The chapter dissects the long-term trends in public opinion and the more contingent, short-term factors that led to the referendum vote to leave the European Union. The UK was a late joiner and therefore unable to shape the early institutional development of the EEC. British political parties and public opinion were always ambiguous about membership and increasingly Eurosceptic from the early 1990s. Yet the UK had a significant impact on the EU’s development, in the development of the single market programme and eastward enlargement. If Brexit goes through, Britain will nevertheless maintain relations with the EU in all policy areas from agriculture to energy and foreign policy. Europeanization will remain a useful theoretical tool to analyse EU–UK relations even if the UK leaves the Union.

Availability and Sales of Alcohol in Four Canadian Provinces: A Time-Series Analysis

2005 ◽  
Vol 32 (3) ◽  
pp. 343-372 ◽  
Author(s):  
Björn Trolldal
Keyword(s):  
Time Series ◽  
Research Question ◽  
Pure Alcohol ◽  
Dependent Variables ◽  
Long Term Trends ◽  
Time Series Analyses ◽  
Canadian Provinces ◽  
Physical Availability ◽  
Total Sales

The research question addressed in the present study, with ARIMA time-series analyses, was the extent to which changes in economic and physical availability had an effect on sales of alcohol in four Canadian provinces during the second half of the 20th century. The annual sales, by type of beverage (spirits, wine and beer) as well as total sales, measured in pure alcohol per inhabitant age 15 and above in each province, were used as dependent variables in the analyses. The inhabitants' real disposable income, the real price of alcohol, and the number of on- and off-premise outlets per 100,000 inhabitants were used as independent variables. All the time-series were differenced to remove long-term trends. The main study period was 1951–2000. In some of the analyses the study periods were shorter, primarily due to lack of data. Changes in economic availability in general, and in price in particular, had larger effects on sales than physical availability. Among the beverages analyzed in the study, the demand for spirits was most sensitive to changes in availability. Economic availability had a greater effect on sales than the number of outlets. However, one might question to what extent the number of outlets really is a feasible measure of transaction costs associated with purchases of alcohol.

Comparison of the Long-Term Trends of the Largest Waves in the Ice-Free Arctic Waters From Different Reanalysis Products

2018 ◽  
Author(s):  
Takuji Waseda ◽  
Takehiko Nose ◽  
Adrean Webb
Keyword(s):  
Arctic Ocean ◽  
The Arctic ◽  
Extreme Value Analysis ◽  
Positive Trend ◽  
Value Analysis ◽  
The Arctic Ocean ◽  
Ship Route ◽  
Long Term Trends ◽  
Horizontal Grid

The long-term trends of the expected largest waves in the ice-free Arctic waters from Laptev to Beaufort Seas was studied analyzing the ERA-interim reanalysis from 1979 to 2016. The analysis showed that the positive trend is largest in October and increased almost 70 cm in 38 years. For ships navigating the Northern Ship Route, it is important to know what the possible largest waves to expect during its cruise. In view of conducting the extreme value analysis, the uncertainty of the largest wave needs to be validated. However, the observation in the Arctic Ocean is limited. We, therefore, rely on the reanalysis wave products in the Arctic Ocean, whose uncertainty is yet to be determined. ERA-Interim and ERA-5 are compared in the Laptev, the East Siberian, Chukchi and Beaufort Seas. The comparison is relevant as the two products differ in its horizontal grid resolution and availability of the satellite altimeter significant wave height data assimilation. During 2010–2016 when the ERA5 is available, only a small difference from ERA-Interim was detected in the mean. However, the expected largest waves in the domain tended to be large for the ERA-5, 8% normalized bias. The tendency was quite similar with a high correlation of 0.98.

scholarly journals West African Summer Monsoon Precipitation Variability as Represented by Reanalysis Datasets

Climate ◽  
2020 ◽  
Vol 8 (10) ◽  
pp. 111
Author(s):  
Kwesi Akumenyi Quagraine ◽  
Francis Nkrumah ◽  
Cornelia Klein ◽  
Nana Ama Browne Klutse ◽  
Kwesi Twentwewa Quagraine
Keyword(s):  
Summer Monsoon ◽  
Southern Oscillation ◽  
West African Monsoon ◽  
West African ◽  
Positive Trend ◽  
In Situ Data ◽  
Dry Conditions ◽  
Long Term Trends

Focusing on West Africa, a region riddled with in situ data scarcity, we evaluate the summer monsoon monthly rainfall characteristics of five global reanalysis datasets: ERA5, ERA-Interim, JRA-55, MERRA2, and NCEP-R2. Their performance in reproducing the West African monsoon (WAM) climatology, interannual variability, and long-term trends for the main monsoon months are compared to gauge-only and satellite products. We further examine their ability to reproduce teleconnections between sea surface temperatures and monsoon rainfall. All reanalyses are able to represent the average rainfall patterns and seasonal cycle; however, regional biases can be marked. ERA5, ERA-Interim, and NCEP-R2 underestimate rainfall over areas of peak rainfall, with ERA5 showing the strongest underestimation, particularly over the Guinea Highlands. The meridional northward extent of the monsoon rainband is well captured by JRA-55 and MERRA2 but is too narrow in ERA-Interim, for which rainfall stays close to the Guinea Coast. Differences in rainband displacement become particularly evident when comparing strong El Niño Southern Oscillation (ENSO) years, where all reanalyses except ERA-Interim reproduce wetter Sahelian conditions for La Niña, while overestimating dry conditions at the coast except for NCEP-R2. Precipitation trends are not coherent across reanalyses and magnitudes are generally overestimated compared to observations, with only JRA-55 and NCEP-R2 displaying the expected positive trend in the Sahel. ERA5 generally outperforms ERA-Interim, highlighting clear improvements over its predecessor. Ultimately, we find the strengths of reanalyses to strongly vary across the region.

scholarly journals A Technique to Detect Microclimatic Inhomogeneities in Historical Records of Screen-Level Air Temperature

2006 ◽  
Vol 19 (6) ◽  
pp. 959-978 ◽  
Author(s):  
K. E. Runnalls ◽  
T. R. Oke
Keyword(s):  
Time Series ◽  
Air Temperature ◽  
Weather Conditions ◽  
Historical Records ◽  
Vegetation Development ◽  
Environment Effects ◽  
Thermal Changes ◽  
Screen Level ◽  
Temperature Records

Abstract A new method to detect errors or biases in screen-level air temperature records at standard climate stations is developed and applied. It differs from other methods by being able to detect microclimatic inhomogeneities in time series. Such effects, often quite subtle, are due to alterations in the immediate environment of the station such as changes of vegetation, development (buildings, paving), irrigation, cropping, and even in the maintenance of the site and its instruments. In essence, the technique recognizes two facts: differences of thermal microclimate are enhanced at night, and taking the ratio of the nocturnal cooling at a pair of neighboring stations nullifies thermal changes that occur at larger-than-microclimatic scales. Such ratios are shown to be relatively insensitive to weather conditions. After transforming the time series using Hurst rescaling, which identifies long-term persistence in geophysical phenomena, cooling ratio records show distinct discontinuities, which, when compared against detailed station metadata records, are found to correspond to even minor changes in the station environment. Effects detected by this method are shown to escape detection by current generally accepted techniques. The existence of these microclimatic effects are a source of uncertainty in long-term temperature records, which is in addition to those presently recognized such as local and mesoscale urban development, deforestation, and irrigation.

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