How does the areal averaging influence the extremes? The context of gridded observation data sets

Wibig, Joanna; Jaczewski, Adam; Brzoska, B.; Konca-Kędzierska, Krystyna; Pianko-Kluczyńska, Krystyna

doi:10.1127/0941-2948/2014/0470

Cited by 11 publications

(11 citation statements)

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“…Such effects are mainly related to the number of stations used for calculating precipitation data in each grid, and as a result not uniform in space. For instance, more averaged stations primarily decreases the number of dry days and the highest daily precipitation totals, but increases moderate precipitation totals (Wibig et al, 2014). During creation of the PaiTuli database used by this study, cases in which the distance between stations was less than 7 km were excluded in order to justify the gridded datasets in areas with high density of stations network.…”

Section: Study Area and Data Usedmentioning

confidence: 99%

Analysing the variability and trends of precipitation extremes in Finland and their connection to atmospheric circulation patterns

Irannezhad

Chen

Kløve

et al. 2017

Intl Journal of Climatology

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Ten precipitation indices recommended by the Expert Team on Climate Change Detection and Indices were used to analyse spatial distribution and temporal changes in annual amount, intensity, frequency and duration of precipitation statistics based on daily data with a focus on extremes in Finland during 1961–2011. Also, the connections between these high resolution (10 km) precipitation indices and six influential atmospheric circulation patterns (ACPs) for climate variability in Finland were studied. On the country scale, the results suggest significant increases in the amount and intensity of precipitation extremes, more precipitation days, and no clear changes in wet and dry spells. Both intensity and frequency of precipitation extremes over Finland decrease from south and southwest to north. The only exception is the distribution of precipitations days which is generally more frequent over eastern and upper areas of northern Finland. Wet (dry) spells were typically longer in the western (eastern) part of Finland. Significant increases in annual total wet‐day precipitation, very wet days precipitation and simple daily intensity index were found over most parts of Finland during 1961–2011. Increasing trends in both extremely wet days and maximum 1‐day precipitation were mostly observed in western, eastern, central and northern Finland. Such spatial pattern was also identified for significant increases in the frequency of heavy and very heavy precipitation days. The precipitation days increased over small parts of western, eastern and northern Finland. Wet spells showed lengthening trends in several grids over southwestern Finland, while dry spells lengthened in some areas over the entire country except southern parts. These variations in precipitation statistics were found to be significantly correlated with the East Atlantic/West Russia, East Atlantic, Scandinavia and Polar patterns.

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Section: Study Area and Data Usedmentioning

confidence: 99%

Analysing the variability and trends of precipitation extremes in Finland and their connection to atmospheric circulation patterns

Irannezhad

Chen

Kløve

et al. 2017

Intl Journal of Climatology

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“…The correlation coefficient for raw in situ data and E‐OBS data for the observation time period available average 0.98. Nevertheless, following an additional weather‐dependent analysis, the measurement site data were used as a reference in assessing the incidence of extreme climate cases since minimum air temperature is extremely sensitive to local conditions and gridded data have the tendency to underestimate the tails of the distribution (Wibig et al , ). It is especially significant in low temperatures so over‐smoothing is stronger in winter time and may also influence the number of spring and autumn frost days.…”

Section: Methodsmentioning

confidence: 99%

Spatial and temporal variability of the frost‐free season in Central Europe and its circulation background

Wypych

Ustrnul

Sulikowska

et al. 2016

Intl Journal of Climatology

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The aim of the study was to investigate the temporal and spatial variability of last spring and first autumn frost events as well as the length of the frost‐free season (FFS) in Central Europe in relation to atmospheric circulation. Studies were conducted for the period 1951–2010 using gridded, daily minimum air temperature data obtained from the E‐OBS dataset at 0.25° spatial resolution. To assess the possible impact of air temperature variability on plants, late spring frost events and severe frost events were also examined with respect to the beginning of the thermal growing season. The role of atmospheric circulation was described using Grosswetterlagen circulation types and NAO index, and finally estimated using empirical orthogonal function analysis (EOF). The results confirm a significant increase in the length of the FFS, up to 10 days per decade in the western parts of Europe. This is mostly a result of earlier occurrence of last spring frost in the west up to 5 days. The occurrence of first autumn frost shows no significant trend in most of the studied regions. The obtained spatial pattern of the trends reflects oceanic (west) and continental (east) climatic conditions of the study area. Detailed analysis of circulation types favouring the occurrence of frost in Central Europe indicates that anti‐cyclonic situations are mainly responsible. EOF analyses for the springtime confirm that the first mode, which accounts for 56% of total variance, is related to an extensive high pressure system over eastern Ukraine and Belarus, which brings an inflow of cold, continental air masses to Central Europe. The results provide a broaden information on the region climatologically important due to its transitional location, which may be relevant for investigating past and future trends in spring freeze risk for perennial crops, as changes in the frequency of these airflow patterns will result in changes in the risk of frost damage.

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“…The shift to positive anomalies appeared in the mountains two years earlier and the annual deviations are larger (up to 4 • C in 2015, Figure 3). Since data gridding and averaging was reported Wibig et al [48] as responsible for the smoothing effect, reaching −0.2 • C for summer temperature extremes (Tx95) in Poland, the results were compared with observations from two stations which represent the average conditions for the area of ≤500 m a.s.l. (Poznań, located in the Polish lowlands) and >500 m a.s.l.…”

Section: Long-term Variability Of Summer Maximum Air Temperaturementioning

confidence: 99%

Temporal Variability of Summer Temperature Extremes in Poland

et al. 2017

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Abstract:The aim of the study is to estimate the trend in summer maximum air temperature extremes in Poland during the period 1951-2015 by demonstrating the changes in the magnitude of temperature anomalies, temperature "surplus", as well as the area influenced by extreme temperature occurrence. To express the latter two variables, daily maps of maximum air temperature were created to calculate the total area affected by temperature extremes. To combine the effect of spatial extent and temperature anomaly, an Extremity Index was introduced. The results confirmed an increase in summer maximum air temperature of about 0.4 • C per 10 years, evidenced also in the increase of summer extremeness. Positive anomalies have dominated since the 1990s, with the largest anomalies occurring during the summers of 1992, 1994, 2010 and finally 2015, the most exceptional summer during the analyzed period.

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How does the areal averaging influence the extremes? The context of gridded observation data sets

Cited by 11 publications

References 0 publications

Analysing the variability and trends of precipitation extremes in Finland and their connection to atmospheric circulation patterns

Analysing the variability and trends of precipitation extremes in Finland and their connection to atmospheric circulation patterns

Spatial and temporal variability of the frost‐free season in Central Europe and its circulation background

Temporal Variability of Summer Temperature Extremes in Poland

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