Empirical Orthogonal Function analysis of the palmer drought indices

Tatlı, Hasan; Türkeş, Murat

doi:10.1016/j.agrformet.2011.03.004

Cited by 63 publications

(27 citation statements)

References 29 publications

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“…According to these figures, the stable atmospheric conditions with low humidity create similar patterns as obtained for the Haines index value equal to 1. This result reveals a parallel with the results in the recent study carried out for Turkey by Tatli and Türkeş (): the principal components of Palmer Drought Severity Index show similar patterns with the patterns extracted for soil moisture. The physical geographical controllers (climate, soil, geomorphology) and atmospheric features have strong inter‐relationships.…”

Section: Resultsmentioning

confidence: 99%

“…In a recently published study of Juli and Santiago (), the forest fires in the Western Mediterranean basin have been becoming larger and more frequent, but according to the European Forest Fire Information Systems (European Commission, ), the number of fires in the southern member states of European Union increased from 1980 to 2000, and has been slightly decreasing since that time. Current climate change trends are towards longer summer droughts and intensification of droughts in other seasons (Tatli et al , , ; Flannigan et al , ; Moriondo et al , ; IPCC, ; Tatli, ; Türkeş et al , ; Türkeş and Tatli, , ; Tatli and Türkeş, ).…”

Section: Introductionmentioning

confidence: 99%

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Climatological evaluation of Haines forest fire weather index over the Mediterranean Basin

Tatlı

Türkeş

2013

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Forest fires are the most crucial natural threat to forests and wooded areas. They destroy many more trees than all other natural catastrophes such as parasite attacks, insects, extreme weather events and others. Forest fires, especially in summer and dry autumn/spring periods, are frequent in the Mediterranean basin and represent growing environmental and ecological problems. The aim of this investigation is to determine a climatic pattern of fire-meteorology over the Mediterranean basin via the frequency analysis of the forest fires weather index (FFWI) of Haines. The FFWI values were obtained by using the hourly data derived from reanalysis fields available from the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) for the period 1980-2010. High frequency values of FFWI, taken to be a sign of moderate-level risk of forest fires, were obtained on the forests, scrubs, succulents and wooded areas in several countries facing the sea including Greece, Italy, Turkey, Syria, Lebanon, Cyprus, Macedonia, Albania, Serbia, Slovenia, France, Portugal, Spain, Morocco and Tunisia, almost all of which are characterized by dry summer, subtropical Mediterranean climates. As expected, the highest-level risk values are found in the arid desert climate regions: the desert areas of the Sahara and Libya in North Africa and the semi-arid steppe climate regions of the Middle East, as well as the semi-arid environments near the Caspian Sea basin.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Climatological evaluation of Haines forest fire weather index over the Mediterranean Basin

Tatlı

Türkeş

2013

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“…The PDSI values are also used to show wet spells by using the corresponding positive numbers. Further details of the computation steps of the PDSI values can be found in the literature (Palmer, 1965;Alley, 1984;Tatli and Türkeş, 2011).…”

Section: Palmer Drought Severity Indexmentioning

confidence: 99%

“…The calculation algorithm of the PDSI values involves a set of algebraic equations and getting to some physical parameterization (Palmer, 1965;Alley, 1984;Tatli and Türkeş, 2011).…”

Section: Palmer Drought Severity Indexmentioning

confidence: 99%

“…For monitoring droughts, many typical drought indices have been developed based on meteorological and hydrological variables to show the size, duration, severity and spatial extent of droughts. The Palmer drought severity index (PDSI) is such an example (Palmer 1965;Alley, 1984;Tatli and Türkeş, 2011). For realizing the nature of the drought events in the Paleoclimatic times, they can also be investigated with the prospect of reconstructing the drought indices.…”

Section: Introductionmentioning

confidence: 99%

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Detecting persistence of meteorological drought via the Hurst exponent

Tatlı

2015

Meteorological Applications

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This study proposes the Hurst exponent (H) to detect persistence in the Palmer Drought Severity Index (PDSI) over Turkey. Since a fractal structure admits the behaviour of global determinism and local randomness, the H exponent values could be used to detect self-similar statistical structure of the time series. Additionally, the H value >0.5 and near 1 shows the intensity level of persistence. The term persistence may be assessed as a criterion to be used as a measure of predictability. Moreover, the predictability index, fractal dimension and autocorrelation function of the PDSI values can also be obtained from the H values. Nevertheless, it is not easy to find a spatial meaning of information content of the results obtained by the methods used in the present study. For that reason, the Mann-Kendall (MK) trend test was also used, and the results showed that significant negative trends are widespread throughout the country. As expected, the H values were close to 1 in places where statistically significant trends exist. The high values of the H exponent in all the regions can be explained by the droughts observed there that might be caused due to the possible associations with the large-scale atmospheric circulations. In this context, it is suggested that the droughts can be predictable by constructing the appropriate general climate circulation models.

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A probabilistic prediction network for hydrological drought identification and environmental flow assessment

Liu

Törnros

Menzel

2016

Water Resources Research

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A general probabilistic prediction network is proposed for hydrological drought examination and environmental flow assessment. This network consists of three major components. First, we present the joint streamflow drought indicator (JSDI) to describe the hydrological dryness/wetness conditions. The JSDI is established based on a high‐dimensional multivariate probabilistic model. In the second part, a drought‐based environmental flow assessment method is introduced, which provides dynamic risk‐based information about how much flow (the environmental flow target) is required for drought recovery and its likelihood under different hydrological drought initial situations. The final part involves estimating the conditional probability of achieving the required environmental flow under different precipitation scenarios according to the joint dependence structure between streamflow and precipitation. Three watersheds from different countries (Germany, China, and the United States) with varying sizes from small to large were used to examine the usefulness of this network. The results show that the JSDI can provide an assessment of overall hydrological dryness/wetness conditions and performs well in identifying both drought onset and persistence. This network also allows quantitative prediction of targeted environmental flow required for hydrological drought recovery and estimation of the corresponding likelihood. Moreover, the results confirm that the general network can estimate the conditional probability associated with the required flow under different precipitation scenarios. The presented methodology offers a promising tool for water supply planning and management and for drought‐based environmental flow assessment. The network has no restrictions that would prevent it from being applied to other basins worldwide.

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Empirical Orthogonal Function analysis of the palmer drought indices

Cited by 63 publications

References 29 publications

Climatological evaluation of Haines forest fire weather index over the Mediterranean Basin

Climatological evaluation of Haines forest fire weather index over the Mediterranean Basin

Detecting persistence of meteorological drought via the Hurst exponent

A probabilistic prediction network for hydrological drought identification and environmental flow assessment

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