Testing a Modification of the Palmer Drought Severity Index for Mediterranean Environments

Pereira, Luís S.; Rosa, Ricardo D.; Paulo, Ana A.

doi:10.1007/978-1-4020-5924-7_8

Cited by 15 publications

(13 citation statements)

References 16 publications

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“…The calculation of PDSI and MedPDSI was performed with local calibration of the indices and is described by Pereira et al (2007) and Pereira and Rosa (2010).…”

Section: Methodsmentioning

confidence: 99%

“…Most relevant indices include the Palmer Drought Severity Index, PDSI (Palmer, 1965) and the Standardized Precipitation Index, SPI (McKee et al, 1993(McKee et al, , 1995, which are considered herein together with a modification of the PDSI for Mediterranean conditions, the MedPDSI (Pereira et al, 2007;Pereira and Rosa, 2010). The SPI is a normalized index for calculating the deviation from the precipitation normal, allowing identification and characterization of droughts at different time scales.…”

Section: Introductionmentioning

confidence: 99%

“…It mainly consists of (a) assuming a rainfed olive orchard as a drought reference crop, (b) replacing the potential climatic evapotranspiration (ET) computed with the Thornthwaite method by the reference ET computed with the FAO-PM method (Allen et al, 1998) to estimate the actual evapotranspiration (ETa) of the reference olive orchard, (c) computing ETa with the dual crop coefficient approach, thus, partitioning it into plant transpiration and soil evaporation to make ETa more sensitive to the available soil water, (d) performing a sequential soil water balance that overcomes the limitations of the original Palmer formulation, (e) replacing the climate characteristic used for the standardization of the Palmer moisture anomaly index z by the inverse of the standard deviation of the monthly moisture departures, which are precursors of the z index. The resulting soil water balance components show a better adherence to the vegetation reality than for the original PDSI, e.g., actual ET for the MedPDSI is higher during winter and spring and is generally lower in summer, and the MedPDSI is more sensitive to dry and wet anomalies than the PDSI (Pereira et al, 2007;Paulo et al, 2012;Rosa et al, 2010a).…”

Section: Introductionmentioning

confidence: 99%

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Spatial and temporal variability of precipitation and drought in Portugal

Martins¹,

Raziei

Paulo³

et al. 2012

Nat. Hazards Earth Syst. Sci.

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Abstract. The spatial variability of precipitation and drought are investigated for Portugal using monthly precipitation from 74 stations and minimum and maximum temperature from 27 stations, covering the common period of . Seasonal precipitation and the corresponding percentages in the year, as well as the precipitation concentration index (PCI), was computed for all 74 stations and then used as an input matrix for an R-mode principal component analysis to identify the precipitation patterns. The standardized precipitation index at 3 and 12 month time scales were computed for all stations, whereas the Palmer Drought Severity Index (PDSI) and the modified PDSI for Mediterranean conditions (MedPDSI) were computed for the stations with temperature data. The spatial patterns of drought over Portugal were identified by applying the S-mode principal component analysis coupled with varimax rotation to the drought indices matrices. The result revealed two distinct sub-regions in the country relative to both precipitation regimes and drought variability. The analysis of time variability of the PC scores of all drought indices allowed verifying that there is no linear trend indicating drought aggravation or decrease. In addition, the analysis shows that results for SPI-3, SPI-12, PDSI and MedPDSI are coherent among them.

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“…The calculation of PDSI and MedPDSI was performed with local calibration of the indices and is described by Pereira et al (2007) and Pereira and Rosa (2010).…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Spatial and temporal variability of precipitation and drought in Portugal

Martins¹,

Raziei

Paulo³

et al. 2012

Nat. Hazards Earth Syst. Sci.

Self Cite

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show abstract

“…The Standardised Precipitation Evapotranspiration Index (SPEI) includes precipitation and potential evapotranspiration (PET) in its formulation; it may express the water supply-demand relation and may accommodate climate change influences (Vicente-Serrano et al, 2010a). Differently, the MedPDSI, which is a modification of the PDSI for Mediterranean conditions, was developed to adopt an updated formulation of the water balance and to consider real evapotranspiration instead of PET, thus approaching better the behaviour of natural and man-made ecosystems in terms of water supply-demand (Pereira et al, 2007;Pereira and Rosa, 2010).…”

Section: Introductionmentioning

confidence: 99%

Climate trends and behaviour of drought indices based on precipitation and evapotranspiration in Portugal

Paulo

Rosa

Pereira

2012

Nat. Hazards Earth Syst. Sci.

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234

121

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Abstract. Distinction between drought and aridity is crucial to understand water scarcity processes. Drought indices are used for drought identification and drought severity characterisation. The Standardised Precipitation Index (SPI) and the Palmer Drought Severity Index (PDSI) are the most known drought indices. In this study, they are compared with the modified PDSI for Mediterranean conditions (MedPDSI) and the Standardised Precipitation Evapotranspiration Index (SPEI). MedPDSI results from the soil water balance of an olive crop, thus real evapotranspiration is considered, while SPEI uses potential (climatic) evapotranspiration. Similarly to the SPI, SPEI can be computed at various time scales. Aiming at understanding possible impacts of climate change, prior to compare the drought indices, a trend analysis relative to precipitation and temperature in 27 weather stations of Portugal was performed for the period 1941 to 2006. A trend for temperature increase was observed for some weather stations and trends for decreasing precipitation in March and increasing in October were also observed for some locations. Comparisons of the SPI and SPEI at 9-and 12-month time scales, the PDSI and Med-PDSI were performed for the same stations and period. SPI and SPEI produce similar results for the same time scales concerning drought occurrence and severity. PDSI and Med-PDSI correlate well between them and the same happened for SPI and SPEI. PDSI and MedPDSI identify more severe droughts than SPI or SPEI and identify drought occurrence earlier than these indices. This behaviour is likely to be related with the fact that a water balance is performed with PDSI and MedPDSI, which better approaches the supplydemand balance.

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“…Despite SPI is the most used in Portugal, other drought indices have also been used in the 56 country, namely the Palmer Drought Severity Index (PDSI, Palmer, 1965), which combines 57 precipitation and evapotranspiration to define a deviation from normal through a soil water balance, 58 and a modification of the PDSI (MedPDSI, Pereira et al, 2007) to better perform the soil water 59 balance using an olive crop as standard perennial crop (Paulo et al, 2012). climates.…”

mentioning

confidence: 99%

Influence of Precipitation Changes on the SPI and Related Drought Severity. An Analysis Using Long-Term Data Series

Paulo

Martins

Pereira

2016

Water Resour Manage

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Abstract:Drought indices, such as the Standardized Precipitation Index (SPI) are used to 10 quantify drought severity. Due to the SPI probabilistic and standardized nature, a given value of SPI 11 computed in distinct time periods or locations indicates the same relative drought severity but 12 corresponds to different amounts of precipitation. Thus, the present study aims at contributing for a 13 comprehensive analysis of the influence of long-term precipitation variability on drought 14 assessment by the SPI. Long records of monthly precipitation, spanning from 1863 to 2007 in 15 several locations across Portugal, were divided into 30 years sub-periods and the SPI with 12-month 16 time scale (SPI-12) was computed for each sub-period and for the entire period of records. The 17 probability distributions adjusted to precipitation in those different time periods were compared 18 envisaging to detect the SPI sensitivity to the reference period and, therefore, to changes in 19 precipitation. Precipitation thresholds relative to the upper limits of SPI-12 drought categories were 20 obtained and the influence of the time period was investigated. Results have shown that when SPI 21 values derived from the full data record for a recent time period are lower/higher than the SPI 22 values derived from data of the considered time period a recent downward/upward shift of 23 precipitation has occurred. Coherently, a common pattern of drought aggravation from the initial 24 until the more recent period was not detected. However, in southern locations, lower precipitation 25 thresholds of the SPI drought categories were generally found in the more recent period, 26 particularly for more severe drought categories, whereas in the northern locations Porto and 27Montalegre, an increase was detected. The impacts of the reference period on the computed SPI 28 drought severity and frequency are shown, bringing to discussion the need for updating ´normal´ 29 conditions when long term precipitation records are available and precipitation changes are 30 observed. 31

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Testing a Modification of the Palmer Drought Severity Index for Mediterranean Environments

Cited by 15 publications

References 16 publications

Spatial and temporal variability of precipitation and drought in Portugal

Spatial and temporal variability of precipitation and drought in Portugal

Climate trends and behaviour of drought indices based on precipitation and evapotranspiration in Portugal

Influence of Precipitation Changes on the SPI and Related Drought Severity. An Analysis Using Long-Term Data Series

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