Assessing precipitation distribution impacts on droughts on the island of Crete

Abstract. Precipitation records from 56 stations on the island of Crete (Greece) revealed that areal mean annual precipitation is of a strong orographic type and its magnitude decreases in west-east direction by as much as 400 mm on average. Amongst many parameters that influence precipitation, the elevation and longitude were the most important and provided the highest spatial correlation. It was found that during the year with minimum precipitation, the precipitation shortage was greater at high elevations while the precipitation excess during the year with maximum precipitation was greater in the western part of the island. The assessment of the spatial and temporal distribution of droughts was carried out with the aid of the Spatially Normalized Standardized Precipitation Index (SN-SPI) for the period 1974–2005 in order to compare drought conditions between neighbouring areas of differing precipitation heights. The analysis showed that severe droughts occurred around the year 1992–1993, with a duration of up to 3 yr. Multiple linear regression (MLR) modeling of precipitation in conjunction with cluster analysis of drought duration exhibits the linkage between precipitation, droughts and geographical factors. This connection between spatial precipitation distribution and geographical parameters provides an important clue for the respective spatial drought pattern. The above findings on the spatio-temporal drought distribution will update the current~drought management plans by developing more precise drought warning systems.

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Evaluation of the TRMM Product for Spatio-temporal Characteristics of Precipitation over Nepal (1998-2018)

Journal of Institute of Science and Technology ◽

10.3126/jist.v25i2.33733 ◽

2020 ◽

Vol 25 (2) ◽

pp. 39-48

Author(s):

Kalpana Hamal ◽

Nitesh Khadka ◽

Samresh Rai ◽

Bharat Badayar Joshi ◽

Jagdish Dotel ◽

...

Keyword(s):

Water Cycle ◽

Winter Season ◽

Temporal Distribution ◽

Tropical Rainfall Measuring Mission ◽

Good Alternative ◽

High Elevation ◽

Large Error ◽

Rain Gauge ◽

Mean Annual Precipitation ◽

Spatio Temporal

Precipitation is a fundamental component of the water cycle and integral to the society and the ecosystem. Further, continuous monitoring of precipitation is essential for predicting severe weather, monitoring droughts, and high-intensity related extremes. The present study evaluated the spatio-temporal distribution of precipitation and trends between 1998– 2018 using Tropical Rainfall Measuring Mission (TRMM) (3B43-V7) with reference to 142-gauge observations over Nepal. TRMM moderately captured precipitation patterns' overall characteristics, although underestimated the mean annual precipitation during the study period. TRMM precipitation product well captured the seasonal variation of the observed precipitation with the highest correlation in the winter season. The decreasing seasonal and annual trend was found in both observed and TRMM products, with the highest (lowest) decreasing trend observed during the monsoon (winter) season. It was also noted that the TRMM product showed a smaller bias before 2007, while a large error was found after 2007, especially in the monsoon months. In general, the TRMM product is a good alternative to observe rain gauge measurement in Nepal. However, there is still space for further improvement in rainfall retrieval algorithms, especially in high-elevation areas during the winter season.

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Spatio-temporal analysis of maximum drought severity using Copulas in Northern Algeria

Journal of Water and Climate Change ◽

10.2166/wcc.2020.070 ◽

2020 ◽

Vol 11 (S1) ◽

pp. 68-84 ◽

Cited By ~ 2

Author(s):

Soumia Mellak ◽

Doudja Souag-Gamane

Keyword(s):

Standardized Precipitation Index ◽

Three Dimensional ◽

Temporal Analysis ◽

Drought Severity ◽

Return Periods ◽

Drought Duration ◽

Northern Algeria ◽

Spatio Temporal ◽

Saf Curves

Abstract Drought mitigation and prevention require a broader knowledge of the spatio-temporal characteristics and return periods of droughts over several years. In this research, drought characteristics (severity, duration, frequency and areal extent) have been analysed in northern Algeria by using the Standardized Precipitation Index to identify drought events from 194 precipitation stations. For frequency analysis, three Archimedean copula families were used to find a relationship between drought duration and severity. The severity–duration–frequency (SDF) and the severity–area–frequency (SAF) curves were obtained. The SDF and SAF curves are then used to build three-dimensional surfaces of drought severity, drought duration and cumulated percentage of the affected area (SDA) for each return period. It has been shown that the return periods of maximum drought events severity vary according to their durations. To address the issue of long-term droughts, a new classification of dry events based on drought severities is proposed. The obtained results show that the western part of Algeria is the most sensitive to severe/extreme droughts of short durations and high probabilities of exceedance. For long-term durations, the study area was sensitive to mild droughts with lower probabilities.

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GIS based mapping of spatio-temporal distribution pattern of ribbonfish Trichiurus lepturus (Linnaeus, 1758) along Saurashtra coast, India

Indian Journal of Fisheries ◽

10.21077/ijf.2016.63.4.52912-02 ◽

2016 ◽

Vol 63 (4) ◽

Author(s):

P. Abdul Azeez ◽

K. Mohammed Koya ◽

K. L. Mathew ◽

G. S. Temkar ◽

R. A. Khileri

Keyword(s):

Fishery Management ◽

Stock Assessment ◽

Temporal Distribution ◽

Fundamental Information ◽

Trichiurus Lepturus ◽

Saurashtra Coast ◽

Management Plans ◽

Spatio Temporal ◽

Gis Software ◽

Fishing Area

Identification of spatio-temporal distribution of fish species represents fundamental information for stock assessment which in turn is essential for formulation of fishery management plans as well as for GIS based decision making. This study investigated the spatio-temporal distribution and abundance of different life stages of ribbonfish, Trichiurus lepturus (Linnaeus, 1758) off Saurashtra coast. Geographical coordinates of fishing and allied information on the time of fishing, depth of the fishing area as well as catch details were collected using a structured schedule, from selected trawlers operated from Veraval. Information was mapped using a GIS software to get the spatio-temporal distribution of the species. It was observed that juveniles were more abundant along the south Saurashtra coast whereas subadults and adults showed a discontinuous distribution with abundance in the waters off south Saurashtra as well as north Saurashtra coasts.

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Drought and wildfires in Portugal at the county scale

10.5194/egusphere-egu21-15135 ◽

2021 ◽

Author(s):

Mário Pereira ◽

Joana Parente

Keyword(s):

Science And Technology ◽

Standardized Precipitation Index ◽

Temporal Distribution ◽

Research Centre ◽

Climate Extreme ◽

Statistical Measures ◽

Spatio Temporal ◽

The Relationship ◽

Fire Incidence ◽

County Scale

Weather and climate extreme events contribute to the increase of wildfire risk. A recent study carried out in Mainland Portugal for the period 1981&#160;&#8211;&#160;2017, using Standardized Precipitation Index (SPI) and Standardized Precipitation Evapotranspiration Index (SPEI) to assess drought conditions, revealed that drought affects 70% of the months and a very strong relationship between the occurrence of drought and the spatio-temporal distribution of extreme wildfires (>&#160;5,000&#160;ha). These results raised additional scientific questions that need to be answered, such as: Is the relationship between droughts and fires equally strong for wildfires of smaller size? The study was carried out at the country level, but what are the regions where the relationship is more and less strong? Therefore the objective of this study is to assess the influence of drought on fire incidence, considering all wildfires or classes of wildfire sizes and in each of the 278 counties of Continental Portugal characterized by different features (landscape, weather/climate, drought and fire incidence). This study benefits from the existence of long and reliable meteorological and wildfire datasets. The methodology comprises cluster analysis, contingency tables, accuracy metrics, statistical measures of association to test the independence and help find interactions between these two natural hazards. Main results include: (i) the characterization of spatio-temporal distribution of drought number, duration, severity, intensity, extension; (ii) wildfire space-time distribution within drought periods and affected area; and, (iii) the assessment of the relationship between droughts and wildfires at county scale. The authors believe that the findings of this study are very useful for the definition of adaptation and mitigation strategies for the impacts of droughts in wildfire occurrence and to assess the climatic wildfire hazard/risk.AcknowledgementsThis work was supported and conducted in the framework of the FEMME project (PCIF/MPG/0019/2017) funded by FCT - Portuguese Foundation for Science and Technology. The study was also supported by: i) National Funds by FCT - Portuguese Foundation for Science and Technology, under the project UIDB/04033/2020; and, ii) National Funds by FCT - Portuguese Foundation for Science and Technology, under the project UID/AMB/50017/2019. Data were provided by the European Forest Fire Information System &#8211; EFFIS (http://effis.jrc.ec.europa.eu) of the European Commission Joint Research Centre.

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