Elsevier

Agricultural and Forest Meteorology

Volume 232, 15 January 2017, Pages 195-209
Agricultural and Forest Meteorology

Exceptionally extreme drought in Madeira Archipelago in 2012: Vegetation impacts and driving conditions

https://doi.org/10.1016/j.agrformet.2016.08.010Get rights and content

Highlights

  • First assessment of the 2012 drought episode in Funchal, the driest in 150 years.

  • Drought characterization through meteorological data (SPI and SPEI at timescales).

  • Differences in drought trends over Madeira when compared with mainland Iberia.

  • Use the NDVI to monitor the variability of vegetation behaviour over drought period.

  • Intense north-easterly trade winds caused strong deficit of moisture availability.

Abstract

This work aims at characterizing the exceptional drought that affected Madeira Archipelago (Portugal) during the 2011–2012 hydrological year while including some major impacts but also the main atmospheric circulation mechanism behind the event. Precipitation records from six meteorological stations are used to assess the extreme drought episode by means of a decile classification. The assessment of the drought duration and severity is further corroborated by the Standardized Precipitation Index (SPI) computed for the 3, 6, 12 and 24 months’ time scales which confirmed that the 2012 drought event was one of the events with higher drought intensity at all scales, being classified as extreme at the 6-month time sale (SPI6 < −1.65) from December 2011 until May 2012 on the majority of the meteorological stations analysed. Long-term precipitation data available since 1865 for the station of Funchal confirm the exceptional dryness of this episode, particularly during the winter season (December to March) corresponding to the driest winter in 150 years.

Vegetation activity is assessed through anomalies of NDVI (Normalized Difference Vegetation Index), confirming several large sectors of Madeira under vegetative stress. The southern sector of Madeira Island suffered up to seven months (out of nine) of extremely negative anomalies. From an operational point of view, obtained results reveal the ability of the developed methodology to monitor vegetation stress and droughts in Madeira. The extreme dryness of the Island favoured an unusually intense summer fire season of 2012 (between June and September) in Madeira being the year with highest number of fires in the last decade (with robust data). Furthermore, the main fire hotspots of the 2012 fire season are mostly coincident with the areas affected by drought.

The large-scale atmospheric circulation responsible for the setting and intensification of the drought is evaluated using reanalysis data. An extensive high pressure anomaly (maximum above 12 hPa in December) persisted over the North Atlantic during the extended winter months (October to April), centred between the Azores Islands and the UK. This feature is in agreement with a positive NAO index (2.25 in December), a negative EA index (−1.76 in January and −1.73 in February) and compatible with enhanced north-easterly trade winds over the region. As a consequence of this uncharacteristic dynamics there was a deficit of moisture availability over the region as evaluated by the vertically integrated horizontal water vapour transport with a negative anomaly up to −120 kg m−1 s−1.

Introduction

During the 2011–2012 winter the Iberian Peninsula (IP) was hit in by one of the most severe drought events ever recorded in this region with major socioeconomic and environmental impacts (Trigo et al., 2013). This event allowed quantifying the impact of the synergistic effects of an extreme drought and plant invasion on the water balance of a natural open woody ecosystem in southern Iberia (Caldeira et al., 2015). At a larger scale, this winter was anomalously dry in southern Europe and warmer than usual in northern Europe (Santos et al., 2013). This widespread event also affected the subtropical north-eastern Atlantic islands, in particular the Madeira and Canary Archipelagos, with important adverse impacts on tourism and populations, including the occurrence of unusual fires (Fig. 1; Scott, 2013) in protected natural environment parks.

Madeira is a volcanic Portuguese archipelago in the North Atlantic (NA) (Fig. 2a), with two main islands (Madeira and Porto Santo, Fig. 2b). Madeira Archipelago (MA) is part of the Macaronesian region – the collective name for the Atlantic archipelagos of the Azores, Madeira, the Savage Islands, the Canary Islands and the Republic of Cape Verde – which is an important transitional climatic zone that encompasses a large part of the eastern NA. A description of the Macaronesian weather and climate is presented by Cropper (2013). Madeira Island is located at approximately 900 km southwest of mainland Portugal and roughly 400 km north of the Spanish archipelago of the Canary Islands. According to the Köppen classification, the climate of Madeira Island is classified as temperate with dry and warm summers (Csa) while Porto Santo Island is classified as hot steppe (BSk). Being an east-west oriented mountainous island, precipitation in Madeira is strongly influenced by orographically-generated rainfall. In summary, MA is characterised by a subtropical climate with small temperature range between winters and summers, thus climatic characteristics which are significantly different from southern Europe and the IP, dominated by semiarid climates.

Attractiveness of these islands is closely linked to its warm temperatures throughout the year, luxurious vegetation and natural landscape. The devastating fires in Madeira and Canary Islands in 2012 summer have irreversibly changed the lives of many people who have been forced to abandon their homes and livelihoods (UNESCO, 2012). In July 2012, the media reported that on the Spanish island of Tenerife a violent forest fire reached the edge of the Teide National Park, a major touristic park on the Teide volcano − Spain's highest peak and a UNESCO world heritage site. Emergency services had to evacuate 50 villagers from their homes overnight, and the fire has spread over 1100 ha (2700 acres). On the same week forest fires occurred across the Portuguese island of Madeira for more than two days, forcing dozens of people to abandon their homes. In August 2012, on La Gomera, a holiday destination in Spain's Canary Islands and a biosphere reserve, a forest fire forced the evacuation of nearly 1000 people by ferry overnight. This fire which has spread with high winds and tinder-dry vegetation has destroyed part of a nature reserve. These catastrophic fires represent unusual extreme weather-driven events in these islands of the Macaronesia region. These high impact events motivated this study on the dynamics of the setting and intensification of the outstanding 2011–2012 drought in MA and its associated impacts.

These considerations have motivated the current analysis which has the following complementary goals. Firstly, this work allows evaluating the extreme event from a longer term perspective through the long-term series (150 years) available for Funchal. Moreover, characterizing the extremeness of the drought in this Atlantic Island has never been performed before. Even though the year analysed is similar to the drought episode evaluated by Trigo et al. (2013) for IP, to the best of our knowledge our work presents the first drought assessment for this Atlantic Island using different datasets (meteorological and satellite data). Secondly, the long-term evolution of droughts in Madeira is here compared with those observed in the case of Iberia (Trigo et al., 2013, Vicente-Serrano et al., 2014), in terms of drought indices. Additionally, the ability of a relative simple vegetation index, such as NDVI, to monitor the temporal and spatial variability of vegetation behaviour and drought impacts in Madeira is shown. Finally, we characterize the large scale atmospheric conditions that favoured such extreme drought event in Madeira Archipelago.

Section snippets

Data and methods

A number of different datasets are used in this study including long-term daily precipitation and temperature data from weather stations and reanalysis data to characterise the drought event over MA and the large and synoptic scale dynamics associated with the event. Additionally two remote sensing products are used with the aim of characterizing the impact of the drought in vegetation health and fires’ location.

Was the winter of 2011–2012 the driest in 150 years in Madeira?

Monthly precipitation data (Table 1 and Fig. 2b) presented previously have been used to characterize the dryness and the drought occurrence in the MA. The chosen meteorological stations have different operational periods, spanning between the long continuous precipitation records since 1865 in Funchal to a shorter period since 1961 in Bica da Cana, Santo da Serra and Lugar de Baixo. Fig. 3 shows the accumulated monthly precipitation (AMP) for the 5 most extreme dry hydrological years (October

Conclusions

The use of precipitation records from six meteorological stations, one of them with long-term data measured since 1865, allowed to put into a longer temporal context the observed level of precipitation shortage in Madeira Archipelago. The exceptional dryness of the 2012 drought episode, particularly during the winter season (December to March), confirmed the 2012 winter as the driest in 150 years in Funchal. By means of the SPI the 2012 drought has been classified as extreme – SPI6 lower than

Acknowledgements

This work was supported by the Portuguese Science Foundation (FCT) through project QSECA (PTDC/AAG-GLO/4155/2012). A. M. Ramos and A. Russo were also supported by FCT postdoctoral grants (respectively FCT/DFRH/SFRH/BPD/84328/2012 and FCT/DFRH/SFRH/BPD/99757/2014) and P. M. Sousa was supported by a FCT doctoral grant (SFRH/BD/84395/2012).

The NDVI dataset and the hotspots were kindly supplied respectively by VITO database (http://free.vgt.vito.be) and by Fire Information for Resource Management

References (42)

  • L. Giglio et al.

    An enhanced contextual fire detection algorithm for MODIS

    Remote Sens. Environ.

    (2003)
  • J. Spinoni et al.

    The biggest drought events in Europe from 1950 to 2012

    J. Hydrol Reg. Stud.

    (2015)
  • Agnew, C.T., 2000. Using the SPI to Identify Drought. Drought Network News (1994-2001), Vol. 12, No. 1....
  • D. Barriopedro et al.

    The 2009/10 drought in China: possible causes and impacts on vegetation

    J. Hydrometeorol.

    (2012)
  • M.C. Caldeira et al.

    Synergy of extreme drought and plant invasion reduce ecosystem functioning and resilience

    Sci. Rep.

    (2015)
  • A.V. Correia et al.

    Impactos e vulnerabilidades às alterações climáticas

    (2015)
  • T. Cropper

    The weather and climate of Macaronesia:past, present and future

    Weather

    (2013)
  • T.E. Cropper et al.

    An analysis of the climate of Macaronesia, 1865–2012

    Int. J. Climatol.

    (2014)
  • M.I. De Lima et al.

    Trends and correlations in annual extreme precipitation for mainland Portugal, 1941–2007

    Theor. Appl. Climatol.

    (2015)
  • W.J. Gibbs et al.

    Rainfall deciles as drought indicators

  • C. Gouveia et al.

    The north atlantic oscillation and european vegetation dynamics

    Int. J. Climatol.

    (2008)
  • C. Gouveia et al.

    Drought and vegetation stress monitoring in Portugal using satellite data

    Nat. Hazards Earth Syst. Sci.

    (2009)
  • T. Hilker et al.

    Vegetation dynamics and rainfall sensitivity of the amazon

    Proc. Natl. Acad. Sci.

    (2014)
  • B.N. Holben

    Characteristics of maximum-value composite images from temporal AVHRR data

    Int. J. Remote Sens.

    (1986)
  • P.D. Jones et al.

    A comparison of Lamb circulation types with an objective classification scheme

    Int. J. Climatol.

    (1993)
  • R. Kistler et al.

    The NCEP-NCAR 50-Year reanalysis: monthly means CD-ROM and documentation

    Bull. Am. Meteorol. Soc.

    (2001)
  • F.N. Kogan

    Global drought watch from space

    Bull. Am. Meteorol Soc.

    (1997)
  • A. Lotsch et al.

    Coupled vegetation-precipitation variability observed from satellite and climate records

    Geophys. Res. Lett.

    (2003)
  • P. Maisongrande et al.

    VEGETATION/SPOT—an operational mission for the earth monitoring: presentation of new standard products

    Int. J. Remote Sens.

    (2004)
  • T.B.N. McKee et al.

    The relationship of drought frequency and duration to time scales

  • E.E. Moreira et al.

    Are drought occurrence and severity aggravating? A study on SPI drought class transitions using log-linear models and ANOVA-like inference

    Hydrol. Earth Syst. Sci.

    (2012)
  • Cited by (20)

    • Causes and processes of two opposite climatic years in the tropical Atlantic warm pools

      2022, Dynamics of Atmospheres and Oceans
      Citation Excerpt :

      In 2012, by contrast, a severe drought caused several social and economic problems in a semiarid area due to an anomalous northward position of the ITCZ during the regular rainy season of Northeastern Brazil (Silva et al., 2013; Marengo et al., 2018). Liberato et al. (2017) pointed out that the period from December 2011 to March 2012 was the driest boreal winter of the last 150 years over the Madeira Archipelago in the Atlantic Ocean. The 2012 severe drought has also significantly impacted the United States along the northwestern Atlantic basin, as reported by several authors (e.g., Rippey, 2015; Park et al., 2016; Zhang et al., 2017).

    • Atractylis arbuscula Svent. &amp; Michaelis (Asteraceae): Two insular endemics from the Canary Islands with different conservation scenarios

      2022, Journal of Arid Environments
      Citation Excerpt :

      Extreme droughts are rare and normally their effects are difficult to be caught in short-term studies. Coincidentally, the sampling phase developed for this study coincides with one of the most intense droughts in last decades (Liberato et al., 2017), which provides us with the possibility of studying how this type of phenomenon affects at population scale, especially when a future increment on its frequency is predicted. Compared to herbaceous plants, woody plants may exhibit a different but as yet undefined response to climate change.

    • Spatiotemporal variation of net primary productivity and its response to drought in Inner Mongolian desert steppe

      2022, Global Ecology and Conservation
      Citation Excerpt :

      The drought indices of SPEI-6 and SPEI-3 were used in the growing season, spring, summer and autumn, and achieved satisfactory results in reflecting the drought characteristics of the study area. Previous researches mainly focused on the relation between vegetation and drought, with few studies considering drought time-scales (Liberato et al., 2017). The response of NPP to SPEI is consistent with the actual environment.

    • Spatio-temporal variability of droughts over past 80 years in Madeira Island

      2019, Journal of Hydrology: Regional Studies
      Citation Excerpt :

      Regarding the southern slope (RPC2 — Fig. 10(b), right panel), a weak long-term linear trend, towards low λ(t) values, is detectable from the year 1950 with λ(t) = 3.0 year−1, to 2007 with λ(t) = 1.2 year−1; beyond this year, it seems to occur in an increasing tendency. This tendency apparently is driven by an exceptionally extreme drought event occurred in 2012 (Liberato et al., 2017), with the highest intensity in the analyzed period. However, this trend occurs only during a relatively short period from 2007 to 2016.

    • Assessing vegetation response to multi-time-scale drought across inner Mongolia plateau

      2018, Journal of Cleaner Production
      Citation Excerpt :

      Drought is an extreme climate-related phenomenon of complex nature, becomes difficult to readily detect and evaluate its onset and evolution (Spinoni et al., 2015). Previous researches mainly focused on the relation between vegetation and drought, with few studies considering drought time-scales (Liberato et al., 2017) or vegetation changes in close relation with different time-scales of droughts, but they are all at regional and global scales (Vicente-Serrano et al., 2013). However, different time-scales of drought at plateau area should be considered with the aim to plenty understand the possible causes behind vegetation response to drought.

    View all citing articles on Scopus
    View full text