Exceptionally Extreme Drought in Madeira Archipelago in 2012

Home , Funchal

Agricultural and Forest Meteorology 232 (2017) 195–209

Contents lists available at ScienceDirect

Agricultural and Forest Meteorology

j ournal homepage: www.elsevier.com/locate/agrformet

Exceptionally extreme drought in Madeira Archipelago in 2012:

Vegetation impacts and driving conditions

a,b,∗ b b b

Margarida L.R. Liberato , Alexandre M. Ramos , Célia M. Gouveia , Pedro Sousa ,

b b c

Ana Russo , Ricardo M. Trigo , Fátima E. Santo

Escola de Ciências e Tecnologia, Universidade de Trás-os-Montes e Alto Douro, UTAD, Quinta de Prados, Vila Real, Portugal

Instituto Dom Luiz (IDL), Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal

The Portuguese Sea and Atmosphere Institute, I. P. (IPMA, IP), Lisbon, Portugal

a r t i c l e i n f o a b s t r a c t

Article history: This work aims at characterizing the exceptional drought that affected Madeira Archipelago (Portugal)

Received 30 December 2015

during the 2011–2012 hydrological year while including some major impacts but also the main atmo-

Received in revised form 6 July 2016

spheric circulation mechanism behind the event. Precipitation records from six meteorological stations

Accepted 14 August 2016

are used to assess the extreme drought episode by means of a decile classiﬁcation. The assessment of the

Available online 27 August 2016

drought duration and severity is further corroborated by the Standardized Precipitation Index (SPI) com-

puted for the 3, 6, 12 and 24 months’ time scales which conﬁrmed that the 2012 drought event was one

Keywords:

of the events with higher drought intensity at all scales, being classiﬁed as extreme at the 6-month time

Extreme drought

sale (SPI6 < −1.65) from December 2011 until May 2012 on the majority of the meteorological stations

Vegetation impacts

Wildﬁres analysed. Long-term precipitation data available since 1865 for the station of Funchal conﬁrm the excep-

NDVI tional dryness of this episode, particularly during the winter season (December to March) corresponding

Madeira 2012 to the driest winter in 150 years.

Euro-Atlantic atmospheric circulation 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 dynam-

ics there was a deﬁcit of moisture availability over the region as evaluated by the vertically integrated

−1 −1

horizontal water vapour transport with a negative anomaly up to −120 kg m s .

1. Introduction (Trigo et al., 2013). This event allowed quantifying the impact of

the synergistic effects of an extreme drought and plant invasion

During the 2011–2012 winter the Iberian Peninsula (IP) was on the water balance of a natural open woody ecosystem in south-

hit in by one of the most severe drought events ever recorded in ern Iberia (Caldeira et al., 2015). At a larger scale, this winter was

this region with major socioeconomic and environmental impacts 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 particu-

lar the Madeira and Canary Archipelagos, with important adverse

∗

Corresponding author at: Escola de Ciências e Tecnologia, Universidade de Trás-

impacts on tourism and populations, including the occurrence of

os-Montes e Alto Douro, UTAD, Quinta de Prados, 5000-801 Vila Real, Portugal.

E-mail address: [email protected] (M.L.R. Liberato).

http://dx.doi.org/10.1016/j.agrformet.2016.08.010

196 M.L.R. Liberato et al. / Agricultural and Forest Meteorology 232 (2017) 195–209

Fig. 1. Wildﬁres on the island of Madeira on July 19, 2012. Natural-colour image obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s

Aqua satellite. Red outlines indicate high surface temperatures associated with actively burning ﬁres. Image NASA courtesy. (For interpretation of the references to colour in

this ﬁgure legend, the reader is referred to the web version of this article.)

unusual ﬁres (Fig. 1; Scott, 2013) in protected natural environment the evacuation of nearly 1000 people by ferry overnight. This ﬁre

parks. which has spread with high winds and tinder-dry vegetation has

Madeira is a volcanic Portuguese archipelago in the North destroyed part of a nature reserve. These catastrophic ﬁres repre-

Atlantic (NA) (Fig. 2a), with two main islands (Madeira and Porto sent unusual extreme weather-driven events in these islands of the

Santo, Fig. 2b). Madeira Archipelago (MA) is part of the Macarone- Macaronesia region. These high impact events motivated this study

sian region – the collective name for the Atlantic archipelagos of on the dynamics of the setting and intensiﬁcation of the outstand-

the Azores, Madeira, the Savage Islands, the Canary Islands and the ing 2011–2012 drought in MA and its associated impacts.

Republic of Cape Verde – which is an important transitional climatic These considerations have motivated the current analysis which

zone that encompasses a large part of the eastern NA. A description has the following complementary goals. Firstly, this work allows

of the Macaronesian weather and climate is presented by Cropper evaluating the extreme event from a longer term perspective

(2013). Madeira Island is located at approximately 900 km south- through the long-term series (150 years) available for Funchal.

west of mainland Portugal and roughly 400 km north of the Spanish Moreover, characterizing the extremeness of the drought in this

archipelago of the Canary Islands. According to the Köppen classi- Atlantic Island has never been performed before. Even though the

ﬁcation, the climate of Madeira Island is classiﬁed as temperate year analysed is similar to the drought episode evaluated by Trigo

with dry and warm summers (Csa) while Porto Santo Island is et al. (2013) for IP, to the best of our knowledge our work presents

classiﬁed as hot steppe (BSk). Being an east-west oriented moun- the ﬁrst drought assessment for this Atlantic Island using different

tainous island, precipitation in Madeira is strongly inﬂuenced by datasets (meteorological and satellite data). Secondly, the long-

orographically-generated rainfall. In summary, MA is characterised term evolution of droughts in Madeira is here compared with those

by a subtropical climate with small temperature range between observed in the case of Iberia (Trigo et al., 2013; Vicente-Serrano

winters and summers, thus climatic characteristics which are sig- et al., 2014), in terms of drought indices. Additionally, the ability of a

niﬁcantly different from southern Europe and the IP, dominated by relative simple vegetation index, such as NDVI, to monitor the tem-

semiarid climates. poral and spatial variability of vegetation behaviour and drought

Attractiveness of these islands is closely linked to its warm tem- impacts in Madeira is shown. Finally, we characterize the large scale

peratures throughout the year, luxurious vegetation and natural atmospheric conditions that favoured such extreme drought event

landscape. The devastating ﬁres in Madeira and Canary Islands in in Madeira Archipelago.

2012 summer have irreversibly changed the lives of many peo-

ple who have been forced to abandon their homes and livelihoods

(UNESCO, 2012). In July 2012, the media reported that on the Span-

ish island of Tenerife a violent forest ﬁre reached the edge of the

2. Data and methods

Teide National Park, a major touristic park on the Teide volcano −

Spain’s highest peak and a UNESCO world heritage site. Emergency

A number of different datasets are used in this study including

services had to evacuate 50 villagers from their homes overnight,

long-term daily precipitation and temperature data from weather

and the ﬁre has spread over 1100 ha (2700 acres). On the same

stations and reanalysis data to characterise the drought event over

week forest ﬁres occurred across the Portuguese island of Madeira

MA and the large and synoptic scale dynamics associated with the

for more than two days, forcing dozens of people to abandon their

event. Additionally two remote sensing products are used with the

homes. In August 2012, on La Gomera, a holiday destination in

aim of characterizing the impact of the drought in vegetation health

Spain’s Canary Islands and a biosphere reserve, a forest ﬁre forced

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