How have daily climate extremes changed in the recent past over northeastern Argentina?

LOVINO, MIGUEL A.; MÜLLER, OMAR V.; BERBERY, ERNESTO H.; MÜLLER GABRIELA V.

GLOBAL AND PLANETARY CHANGE

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2018 vol. 168 p. 78 - 97

0921-8181

Changes in climate extremes affect socioeconomics andnatural systems in northeastern Argentina (NEA) and may increase itsvulnerability leading to unprecedented disasters. This study investigates thelow frequency variability of daily temperature and precipitation climate extremesand assesses to what extent global reanalyses reproduce the observedvariability in the recent past. Datasets include quality-controlledobservations (1963-2013) and ERA-Interim and NCEP2 reanalyses (1979-2011).Climate extremes are characterized by 15 ETCCDI indices (proposed by the ExpertTeam on Climate Change Detection and Indices) evaluated in space and time. ASingular Spectrum Analysis was carried out to extract the leading modes of thearea-averaged index time series. The spatial distribution of mean changes wasestimated by fitting nonparametric linear trends to each index time series.Temperature extremes are changing toward warmer conditions. Warm days areincreasing while cold days are decreasing since 1990. Warm and cold nights showa significant signal of warming that seems to be stabilizing in the lastdecades. The number of frost days also remained stable although they are influencedby high interannual and decadal variability. Heat waves almost double thefrequency and duration of cold waves, and the duration of heat waves increasedwhile cold spells decreased in last decades. Longer heat waves are related tolonger dry spells. As well, intense precipitation events increased steadilysince 1970. The annual maximum amount of 1-day and 5-day precipitation eventsincreased from the 1970s to the 2000s, stabilizing in recent years. TheERA-Interim and NCEP2 reanalyses represent climate extremes with differentsuccess. ERA-Interim successfully represents temperature extremes in time andspace, while NCEP2 presents slightly systematic positive errors. Bothreanalysis reproduce dry spells in space and time and correctly simulate thetemporal variability of the annual maximum 5-day precipitation. Thus,reanalysis add valuable information for temperature and precipitation extremesin areas of scarce observations.