Abstract
Abstract. Rapid advection of extremely warm and dry air is studied during two events in the Mediterranean Basin. On 27 August 2010 a rapid advection of extremely warm and dry air affected the northeast Iberian Peninsula during a few hours. At the Barcelona city center, the temperature reached 39.3 ° C, which is the maximum temperature value recorded during 230 yr of daily data series. On 23 March 2008 a rapid increase of temperature and drop of relative humidity were recorded for a few hours in Heraklion (Crete). During the morning on that day, the recorded temperature reached 34 °C for several hours on the northern coastline of this island. According to the World Meteorological Organization none of these events can be classified as a heat wave, which requires at least two days of abnormally high temperatures; neither are they a heat burst as defined by the American Meteorological Society, where abnormal temperatures take place during a few minutes. For this reason, we suggest naming this type of event flash heat. By using data from automatic weather stations in the Barcelona and Heraklion area and WRF mesoscale numerical simulations, these events are analyzed. Additionally, the primary risks and possible impacts on several fields are presented.
Highlights
The World Meteorological Organization (WMO) defines a heat wave as a phenomenon in which the daily maximum temperature of more than five consecutive days exceeds the average maximum temperature by 5 ◦C, with respect to the period 1961–1990 (Frich et al, 2012)
In all scenarios shown in the 4th IPCC report (Trenberth et al, 2007), the Mediterranean Basin will be one of the most significant regions affected by an increase in both the intensity and frequency of heat waves during this century
Automatic weather stations located in the Barcelona city center recorded 39.3 ◦C and the relative humidity dropped to 19 %
Summary
The World Meteorological Organization (WMO) defines a heat wave as a phenomenon in which the daily maximum temperature of more than five consecutive days exceeds the average maximum temperature by 5 ◦C, with respect to the period 1961–1990 (Frich et al, 2012). If a smaller scale is considered, the glossary of AMETSOC defines a heat burst as a rare atmospheric event characterized by gusty winds, rapid temperature increase, and a decrease in relative humidity, typically occurring at night or early morning (Johnson, 1976; Glickman, 2000) It is usually associated with descending air during a thunderstorm. This paper aims to study two events associated with an increase in temperature and decrease in relative humidity occurring at intermediate temporal and spatial scales We will call this phenomenon flash heat, because it occurs within a timescale shorter than a heat wave but longer than a heat burst. This event cannot be classified according to the above definitions either as a heat wave or as a heat burst
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