Guest blog by Hakki Baltaci
Technical University of Gebze, Turkey

Variations and atmospheric bottom mechanisms triggering simultaneous drought and heat wave events is a phenomenon of natural origin that affects approximately 1.5 billion people and is responsible for one third of all impacts of natural disasters. The Northeast of Brazil (NEB) is one of the regions that extremely suffering from drought events, affecting mainly the most vulnerable, with regard to water availability, causing disorder in various sectors, bringing risks mainly to food and energy security. There are strong indications that extremes of drought are increasingly frequent and refer to human-induced climate change. The largest number of people living with poverty is in the northeast of Brazil and they are mostly affected by the absence of rains, and almost 95% of the cultivated land is destined for rainfed agriculture.

Apart from the precipitation deficit, the dramatic increase in temperature also affects the NEB region. It was shown that there are a few studies focused on the background atmospheric mechanisms triggering heat wave events (HWs) for Brazil. In addition to the limited drought and heat wave studies for NEB, the combined effect of these two natural disasters has a greater impact on different sectors and human life living in the NEB.

During the Short-term scientific mission (STSM), Hakki Baltaci (Gebze Technical University) and Helber Gomes (University of Alagoas) focused on the atmospheric mechanisms triggering concurrent drought and heat waves, an STSM conducted in March 2022 within the COST action DAMOCLES. During the study period, we selected possible meteorological stations to study to work on by using quality control and homogeneity procedures. Later, we have finished extracting heat wave events by using the 90th percentile and at least three consecutive days to daily maximum (Tmax) and minimum temperature (Tmin). At the second step, we have focused on drought conditions and we calculated SPI-1 (The Standard Precipitation Index) for NEB, and with SPI, we had possibility to compare our results with the previous studies. At the third step, the methodology from Kong et al. 2020 was adapted to our study in order to find co-occurrence of the HWs and droughts. 

The results of this STSM will contribute to achieving the goals of DAMOCLES and it will help us to understand the atmospheric mechanisms causing droughts and heat waves. Final results will help to better understand the relationship between these hazards in different places around the world.

Kong Q, Guerreiro S.B, Blenkinsop S, Li X-F, Fowler H.J. 2020. Increases in summertime concurrent drought and heatwave in Eastern China. Weather and Climate Extremes, 28, 100242.