Giacomo Roversi giacomo.roversi2@studio.unibo.it April 12, 2020 The extraordinary events at the end of October 2018 in northern Italy seen through MODIS eyes Radiative Transfer and Remote Sensing A.A. 2016-2017 - Lab report Università di Bologna, Laurea Magistrale in Fisica del Sistema Terra 1 Introduction During the last week of October 2018 the northern part of Italy experienced a rapid succession of meteorological extremes. The registered values of temperature, wind speed and precip- itation amount are among the highest of the recent past since instrumental measurements exist (Nimbus Web, 2018a,b). The consequences of those extremes on human activities, in- frastructures and natural environment are unfortunately well known (ARPAV Regione Veneto, 2018; ARPAE Emilia-Romagna, 2018; RaF Italia, 2019). This work aims to detect the main fea- tures of that period through the analysis of the MODIS Level 1B calibrated radiances (products MOD021KM and MYD021KM, from satellites Terra and Aqua respectively) carried out with the Hydra2 software. 1.1 Meteorological events On the afternoon of October 24, 2018 extremely high temperatures were recorded in vast areas of northern Italy, reaching and in some cases surpassing 300 K, scoring a warmth record for the month of October on a century scale. The cause was a diffuse foehn-effect over the whole Alpine ridge (Nimbus Web, 2018a). These conditions produced high winds constrained be- tween the steep walls of the alpine valleys. In Cordevole valley near Cencenighe (BL, 46.35 N, 11.97 E) and Taibon Agordino (BL) around 14 UTC some trees fell on a high voltage pylon, start- ing a massive fire which propagated fast thanks to the favouring meteorological conditions and lasted several days (Il Dolomiti, 2018). A few days later, between October 27 and 30, thanks to the "Vaia" barometric low (978 hPa over the upper Tyrrenian sea) the same region was hit by Scirocco gusts at 150-200 km/h and heavy rains (up to 600 mm in three days, ARPAV Regione Veneto (2018)). Trees of many forests were knocked down (cumulative area of 415 km 2 around 3% of the total vegetated surface, 8.7 million m 3 of wood mass, RaF Italia (2019)) and there were widespread landslides and floods (Nimbus Web, 2018b). Filename Weather Case study MYD021KM.A2018297.1220.061.2018298155949.hdf Clear sky (foehn) RGB, Surface temperature, cloud properties, water vapour, lee waves MOD021KM.A2018297.2145.061.2018298073018.hdf Clear sky (cirri) Fire detection MYD021KM.A2018304.1225.061.2018305152241.hdf Partly cloudy Soil moisture, flooding, sea colour Table 1: List of MODIS files with relative main weather condition and case studies. 1