# Satellite and Ground Based Thermal Observation of the 2014 Effusive Eruption at Stromboli Volcano
## 4 Results
### MODIS Observations  
Spectral radiances for the detected thermal anomalies derived from MODIS data are archived in the MODVOLC database [21; 35]. [PERSON] and [PERSON] [24] suggested the use of this data to estimate the _VRP_ with the use of [PERSON]'s method [58]. Figure 7 shows _VRP_ observations from MODIS, TET-1 and one field thermal cameras (boat observations in Section 4.1). The plot in Figure 7 is scaled in such a way that the details are also seen in the second half of eruption. However, it is impossible to see the three highest _VRP_ values observed by MODIS at the beginning of the eruption. The maximal observed _VRP_ was 4.2 GW. The plot shows significant fluctuations in the MODIS _VRP_. These are most likely the consequence of cloud coverage. In our previous work [25; 26] we were dealing with uncertainties in _VRP's_ time series. However, we cannot use the methodology based on the Kalman filter to filter out the outliers, as we have only used the MODVOLC database, which is more convenient than processing a large number of MODIS images. The outliers were removed using a moving window analysis--if an observation was three-times smaller than the maximal _VRP_ within the five nearest observations, this observation was considered to be affected by clouds. The filtered results (one third of situations were removed) in Figure 7 seem to be much smoother than the original time series (not shown here), but they still contain fluctuations. MODIS data with a zenith angle greater than 50\({}^{\circ}\) was not further considered as well. One pixel was saturated in channel 21 at the very beginning of the eruption, thus it was assigned to contain a value of the saturation limit (radiance of 98 W/m\({}^{2}\)/\(\mu\)m/sr). As MODIS has a wide swath, the pixel area, which influences the \(k_{inst}\) in the Wooster method, was also considered. The estimation of the _VRP_ with the use of the MODVOLC database is straightforward. However, it is impossible to estimate the effective temperature of the lava flow and the fraction of the pixel it covers. This is because the background temperature is unknown--MODVOLC only stores data for a detected anomaly but not for its vicinity. As _TADR_ estimation using Equation (7) could not be used, we followed the radiant density approach proposed by [PERSON] _et al._[61]. They propose that radiant density is a function of the silica content within the magma. Using their methodology, the radiant  
Figure 7: _VRP_ in MW as observed from TET-1, MODIS, and field cameras. density for Stromboli, containing 50% of silica, equals 1.4 \(\times\) 10\({}^{8}\) J/m\({}^{3}\) (see Section 5.2). At the start of the eruption, this corresponds to _TADR_ of \(\sim\)30 m\({}^{3}\)/s. As this value was not realistic (compared to previous eruptions) [8], we used TET-1 data to fit the radiant density (Figure 8). Using the linear fit between TET-1 _VRP_ and the averages of the min/max _TADR_, the radiant density was estimated to 4.1 \(\times\) 10\({}^{8}\) J/m\({}^{3}\). This value is almost three times higher than the theoretical value suggested by [PERSON] _et al._[61]. Two additional fits were estimated based on the scatter pattern in TET-1 data (Figure 8), but neither of them presented a good fit for the theoretical value. The estimate for MODIS _TADR_ is given in Equation (9):  
\[TADR\approx\frac{VRP}{4.1\cdot 10^{8}\ Jm^{-3}} \tag{9}\]  
Figure 9 compares observed _TADR_ (mean of TET-1 values in Figure 6, values derived from MODIS using Equation (9), and boat observations) and model outputs (see Section 5.1). Contrary to our TET-1 data the MODIS data also captured the intense beginning of the eruption with a maximum _TADR_ of 10.4 m\({}^{3}\)/s. Some days later, the average value dropped below 1 m\({}^{3}\)/s. At the end of August, _TADR_ was about 0.5 m\({}^{3}\)/s. This was also revealed by the first TET-1 data. The first half of September was relatively cloudy, thus the estimated values cannot be considered reliable (see Figure 5).