The Popocatepetl volcano (19.02° N, 98.62° W, 5425 masl) began its current eruptive phase at the end of 1994 and since then it has presented an eruptive history characterized by low and medium intensity events (VEI 1 to 3) [1]. Due to the elevation of the volcano's crater, these types of eruptive events place volcanic products such as ash at altitudes between 6 km and 8 km corresponding to the flight level ranges between FL180 and FL260. Volcanic ash placed at these flight levels is rapidly dispersed by wind, causing a large area of airspace used by air navigation to be frequently affected. During the years 1999 to 2023, the Washington VAAC reported a total of 2381 days with the presence of volcanic ash in the Popocatepetl region, as a result of eruptive events of which about 90% reached the airspace region previously mentioned, representing a serious risk to commercial aviation over this area.

To generate a preventive tool that can be used for the mitigation of risks in aviation due to the presence of volcanic ash in the airspace region, combined tools of Remote Sensing and Mathematical Modeling were used to identify the regions around the Popocatepetl volcano. We focus most likely on areas to be affected in the event of an eruption, taking into account the time of year in which it occurs.

First, an upper-level wind characterization study was carried out in the region of the Popocatepetl volcano to identify the behavioral patterns over the months of the year. Wind profiles in the atmosphere's vertical structure above the volcano crater were obtained from the Real-time Environmental Applications and Display sYstem (READY) web-based [2], using NOAA (National Oceanic and Atmospheric Administration) NCEP/NCAR (National Center for Environmental Prediction/National Center for Atmospheric Research) Reanalysis 1 data 4 times per day over the period 2000 to 2021.

Secondly, MODIS images concurrent to the development of the eruption were collected from the Terra and Aqua platforms. It was possible to identify 60% of the eruptive events reported by the Washington VAAC. Each image was analyzed for ash emission signature using the brightness temperature difference (BTD) between bands 31 (11 μm) and 32 (12 μm). The brightness temperature was obtained by the rearranged version of the Planck radiative transfer function formula [3].

Finally, to normalize the data of the regions identified in each eruptive event, we identified the MODIS images containing information about the start of the eruption and those with clouds without connection between the emission and the volcano crater. Then, the volcanic ash cloud dispersion model HYSPLIT developed by NOOA was used. With the help of HYSPLIT, the displacement pattern of the ash cloud is identified by comparing it with the satellite image. All eruptions will be standardized to identify the development of the ash cloud at a time of 8 hours after the eruption, rebuilding in cases where information was missing due to the lack of connection between the cloud and the crater of the volcano. Afterwards, the complete area affected by the volcanic event is identified.

The combination of these tools made it possible to identify patterns of ash dispersion emitted in the eruptive events of the Popocatepetl volcano. One pattern with displacement between NNW and ESE was identified for the months of November to May, while another pattern of dispersion between SSW and WNW occurred from July to September. This information can be used to create volcanic ash risk mitigation maps used in aviation safety for the Popocatepetl volcano region.

References

1. Jiménez-Escalona, J. C., Poom-Medina, J. L., Roberge, J., Aparicio-García, R. S., Avila-Razo, J. E., Huerta-Chavez, O. M., & Da Silva, R. F. (2022). Recognition of the Airspace Affected by the Presence of Volcanic Ash from Popocatepetl Volcano Using Historical Satellite Images. Aerospace, 9(6), 308.

2. Rolph, G.; Stein, A.; Stunder, B. Real-time Environmental Applications and Display system: READY. Environ. Model. Softw. 2017, 95, 210–228.

3. Wen, S.; Rose,W.I. Retrieval of sizes and total mass of particles in volcanic clouds using AVHRR bands 4 and 5. J. Geophys. Res. 1994, 99, 5421–5431.