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Did Saudi Arabia Know an Attack was Coming?

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On September 14th 2019, a combination of drone and missile attacks targeted Saudi Arabia’s oil infrastructure at the Abqaiq and Khurais Aramco facilities, cutting the country’s oil production by over 50% and leading to the largest spike in the price of oil ever recorded . The attack was particularly embarrassing for Riyadh because billions of dollars' worth of air-defense systems were thwarted by drones that may have cost as little as $15,000 . A year later, the expert consensus seems to be that the attack was successful because the Saudis were caught off guard, with the element of surprise giving the assailants a decisive edge.  An open source analysis of radar interference from Saudi Arabian air defenses suggests that the Kingdom might actually have been expecting an Iranian attack on its oil infrastructure: five days before the attack, a missile defense system pointed at Iran was switched on for the first time at one of the largest refineries in the country. This analysis also
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Calculating High-Resolution Standardized Precipitation-Evapotranspiration Index

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This post outlines a workflow for the calculation of a high-resolution version of the Stardardized Precipitation-Evapotranspiration Index (SPEI). This is accomplished in four steps, utilizing Python, R, and JavaScript. Quantifying the precise onset, duration, and end of droughts is difficult. Most approaches have historically measured drought as a prolonged deviation from the mean rainfall in an area. The Standardized Precipitation-Evapotranspiration Index (SPEI) builds on previous approaches by incorporating temperature data to account for the amount of water lost to evaporation. This is important because in an arid climate, a six week shortage in rainfall during the summer would have a much greater impact on soil moisture than the same shortage during the winter. This is especially important for drought forecasting that accounts for anthropogenic climate change. Indices that do not incorporate temperature data will persistently underestimate drought incidence as global t
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Building a 3D Model of the Beirut Explosion

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Blast damage assessment in Beirut is being carried out using two-dimensional satellite imagery. These approaches underestimate damage by failing to capture damage done to the sides of buildings. I outline an alternative approach using Open Street Map data to create a 3D model of Beirut and the explosion to analyze directional blast damage.  Satellite Imagery and its Limits Following the recent explosion in Beirut, I built a tool that uses Sentinel-2 imagery to map the destruction caused by the blast. After some trial and error, I arrived at a fairly simple two step process: first, measuring the change in spectral signatures between pre- and post-explosion images. Second, applying an X-Means clustering algorirthm to the resulting image (yielding the map on the right), or taking the absolute difference (yielding the map on the left): Red areas on the left indicate high levels change between the pre- and post- explosion images. On the right, the magnitude, direction, and spectral
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