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The 2021 Fagradalsfjall basaltic fissural eruption in Iceland was closely studied due to its proximity to Reykjavík, which allowed easy installation and maintenance of monitoring equipment. Here we present the results from a network of calibrated webcameras maintained by the Icelandic Meteorological Office and Department of Civil Protection and Emergency Management which were used to monitor volcanic plume height and fire fountain height. A number of different camera designs optimised for different power and communications constraints were used, some built in house at IMO, and they will be presented here. To make a 3D height measurement from a 2D web camera image requires extra geometric constraints, which are provided by assuming the vent location and wind direction, in a similar manner to the method applied at Etna. We have implemented this technique as a react.js single page app, which is kept updated by a messaging queue system which pushes new images through the servers at IMO. Additionally, the webcameras have to be calibrated, in that the geometry of the camera and lens distortion parameters have to be known - this is either perfomed in the laboratory, or where the cameras were not available before installation, using one of a number of vicarious calibration techniques developed for this purpose. The resulting plume heights were used to constrain SO2 dispersion models that were the basis for air quality forecasts during the eruption.

Lidar systems have been used widely to measure wind profiles and atmospheric aerosols. The scanning Doppler lidars operated by the Icelandic Meteorological Office can provide continuous measurements of the wind velocity and direction based on the Doppler effect, from the emitted signal, as well as the backscatter coefficient and depolarization ratio for retrieving aerosol properties. In this project, we investigate the use of Doppler lidars in Iceland, especially for enhancing aviation safety. The project was divided into three main tasks have been conducted: 1) atmospheric turbulence measurements; 2) airborne aerosol detection; 3) real-time lidar signal classification with machine learning algorithms. In the first task, an algorithm was developed based on the Kolmogorov theory to retrieve eddy dissipation rate, as an indicator of turbulence intensity, from lidar wind measurements. The method was tested on two cases from 2017. In the second task, the Doppler lidar was used in combination with ceilometers, a sun-photometer and other instruments, to detect aerosols, including dust and volcanic ash in Iceland. In the third task, both supervised and unsupervised machine learning algorithms were developed to identify the noise signal and classify the lidar measurements, with the aim of providing real-time lidar signal classification for potential end-users. The results indicate that the Doppler lidar can significantly improve aviation safety and complement meteorological measurements by detecting atmospheric turbulence or volcanic ash clouds in Iceland., Vind- og agnasjár (e. lidar) hafa verið notaðar víða til að mæla vindsnið og nema svifryk og aðrar agnir í lofthjúpnum. Veðurstofa Ísland á tvo Doppler agnasjár sem geta veitt samfelldar mælingar á vindhraða og -stefnu, byggðar á Dopplerhrifa, og endurkastsstuðul og tvípólunarhlutfall (e. depolarization ratio) agna. Í þessu verkefni var könnuð notkun Doppler agnasjár á Íslandi til að auka flugöryggi. Verkefninu var skipt niður í þrjá verkþætti: i) ókyrrðarmælingar í jaðarlaginui; ii) svifryk og aðrar agnir í lofthjúpnum; iii) rauntímaflokkun agna með vélrænu námi (e. machine learning). Í verkþætti i) var þróuð reikniaðferð byggð á kenningu Kolmogorov til að meta sveipeyðingarákefð (e. eddy dissipation rate) frá vindmælingum, sem vísbendingu um ókyrrðarstyrk Aðferðin var prófuð í tveimur tilvikum frá árið 2017. Í verkþætti ii) voru gögn frá Doppler agnasjánni notuð, með gögnum úr skýjahæðamæli, sólarljósamæli og öðrum tækjum til að greina svifryk, þar með talið ryk og eldfjallaösku á Íslandi. Í verkþættii iii) var þróaðvélrænt nám, bæði undir eftirliti og án eftirlits, til að bera kennsl á suð og flokka mælingarnar með það að markmiði að veita rauntímaliðaflokkun fyrir hugsanlega notendur. Niðurstöðurnar benda til þess að Doppler vind- og agnasjá geti bætt verulega flugöryggi og verið góð viðbót við hefðbundnari veðurmælingar á Íslandi, með því að greina ókyrrð og öskuí lofti., ISAVIA