Composing music for string quartet from earth observation datasets – how does the composer’s intervention enrich sonification works?
Authors: Nagai Hiroto 
Published: February 2023

Sonification, making non-verbal sounds from various signals, is being attempted in the field of earth science. A typical motivation is to raise awareness of global warming, resulting in composing musical works from climatic data. The archiving of geoscience data can be an infinite source for composition but basic methodology has not been established. Sound made directly from raw data conversion would not touch human&#8217;s emotion greatly. For more musically-meaningful creation we should know how the composer&#8217;s personal idea and general music theory can be added to sonificated works to vibrate human emotion. In this study, therefore, an ensemble piece is composed from earth-observational datasets and scientific-and-artistic findings are collected then evaluate effects of artificial editing.&#160;Temporal records of climatic parameters are collected at four sites in the polar regions. An ice-core drilling site in Greenland (SIGMA-D; [59.1&#176;W, 78.6&#176;N]), satellite-communication facilities in the Svalbard islands (SvalSat; [15.4&#176;E, 78.2&#176;N]), a Japanese Antarctic base (Showa Station; [39.6&#176;E, 69.0&#176;S]), and an ice-core drilling site in the Antarctica (Dome Fuji; [39.7&#176;E, 77.3&#176;S]). These are assigned to two violins, one viola, and one cello.Temporal records of downward shortwave/longwave radiations, surface temperature, cloud optical thickness and precipitation amount are obtained from ERA5 (1981~) and MODIS products (2000~) via Google Earth Engine. Those exported values are converted to tone pitches in the 12-tone scale and saved as MIDI files. The MIDI files are imported and edited in a DAW software, Logic Pro. The composer performs (1) transpose to available and effective position for string instruments, (2) arrangements on tone length, rhythm, and volume dynamics, (3) orchestration and articulation definitions (e.g. staccato, pizzicato, legato, sul tasto and sul ponticello). The composer's subjective ideas based on classical music theory are less prevalent in the beginning and more dominant in the end.&#160;A six-minute work namely String Quartet No.1 "Polar Energy Budget" was composed (http://urx.blue/WCIp). Contained tone sequences are categorized into three patterns of (1) seasonal-cycle dominance, (2) that with continuous bottom tones (e.g. winter solar radiation at the poles), and (3) randomness dominance (i.e. precipitation). Actual performance gave an impression of &#8220;minimal music with irreproducible swaying&#8221; because of small fluctuations along the seasonal cycles. Careful definition of tone range was needed to avoid unplayable tones, whereas 12-tone definition enables straight transpose without considering the harmonic theory. Dynamics of tension and relaxation throughout the piece can only be made by the composer's idea.This study demonstrated the availability of geoscience sonification and application for string quartet. For scientists, a new way to explain various aspects of the earth system with emotional approaches was given. For artists, expanding availability of music composition was suggested. The impression of &#8220;minimal music with irreproducible swaying&#8221; implies a new musical style, which was not easily and automatically done in previous ways of contemporary music. Not only scientists but also artists might be regular users of earth observation dataset.