VMAP - Vog Measurement & Prediction

Hawaiian Islands Vog Prediction Model

The objectives of the Vog Measurement and Prediction (VMAP) project have been to create a real-time volcanic gas modeling and forecast capability to predict the concentration and dispersion of SO2 and sulfate aerosols from the Kilauea volcano based on state-of-the art gas dispersion and numerical wind models; and to develop and deploy an array of FLYSPEC UV spectrometer systems1,2 which provide near real-time measurements of SO2 emissions from the Halema`uma`u 2008 vent at the summit of Kilauea Volcano at high temporal resolution to feed into dispersion models. Recent models of SO2 plume are shown below. Current predictions can be accessed at http://weather.hawaii.edu/vmap/

Monitoring Approach

The FLYSPEC array consists of 9 units (F1-F9) deployed approximately 3 km from the vent in a 3 km arc which encompasses the expected extent of the plume under prevailing NE trade winds. A 10th FLYSPEC (F,sub>0) is situated 200 m upwind from the center of the array and is used as the WiFi communications node and lead instrument for determining the plume speed3. Raw spectral data and SO2 path-concentration results are stored on each field unit. The results are telemetered to a base computer located at HVO which ingests data from all of the field systems.

FLYSPEC Array Deployment

System Description


Two of the self-contained FLYSPECs, each showing spectrometer, gas correlation cells, and control computer. Additional components mounted below include cell motor controller, temperature sensor, voltage and/or current sensors, GPS, and POE unit for network connection.


One unit deployed in field. FLYSPEC is the small black box on the left. Large container on right houses the deep cycle 12V batteries and solar charge controller. Both are housed below the solar panel. WiFi unit is in the small grey box on left and a directional antenna is mounted at top of 2 m mast, pointed back to the F0 unit.

Each field system is currently programmed to boot up each morning and shut off at the end of daylight hours. Each morning the field computers access a time server in order to synchronize their clocks. Integration time for spectral data collection is adjusted throughout the day to maintain appropriate signal level as light levels change. Spectrometer dark levels are collected every hour which causes a break in the data flow for about 2 minutes

The FLYSPEC base computer at HVO acts as the array server. The server program accepts data from all field units from 0800 to 1800, although this is adjustable. Data rate for each field system is nominally 1Hz.


1.Horton, K. A., G. Williams-Jones, H. Garbeil, T. Elias, A. J. Sutton, P. Mouginnis-Mark, J. N. Porter, S. Clegg. Real-time measurement of volcanic SO2 emissions: Validation of a new UV correlation spectrometer (FLYSPEC), Bull. Volc. 68: 4, 323-327, 2006a, DOI 10.1007/s00445-005-0014-9. - (PDF)

2.Horton, K.A., J. Porter, P. Mouginis-Mark, C. Oppenheimer, H. Garbeil, 2006b, Apparatus for Measuring Radiation and Method of Use (FLYSPEC), U.S. Utility Patent No. 7,148,488.

3.Williams-Jones, G., K. A. Horton, H. Garbeil, P. J. Mouginis-Mark, A.J.L. Harris, T. Elias and A. J. Sutton, 2006, Accurately measuring volcanic plume speeds with multiple UV spectrometers, Bull. Volc. 68: 4: 328-332, DOI 10.1007/s00445-005-0013-x. - (PDF)