atmospheric modeling
; dispersion
; lidar
; remote sensing
; satellite data
; sensor
; size distribution
; three-dimensional modeling
; volcanic ash
; volcanic eruption
; Alaska
; Aleutian Islands
; Andreanof Islands
; Kasatochi Island
; United States
英文摘要:
The current work focuses on improving volcanic ash forecasts by integrating satellite observations of ash into the Lagrangian transport and dispersion model, HYSPLIT. The accuracy of HYSPLIT output is dependent on the accuracy of the initialization: the initial position, size distribution, and amount of ash as a function of time. Satellite observations from passive infrared, IR, sensors are used both to construct the initialization term and for verification. Space-based lidar observations are used for further verification. We compare model output produced using different initializations for the 2008 eruption of Kasatochi in the Aleutian Islands. Simple source terms, such as a uniform vertical line or cylindrical source above the vent, are compared to initializations derived from satellite measurements of position, mass loading, effective radius, and height of the downwind ash cloud. Using satellite measurements of column mass loading of ash to constrain the source term produces better long-term predictions than using an empirical equation relating mass eruption rate and plume height above the vent. Even though some quantities, such as the cloud thickness, must be estimated, initializations which release particles at the position of the observed ash cloud produce model output which is comparable to or better than the model output produced with source terms located above and around the vent. Space-based lidar data, passive IR retrievals of ash cloud top height, and model output agree well with each other, and all suggest that the Kasatochi ash cloud evolved into a complex three-dimensional structure. Published 2016. This article has been contributed to by US Government employees and their work is in the public domain in the USA.
资助项目:
"The authors are grateful to the Federal Aviation Administration (FAA) for funding part of this study. The views expressed are those of the authors and do not necessarily represent the official policy or position of the FAA or NOAA. CALIOP data were obtained from the NASA Langely Research Center Atmospheric Science Data Center. ECMWF data were obtained using their publicly available web and python api's http://apps.ecmwf.int/datasets/. The HYSPLIT model is available at http://ready.arl.noaa.gov. The MODIS satellite data and HYSPLIT model output and input files are available from the authors (alice.crawford@noaa.gov). We are grateful to Jaime Kibler, Greg Gallina, and Grace Swanson for many conversations regarding VAAC operations
; to Justin Sieglaff for providing technical assistance on interpreting and utilizing the satellite retrievals
; and to Roland Draxler, Ariel Stein, and Tianfeng Chai for their insightful comments on the use of the HYSPLIT model and this manuscript.
Cooperative Institute for Climate and Satellites, University of Maryland, College Park, MD, United States; Air Resources Laboratory, NOAA, College Park, MD, United States; Center for Satellite Applications and Research, NOAA, Madison, WI, United States
Recommended Citation:
Crawford A.M.,Stunder B.J.B.,Ngan F.,et al. Initializing HYSPLIT with satellite observations of volcanic ash: A case study of the 2008 Kasatochi eruption[J]. Journal of Geophysical Research: Atmospheres,2016-01-01,121(18)