Numerical simulation of "an American haboob"
Other literature type, Article
Kumjian, M. R.
Prasad, A. K.
El-Askary, H. M.
Paris, B. C.
Sprigg, W. A.
- Publisher: Copernicus Publications
(issn: 1680-7324, eissn: 1680-7324)
Chemistry | QD1-999 | Physics | QC1-999
A dust storm of fearful proportions hit Phoenix in the early evening hours
of 5 July 2011. This storm, an American haboob, was predicted hours in
advance because numerical, land–atmosphere modeling, computing power and
remote sensing of dust events have improved greatly over the past decade.
High-resolution numerical models are required for accurate simulation of the
small scales of the haboob process, with high velocity surface winds
produced by strong convection and severe downbursts. Dust productive areas
in this region consist mainly of agricultural fields, with soil surfaces
disturbed by plowing and tracks of land in the high Sonoran Desert laid
barren by ongoing draught.
Model simulation of the 5 July 2011 dust storm uses the coupled
atmospheric-dust model NMME–DREAM (Non-hydrostatic Mesoscale Model
on E grid, Janjic et al., 2001; Dust REgional Atmospheric Model, Nickovic
et al., 2001; Pérez et al., 2006) with 4 km horizontal resolution. A mask of
the potentially dust productive regions is obtained from the land cover and
the normalized difference vegetation index (NDVI) data from the Moderate
Resolution Imaging Spectroradiometer (MODIS). The scope of this paper is
validation of the dust model performance, and not use of the model as a tool
to investigate mechanisms related to the storm. Results demonstrate the
potential technical capacity and availability of the relevant data to build
an operational system for dust storm forecasting as a part of a warning
system. Model results are compared with radar and other satellite-based
images and surface meteorological and PM<sub>10</sub> observations. The
atmospheric model successfully hindcasted the position of the front in space
and time, with about 1 h late arrival in Phoenix. The dust model
predicted the rapid uptake of dust and high values of dust concentration in
the ensuing storm. South of Phoenix, over the closest source regions
(~25 km), the model PM<sub>10</sub> surface dust concentration
reached ~2500 μg m<sup>−3</sup>, but underestimated the
values measured by the PM<sub>10</sub> stations within the city. Model results
are also validated by the MODIS aerosol optical depth (AOD), employing deep
blue (DB) algorithms for aerosol loadings. Model validation included
Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO),
equipped with the lidar instrument, to disclose the vertical structure of
dust aerosols as well as aerosol subtypes. Promising results encourage
further research and application of high-resolution modeling and
satellite-based remote sensing to warn of approaching severe dust events and
reduce risks for safety and health.