Using Kriging and Interactive Graphics in Web-Based Application for Spatial-Temporal Trend Analysis of Ozone and Weather Systems in Central America

1
Using Kriging and Interactive Graphics in
Web-Based Application for Spatial-Temporal Trend
Analysis of Ozone and Weather Systems in Central
America
Kening Wang, Charles Stegman, Sean W. Mulvenon,
and Yanling Xia University of Arkansas,
Fayetteville, AR, 72701
Abstract
Results
Users can view the longitudinal prediction maps
of ozone and surface temperature.
Users can view graphics of elevation.
This study illustrates a demo system which was
designed for supporting web-based interactive
visualization and spatial-temporal trend analysis
of ozone and weather data in Central America.
Longitudinal prediction maps of ozone and surface
temperature were generated using Kriging method.
Bar charts of air pressure, cloud coverage, and
elevation at each measured location were plotted
on the maps. Prediction maps, time-series chart,
and 3-D graphics are linked and presented through
this system. Through building up a relationship
between maps and other graphical representations,
users are able to effectively explore the data in
many different ways and from many different
angles.
To illustrate the applicability of the proposed
approach, we have developed a full-featured demo
system at our web site http//normes.uark.edu/ASA
_Comp/.
Users can view graphics of air pressure.
Introduction
Environmental data collected by federal
government agencies usually are
spatial-temporally referenced massive datasets
with multivariate measures covering a huge
geographic area. Effective visualization and
exploration of this kind of datasets create
greater challenges. Web-based data visualization
can provide users with high user interactivity
and it is likely to be very useful for exploring
this kind of data. Meanwhile, use of the internet
for delivery of data and information also enables
a large amount of graphics to be accessible to
the public, and encourages users to explore the
data in a playful way.
Users can view 3-D graphic of globe, which shows
the geographic area data collected, and project
description when they clicking the tab MY
PROJECT OVERVIEW.
Users can view graphics of cloud coverage.
Objectives
1) To provide a graphic summary of important
features of the data, and to make the results
easily understandable to publics who are not
familiar with using geostatistical methods to
generate prediction maps. 2) To demonstrate
effectiveness of web-based data visualization for
exploiting the important relationships between
the variables and for revealing the
spatial-temporal trends.
Ozone Patterns
Conclusions
Users can view Time-series chart of ozone.
The distribution of ozone exhibits strong
latitude dependence. Total ozone amounts near
the equator are rather low over the course of
each year, and increase as we move from tropics
to higher latitudes. This phenomenon can be
explained by stratospheric circulation, also
known as Brewer-Dobson circulation, which
transports high ozone from the tropics to the
lower stratosphere of the high latitudes. The
distribution of ozone also shows strong
seasonality dependence. Ozone amounts over the
northern region are rather high, with the highest
amounts in April, May, and June, then decreasing
over summer. The lowest amounts are present in
October, rising again over the course of winter.
In the winter, we see ozone column amounts are
large at high northern latitudes, and low at the
tropics. Moving into the summer, we find ozone
amounts at high northern latitudes falling off
from winter time, and at the same time, tropical
ozone increases. Wind transport of ozone is
principally responsible for the seasonal
evolution of these higher latitude ozone patterns.
Buja et al. (1996) proposed a rudimentary
taxonomy of interactive view manipulations for
high-dimensional data, and they are focusing
individual views, linking multiple views, and
arranging many views. This web-based
interactive data visualization demo system is one
example of focusing, linking, and arranging
views and it is also a valuable complement to
the techniques of exploration of large
multidimensional datasets which have
spatial-temporal components.
Method
Kriging method has been reported to be used for
ozone prediction (Lefohn et al., 1994). In this
study, prediction maps of ozone and surface
temperature were generated using Kriging method.
Three frequently used models in this study for
Kriging are 1) Spherical model, 2) Exponential
model, 3) J-Bessel model. The software ESRI
ArcGIS Geostatistical Analyst was used to create
prediction maps, because Geostatistical Analyst
bridges the gap between Geostatistics and GIS,
and it contains a series of easy-to-use
tools. The software Nvu, which is a complete web
authoring system, was used to develop the web of
this project.
REFERENCES
Buja, A., Cook, D., and Swayne, D. (1996)
Interactive High-Dimensional Data Visualization.
Journal of Computational and Graphical
Statistics, 5, 7899. Lefohn, A.S. Simpson, J.
Knudsen, H.P. Bhumralkar, C. Logan, J.A. (1994
) An evaluation of the kriging method to predict
7-h seasonal mean ozone concentrations for
estimating crop losses. Journal of Air Pollution
Control Association, 37, 595602.