INTEGRATION WITH GIS
In the new millenium the need for instant information, with the click of a mouse, is not only desired, it is expected. Information renders knowledge; and knowledge spurs prudent decision making. Since the weather affects every facet of our lives from food production to energy consumption to public safety and travel, its impact is extensive. With the introduction of real-time weather data in GIS (Geographical Information System) formats, the diverse needs of communities worldwide can now be addressed.
Praxis Software is working with DTN/Kavouras and Esri (Environmental Systems Research Institute) to deliver real-time surface weather data in Point Shapefile formats—the de facto standard for the GIS industry. Using Praxis’ WeatherActive technology the capability of accessing up-to-the-second wind speed/direction, rainfall, barometric pressure, temperature, lightning and more from precise geographic locations changes the way weather data is used. Analysis and storm tracking capabilities are improved to provide faster, pinpointed forecasts and warning systems. The integration of weather data with other geographically based information such as street-level maps, land topography and population densities revolutionizes public notification and ultimately saves lives.
Figure 1
Rainfall Amounts and NEXRAD Radar in the Northeast
Forest fires are one of the most devastating natural disasters—and one of the most difficult to predict and track. Moving people and animals out of harm’s way, and protecting infrastructure is a daunting task. The incorporation of real-time weather information into a GIS can help public officials plan evacuations of populated areas based on their proximity to the fire; it can help them determine the best course of action to contain the scorching flames based on land terrain; and it can aid in traffic management and pollution control by predicting smoke drift.
In the West Texas Panhandle storms materialize around dry lines. Before Doppler radar can even detect their formation, real-time surface data, especially humidity, can help to predict eventual location and intensity. With the integration of this point-specific surface data into a GIS, ground truth takes on a whole new dimension, expanding traditional visualization techniques to include other types of non-weather data that have geographical locations associated with them. Steve Kersh, Chief Meteorologist at KVII-TV in Amarillo says that before they installed their network of remote weather systems dubbed Schoolnet, there were only 6 National Weather Service sites to cover a viewing area of 51 counties in 5 states. "With the addition of 52 reporting sites at schools and other educational facilities we can now report localized weather events like dry lines, cold fronts and thunderstorms more accurately. This is not only a benefit to our viewers but a catalyst for bringing weather and technology into our classrooms."
Figure 2
Wind Speed, humidity and lightning data from the KVII-TV Schoolnet in Amarillo, Texas
The real-time weather information used in KVII’s Schoolnet and other Praxis’ real-time networks is gathered through a set of instruments that have the capability to measure everything from soil temperature/moisture to rainfall and solar energy. This data is converted, on the fly, to Point Shapefile format. It is displayed in either Esri’s ArcViewÒ or ArcInfoÒ , alongside weather data like NEXRAD Doppler radar, NWS observations and weather satellite imagery from DTN/Kavouras. It may also be viewed on the World Wide Web in a JAVA applet. Several locations and their virtually "live" weather data can be placed on map backgrounds. Browser users can navigate to different areas of the map, modify weather parameters and change units of display. The point-specific data from the individual locations is not only collected and presented in real time, it is also archived for subsequent access and analysis.
Table 1
With WeatherActive a distinct site or a group of sites can be queried for archived data. This data can then be presented using the industry-leading report generation package, Crystal Reports. Long-term trends and weather extremes from point specific locations provide a powerful analytical tool when used in conjunction with a GIS. Microclimate reporting takes on new meaning.
Notifications via e-mail, fax or pager inform authorities on certain real-time weather conditions. These notifications, definable within the Praxis WeatherActive software, enhance GIS-based decision support systems. Working with the DTN/Kavouras StormSentry
ä PC, precipitation estimates, accumulations, current and forecast temperatures, storm cell tracking and more can be accessed. Data can be converted into Point Shapefile and Polygon Shapefile formats for use in a GIS. With the addition of real-time weather data industries such as utilities can monitor wind speeds to position repair crews ahead of outages. Farmers can be alerted when temperatures in their area drop below freezing so that they can turn on heaters to save valuable crops. Highway maintenance crews can discontinue roadwork when weather conditions indicate the approach of precipitation that would wash off expensive applications of paint or pesticides. Even police can inform the public to avoid snow-covered roadways until officials have applied chemical treatments and pavement conditions improve.
THE WEATHERACTIVE
ä SYSTEMThe Praxis WeatherActive Internet System uses the same client/server model that forms the basis of a TCP/IP network. It allows the transfer of real-time weather data from a Weather Station or other sensors connected to a PC, via a TCP/IP network (such as the Internet, or a local Intranet).
The Weather Station is connected to a designated PC on the network via an RS232 or similar serial interface. This PC runs the WeatherActive Internet Server (WAIS) software. The purpose of WAIS is to read the weather data collected by the weather station (from its sensors) and make this data available to any PC on the network that runs a WeatherActive Client program. WAIS is thus the "server" or the "gateway" to the weather station. WAIS delivers this data to its clients in real time every 2 seconds. WAIS allows simultaneous client access to this data via the underlying TCP protocol. The number of clients that can simultaneously connect to WAIS is limited only by the number of TCP sockets that the Operating System can support.
WAIS makes use of an encrypted proprietary protocol in transporting the data over a network. Even though the underlying mechanism for delivering the data is TCP/IP, a reliable protocol, WAIS sends all data with error detection and correction codes embedded in the data stream. All real-time and historical data collected from the sensors is "packaged" into variable length records (497 to 512 bytes) and delivered to the Windows Sockets (winsock) interface for distribution over the network. In addition to weather data, geographical information such as the latitude, longitude and elevation of the site is imbedded into the packet, as well as codes to uniquely identify a remote site. This information is used to autoplot the data on the appropriate maps.
The interface to the GIS subsystem is accomplished by a central data collection point known as WeatherActive Transfer Server (WATS). Like WAIS, WATS is a TCP Server and is capable of many simultaneous socket connections limited only by the operating system. WATS however does not interface directly to the weather stations. Instead it collects the data from remote systems running WAIS and makes that data available to the GIS and other systems that do not have the capability to interact directly with WAIS. Typically the transfer of data takes place through a file that is structured using the Kavouras encoded data file format. However, this data may also be obtained by directly connecting to a listening socket present in WATS. In either case, data is asynchronously updated every 2 seconds.
SUMMARY
With a GIS, weather monitoring, analysis and planning take an enormous leap into the 21st century. The ability to better determine the weather conditions at specific locations and their impact on the populations, environment and infrastructures in those areas have improved dramatically through the efforts of DTN/Kavouras, Esri and Praxis. Industries, government and education now have the opportunity to evaluate weather data in significant ways that they may have only dreamed of a few years ago.