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Forecasting waves

Brazilian-made meteorological radar predicts rains three hours ahead of time

Illustration over photo by Arun Kulshreshtha/WikimediaOn an afternoon in 2008, the warning system of the Emergency Management bureau in the city of Barueri in the Greater São Paulo area received the forecast of a storm that was to take place within two to three hours directly from the meteorological radar system maintained thanks to a partnership agreement between the city council and IAG, the Institute of Astronomy, Geophysics and Atmosphere Sciences at the University of São Paulo (USP). The Emergency Management staff promptly isolated certain areas, hilly areas in particular, most likely avoiding the death of the inhabitants of two houses that were destroyed by the rain. The example shows how important it is to monitor the weather in a region such as São Paulo, with its huge urban concentration.

The meteorological radar that monitors clouds and the approach of storms and hail, as well as wind speed and a number of other weather variables, is an instrument that has been incorporated into the routine of the meteorology researchers at IAG-USP since 2007. It was financed by FAPESP via the São Paulo State Program for an Integrated Hydrometeorology System (Sihesp), a partnership agreement between the Hydrometeorology Council (Cehidro) and the current State Development Bureau. The project and its assembling were done by Atmos, a company in São Paulo city, which used imported instruments and software plus domestic technology. The mobile radar has been set up on a truck, with a multidirectional antenna, equipment and computers, besides a diesel generator, which enable it to operate anywhere. Under the coordination of professor Augusto José Pereira Filho, from IAG’s Hydrometeorology Laboratory (Labhidro), the radar is part of a hydrometeorological forecast system that includes atmospheric and hydrological modeling in order to provide support for the forecast of heavy rainfall and the likelihood of flooding, as well as for weather forecasting as much as two days ahead of time, conducted with the Advanced Regional Prediction System (ARPS), another numerical forecast system. Heavy rainfall forecast with this system is monitored with the IAG radar, which provides a highly detailed forecast two to three hours ahead of time for the area that it covers.

“Mobile radars are more suitable for research and the main ones are found in the United States and in Japan. In the United States, they are often used to monitor tornadoes. Our radar is the first in the world to be run with both operating and research purposes,” says Pereira Filho. The radar monitors and forecasts rain over a 150 km radius, which encompasses part of the Paraiba valley, the Baixada Santista coastal area, the Serra do Mar mountain range, the city of Campinas, the São Paulo Metropolitan Area and part of western São Paulo state. It enables the analysis of increased rainfall in the São Paulo Metropolitan Area and the lower rainfall round the city outskirts on days with isolated storms, as occurs near water sources. It rains more in the cities because the air is hotter near the ground due to the presence of a lot of concrete and asphalt, which absorb solar energy and then return it in the form of heat. Especially in summer, the dry hot air is often mixed with the moist cold air of the ocean breezes. The result is the fast formation of storms and of heavy showers, gusts of wind, hail, lightning and, consequently, floods and landslides. “What we have in São Paulo, in the case of heavy rainfall and floods, is a local and very particular formation of microclimate meteorological events,” concludes Pereira Filho. In 2010 alone, a year that Pereira Filho had forecast would be very rainy, the forecast system issued more than 50 storm warnings. “The amount of heavy rain last January was also connected with the El Niño climate phenomenon, which concerns higher than normal temperatures on the surface of the Southern Atlantic Ocean. As a result, a great deal of moisture is released into the air and is carried to the continent by atmospheric circulation .”

Augusto Pereira Filho/IAG-USPRadar in Barueri: research into rain and monitoringAugusto Pereira Filho/IAG-USP

The IAG and Barueri city council agreement that provides support for this system was signed in 2008. “This allowed us to train the city’s Emergency Management personnel to run the radar round the clock during the rainy season, from September to March.” The mobile radar is also used in the education and research of undergraduate and graduate students of meteorology at IAG and of environmental engineering at USP’s Polytechnic School. “They go to the radar and find out how works,” says professor Pereira Filho. At present, a truck loaded with all the equipment is parked on some elevated land in Barueri. A large mass of data, such as maps of rainfall, wind and size of raindrops, is available on the Labhidro website for use of emergency management departments, state bureaus and other public organizations that have meteorologists. The home page of the site is open to the public and has the weather forecast, including the temperature, humidity, winds and rain, besides storm warning bulletins. The volume of information that the radar generates is very large: some 10 megabytes (MB) every five minutes. Overall, 20 products are available. “We have already reached thousands of users on very rainy days,” he says. The information captured by the radar is sent to IAG via a microwave system and these data are stored in a server. These files show the various phenomena monitored, starting with cloud formation and going all the way to the dissipation of storms. The fast and accelerated records make it easy even for the lay person to understand the phenomenon on a computer screen.

The radar’s data collection sequence was broken mainly in 2009. “During the summer of that year, we were unable to survey because the radar was out of order for six months due to technical problems,” says Pereira Filho. Besides the radar, the professor’s team, comprising other faculty members, IAG students and the trained staff of the Barueri city council has two more land-based meteorological stations and sensors for measuring the humidity of the soil and the spectrum of drops, among others, acquired with funding provided by FAPESP as part of the Sihesp project, for the state’s research institutions to acquire instruments for studying the weather and the climate. One station has been set up in the Technology and Science Center (Cientec) at USP, on the south side of São Paulo city, while the other is at the USP Leste (East) campus. The same program also provided for the renovation of the meteorological radars in the cities of Bauru and  Presidente Prudente, and the Meteorological Research Institute (Ipmet) at Paulista State University (Unesp). It also enabled the installation of a computer system to process the state’s climate information at IAG.

Corporate training
In 2005, the Sihesp Program and FAPESP resolved to have the construction of the mobile meteorological radar conducted by Atmos, the only Brazilian firm that submitted a proposal, because the Foundation preferred to strengthen a domestic firm for the provision of this type of equipment. Headquartered in São Paulo, Atmos was established in 2004 as a branch of the Citrus Technological Applications Foundation (Atech), a non-profit enterprise created in 1997 to integrate Sivam, the Amazon Region Surveillance System,  that currently renders services to the Brazilian air traffic control system. Another enterprise also took part in setting up Atmos: Omnisys, which develops and provides maintenance for air traffic radar systems. Atech and Omnisys built a fixed meteorological radar in the city of Mogi da Cruzes, based on their Sivam experience, which served as a trial for the creation of Atmos.

“To produce the mobile radar, professor Augusto provided the technical requirements and we tried to fulfill them and to solve the electronic and mechanical challenges, such as developing the antenna’s pedestal and replacing the truck’s conventional suspension by a pneumatic system that inhibits vibration,” says Claudio Carvas, director-president of Atmos. One of the requirements was that the radar should operate on band X, an electromagnetic frequency of 9.3 gigahertz (GHz), suitable for monitoring the atmosphere and for measuring the volume of clouds and the amount of rain that is expected to fall during a certain period. The so-called band S, used in other meteorological radars, runs at 2.8 GHz. Band X works well up to a radius of 150 km, whereas band S covers as much as 240 km.

Radar shows storms in the capital city. By the side, software “sees” the amount of water inside clouds

The peak power of radar, which Labhidro named MXPol (for mobile X-band polarimetric weather radar) is 80 kilowatts (kW). “This means that the radar transmits narrow pulses of high power that spread through the atmosphere and reach atmospheric phenomena such as clouds, rain, hail and snow,” says Paulo Eduardo Martins, the technical manager of the Atmos project. Another advantage of the mobile radar, according to professor Pereira Filho, is its double polarization, which allows one to observe the phenomenon both in the vertical strip and the horizontal one. One can analyze the interior of clouds using a software program and identify the amount of water or hail, as opposed to merely seeing these formations from below and above. Another resource, the Doppler system, allows detection of the dislocation of clouds and storms.

Innovative pedestal
To set up the mobile radar, the budget for which was R$2 million, the project provided for the purchase in Brazil of a regular factory-made truck, a diesel generator, air conditioning equipment, racks and a container, as well as for the importing of transmission and reception systems, digital processors, software programs and computers from the United States, antenna motors from Italy and a reflector from Finland. Atmos developed an innovative system for the pedestal of the 2.44 meter diameter parabolic antenna, which does away with the need for oil lubrication. The evaluation and adaptation tests prior to delivery were conducted by the French engineer Frédéric Cazenave, a researcher at the Hydrology Laboratory of the University of Grenoble.

As a lot of the equipment and of the software programs are still imported and often very extremely expensive, Atmos decided to developed radar products domestically. The first one, funded via the FAPESP Pipe Program of Innovative Research at Small Companies and coordinated by Fabio Fukuda, the company’s technical director, was a digital receptor for radar. “This device processes to the software the signals received and does this with far better precision that the analog receptors currently used. We developed this equipment for use in our radars and also to sell to other manufacturers,” says Martins. This product is only made by German and American companies. Another development of the company is a meteorology software program that generates all the products (information on clouds, hailstones, raindrops, winds, etc.) received from the radar signal processor. “Today, this type of software is only available abroad and the licensing cost is as high as US$200 thousand per radar,” says Carvas. To develop this product, in 2007 the company obtained approval from Finep (the Studies and Projects Finance Agency) to get funding from its Economic Subvention Program in the amount of R$855 thousand.

Besides building and developing equipment, the company provides maintenance services for the air surveillance radars of the Aeronautics area and for air traffic control. It also expects to sell meteorology services to the company Somar, from São Paulo, with the Mogi radar, which is to be transferred in the next few months to the Imigrantes highway in order to improve its positioning. “We also conducted the upgrade and reformulation of the radars of the São Paulo aircraft carrier, as well as repairing S-band and X-band frequency generators for six Brazilian Navy corvettes. We currently have 26 engineers at the Navy Systems Maintenance Center,” says Carvas. Additionally, Atmos has entered into several international partnership agreements with companies in the United States and in Europe to supply technological niche products, such as equipment for aircraft approach at airports, radar for military use and surveillance equipment for air traffic management based on GPS information.

The prospects for new radars in Brazil is huge. The country has 25 meteorological radars, 17 of which are linked to air traffic control. “To get the country properly covered, we would need about 400. In the United States there are networks with as many as 200 meteorological radars,” says Martins.

The projects
1. Hydrometeorological forecast system of the Upper Tietê River Basin (nº 01/13952-2Type São Paulo State Integrated Hydrometeorology System (Sihesp); Coordinator Augusto José Pereira Filho – USP; Investment R$ 1,820,586.34 and US$ 409,727.04 (FAPESP)
2. Development of digital receptor for Doppler meteorological radars  (nº 06/51396-8); Type Innovative Research in Small Companies (Pipe); Coordinator Fábio Haruo Fukuda – Atmos; Investment R$ 94,773.75 and US$ 43,549.52 (FAPESP)