FOROYAA Newspaper (Serrekunda)
Lamin Mai Touray
30 July 2007
column
Department of Water Resources
We are all interested in the weather. If we are ever unable to watch the weather forecast on TV or listen to it on the radio, we might ask our family or our friends in the morning; "What will the weather be like today?" We usually need to know this, so that we may decide on how to dress, whether to take an umbrella with us to work or to school, or whether to pack a sun protection cream in our sports bag (for tourists). Organizers of sports events and other outdoor activities, as well as tourist operators, often rely on weather and climate information to make certain that we shall be able to make the most of our holidays and leisure activities.
Similar information can also be used to ensure that our natural environment will remain a healthy one for us and for future generations.
Meteorologists and climatologists provide advice for urban planning, building design and location, including for renewable energy structures. They also assist farmers and foresters in selecting the best times for sowing, planting, irrigating and harvesting and in avoiding and controlling diseases and pests.
Mariners and aviators and road companies, all use meteorological information to delay departures whenever necessary or to plan their routes in order to avoid hazardous weather conditions.
No community is fully immune to natural disaster, but some are certainly more vulnerable than others. Meteorologist can assist those communities by providing them forecasts and warnings, not only before and during a hazard, but also throughout the difficult weather conditions that may follow.
These few aspects of meteorology and climatology - and there are many others - contribute to making life safer, healthier and more comfortable for all. They further ensure that lives and livelihoods will be evolving in a sustained environment whose precious resources will also be protected.
Meteorologists are not high-profile people; they are men and women working behind the scenes for our safety. Their work is very much of a team effort, hence the slogan of the World Meteorological Organization (WMO) "Working together in weather, climate and water" Perhaps you had not considered before the role that meteorologists play in our daily lives. I hope that this article will stimulate you to do so, by providing you a glimpse of their work and their contributions to society. Better still, I hope that it may even encourage you to consider, as I did years ago, a career in this highly gratifying field.
Towards a Better World
Nearly all areas of human activity are weather, climate and water sensitive. Of particular importance is the impact of weather and climate fluctuations on food production. Other areas, including fisheries and forestry, energy and water resources management, land, marine and aviation transport, banking and insurance, construction and urban design, all benefit directly from services provided by meteorologists. The provision and application of accurate and timely weather information, forecasts and warning contribute to human well-being and are of considerable benefit to socio-economic development and environmental protection.
Every dalasi invested in meteorological services produces an economic return many times greater, often 10 times or more.
There is growing concern about the impacts on human societies of extreme weather and climate events such as tropical storms, floods and drought. Some of these events cause enormous destruction and loss of life with long-lasting effects. Meteorologists, in collaboration with hydrologists, issue early warnings of natural disasters so that immediate action can be taken.
Exactly what meteorologists do depends upon local requirements and the structure of the National Meteorological Services.
Improving our well-being Weather and Climate are both natural resources and hazards. They support but can also pose a threat to life, property and the environment. In some cases, such as thunderstorms, the impact is usually limited to a relatively small area over a short period of time and affects only a few people. By contrast, drought and flooding cause widespread and long-lasting damage. As well as the immediate threat posed by severe and extreme weather, indirect effects include disease and famine.
Meteorologists play a key role when disasters occur. They help educate the public and raise awareness about weather-related disasters. Their advice assists in preparing for disasters and finding ways of preventing them from happening.
In the developed countries, many commercial organizations use specialized weather and climate information services to support their decision-making. Agriculture, road and marine transport, energy and water resources management, aviation and tourism are particularly sensitive to the weather. Good weather forecasts and climate information help ensure that these activities are carried out safely and efficiently and that long-term plans take full account of any expected changes in the climate.
Demand for energy supplies is highly weather-dependent (cooling in hot). Forecasters provide information that assists suppliers in ensuring that day-to-day requirement for electricity are met. Similarly, the management of water resources requires timely and accurate information about the weather, especially rainfall, to be provided by forecasters.
Weather information, forecasts, and warnings improve public safety and are of enormous potential economic benefit.
Observing the weather
Accurate observations about the current weather are the basis of a good weather forecast. This information is also required to monitor the climate. Traditional sources of observations are observing stations on land and at sea and upper-air-sounding. Today satellites, radar and aircraft are increasingly vital sources of information.
There are many different instruments at an observing site. Some measure temperature and humidity. Others measure air pressure, wind speed and direction, rainfall and sunshine duration.
Upper-air-sounding are obtained by releasing a balloon which carries instrument through the atmosphere. Information about pressure, temperature, humidty and wind is sent back to a ground station.
Wind and other useful atmospheric information is also deduced from satellite data. Satellite meteorologists develop the processes for turning the vast amount of data into useful information and products.
The improved accuracy of weather forecasts over the last 30 years is partly due to the increase in the amount of satellite data available, along with advance in extracting useful information for use in computer models.
Forecasters depend upon information from satellites to help identify the location and development of weather systems, especially over the oceans. In addition, radar pictures provide forecasters with detailed information about the structure of rainfall. A series of satellite and radar images helps forecasters make detailed predictions of the weather over the next six hours or so. Such techniques are especially useful for providing warnings of heavy rainfall.
Turning data into products Observations are collected using national telecommunication networks and are then transmitted around the world. A vast network has been established to do this - the WMO Global Telecommunication System (GTS). It is also used to share weather products.
Observational and forecast data need to be stored in databases so that the data are available whenever required. The quantity and variety of data and the need to provide ready access pose significant problems for information and communication technology specialists.
Forecasters need to be able to display observations, analyses and forecasts on meteorological workstations. These workstations prepare weather products and warnings and send them to the appropriate users.
Forecasting the weather
The behaviour of the atmosphere is simulated using computer models which take a detailed analysis of the state of the atmosphere at a particular time using the latest available observations and then apply the laws of physics to forecast what will occur.
Most computer models use a three-dimensional grid to represent the atmosphere. At each grid point, information is recorded about pressure, temperature, humidity and wind.
The starting point for making a forecast is to collect observations from around the world using the GTS, which transmits surface observations, as well as data from satellites, radar and aircraft. Once the observations have been checked, they are used to determine the atmospheric variables at each grid point at the start of the forecast.
Some of the complex processes taking place in the atmosphere cannot be fully described and represented precisely in the models so their effects have to be estimated. This is called "Parameterization".
The numerical models use the initial grid point values, laws of physics regarding the behaviour of fluid and parameterization schemes to make a prediction of the change in grid point values a short time ahead. New grid point values are then calculated and the process is repeated. In this way, a forecast is built up.
Today, predictions made by computer models include a wide range of geographical coverage and time-scales. Some models can predict weather conditions with great detail in the short range, i.e. two to three days into the future, while others can predict general weather patterns several seasons ahead.
Reaching People Weather forecast presentations on television are popular and attract a consistently high number of viewers. Radio broadcasts are another important way to provide weather information to the public.
Dealing with climate change
Climate influences a wide variety of human activities and is very important for social and economic well-being. Climate varies naturally from year to year and may lead to extreme weather events such as severe storms, floods and droughts.
Climatologists monitor the climate. They do this by examining averages and extreme values of various weather elements, such as rainfall and temperature, and the frequency with which weather events occur over a long period of time, usually about 30 years. Climate summaries of this information and analyses of change over time help people make decisions about weather-sensitive activities. Construction, agriculture and insurance are a few examples.
Making travel safer
Aviation forecasters provide services that help reduce departure delays, flight times and fuel consumption, and ensure the safety and comfort of passengers. Of particular importance in these forecasts is advice concerning weather conditions that may be hazardous to aircraft on take-off and landing and in flight, such as strong wind, thunderstorm, turbulence and icing.
Fog, dust storm, heavy rain and strong winds create hazardous conditions for road traffic. Forecasters provide warnings about the possibility of their occurrence, taking into account expected changes in local weather. Drivers should act on warnings to cancel or postpone a journey or be prepared for a longer journey time or choose another mode of transport.
Saving lives and property
Natural disasters include tropical cyclones (also called hurricanes and typhoons), severe storms, tornadoes, floods, drought, storm surge, land- and mudslides, avalanches, wildland fires and sandstorms.
According to WMO, during the 10-year period 1992-2001, about 90 per cent of all natural disasters were weather, climate or water related. They killed 622, 000 people and affect over two billion others. The total value of economic losses over the same period was estimated at US$446 billion, accounting for about 65 per cent of damage arising from all natural disasters.
Human and material losses caused by natural disasters are a major obstacle to the sustainable development of developing countries, where their economic impact is often devastating. The destruction of buildings, transport infrastructure and agriculture has catastrophic impacts on local and national economies. In the last decade, developing countries shouldered a great share of the economic impacts of natural disasters than developed countries. Their consequences continue to be felt long after the event.
Forecasters identify such events in the early stages and monitor their progress. With the use of surface and satellite data, computer models and knowledge of local climate and weather conditions, they predict future developments.
Protecting our health
Increasing concern about environmental and sustainable development issues has created a demand for scientific advice and information on topics such as air quality, solar radiation, the spread of pollutants and infectious diseases and the onset of extreme climate conditions.
Weather and climate play a key role in the initiation and propagation of potentially dangerous infectious diseases, such as bird flu and Severe Acute Respiratory Syndrome (SARS), which are carried in droplets and particles in the air.
Mosquitoes are bearers of severe deadly diseases such as malaria, dengue, yellow fever and rift valley fever. Hot and wet weather conditions favour their development and trigger outbreaks of these diseases.
Early warning systems for these hazardous conditions are developed by weather and climate experts in partnership with health and social services, allowing the public to be suitably prepared.
Feeding the world
All around the world, agriculture is critically dependent upon the weather. Accurate weather and climate information helps farmers cultivate healthy crops and livestock and expand production. Similar information is used by fishermen, foresters and horticulturalists.
Agro meteorologists provide services based on an understanding of the interaction of weather and agricultural activities. They use data which concern the development of crops, including damage by pests and diseases and soil moisture.
Each day a farmer needs to make decisions about which activities to carry out. To help them do this, weather bulletins are issued on a daily or decadal (every ten days) basis. The decadal bulletins provide information about past and forecast weather and identify the activities that can be carried out.
Environmental factors affect the incidence of plant and animal diseases and pests. For example, desert locust swarms ravage crops and destroy livelihoods, leading to starvation. Knowledge of these factors and of the stages in development of diseases and pests when they are most harmful to crops and livestock allows farmers to take preventive action. Information provided by agro meteorologists helps farmers with control operations, such as forecasting optimal wind conditions for spraying crops with insecticide.
Farmers need to be aware of the likely range of variability in the climate from year to year. Awareness of the likely onset of droughts, heavy rain and temperature extremes enables farmers to decide which are the most resistant crops to grow to minimize losses.
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