U.S. Navy
Weather map prepared and printed out by computer gives data in graphical form. Enlarged view of weather “picture” (above) shows how it is formed by printed digits representing the pressure at reporting stations.
There was even the mathematics to make this possible in Richardson’s day: the so-called “primitive equations” of the pioneer mathematician Euler. These are six partial differential equations involving velocity, pressure, density, temperature, and so on. But though the principle is simple, the practical application is hopelessly involved—unless you have a stadium filled with 60,000 willing mathematicians or a fast computer of some other type.
In 1950 the stage was finally set for the implementation of numerical weather prediction. First, electronic computers were available. Second, and importantly, mathematician C. G. Rossby had worked some magic with the original primitive equations and reduced them to a single neat equation with only four terms. The new tool is called the Rossby equation. Meteorologists and mathematicians at Princeton’s Institute for Advanced Study decided to combine the Rossby equation, the MANIAC computer, and some money available from the Office of Naval Research. The result was JNWPU, Joint Numerical Weather Prediction Unit, later to become NANWEP, for Navy Numerical Weather Problems Group. It is too bad that pioneer Richardson did not live to see the exploitation of his dream.
What NANWEP does is to take the meteorological data from some 3,000 reporting stations, compare them with those existing yesterday, and print out a weather map for the Northern Hemisphere for tomorrow. Because there are so many more stations reporting than the handful that Richardson used, the number of computations has risen to the astronomical total of about 300,000,000. Despite this, a Control Data Corporation 1604 digital computer does the job in a good bit less time than the three months it took Richardson. NANWEP prints out its weather maps 40 minutes from the time all data are in.
Teletype reports come in from the thousands of weather stations; these are punched on tape and fed to the 1604. Since the information includes geographical position in addition to meteorological data, the computer prints out numbers that form a map of weather coming up. Although the meteorologist adds some clarifying lines by connecting points of equal pressure, the “raw” map with its distinctive shaded areas is meaningful even to the layman.
Further refinements are in the offing. As many as 10,000 weather stations may eventually report to the central computer, which may also learn to accept the teletype information directly with no need for the intermediate step of punching a tape. Although it will be a long time before a positive forecast, exact in every detail, is possible, NANWEP already has lifted weather prediction from the educated guesswork of the older meteorologists to truly scientific forecasting.
It turns out that numerical weather prediction brings with it some bonuses. NANWEP can predict the action of ocean waves three days in advance, in addition to its regular wind, temperature, and precipitation information. So it is now being put to work preparing optimum routes for ships. Here’s the way it would work. A ship sailing from California to Japan requests the best routes for the voyage. Initially the computer is given the ship’s characteristics and told how it will perform in various sea conditions. It then integrates this information with the predicted sea conditions for the first day’s leg, and plots several different courses. Distances the ship would travel on each of these courses are plotted, and a curve is drawn to connect them. Now the computer repeats the process for the next day, so that each of the tentative courses branches out with its own alternates. The process is repeated for each of the five days of the voyage. Then the computer works backward, picking the best route for the entire voyage, and gives the course to be followed for optimum time. If that isn’t sufficiently informative for the captain, he can request and receive not one but three courses: one for the fastest trip regardless of sea condition, another for the fastest trip with waves of only a certain height, and finally a course for the fastest trip through calm water! The advantages of such a service are immediately obvious and give a hint at many other applications of the technique to air travel, truck transport, and so on.
NANWEP is ground-based, of course. There are also airborne weather computers like those of the U.S. Weather Bureau’s National Severe Storm Research Aircraft Project. The Weather Bureau has jumped its computer budget from $1.5 to $2.5 million to extend this and other projects. The compact airborne computers ride along in DC-6 and B-57 aircraft to monitor hurricanes off Florida and tornadoes in the Great Plains area. The computers gather forty different kinds of information and convert it to digital form at thousands of characters a second. Such monitoring of violent weather by means of computers suggests an intriguing use of the machine. Man has long considered the prospect of going the step beyond weather recording and prediction to actually changing or even creating his own weather. He has done a few rather startling things of this kind, admittedly on a small scale but with tremendous implications. Cloud-seeding experiments are samples, as attempts both to induce precipitation and to create or destroy storms. These experiments, though inconclusive, have led to results—including precipitation of lawsuits and ill feeling. Meteorologists attempted to divert a hurricane along the Atlantic coast line once, apparently with results. But the storm swerved too far and the weathermen incurred the justifiable wrath of those living in the area affected. Why not simulate such an experiment in the computer? Besides being safer, it is also far cheaper. In the long run, we may do something about the weather at that.
Computers in Space
There are many points in history when seemingly fortuitous happenings take place. The invention of the printing press appears to have occurred at a fork in the road as literature flowered. The discovery of gasoline and the automobile went hand in hand. So it is with the electronic computer and the spacecraft. Is the computer here because it was needed for such an application, or did it actually cause the advent of space flight? Our conclusions must depend on our belief or disbelief in such things as causality. A realistic view might be merely to applaud and appreciate the confluence of two important streams of thought to make a river that will one day flow to the other planets and finally out of the solar system entirely.