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When Science Fiction Becomes Reality: Digital Earth

  In the science fiction novel “Cloud Ball”, scientists simulated a digital earth that is almost identical to the earth in the computer. Today, the Digital Earth is fully a reality.
digital ocean engineering

  In ancient Greek mythology, Jason and a group of heroes went to the Black Sea coast to find the rare treasure “Golden Fleece”. They took the “Argo” built by the legendary boatman Argo. In November 2007, the global ocean observation network consisting of 3,000 buoys was fully completed. This ocean monitoring project, which involved more than 30 countries, was named “Argo Plan”, and its official name was “Real-time Geospin Oceanographic Observation”. array”. Just like the astronomical observation network and the seismic network composed of observatories and seismic monitoring stations on the ground, Argo plans to establish a monitoring network covering the ocean.

The legendary “Argo” that escorted heroes on their treasure hunt

  Today, the more than 3,000 satellite-tracked profiling buoys that Argo plans to distribute in the world’s oceans are able to quickly and accurately collect data on sea temperature, salinity, current movement and more on a global ocean scale. The buoy has a working cycle of 10 days. In the first 9 days, the buoy will be suspended at 1,000 meters below the sea surface; on the 10th day, the buoy will dive to a 2,000-meter deep ocean area, collect the seawater temperature information there and return to the sea surface. Scientists can also adjust the buoy’s duty cycle as needed.
  The Argonaut project can collect massive amounts of ocean data every day, most of which are deep seawater data that cannot be collected by satellites. With the help of ocean-monitoring networks such as the Argonaut Project, ocean scientists around the world have collected several times as many deep-sea profiles in the first 20 years of the 21st century as they have in the past 100 years.

Argonaut plan buoy duty cycle
What technologies are needed for a digital earth?

  Argonaut plans to digitize the world’s oceans, and scientists even want to digitize the entire planet. In 1998, Gore, then the vice president of the United States, proposed the concept of “digital earth”, which is to fully collect information from every corner of the earth and store it in a distributed computing network to form a real-time digital model of the earth. Let people all over the world quickly and intuitively understand the changes happening on the earth.
  In order to achieve the goal of digital earth, we need to make great progress in the following technical means:
  Mass storage technology Digital geoengineering will have massive information entering the distributed computing network at any time. In 1998, when Gore proposed the concept of digital earth, the hard disk storage capacity installed on personal computers was mostly only a few dozen GB. Today, the data storage capacity of big data processing centers has gradually increased from TB level to PB level, even EB level, ZB level and YB level.
  Various data monitoring networks As of 2019, the number of satellites in orbit around the world reached 2,460. The accuracy of satellite imaging has also gradually improved in recent years. The resolution of my country’s Gaofen-11-02 optical remote sensing satellite at close range (the operating period of the satellite in an elliptical orbit close to the earth) can reach 0.1 meters. In addition to satellite networks, many real-time monitoring networks such as oceans, atmosphere, and rivers also provide a steady stream of information for the digital earth.
  Large-capacity network bandwidth Digital Earth not only needs to input a large amount of information, but also needs to publish various information on the network. Otherwise, it will be difficult to upload or download a large amount of data in time, which will greatly affect the practicability of the digital earth.
  Interoperability The rapid spread of the Internet is largely due to the adoption of a series of common underlying protocols, uniform standards that enable smooth data exchange. The application of digital earth also faces the problem of unified standards, that is, “interoperability”, which refers to the ability of different systems and organizations to cooperate and work together.
  metadataMetadata is “data that describes data”. In Romance of the Three Kingdoms, Zhang Fei’s appearance is described in this way: he is eight feet long, with a leopard’s head and eyes, a swallow’s chin and a tiger’s beard. In this description, readers can get information about Zhang Fei’s height, appearance, voice and behavior characteristics, and data such as “height” and “appearance” are metadata. If the various data collected by the digital earth from all over the world can be interpreted by scientists from all over the world, a series of “name”, “collection location”, “author or source”, “data format” and “resolution” should be marked on the data. information to increase the availability of these data.
  Von Neumann, who proposed the computer architecture of computational science , once said: “Science never attempts to explain natural phenomena, nor even attempts to explain natural phenomena, but only to establish scientific models.” Establishing scientific models refers to Represent a simplified natural world using mathematical formulas, computer simulations, or simple diagrams. As humans make more and more breakthroughs in areas such as algorithms, scientists can already model natural phenomena such as atmospheric activity.
Complex systems are the devil and the truth

Subtly different always parameters, may output completely different results

  The 2021 Nobel Prize in Physics has been awarded to Japanese-American scientist Shuro Manabe, German scientist Klaus Hasselmann and Italian scientist Giorgio Parisi for their contributions to understanding complex phenomena such as atmospheric motion. groundbreaking contribution.
  Composed of many interacting components, complex systems are filled with randomness and disorder. Weather is one of the typical complex systems, and a large number of equations are needed to predict the weather. Scientists can only guarantee the accuracy of short-term weather forecasts at present, and once the medium and long-term weather is predicted, the accuracy will be greatly reduced.
  In the 1960s, American meteorologist Lorenz took a laziness while studying numerical weather forecasting and entered an iterative calculation code. The so-called iterative calculation is to use the result of this calculation as the original data of the next calculation, and then perform the calculation, and so on. Iterative algorithms save the trouble of manually entering raw data. However, the computers at the time were very slow, and Lorenz went out for coffee while the computer was running. When he returned to the lab, he found that the computer’s results were a mess. At that time, he was puzzled and thought that even if the error was taken into account, the calculation results should not be so outrageous. After more than ten years, he finally got inspiration from the events of that year and proposed the “butterfly effect” to explain the phenomenon that happened in that year. The “butterfly effect” means that in a complex system, a small change in a variable can have unpredictable consequences.

  Due to the excessive number of interacting factors involved in complex systems, many related scientific experiments in the past have been limited by computer performance and cannot be further carried out. But today, the computing power of computers has greatly improved, not only that, but also the advancement of storage devices, mobile devices, high-speed broadband and distributed computing networks, making processing complex systems no longer an impossible task.

Complex systems are the devil and the truth
Digital Earth project launched

  In order to promote the EU’s plan to achieve carbon neutrality by 2050, EU scientists launched the “Destination Earth” plan in 2021. The program is expected to run for 10 years, during which high-precision digital Earth models will reflect climate change patterns and extreme events on Earth as accurately and in time as possible with spatial and temporal precision. Scientists call this model the “Earth Twin”. In addition to simulating the Earth’s atmosphere and ocean systems in real time, its more important function is to predict the future.

Making Digital Earth the Earth’s Twin

  Earth twins can help with decision-making. For example, if a hydropower plant needs to be planned in a certain area of ​​the Netherlands, the computer can infer the approximate amount of electricity generated by the hydropower plant in the next few decades and its impact on the environment through the simulation of Earth Twins. The planning choices for wind power plants, photovoltaic power plants, and even farms can all be informed by the predictions of the Earth Twins.
  The role of Earth Twins is also mainly reflected in simulating future climate patterns around the world and predicting extreme weather. The prediction of the atmosphere by the Earth Twins not only combines the weather map method, numerical forecast method and mathematical forecast method used in traditional weather forecasting, but also combines a series of small-scale weather factors that were easily overlooked in the past to achieve high-precision weather simulation and prediction. Thereby depicting the complex motion process of the entire earth’s atmosphere.
  Digital Earth is a typical discipline of scientific big data. Scientists are not satisfied with the current scale of information collection. They hope that the next step will be to input the information of human activities on the earth into the earth twin model, so that the model can truly simulate the impact of human activities on the earth, so as to truly realize the digitization of the earth.

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