Truth, Justice, and the American way. TRUTH: Helping to correct people's misconceptions about history, science, and the state of the world. JUSTICE: Meant in the biblical sense. Fair treatment of other people, rational laws, and assisting the disadvantaged. THE AMERICAN WAY: A classless society where everybody has an opportunity to meet their potential and for economic advancement, regardless of race, ancestry, religion, gender, or sexual orientation.

Tuesday, October 10, 2017

Improving prediction of tropical storms and hurricanes

Unfortunately, the paths of cyclones are not predictable enough yet to pin down exactly where a storm will travel. Cyclone paths respond to temperature, pressure, and flow variations at the ocean surface, and the entire column of air up to a level higher than the clouds generated by the cyclone.

Our best knowledge of actual conditions is at sea level. Satellites report temperature, flow, and the sea level. Satellites can provide some mid-atmosphere data by cloud-top temperature and cloud movement, but it is difficult to determine temperatures and motion of clear air. Aircraft only measure a small part of the atmosphere. Upper atmosphere data samples can be hundreds of kilometers apart outside of aviation lanes.

One proposed solution is to place anchored smart buoys in a grid throughout the oceans, using GPS satellites to create a tomographic picture of the atmosphere (like a CAT scan). Covering the oceans with 300 km squares would require almost 3000 buoys (additional buoys would be placed strategically). The Doppler effect of the earth's atmosphere would create tiny changes in the calculated 4-dimensional location reported from the satellite data. By using at least 5 satellites at a time, each buoy could compute both the radio wave absorption and the Doppler effect along the path through the atmosphere of radio signals from each of the satellites. As the satellites move, the radio signal from each satellite forms a slice through the atmosphere every 30 minutes. Using more satellites would create a more dense mesh of slices.

GPS satellites only send information (they only receive information from command centers for station-keeping). All of the GPS receivers calculate the distance to a satellite by using the time the radio signal takes to reach the receiver. By using 4 satellites the location of a GPS receiver can be computed in three dimensions. Aircraft and ships on the open ocean are in "line of sight" to at least 7 GPS satellites. When somebody says they are using GPS to locate an item such as a mobile phone or car, they are sending the item a command to report its location (as measured by GPS), the GPS system itself does not respond to those requests.

The problem with this proposal is the expense of the buoys, their deployment, anchoring, and maintenance. Paying for and deploying buoys in the open ocean would have to be a multi-national effort and would have to be approved by the UN. The US GPS system is the most extensive but other nations have deployed similar systems. The satellite systems are all primarily intended for military use and the most precise information is encrypted. Another problem is that the buoys could also interfere with ships and the local habitat.

The buoys would obtain their power from solar cells and/or wave motion. The batteries would require replacement about every decade. They would also have reflectors to make to warn approaching ships at night. They would not be visible to submarines unless each buoy generates a periodic sonar chirp, which could interfere with sea life.

Because they use a solar panel, bird lime could cause a problem. By locating the antennas away from the solar panel and making the antennas bird perches, bird lime on the solar cells could be minimized. Wave motion generators would use the vertical motion of the buoy on the tether to generate electricity. The tether would need a Teflon-like coating to eliminate fouling by sea life.

The buoys would report their data using a Bluetooth-like system in cooperative mode. Cooperative mode means each buoy retransmits the data it receives from some of its neighbors. The data would eventually be received by land-based stations. Use of five-watt transmitters would limit interference with other radio frequency use.The antenna for communication between buoys would have to be high enough that waves and the earth's curvature will not block line-of-sight communication.

About Me

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Canoga Park, California, United States
Software Engineer with Ph.D. in Computer Science. I have a deep background in the sciences and in computer-human interaction. I was a college professor for 11 years, followed by over a decade of work in industry.