Sealevel’s SeaMAX software drivers and utilities make installation and operation easy using Windows operating systems. SeaMAX is supported on 32-bit and 64-bit versions of: Microsoft Windows 10; Microsoft Windows 8.1; Microsoft Windows 7.Windows 7 requires the following updates: Service Pack 1; KB3033929 – SHA-2 Support (Important! Extrinsic Drivers of Sea Level Change Earth Orbit, Solar Insolation Variability & Sea Level Change Reconstruction of Sea level change over three time periods: a. 35 million years, b. 5.33 million years, c.
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Extrinsic Drivers of Sea Level Change
Earth Orbit, Solar Insolation Variability & Sea Level Change
Take look at the graphs showing changes in sea level through the history of the Earth. The top figure covers 35 million years, the middle one covers a little more than 5 million years, and the bottom one zooms in to the past 500,000 years. What do you notice? Is there a regularity in the pattern of sea level ups and downs?
Through Earth’s history, there appears to have been a regular spacing of glacial maximum events, at roughly 120 thousand years (ky). When variations in Earth's orbit produce repetitive changes in climate and sea level, the observed cycles are often referred to as Milankovitch Cycles. Many sedimentary rock sequences have been shown to have stacking patterns that reflect these time scales, as do ice core data.
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Milankovitch Cycles
Mathematician Milutin Milankovitch proposed an explanation for the changes in the way the Earth orbits the sun. These changes define the sequence of ice ages and warm periods.
- The Earth’s orbit changes from being nearly circular to slightly elliptical (eccentricity). This cycle is affected by other planets in the solar system and has a period of around 100,000 years.
- The angle of tilt of the Earth’s axis changes from 22.1° to 24.5° (obliquity). This cycle has a period of 41,000 years.
- The direction of the tilt of the axis changes (precession) on a cycle of 26,000 years.
- These changes influence the length of the seasons and the amount of solar radiation received by the Earth.
Optional Video
Please watch Milankovitch Cycles in 5 Minutes (5:00), if you are not already familiar.
Click for the 'Milankovitch Cycles in 5 Minutes' video transcript.
The Sun is the Earth's main energy source. In fact, it provides 99.96 percent of all the energy that drives the Earth's climate. Some of the energy produced by nuclear fusion in the sun's interior will eventually strike the top of the Earth's atmosphere. The amount of energy that does strike the atmosphere depends on two main factors: the total amount of energy produced and transmitted by the Sun, and the orbital cycles of the Earth with respect to the Sun. The energy transmitted by the Sun is in a constant state of flux depending on solar activities such as sunspots, solar flares, coronal loops, and coronal mass ejections. The relationship between the Earth's orbital cycles and climate change was proposed by Milutin Milankovitch. Milankovitch was a Serbian engineer, and during the 1930s, he proposed that the changes in the intensity of solar irradiation received on the Earth were affected by three fundamental factors: precession, obliquity, and eccentricity. These factors are now collectively known as the Milankovitch cycles. The Milankovitch cycles are widely accepted by climate change scientists and are well documented by, for example, the IPCC. A more detailed description of the cycles is available by clicking on the tab above, but the remainder of this video will provide an excellent overview. The Earth rotates on its axis every 24 hours. Around once in 27 days, the Sun also rotates on its axis. Its average distance from the Earth is approximately 150 million kilometers (93 million miles). It is an average distance because this Earth's orbit around the Sun is not fixed. Its orbit cycles from being almost a circle to that of an ellipse to almost a circle again. The cycle takes place over a period of around 100,000 years. The rotation of the Earth is at an angle to the vertical, and this angle changes over time. It moves from 22.1 degrees to 24.5 degrees and back again. This is over a time span of approximately 41,000 years. The Earth also goes through a cyclic wobble. It moves from its current position of the north pointing to the star Polaris to where the North points to the star Vega and returns to pointing at Polaris. The full cycle takes place between 19 to 26 thousand years. The combined effects caused the seasons to gradually cycle relative to the perihelion and aphelion, this over a time span of about 21 thousand years.[music]
How do these variations in Earth’s orbit affect climate and sea level? Collectively, variations in Earth's orbit (eccentricity, obliquity, and precession) can either reinforce signatures of cooling or warming, or they can work to counteract each other and produce less severe or ameliorated climate change. When the multiple variables reinforce each other, the amount of climate change and, as a result, sea level change can be significant.
A new NASA sea level simulator lets you bury Alaska’s Columbia glacier in snow, and, year by year, watch how it responds. Or you can melt the Greenland and Antarcticice sheets and trace rising seas as they inundate the Florida coast.
Computer models are critical tools for understanding the future of a changing planet, including melting ice, rising seas and shifting precipitation patterns. But typically, these mathematical representations — long chains of computer code giving rise to images of dynamic change — are accessible mainly to scientists.
The new simulator, however, allows anyone with a computer to perform idealized experiments with sea level and learn about its complexities. Developed by scientists at NASA's Jet Propulsion Laboratory in Pasadena, California, the interactive platform, called the Virtual Earth System Laboratory (VESL), provides the public with a taste of how NASA models important Earth processes.
The platform will also prove useful to scientists as a convenient way to create visual representations of data.
While many interface tools are available to explore sea level effects, VESL stands apart for its strong representation of Earth’s cryosphere – the melting ice caps, ice sheets and glaciers that are major contributors to sea level rise.
And the simulator is not just a simplified version of a model or a menu of preexisting results. It is direct access to the complex, number-crunching model itself, though with limited scenarios and factors that can be adjusted.
“It’s the real software, being used on the fly, live, without being prerecorded or precomputed,” said Eric Larour of JPL, who led VESL’s development. “You have access to a segment of an ice sheet model or sea level model, running NASA’s software.”
Despite these capabilities, VESL won’t overtax computers.
“A key to making the interface tool work is cloud computing,” Larour said. Instead of burdening your own computer with heavy demand, “you can access a JPL cloud to run big simulations.”
The VESL platform allows the user to control one or two parameters for each model scenario. For example, in a version of the model configured to represent Columbia Glacier, a slider allows users to change snowfall amounts and examine how the change affects the glacier’s behavior in subsequent years. For a sea level simulation, sliders control the rates at which the ice sheets on Antarctica and Greenland are melting.
“You can explore different aspects of the model that maybe even the scientists didn’t explore,” Larour said.
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The site will be updated frequently to keep up with the latest, peer-reviewed research. Scientists will eventually be able to use the graphical interface to display and present new data sets or model results, while lay users will be able to replicate published research results for themselves using models that are “open source,” or publicly available.
“As we make progress, [the public] can rerun the science that we actually do,” Larour said. “If anybody has concerns or finds issues with our simulation, they have the ability to replicate our results. We would welcome feedback and inputs to improve our science.”
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VESL was developed over five years by members of the Ice Sheet System Model development team at JPL and the University of California, Irvine (UCI), with the help of several students, including Dan Cheng from UCI and Gilberto Perez, who attended both Cal Poly Pomona and UCI.
The website hosting the simulator will also include a public outreach section, being developed by Daria Halkides, a scientist and outreach exhibit developer of Earth & Space Research in Seattle and a JPL affiliate.
“VESL was initially intended for scientists,” Larour said. “Then we realized it could also be an excellent tool for public outreach. These simulations are so easy to run, and visually so compelling, that any person from the public can go and run them and probably understand what is going on.”
You can find VESL at:
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A paper describing the development of the ice sheet simulator, titled 'A JavaScript API for the Ice Sheet System Model: Towards on online interactive model for the Cryosphere Community,' appears today in the journal Geoscientific Model Development.
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A paper describing the development of the ice sheet simulator appears today in the journal Geoscientific Model Development.
News media contact
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Alan Buis
Jet Propulsion Laboratory, Pasadena, California
818-354-0474
Alan.Buis@jpl.nasa.gov