NASA – Top Story – CHANGES IN THE EARTH’S ROTATION ARE IN THE WIND – March 4, 2003

For more information contact:

Rob Gutro NASA Goddard Space Flight Center (Phone: 301/286-4044)Stephanie Kenitzer American Meteorological Society (Phone: 425/432-2192)

Special Bureau for the Atmosphere of the International Earth Rotation Service (IERS), at Atmospheric and Environmental Research, Inc.

The LAGEOS 1 & 2 Satellites

Gravity Recovery and Climate Experiment (GRACE) satellite

NASA’s Earth Science Enterprise

Caption for Image 1: THE SPINNING EARTH IS AFFECTED BY WINDS Angular momentum describes the rotation of the Earth around its axis as depicted in this animation. A normal, 24-hour, day is based on the mean speed of the rotation of the whole Earth, including its atmosphere and ocean. When the motions in these fluids move mass to different positions, the angular momentum changes in them and will affect the solid Earth rotation. Given the rotation rate, fluid mass and distance from the Earth’s radius, If one variable is changed, at least one other variable also must also change. For example, a spinning ice skater spins slower with extended arms and faster when his arms are pulled in. Similarly, the spinning Earth is affected by many factors, including changes in the way the winds blow or currents in the ocean. Some of these factors can act to speed the planet up, while others literally drag it down. Of course these effects are very small, but observable by advanced scientific techniques. CREDIT: NASA SVS, Jim Strong and Horace Mitchell

Caption for Image 2: ATMOSPHERIC ANGULAR MOMENTUM AND LENGTH OF DAY

This graph displays the close connection between the global angular momentum of the atmosphere derived from wind analyses (darker red curve, scale on right) and the observed changes in the length of day (lighter green curve, scale on left), after removing low frequencies, for the years 2000/2001. The remarkable agreement demonstrates that a close coupling exists between motions of the atmosphere and the solid Earth. CREDIT: Atmospheric and Environmental Research, Inc.

For more information contact:

Rob Gutro NASA Goddard Space Flight Center (Phone: 301/286-4044)Stephanie Kenitzer American Meteorological Society (Phone: 425/432-2192)

Special Bureau for the Atmosphere of the International Earth Rotation Service (IERS), at Atmospheric and Environmental Research, Inc.

The LAGEOS 1 & 2 Satellites

Gravity Recovery and Climate Experiment (GRACE) satellite

NASA’s Earth Science Enterprise

Caption for Image 1: THE SPINNING EARTH IS AFFECTED BY WINDS Angular momentum describes the rotation of the Earth around its axis as depicted in this animation. A normal, 24-hour, day is based on the mean speed of the rotation of the whole Earth, including its atmosphere and ocean. When the motions in these fluids move mass to different positions, the angular momentum changes in them and will affect the solid Earth rotation. Given the rotation rate, fluid mass and distance from the Earth’s radius, If one variable is changed, at least one other variable also must also change. For example, a spinning ice skater spins slower with extended arms and faster when his arms are pulled in. Similarly, the spinning Earth is affected by many factors, including changes in the way the winds blow or currents in the ocean. Some of these factors can act to speed the planet up, while others literally drag it down. Of course these effects are very small, but observable by advanced scientific techniques. CREDIT: NASA SVS, Jim Strong and Horace Mitchell

Caption for Image 2: ATMOSPHERIC ANGULAR MOMENTUM AND LENGTH OF DAY

This graph displays the close connection between the global angular momentum of the atmosphere derived from wind analyses (darker red curve, scale on right) and the observed changes in the length of day (lighter green curve, scale on left), after removing low frequencies, for the years 2000/2001. The remarkable agreement demonstrates that a close coupling exists between motions of the atmosphere and the solid Earth. CREDIT: Atmospheric and Environmental Research, Inc.

For more information contact:

Rob Gutro NASA Goddard Space Flight Center (Phone: 301/286-4044)Stephanie Kenitzer American Meteorological Society (Phone: 425/432-2192)

Special Bureau for the Atmosphere of the International Earth Rotation Service (IERS), at Atmospheric and Environmental Research, Inc.

The LAGEOS 1 & 2 Satellites

Gravity Recovery and Climate Experiment (GRACE) satellite

NASA’s Earth Science Enterprise

Caption for Image 1: THE SPINNING EARTH IS AFFECTED BY WINDS Angular momentum describes the rotation of the Earth around its axis as depicted in this animation. A normal, 24-hour, day is based on the mean speed of the rotation of the whole Earth, including its atmosphere and ocean. When the motions in these fluids move mass to different positions, the angular momentum changes in them and will affect the solid Earth rotation. Given the rotation rate, fluid mass and distance from the Earth’s radius, If one variable is changed, at least one other variable also must also change. For example, a spinning ice skater spins slower with extended arms and faster when his arms are pulled in. Similarly, the spinning Earth is affected by many factors, including changes in the way the winds blow or currents in the ocean. Some of these factors can act to speed the planet up, while others literally drag it down. Of course these effects are very small, but observable by advanced scientific techniques. CREDIT: NASA SVS, Jim Strong and Horace Mitchell

Caption for Image 2: ATMOSPHERIC ANGULAR MOMENTUM AND LENGTH OF DAY

This graph displays the close connection between the global angular momentum of the atmosphere derived from wind analyses (darker red curve, scale on right) and the observed changes in the length of day (lighter green curve, scale on left), after removing low frequencies, for the years 2000/2001. The remarkable agreement demonstrates that a close coupling exists between motions of the atmosphere and the solid Earth. CREDIT: Atmospheric and Environmental Research, Inc.