When
3:30 p.m., April 27, 2010
Where
Kuiper Space Sciences Building 308
Dr. Betty Pierazzo from the Planetary Sciences Institute is the scheduled speaker.
According to the Spaceguard program about 85% of all Near-Earth Objects (NEOs) larger than 1 km in diameter have been discovered and catalogued. While currently there are no asteroids capable of causing mass extinctions threatening Earth, there is still a large number of undiscovered NEOs between 500 m and 1km in diameter that are looming in the Earth’s neighborhood. The consequences of a collision of a NEO in this size range with the Earth have never been explored in detail. If headed on a collision course with Earth, such NEOs will be about 2 times more likely to hit the Earth’s oceans than continental areas. Much effort has been devoted lately to the risk of tsunami generated by oceanic impacts, but little work has been done so far to assess the atmospheric (and thus, climatic) effects of oceanic impacts of mid-size bolides.
I will present initial results of an investigation aimed at characterizing the effects of medium-size oceanic impacts 500m and 1 km in diameter on the lower and middle atmosphere, estimating ozone loss and potential danger from UV radiation at the Earth’s surface. The work combines simulations with a shock physics code (SOVA, from the Institute for Dynamics of Geospheres), to evaluate the effects of impacts, with simulations with a state-of-the-art whole atmosphere general circulation model with an interactive chemistry model (the Whole Atmosphere Community Climate Model, from the National Center for Atmospheric Research), to characterize the perturbation of atmospheric chemistry. Final estimates of the change over time in UV flux at the surface due to the modeled impact-induced ozone change over time are then carried out using a radiative transfer model (TUV, Tropospheric Ultraviolet-Visible, from the National Center of Atmospheric Research).
According to the Spaceguard program about 85% of all Near-Earth Objects (NEOs) larger than 1 km in diameter have been discovered and catalogued. While currently there are no asteroids capable of causing mass extinctions threatening Earth, there is still a large number of undiscovered NEOs between 500 m and 1km in diameter that are looming in the Earth’s neighborhood. The consequences of a collision of a NEO in this size range with the Earth have never been explored in detail. If headed on a collision course with Earth, such NEOs will be about 2 times more likely to hit the Earth’s oceans than continental areas. Much effort has been devoted lately to the risk of tsunami generated by oceanic impacts, but little work has been done so far to assess the atmospheric (and thus, climatic) effects of oceanic impacts of mid-size bolides.
I will present initial results of an investigation aimed at characterizing the effects of medium-size oceanic impacts 500m and 1 km in diameter on the lower and middle atmosphere, estimating ozone loss and potential danger from UV radiation at the Earth’s surface. The work combines simulations with a shock physics code (SOVA, from the Institute for Dynamics of Geospheres), to evaluate the effects of impacts, with simulations with a state-of-the-art whole atmosphere general circulation model with an interactive chemistry model (the Whole Atmosphere Community Climate Model, from the National Center for Atmospheric Research), to characterize the perturbation of atmospheric chemistry. Final estimates of the change over time in UV flux at the surface due to the modeled impact-induced ozone change over time are then carried out using a radiative transfer model (TUV, Tropospheric Ultraviolet-Visible, from the National Center of Atmospheric Research).
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