Ernie Tretkoff

Space Weather and Satellite Engineering: An Interview With Michael Bodeau

Michael Bodeau is a technical fellow at Northrop Grumman. Over his career, which has included positions at TRW, Hughes, and Boeing, he has designed telecommunications and scientific satellites for government and commercial operators and has studied the effects of space weather on satellites. In this interview, Bodeau describes how satellite engineers create “building codes” to help them design satellites that can withstand space weather events.

Forests at risk

The forests of the southwestern United States are especially vulnerable to climate change, according to studies presented at the AGU Fall Meeting. Park Williams of the University of California, Santa Barbara and colleagues compared tree ring growth records from the Southwest to climate records. The records show a clear correlation between growth rate and temperature and growth rate and precipitation, with tree growth rates slowing during hotter and drier years. The researchers concluded that southwestern United States forests are particularly sensitive to heat and drought. A global overview of tree death presented at the meeting showed that the American Southwest is not the only vulnerable region. Craig Allen of the U.S. Geological Survey reported that there have been episodes of significant tree death around the world in recent decades and suggested that these die-offs are likely linked to climate-induced stress. Such losses could increase as warming continues. “No forest type on this planet is immune to drought and heat-induced mortality,” said Allen.

Water vapor trends over Boulder, Colorado

Water vapor in the atmosphere is responsible for a significant portion of the greenhouse effect, and even small changes in the upper troposphere or lower stratosphere can have a large effect on climate. A new analysis of water vapor measurements by balloon-borne frost point hygrometers over Boulder, Colo., shows that stratospheric water vapor has increased over the past 30 years. Hurst et al. broke the long measurement record into four discrete time periods and determined the water vapor trends in each period for five 2-kilometer-thick stratospheric layers (16–26 kilometers in altitude). The scientists found that, on average, stratospheric water vapor increased by about 1 part per million by volume (27%) over the past 30 years, though there were many shorter-term variations in the record. Water vapor levels increased during 1980–1989 and 1990–2000, decreased from 2001 to 2005, and then increased again after 2005. The authors found that, at most, 30% of the observed water vapor increases can be attributed to greater amounts of methane oxidation in the stratosphere. The 2001–2005 decrease in midlatitude water vapor has been linked to observations of anomalously low tropopause temperatures in the tropics, but, to date, no connection between the observed water vapor increases and tropical tropopause temperatures has been found despite ongoing efforts. (Journal of Geophysical Research-Atmospheres, doi:10.1029/2010JD015065, 2011)

Research Spotlight: Has the ozone hole caused Antarctic sea ice extent to increase?

While sea ice extent has declined dramatically in the Arctic in recent years, it has increased slightly in the Antarctic. Some scientists have suggested that increased Antarctic sea ice extent can be explained by the ozone hole over Antarctica. Previous simulations have indicated that the ozone hole induces a large change in atmospheric circulation in austral summer and that this change in circulation could contribute to the changing Antarctic sea extent.

Research Spotlight: Tropical cyclone size distribution characterized

What are the mechanisms controlling the dynamics of tropical cyclones? To answer this question, a new characterization of the distribution of tropical cyclone sizes was created by Chavas and Emanuel using near-surface wind measurements taken during 1999–2008 using the QuikSCAT satellite microwave scatterometer.

Research Spotlight: Split tectonic plate beneath western Japan explains earthquake activity

Western Japan, a densely populated region, is prone to large earthquakes and volcanic eruptions, but the tectonics of the underlying region is not well understood. The shape of the Philippine Sea plate subducting beneath western Japan is a key factor in understanding the spatial distribution of earthquakes.

Research Spotlight: Mapping moisture recycling and global water resources

Water that falls as precipitation in one region may have originated in a distant region, or it may be recycled moisture that originated as evaporation within the region. Global wind patterns, topography, and land cover all play a role in moisture recycling patterns and the distribution of global water resources. Land use changes such as irrigation, dams, and deforestation can alter evaporation patterns in a region, potentially affecting water resources in distant regions.

Research Spotlight: Thick water ice observed in lunar craters

Water ice exists in large quantities in many small craters near the Moons north pole, according to a new study. Spudis et al. present initial results from the miniature synthetic aperture radar (Mini-SAR) experiment on board Indias Chandrayaan 1 spacecraft, which mapped most of the area near the north pole of the Moon between February and April 2009. The Mini-SAR instrument collected data on the polarization of radio waves reflected off the lunar surface. These data give the researchers insight into lunar surface features. For instance, high values of the circular polarization ratio (CPR) indicate either surface roughness or ice.

Research Spotlight: New samples taken along Pacific Antarctic Ridge

Understanding the geochemistry along ocean ridges around the world can help scientists understand the spatial dynamics and evolution of the mantle. Building on previous sampling of the Pacific Antarctic Ridge, Hamelin et al. collected data on major elements; trace elements; and strontium (Sr), neodymium (Nd), and hafnium (Hf) isotopes in basalts gathered along the ridge from 41° to 53°S. These were the first Sr-Nd-Hf isotope data collected in that area, a section of the Pacific Antarctic Ridge that does not have hot spots,which would affect the geochemistry.

Research Spotlight: Climate change and urbanization increase urban heat island effect

The urban heat island effect, in which an urban area is notably warmer than surrounding nonurbanized areas, will likely increase in coming decades as urbanization is projected to increase dramatically (one estimate projects that there will be 6 billion urban dwellers worldwide by 2050). However, many climate model projections have not included urbanization trends.