Keah C. Schuenemann

Synoptic Forcing of Precipitation over Greenland: Climatology for 1961–99

Abstract Analysis of the synoptic climatology and precipitation patterns over the North Atlantic region allows for a better understanding of the atmospheric input to the mass balance of the Greenland ice sheet. The self-organizing map (SOM) technique was applied to the 40-yr European Centre for Medium-Range Weather Forecasts Re-Analysis (ERA-40) daily sea level pressure (SLP) data from 1961 to 1999 to objectively identify synoptic SLP patterns over the North Atlantic region. A total of 35 different SLP patterns were identified. Patterns common to the winter season are characterized by deep low pressure systems that approach Greenland through an active North Atlantic storm track, whereas patterns most common to the summer months are generally weaker and approach the ice sheet from the west through Baffin Bay. The blocking, splitting, and intensification of cyclones by the high elevations of the Greenland ice sheet were identified in this analysis. Analysis of ERA-40 precipitation associated with each SLP p...

Changes in synoptic weather patterns and Greenland precipitation in the 20th and 21st centuries: 2. Analysis of 21st century atmospheric changes using self‐organizing maps

Predictions of Greenland precipitation are analyzed using self-organizing maps (SOMs). An ERA-40 sea-level pressure synoptic climatology is used to evaluate 20th century simulations of IPCC AR4 models for the period 1961-1999. The models that best reproduce the North Atlantic surface synoptic climatology and Greenland precipitation in ERA-40 are the CCCMA-CGCM3.1(T63), MIROC3.2(hires), and MPI-ECHAM5. Using these models in a 3-model ensemble, daily SLP and precipitation data from model simulations for time periods 1961-1999, 2046-2065, and 2081-2100 are compared, where future simulations are based on the Special Report on Emissions Scenarios (SRES) A1B climate scenario. Precipitation over Greenland is predicted by this ensemble to increase from 35.8 cm yr-1 to 45.8 cm yr-1 by the end of the 21st century, a 27.8% increase. This is equivalent to an annual decline in sea level of 0.5 mm yr-1. The precipitation change is attributed to changes in atmospheric circulation and thermodynamics during the future time periods. Results indicate that the North Atlantic storm track is predicted to shift northward through the 21st century, resulting in less precipitation being produced dynamically over the southeast coast of Greenland, but increased precipitation over the remainder of the ice sheet. Thermodynamic changes, explained by a strong increase in temperature and specific humidity predicted by the 3-model ensemble, dominate the future precipitation changes, accounting for 82.5% of the total change. This combination of shifting the midlatitude cyclones that act as the forcing for Greenland precipitation, while increasing the available precipitable water in the atmosphere, produces more precipitation over Greenland under global warming conditions. These changes are predicted to most dramatically affect the northern and eastern Greenland regions during the first half of the 21st century, then the western, central, and southern regions during the second half of the 21st century.

Examination of Precipitation Variability in Southern Greenland

The surface mass balance of the Greenland ice sheet has decreased in recent decades with important implications for global sea-level rise. Here, a climate reanalysis model is used to examine observed circulation variability and changes in precipitation across southern Greenland to gain insight into the future climate in the region. The influence on precipitation from the North Atlantic Oscillation (NAO), Atlantic Multidecadal Oscillation (AMO), Icelandic Low, Azores High, regional blocking patterns, as well as near-surface temperature and winds are explored. Statistically significant correlations are higher between precipitation and the Icelandic Low and near-surface winds (0.5–0.7; p < 0.05) than correlations between precipitation and either the NAO or AMO climate indices (southwest Greenland: r = 0.12 and 0.28, respectively; and southeast Greenland: r = 0.25 and -0.07, respectively). Moreover, the recent enhanced warming in the Arctic (Arctic amplification) and the increase in the Greenland Blocking Index coincide with increased mean annual precipitation and interannual variability in southwest Greenland.

Using Student-Generated Blogs to Create a Global Perspective on Climate Change

ABSTRACT Each student in an introductory college course, Global Climate Change, spends the semester blogging about a countrys climate, contribution to global warming through carbon emissions, impacts of climate change, plans to adapt to their changing climate, and attempts to mitigate the problem. Students read and comment on each others blogs throughout the semester, instilling a global perspective through the use of student-generated content. While the first half of the course focuses on the science of climate change, these blogs supplement course content for the second half of the class and feed class discussions. Students were surveyed before and after the course. When comparing students entering the course to an American population, students were more open minded and more interested in learning about global warming. At the end of the course, students showed significant gains in their knowledge of global warming, but they also gained an increase in perception that people in developing countries would be harmed by global warming. This indicates significant gains in global perspective. Students enjoyed the blogging project, gained computer and science skills, such as with spreadsheet and graph-making software, and believe it helped to change their worldview and awareness of this global issue.