Reconstructing storm track variability in the Pacific Northwest

The area in the rain shadow of the Cascade Mountains in Washington state has different ENSO teleconnections than the rest of the Pacific Northwest.  One reason for this appears to be differences in storm trajectories.  Using the isotopic composition of tree rings and partnering with local volunteers, we are attempting to reconstruct storm track variability to better understand the mechanisms of past drought and the potential for future drought.

Instability in PDO teleconnections

The Pacific Decadal Oscillation or PDO is an index of Pacific Ocean surface temperature variability used in seasonal forecasting and in understanding links between climate and ecosystem processes.  It's influence on climate, however, does not appear to be stable over time. Find the paper in Journal of Climate.  Highlights were also covered in a NWS Climate Services webinar

Snow projections for Alaska

Future snowfall can be challenging to project for a host of reasons, yet in many places, information on future snow scenarios is critical for planning.  Using a combination of station data and downscaled temperature projections, this project produced decadal average snow-day fractions for Alaska.  See more and get the data from SNAP. The paper is available from Hydrological Processes. Supplementary Info. An ACCAP webinar on the topic is also available.  For a shorter take, try local press coverage from Anchorage Daily News, Alaska Dispatch News, and Alaska Public Media

Understanding controls on potential evaporation (PET) and avoiding "doing the wrong thing more precisely"

We often develop high resolution PET data and projections using temperature and precipitation data because they are widely available and of good quality.  But simple projections can be misleading, especially at high latitudes where changes in cloud cover can offset temperature increases.  Understanding the limitations can help us avoid "doing the wrong thing more precisely" as Roger Pulwarty would say. The paper and supplementary information are available from Climatic Change

Tracking precipitation trends in Alaska

Published studies of precipitation trends in Alaska disagree.  This can be problematic for subsequent research using those papers, as different research groups can start with conflicting ideas about the direction of change in precipitation. Papers describing the study are in Journal of Geophysical Research - Part 1Journal of Geophysical Research - Part 2. There is also an ACCAP webinar for a user-friendly take.

Potential for bias propagation in Earth System Models

It is well known that general circulation models have biases in mean temperature and precipitation.  A simple analysis using the Koppen-Geiger classification demonstrates that this provides the potential for inappropriate feedbacks in models where vegetation is coupled to climate. Find the paper in Geophysical Research Letters.


The Pacific Storm track and western US precipitation change

Most winter precipitation in the western US is delivered by storms developing in and traveling along Pacific storm tracks.  The location of the storm track as tracked by the Northern Annular Mode index has a critical influence on spring precipitation in the Southwest, and biases in storm track location in CMIP3 models appear to influence projections. The paper on the NAM-Geophysical Research Letters, was covered in Nature Research Highlights, and the Arizona Daily Star with a focus on fire in the SW. CMIP3 results were published in Climate Dynamics