February 2012 Archives

In class today, we discussed the regions that students will use as a focus for their climate history projects. If anyone wants to make a different choice, you should probably switch sooner than later.

Peter Greenland/Iceland
Eric: Southern England
Max: Southern Cascades (CA/OR)
Ben: Colorado Front Range
Phil: Wisconsin/Upper Great Lakes
Will: Yucatan Peninsula

To prepare for your presentations on modern climatology (due March 21), everyone should submit a list of 10 scholarly sources (either journal articles or data archives) in class on March 7.

Exercise One Reanalysis assignment

Due March 7

Just as a reminder, as part of Wednesday's class, we'll discuss the study regions for your climate and paleoclimate exercises later in the term. So, if you haven't settled on your region of interest, give it some thought before we meet.

I don't have any firm rules about the geographic scope of your projects, but as a general rule of thumb, it'd be best to focus on a region with a homogeneous climate. So, something like 'southwestern Australia', 'northern Minnesota', or 'the Amazon basin' would be OK but 'South America' or 'Duluth' would be either too broad or too specific.

Next week we'll introduce one of the main tools used by climatologists and paleoclimatologists to understand how the climate system has behaved over the last six decades: the NCEP/NCAR Reanalysis. The Reanalysis is a online tool that allows users to map or analyze climate data collected since the late 1940s across the entire globe. This data is not just the observations though; each measurement is 'assimilated' by a state-of-the-art climate model, which ensures that the observations are correct and consistent with our understanding of how the Earth's climate operates.

I'll give a brief introduction to the Reanalysis in class, but we'll spend most of our time getting to know how the tool works. We'll help each other get familiar with making maps and conducting basic analysis, and then I'll ask you to work through a short exercise to be completed by our following class. Please bring your own laptop to class next week.

To get ready, please read through this article by Kalnay et al., which lays out the need for the reanalysis and explains (in great detail) how it was produced. I realize this paper is very long and pretty technical but skimming through it should help you get ready for our hands-on exercise next week.

Kalnay et al., 1996, The NCEP/NCAR 40-Year Reanalysis Project.pdf

If you'd like to poke around with the Reanalysis in advance, here it is:
http://www.esrl.noaa.gov/psd/data/reanalysis/reanalysis.shtml

Next week we'll read three papers focused on global temperature. We'll start with an older article by Phil Jones and Keith Briffa from 1992 that describes how long instrumental records are put together and outlines some of the challenges involved with the observational temperature record. We'll then read two papers that use tree-ring records and other proxies to estimate how global or hemispheric temperatures have varied during the last several centuries (including the famous 'hockey-stick' paper).

As a reminder, all of us will be responsible for reading all three papers and bringing a list of related questions (either about the main ideas of the paper, technical questions or terminology).

Peter and Will, as discussion leaders, I'll ask you to start us off with a brief summary of the main aspects of each paper (What was the goal of the research, what data and tools did it use, what were the main results and conclusions). If you find a key diagram that you would like to project on the screen, bring that in as a PDF or presentation file (but please don't prepare a formal presentation).

Jones and Briffa, 1992, Global surface air temperature variations during the twentieth century: Part 1, spatial, temporal and seasonal details

Mann et al., 1998, Global-scale temperature patterns and climate forcing over the past six centuries

Osborn and Briffa, 2006, The Spatial Extent of 20th-Century Warmth in the Context of the Past 1200 Years

I hope everyone enjoyed our visit to the Limnological Research Center and the Center for Dendrochronology yesterday. I think it's important to understand the much of Holocene paleoclimatology depends on information recorded by complex biological and geological systems, and I hope seeing things first-hand gave you a better sense for the challenges involved with pulling information out of wood or mud.

Next week, we'll have the last of our 'orientation' discussions (afterwards, we'll start talking about specific questions/systems). We'll start class by discussing how tree-ring records are used as proxies (surrogates) for past climate change, so please re-read 'Dendroclimatology' by Brian Luckman.

In the second half of class, we'll talk about how paleoclimatologists use statistics to describe their data and to make inferences about the past behavior of the climate system. To prepare for that discussion, please read 'Timescales of changeby Pat Bartlein.

Because we'll only spend one class on statistical methods, we'll focus on understanding the terms used commonly in climate science and try to develop a 'survival guide' that will help us interpret some of these tools.