Author Archives: goirish

Adjusting Pristine Data

On September 15, 2008, Anthony DePalma of the New York Times wrote an article about the Mohonk Lakes USHCN weather station titled Weather History Offers Insight Into Global Warming. This article claimed, in part, that the average annual temperature has risen 2.7 degrees in 112 years at this station. What struck me about the article […]

Sea Ice Stretch Run #3

Continuation of Sea Ice Stretch Run #2.

December 1986 – Irony

In my post December 1986, I presented a histogram showing the GISS estimate of December 1986 minus the actual for GHCN stations in Europe and Russia. As noted, GISS under-estimated December 1986 for this region by a greater than 2 to 1 margin. The result was, when GISS combined multiple records for a single station, […]

December 1986

After I posted GISS Spackle and Caulk, a number of commenters marveled at the symmetry of the histogram (GISS temperature estimate minus actual temperature). Some were dismayed that there was not a clear warming bias in the plot. Others were giddy for the very same reason. A few noted (as I hoped) that the differences […]

GISS Spackle and Caulk

Earlier this year I did a post on the amount of estimation done to the GHCN temperature record by GISS before generating zonal and global averages. A graphic I posted compared the amount of real temperature data with the amount of estimation over time. To read the graphic, consider 2000 as an example. As of […]

Another quiet GISS update

Yesterday I surfed to the Datasets and Images page on GISS, something I ordinarily do only around the fifth of each month as I wait for the latest monthly temperature updates from GISS. The information on that page rarely changes, so I was surprised to see the following addition: June 9, 2008: Effective June 9, […]

Cedarville Sausage

In May I began a quest to better understand how GISS does its homogeneity adjustment, also known as GISS Step 2. Steve McIntyre took the ball from that scrum and ran with it, producing a set of R tools that nearly replicate the GISS method. Some of the endpoint cases continue to confound those of […]

Homogeneity Adjustment – Part II

Yesterday I described the work done to the surface station records in Hansen Step 2 in preparation for adjusting urban stations to match the trend of nearby rural stations. The basic substeps are Deciding which stations are rural and which are urban. The methodology used for most of North America differs from that applied to […]

Homogeneity Adjustment – Part I

My curiosity in the mathematics behind the homogeneity adjustment caused me to finally take a close look at Hansen Step 2. This turned out to be an incredibly torturous task. A quote from a Stephen King short story, The Jaunt, came to mind as I plowed through lines of code: “It’s eternity in there…“. However, […]

GISS Estimation Case Study

In my post The Accidental Tourist I discussed the relationship between the Russian Meteo daily temperature record for Kurgan and two of the GHCN records for that same weather station. One surprise I learned was that GHCN discarded an entire month’s worth of data when a single data point was suspect. Doing so left GISS […]