A review of the major global temperature metrics for April 2008: Still globally cooler than 1 year ago

21 05 2008

Here is a review of the major global temperature metrics in tabular and graph form. There is a bit of disagreement this month. GISS still comes out the warmest, as it did last month, and the month before, and there is a bit of divergence between the RSS and UAH satelitte derived datasets.

I’m a little late to this game as I’ve been busy catching up on personal business since my trip to NCDC Asheville and 20 station survey across North Carolina, but I thought it was worth a review.

RSS (Remote Sensing Systems of Santa Rosa, CA) RSS Microwave Sounder Unit (MSU) global temperature anomaly data by For April 2008 has moved a tiny bit higher, with a value of .080°C for a change (∆T) of 0.001°C globally from March.

RSS
2008 1 -0.070
2008 2 -0.002
2008 3 0.079
2008 4 0.080


click image for a ZOOMED 1998 -2008 DATA PORTION of the 1979-2008 image

RAW RSS data is available here

Note that there does not appear to be any sustained upwards trend post 1998.

Here is the entire RSS MSU dataset plotted:


click for a larger image
Reference: RSS data here (RSS Data Version 3.1)

University of Alabama, Huntsville (UAH) published their data set for April 2008, and it is in slight disagreement with the RSS data, dropping with greater magnitude than RSS.  The ∆T for April 2008 was -.079°C for an anomaly value of 0.015°C

UAH
2008    1  -0.046  
2008    2    0.020
2008    3    0.094
2008    4    0.015


Click for a larger image
Reference: UAH lower troposphere data

Both RSS and UAH datasets are just slightly about the zero anomaly line, which when compared to the last peak in global temperature in January 2007, is about 0.5°C cooler. That drop in the last year seems to be holding for now.

HadCRUT (Hadley Climate Research Unit Temperature, UK) surface, land-ocean

Last month HadCRUT took a positive jump to 0.430°C but went down again this month in agreement with drops noted in RSS and UAH global datasets. This month’s anomaly is 0.250°C for a change (∆T) of -0.18°C globally from March 2008.

2008/01  0.056 
2008/02  0.187 
2008/03  0.430
2008/04  0.250


Click for a larger image

Reference: HadCRUT3 anomaly data which can be found here
description of the HadCRUT3 data file columns is here

GISS (Goddard Institute for Space Studies, New York)
(surface, land-ocean, polar estimates)
Year      Jan   Feb   Mar   Apr  May  Jun  Jul   Aug  Sep  Oct  Nov  Dec
2007    .86   .63   .60   .64   .56   .53   .53   .57   .51   .55   .49   .40
2008    .12   .26   .67   .41
2008    .13   .26   .60   .41

I don’t bother plotting GISS global temperature anomaly data anymore for two reasons:

1) The format that the data is presented in requires me to do extra work to get it into an easily plotable form since it spans rows and columns, instead of being one long linear column of data for easy import.

2) I simply don’t trust the representivity of the GISS dataset. Since GISS uses polar “interpolated” data which does not exist in any of the other three datasets, I see GISS as an outlier and not truly representative of global temperature.  For example, GISS interpolates from the closest high latitude surface stations and adds that data for the very high latitude arctic where no weather stations exist. None of the other 3 data sets use interpolation to create data for the arctic where no measurements exist. Hence, I have a greater degree of trust for RSS, UAH, and HadCRUT global temperature anomaly data.

And there’s more, see a post called “The Accidental Tourist” about GISS data problems, from John Goetz (originally posted on Climate Audit) which I’ve reposted as the next item down.

Reference: GISS dataset temperature index data here

In summary, it appears that all four global datasets are maintaining the drop in temperature noted globally in the last year since the last peak in January 2007. With the exception of GISS, the other three datasets show an anomaly just slightly above the zero baseline for April 2008.

UPDATE: A couple of commenters point out that GISS has revised it’s March 2008 data down from .67 to .60 plus a .01 adjustment of GISS data in January 2008. The data I used was from my last post on GISS in March and the change has been made to reflect their revision. Paul Clark at the WoodForTrees.org website has written a program to automatically decode the GISS column and row presentation and and plot it, and I present his 4 metrics (smoothed 12 month mean with offset) comparison below:

Click for an interactive graph
Additionally, Barry Hearn, editor of JunkScience.com writes that he has an automated process written to decode the unwieldy GISS data table and convert it into a CSV file for use in Excel and other data plotting programs. I’ll make that available in the Resources page. The junkscience.com script processes the GISTEMP global data into a linear csv file here. Data format is year, month, [empty column] , anomaly.

UPDATE2: Thanks to Barry Hearn at http://www.junkscience.com and his processed CSV file I was able to easily plot the GISS Global Temperature anomaly without going through formatting conversions, the result is shown below:


Click for a larger image

I noted that unlike the other three metrics, GISS shows peaks in 2002 and 2007 that exceed the peak of 1998 in magnitude. How can GISS arrive at these values with combined land+ocean when HadCRUT does not? Curious.


Comments : 45 Comments »

Categories : Science, climate_change

The Accidental Tourist (aka The GISS World Tour)

21 05 2008

A guest post by: John Goetz, originally posted on Climate Audit.

Occasionally I will take a trip after much careful planning and preparation, only to find myself going off into uncharted territory soon after embarking on my adventure. That is what happened to me recently when I started to take a fresh look at worldwide station coverage. Where I ended up and what I found when I got there was incredibly surprising.

It all began last week when GISS released their global mean summary for April, 2008. Following this release I went to view their global maps to get an idea as to where the “hot” and “cold” spots were last month. I viewed the data using both a 1200km and a 250km smoothing radius. Doing so helped me gauge the station coverage and the extent the 1200km smoothing algorithm estimates temperatures over the vast unsampled swaths of the planet.

It occurred to me that it would be interesting to compare April 2008 with April 1978 using a 250km smoothing radius. I was looking for “holes” in 2008 station coverage not present in 1978. I selected 1978 for two reasons. One was that the worldwide station coverage was near its peak that year. The second reason was that 1978 fell in the 1951-1980 30-year base period for calculating anomalies.

My thought was to identify multiple stations within a hole that were still reporting data today but were not being captured by GHCN. I wanted to see if the data from those stations supported the anomaly estimated by the 1200km smoothing. The 250km smoothed plots would be ideal for visually identifying holes. Here are the plots for April 1978 and April 2008:

April 1978 anomalies
Click for a larger image

April 2008 anomaly
Click for a larger image

There were lots of holes to choose from: Russia, China, Australia, Canada, Africa, and South America. I decided to start with Russia as I already knew where to look for recent temperature data from “discontinued” GHCN sites: meteo.ru. But first, I had to locate some stations to examine. Read the rest of this entry »


Comments : 5 Comments »

Categories : Uncategorized

Sunspot cycle more dud than radiation flood

21 05 2008

Interesting article at the Arizona Daily Star (Tucson, home to Kitt Peak and other observatories). (h/t to Ric Werme)


Picture for illustration only – not from article

Sunspot cycle more dud than radiation flood
By Dan Sorenson
arizona daily star
Tucson, Arizona | Published: 05.19.2008

Many solar scientists expected the new sunspot cycle to be a whopper, a prolonged solar tantrum that could fry satellites and raise hell with earthly communications, the power grid and modern electronics.

But there’s scant proof Sunspot Cycle 24 is even here, let alone the debut of big trouble.

So far there have been just a couple minor zits on the face of the sun to suggest the old cycle is over and the new one is coming.

The roughly 11-year cycle of sunspot activity should have bottomed out last year, the end of Cycle 23 and the beginning of Cycle 24. That would have put the peak in new sunspot activity around 2012.

But a dud sunspot cycle would not necessarily make it a boring period, especially for two solar scientists with the Tucson-based National Solar Observatory.

Two years ago, William Livingston and Matt Penn wrote a paper for the journal Science predicting that this could not only be a dud sunspot cycle, but the start of another extended down period in solar activity. It was based on their analysis of weakening sunspot intensity and said sunspots might vanish by 2015.

The paper, rejected in peer review, was never published by Science. Livingston said he’s OK with the rejection.

“I accept what the reviewers said,” Livingston said. “‘If you are going to make such statement, you had better have strong evidence.’ ”

Livingston said their projections were based on observations of a trend in decreasingly powerful sunspots but reviewers felt it was merely a statistical argument.

Read the entire article here at this link


Comments : 75 Comments »

Categories : Uncategorized