Guest Post By Walter Dnes
In continuation of my Temperature Anomaly projections, the following are my February projections, as well as last month’s projections for January, to see how well they fared.
|HadCRUT4 2017/02||+0.817 (incomplete data)|
The Data Sources
The latest data can be obtained from the following sources
- HadCRUT4 http://www.metoffice.gov.uk/hadobs/hadcrut4/data/current/time_series/HadCRUT.184.108.40.206.monthly_ns_avg.txt
- GISS https://data.giss.nasa.gov/gistemp/tabledata_v3/GLB.Ts+dSST.txt The GISS site has switched from “http” to “https” (i.e. secure http) and may require upgrading “wget” if you use it to retrieve the data.
- UAH http://vortex.nsstc.uah.edu/data/msu/v6.0/tlt/tltglhmam_6.0.txt
- RSS http://data.remss.com/msu/monthly_time_series/RSS_Monthly_MSU_AMSU_Channel_TLT_Anomalies_Land_and_Ocean_v03_3.txt Note: this URL is a recent change
- NCEI https://www.ncdc.noaa.gov/cag/time-series/global/globe/land_ocean/p12/12/1880-2016.csv
A review of the past year of data indicates that a slightly better correlation between NCEP/NCAR and 4 of the 5 data sets can be achieved by sliding the monthly window back one day; e.g. for February’s projection, use January 31st through February 27th NCEP/NCAR data. This is probably due to the fact that NCEP/NCAR uses an arbitrary 0000 UTC day boundary, while in real life, daily temperatures follow local standard time around the globe. Another advantage of sliding back one day is that NCEP/NCAR data runs 2 days behind. This means that February 26th data is used as a guesstimate for only the 27th, rather than the 27th and 28th. Effective this month, my projections will switch to a window trailing one day behind the calendar month. E.g. for February, I’ll be using January 31st through February 26th data, and assuming that February 27th’s anomaly is equal to February 26th’s anomaly.
At the time of posting 4 of the 5 monthly data sets were available through January 2017. HadCRUT4 is available through December 2016. The NCEP/NCAR re-analysis data runs 2 days behind real-time. Therefore, real daily data through February 26th is used, and the 27th is assumed to have the same anomaly as the 26th.
The projections are derived from the previous 12 months of NCEP/NCAR anomalies compared to the same months’ anomalies for each of the 5 data sets. For each of the 5 data sets, the slope() value (“m”) and the intercept() value (“b”) are calculated. Using the current month’s NCEP/NCAR anomaly as “x”, the numbers are plugged into the high-school linear equation “y = mx + b”, and “y” is the answer for the specific data set. The entire globe’s data is used for HadCRUT, GISS, and NCEI. For RSS and UAH, subsets of global data are used, to match the latitude coverage provided by the satellites.
February’s NCEP/NCAR anomaly has risen to the highest level since April 2016. The relatively warm January has made any potential long pause more difficult to achieve. Even the “short pause” isn’t that great. My post for January had the “pause” in the daily NCEP/NCAR data going back to July 7th 2015 https://wattsupwiththat.files.wordpress.com/2017/01/daily.png but this month it has retreated to July 11th 2015.
The graph immediately below is a plot of recent NCEP/NCAR daily anomalies, versus 1994-2013 base, similar to Nick Stokes’ web page. The second graph is a monthly version, going back to 1997. The trendlines are as follows…
- Black – The longest line with a negative slope in the daily graph goes back to early July, 2015, as noted in the graph legend. On the monthly graph, it’s August 2015. This is near the start of the El Nino, and nothing to write home about. Reaching back to 2005 or earlier would be a good start.
- Green – This is the trendline from a local minimum in the slope around late 2004, early 2005. To even BEGIN to work on a “pause back to 2005”, the anomaly has to drop below the green line.
- Pink – This is the trendline from a local minimum in the slope from mid-2001. Again, the anomaly needs to drop below this line to start working back to a pause to that date.
- Red – The trendline back to a local minimum in the slope from late 1997. Again, the anomaly needs to drop below this line to start working back to a pause to that date.
NCEP/NCAR Monthly Anomalies: