Temperature Adjustments In Alabama

By Paul Homewood

 

http://www.ncdc.noaa.gov/cag/

 

 

I briefly mentioned the new nClimDiv Dataset, introduced by NOAA this month. Let’s take a closer look at how it affects Alabama.

A comparison of the annual mean temperature for 1934 & 2012, under the new NCDC system shows:

 

1934	2012	Diff
63.4F	64.9F	1.5F

http://www.ncdc.noaa.gov/cag/

 

So they claim that 2012 was 1.5F warmer, but is this supported by the individual temperature records?

 

There are only 13 stations that have records for both 1934 and 2012, and they are listed in the Appendix. They are distributed across eight Climate Divisions.

Using the State Climatological reports for 1934 and 2012, we can compare annual mean temperatures for the two years. These are then averaged within each division, and these divisional averages are weighted by area to give a Statewide figure.

 

To summarise the results:

 

	1934	2012	Diff
NCDC	63.4	64.9	1.5
Station averages	64.9	65.1	0.2
Difference			1.3

 

Somehow, the new NCDC system finds an extra 1.3F of warming, that does not exist on the individual station analysis.

It is worth pointing out that only one site, Gadsden, records a difference of 1.5F or more. According to Wiki, Gadsden has a population of 37000, and the station metadata shows the weather station slap bang in the middle of a water works. It may be that Gadsden is therefore not a reliable site, and it certainly is an outlier.

It is true that temperatures since the 1930’s have been adjusted for TOBS (Time of Observation Bias), but according to NOAA, this should only account for about 0.3F, which still leaves a gap of 1.0F to explain.

 

 

The usual excuse thrown for these differences is the all encompassing “homogenisation”. But the above stations are all discrete records, and have no need to be homogenised. And as can be seen from the Appendix, which shows populations, many of the sites have quite sizeable populations, so some allowance should be made for UHI.

 

It is clear that the new NCDC system is not reflecting the reality on the ground, and is artificially adding a significant amount to the warming trend since the 1930’s.

 

 

APPENDIX A

Alabama Annual Mean Temperatures

DIV		POP	1934	2012	DIFF
		X 1000
1	DECATUR	84	63.8	63.4	-0.4
2	SCOTTSBORO	14	61.7	62.3	0.6
	ST BERNARD	R	60.8	61.7	0.9
	DIV 2		61.3	62.0	0.8
3	CENTREVILLE	R	64.4	63	-1.4
	CLANTON	R	64.4	63.9	-0.5
	DIV 3		64.4	63.5	-1.0
4	GADSDEN	37	62.6	65.6	3.0
5	AUBURN	57	65.5	64.8	-0.7
6	SELMA	24	66.4	66.4	0.0
	UNION SPRINGS	R	66	64.3	-1.7
	DIV 6		66.2	65.4	-0.9
7	BREWTON	R	66.6	68	1.4
	GREENVILLE	R	66.7	64.4	-2.3
	THOMASVILLE	R	64.5	66.8	2.3
	DIV 7		65.9	66.4	0.5
8	MOBILE	443	67.7	69	1.3
		R = <10,000

 

 

APPENDIX B

Temperatures Weighted By Division

			WEIGHTED TEMPERATURE
DIV	1934	2012	1934	2012
1	63.8	63.4	5.7	5.7
2	61.3	62	6.0	6.0
3	64.4	63.5	9.5	9.4
4	62.6	65.6	4.9	5.1
5	65.5	64.8	6.4	6.3
6	66.2	65.4	9.9	9.8
7	65.9	66.4	18.8	18.9
8	67.7	69	3.8	3.9
STATE			64.9	65.1

 

 

APPENDIX C

Divisional Areas

AREA SQ MILES		WEIGHTED
1	4609	0.0893043984
2	5027	0.097403604
3	7648	0.1481883356
4	4000	0.0775043596
5	5006	0.0969967061
6	7716	0.1495059097
7	14719	0.2851966673
8	2885	0.0559000194
TOTAL AREA	51610