10 March 2017

RSS temp anomaly for Australia corrected for longitude


I've discovered a mistake in my first attempt at unlocking the RSS temperature file for lower tropospheric temps: my longitude was off by 180 degrees.

Some time around that first attempt I took the time to verify the latitude (described here) but not the longitude. I discovered my mistake when I decided to verify the longitude for an upcoming post. Here is how the latitude and longitude numbers in the 144 x 72 x 458 array should look on a world map:


I was going from the prime meridian instead of the anti-meridian. Whereas I thought I was measuring temp in a rectangle over Australia as shown here:


With temp graph output:



I was in fact measuring southern Brazil, Uruguay and a bit of the Atlantic (blue rectangle):


The correct Australia temp anomaly for the rectangle outlined above should be:

Key lines of Matlab code:
a1 = ncread('uat4_tb_v03r03_anom_chtlt_197812_201602.nc3.nc','brightness_temperature_anomaly')
AusNew = squeeze(tsnansum(a1(118:131,:,:)))
AusNew2 = squeeze(tsnansum(AusNew(23:30,:)))
Aus3=AusNew2'
Aus4 = Aus3/(8*14)
plot(Aus4)


Here is the Steven Goddard graph for comparison. Note the time scale is slightly shorter at both ends of the x-axis:


It's a much better match. Although I got the longitude wrong initially, turns out the latitude was more important than the longitude and there wasn't that much difference due to my mistake. As the above graph shows, Australia has not warmed during the satellite period!

The way I verified the longitude was to take two lines of longitude separated by 180 degrees, one over the North Atlantic (30 W) where there is a smaller seasonal temperature difference than the other line over Siberia (150E).


The graphs of the North Atlantic show a much smaller seasonal difference except for the most northern two lines of latitude I measured over Greenland.


Over Siberia the seasonal temp differences are larger in the north and only gets to a narrower range over the Pacific around latitude 20N.



Also handy for interpreting the above graphs is map of earth average temperature by position here:



Hence I feel confident I've got the data sussed now in preparation for an upcoming post. I've also improved the conversion table I made to convert real latitude and longitude to that required for the .nc file matrix (whole excel sheet here).

Matlab number Longitude° W/E Latitude° S/N
1 178.75 88.75
2 176.25 86.25
3 173.75 83.75
4 171.25 81.25
5 168.75 78.75
6 166.25 76.25
7 163.75 73.75
8 161.25 71.25
9 158.75 68.75
10 156.25 66.25
11 153.75 63.75
12 151.25 61.25
13 148.75 58.75
14 146.25 56.25
15 143.75 53.75
16 141.25 51.25
17 138.75 48.75
18 136.25 46.25
19 133.75 43.75
20 131.25 41.25
21 128.75 38.75
22 126.25 36.25
23 123.75 33.75
24 121.25 31.25
25 118.75 28.75
26 116.25 26.25
27 113.75 23.75
28 111.25 21.25
29 108.75 18.75
30 106.25 16.25
31 103.75 13.75
32 101.25 11.25
33 98.75 8.75
34 96.25 6.25
35 93.75 3.75
36 91.25 1.25
37 88.75 1.25
38 86.25 3.75
39 83.75 6.25
40 81.25 8.75
41 78.75 11.25
42 76.25 13.75
43 73.75 16.25
44 71.25 18.75
45 68.75 21.25
46 66.25 23.75
47 63.75 26.25
48 61.25 28.75
49 58.75 31.25
50 56.25 33.75
51 53.75 36.25
52 51.25 38.75
53 48.75 41.25
54 46.25 43.75
55 43.75 46.25
56 41.25 48.75
57 38.75 51.25
58 36.25 53.75
59 33.75 56.25
60 31.25 58.75
61 28.75 61.25
62 26.25 63.75
63 23.75 66.25
64 21.25 68.75
65 18.75 71.25
66 16.25 73.75
67 13.75 76.25
68 11.25 78.75
69 8.75 81.25
70 6.25 83.75
71 3.75 86.25
72 1.25 88.75
73 1.25
74 3.75
75 6.25
76 8.75
77 11.25
78 13.75
79 16.25
80 18.75
81 21.25
82 23.75
83 26.25
84 28.75
85 31.25
86 33.75
87 36.25
88 38.75
89 41.25
90 43.75
91 46.25
92 48.75
93 51.25
94 53.75
95 56.25
96 58.75
97 61.25
98 63.75
99 66.25
100 68.75
101 71.25
102 73.75
103 76.25
104 78.75
105 81.25
106 83.75
107 86.25
108 88.75
109 91.25
110 93.75
111 96.25
112 98.75
113 101.25
114 103.75
115 106.25
116 108.75
117 111.25
118 113.75
119 116.25
120 118.75
121 121.25
122 123.75
123 126.25
124 128.75
125 131.25
126 133.75
127 136.25
128 138.75
129 141.25
130 143.75
131 146.25
132 148.75
133 151.25
134 153.75
135 156.25
136 158.75
137 161.25
138 163.75
139 166.25
140 168.75
141 171.25
142 173.75
143 176.25
144 178.75

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