Here are the Plots of the band-averaged Spectral Response Functions for all channels for the Imager and Sounder (using the "new" SRF data released in 1999 - see next entry below). These were made for completeness and to be displayed from the new CIMSS/ASPT Calibration Homepage.

On June 23, 1999 ITT released new spectral response functions for the GOES-10 sounder. The GOES-8 and GOES-10 band 13 spectral responses show that GOES-8 and GOES-10 are still dissimilar and that the new GOES-10 response function is very similar to the original. The updated GOES-10 is now more similar to the GOES-8 band 15 spectral response than it was originally, but it is not as close as it was after the April 2, 1998 version of GOES-10 response functions were released.

Note: GOES-10n refers to the spectral response functions released on April 2, 1998. GOES-10699 refers to the spectral response functions released on June 23, 1999.

These plots shows the mean differences of GOES-10 imager channels 1-5 and the corresponding GOES-10 sounder channels (imager - sounder). The differences are plotted for each hour during a 24-hour period starting around 1600 UTC, March 28, 1998, over the land and ocean . The area and time were selected such that the imager and sounder view the area within approximately one minute.

For visible channel, the earth appears more reflective to imager than to sounder. The difference has little day to day variation over ocean. The peak difference over land, which normally occurs around local noon, may vary from 2% (March 28) to 6% (not shown but is hinted in March 29 data from 12-15 UTC). March 29 is more cloudy (thus higher average albedo) over the land region than March 28. The difference is about 10-15% of the average albedo over land and 20-30% over ocean.

There is no sounder channel that correspond well to imager Channel 2 (near IR, 3.9 micron). Instead, average of sounder channels 17 (4.0 micron) and 18 (3.8 micron) is compared with imager channel 2. The difference is small at night and becomes larger during day, due to differential response of each channel to solar reflection. Similarly, average of sounder channels 11 (7.0 micron) and 12 (6.5 micron) is compared with imager channel 3 (6.7 micron, the water vapor channel).

Finally, the window channels (Ch. 4 of imager vs Ch. 8 of sounder and Ch. 5 of imager vs Ch. 7 of sounder) compare well with each other. The difference is normally within +/- 0.5 degree.

The GOES-8 and GOES-10 brightness temperatures were again compared after the updated spectral response coefficients for the GOES-10 sounder were put in (7 UTC on April 2, 1998). While most of the bands compare very well, some of the differences for shortwave bands (13-15) still seem too large.

The GOES-8/9 and GOES-10 band 13 spectral responses show that GOES-8 and GOES-9 are more similar than either of the GOES-10's. Yet, the updated GOES-10 is now 'in family' for band 15 compared to the other satellites.

Shown are examples of co-located (meractor re-map) GOES Sounder DPI for both GOES-8 and GOES-10 over the south central US.

The return flow of moisture during the day on 2 Apr 1998 (98092) from GA across to E TX and northward to E KS is evident, as the total precipitable water (PW) Derived Product Images (DPI) between 12z and 00z show [G2P80921.GIF, G2P80922.GIF]. Similar comparisons with raob values overplotted [R2P80921.GIF, R2P80922.GIF] also show that the GOES-8 and GOES-10 products are substantially the same in their overlap region. Anticipated de-stabilization across the south central US was rather small as of 00z, as noted by the GOES Sounder lifted index (LI) DPI at that time [G2L80922.GIF, R2L80922.GIF]. The two satellites again appear much more similar than dissimilar. (Convection that first started just after 00z was near the LA/AR line, close to the only region showing LI values in the GOES DPI in the 0 to -4C range, despite extensive obscuring clouds. More convection developed later about 03z along the OK/AR line.)

GOES-10 Cloud top pressures from March 27, 1998 near 13 UTC are compared to GOES-8 are in good agreement. Scatter plots of co-located observations cloud top pressure for one time period is within 1 hPa on the average. Scatter plots of co-located observations effective cloud amount for one time period is within 2% on the average. A further explanation of the scatter diagrams is found in the table.

Special GOES-10 sounder sectors which include space views allow for the noise values to be determined by looking at the scatter of the uniform space. Preliminary indications from March 25 at 18:02 UTC show the GOES-10 noise seems to be the first sounder to to be within spec for all the channels (table).

Channel 12 at 10:02 UTC on March 20 (and 25), 1998 shows a "banding" which correlates to the space looks. This barely noticeable (in only the most sensitive channels) effect is due to the rapidly changing calibration bias between the space looks. It can be seen that the slope of the bias changes sign near 11 UTC by looking at the channel 12 at 10:02 and 12:02 UTC.

Derived products from the GOES-10 sounder are being generated. Channels 13, 14 and 15 were not used for this example.

The GOES visible (band=19) sounder spectral response functions are shown for all three satellites. The same plot for the GOES-/8/9/10 imager spectral response functions for channel 1 (visible).

Channels 13 and 15 of the GOES-10 sounder are too cold (by over 6 degrees), compared to GOES-8 sounder data. This has the effect of making the GOES-10 retrievals too dry (dots). Updating the GOES-10 radiance bias adjustment file helps to midigate this problem (crosses). Now the differences look more like the GOES-8 retrievals and the radiosondes (not shown).

The calculated brightness temperatures for the 18 sounder channels before and after the update for the correct filter temperatures with the GOES-10 sounder spectral response functions (RTTOVS forward model):

Un-corrected for the shift due to filter temperatures
WFGIM 1 18 SAT=10    
  223.57  223.03  239.18  254.51  265.67  282.68  285.59  286.44  260.57   
  257.65  245.87  231.21  271.91  259.42  236.74  280.77  285.95  286.36  

Corrected for the shift due to filter temperatures
WFGIM 1 18 SAT=10                               
  223.68  222.84  239.11  254.63  265.13  282.66  285.57  286.44  260.67
  257.64  245.80  231.23  273.27  259.61  238.94  280.49  285.92  286.37

Un-corrected for the shift due to filter temperatures
CH  WAVENO(CM-1) WAVELEN(MICRON)                
 1 679.8178711 14.70982265                   
 2 696.1438599 14.36484718                  
 3 712.8988037 14.02723598                 
 4 732.2866211 13.65585518                
 5 747.8747559 13.37122250               
 6 790.6661987 12.64756203              
 7 830.8142090 12.03638554             
 8 909.5220947 10.99478531            
 9 1029.512085 9.713338852           
 10 1340.128662 7.461970329         
 11 1423.657837 7.024159908        
 12 1535.478027 6.512629986       
 13 2189.547852 4.567152977      
 14 2215.627197 4.513394833     
 15 2252.250000 4.440004349    
 16 2420.379395 4.131583691   
 17 2512.697510 3.979786634  
 18 2665.164551 3.752113581 

Corrected for the shift due to filter temperatures
CH  WAVENO(CM-1) WAVELEN(MICRON)                
 1 679.1133423 14.72508240                                 
 2 695.3190918 14.38188648                                
 3 712.7325439 14.03050804                               
 4 731.4750366 13.67100620                              
 5 747.4318848 13.37914562                             
 6 789.8816528 12.66012478                            
 7 830.2354736 12.04477596                           
 8 908.8108521 11.00338936                          
 9 1028.894897 9.719165802                         
 10 1340.770874 7.458395958                       
 11 1424.113525 7.021912098                      
 12 1535.095459 6.514252663                     
 13 2187.515381 4.571396351                    
 14 2211.469238 4.521880627                   
 15 2248.089355 4.448221684                  
 16 2418.688965 4.134471416                 
 17 2511.202881 3.982155323                
 18 2662.761230 3.755500078               
        

Earlier field experiments with GOES-8 sounder showed an un-explained difference for channels 13 and 15 when comparing to the HIS. Preliminary indications show the updated calculated brightness temperatures reduce those differences. Note the 'C's marked on the difference plot between the GOES measurements and the averaged HIS.

LA 7840 7860
  area  ss  yyddd hhmmss  lcor  ecor lr er zr  lsiz  esiz z    bands
  ---- ---- ----- ------ ----- ----- -- -- -- ----- ----- -    -----
  7848  75  98028 172000  5081 10841 10 10 19   156   300 2 123456789ABCDEFG
  7849  71  98028 172000  5401  6341 10 10 19   160   292 2 123456789ABCDEFG
LA: Done

GOES-10....
AREASTATY 7848 7848 20   75   200 1 18  LAT,15 25 LON,70 80
     Min/Max Lat./Long. =      15.00     25.00,     70.00     80.00
 area yyddd hhmmss averageTBB   StndDev.     N    CH  SS
 7848 98028 172000 215.640869   1.719851    7805   1  75
 7848 98028 172000 217.140228   1.180145    7805   2  75
 7848 98028 172000 239.865936   1.789296    7805   3  75
 7848 98028 172000 255.997070   2.252367    7805   4  75
 7848 98028 172000 268.613556   3.509661    7805   5  75
 7848 98028 172000 285.314087   4.918376    7805   6  75
 7848 98028 172000 288.442963   5.672656    7805   7  75
 7848 98028 172000 290.108459   5.775917    7805   8  75
 7848 98028 172000 267.637543   4.296698    7805   9  75
 7848 98028 172000 267.635925   3.606896    7805  10  75
 7848 98028 172000 262.780823   3.905803    7805  11  75
 7848 98028 172000 242.073593   3.246333    7805  12  75
 7848 98028 172000 272.234711   3.759977    7805  13  75
 7848 98028 172000 260.843567   2.548309    7805  14  75
 7848 98028 172000 234.507812   1.609572    7805  15  75
 7848 98028 172000 286.995544   4.115541    7805  16  75
 7848 98028 172000 297.135651   4.605953    7805  17  75
 7848 98028 172000 301.907898   4.805789    7805  18  75

 -- AREASTAT Done --
STOP  

GOES-8....
AREASTATY 7849 7849 20   75   200 1 18  LAT,15 25 LON,70 80
     Min/Max Lat./Long. =      15.00     25.00,     70.00     80.00
 area yyddd hhmmss averageTBB   StndDev.     N    CH  SS
 7849 98028 172000 213.595993   1.346970   10288   1  71
 7849 98028 172000 216.229050   1.036191   10288   2  71
 7849 98028 172000 240.803711   1.446372   10288   3  71
 7849 98028 172000 259.261169   2.213167   10288   4  71
 7849 98028 172000 269.354767   2.878719   10288   5  71
 7849 98028 172000 286.827148   4.937650   10288   6  71
 7849 98028 172000 289.975159   5.646367   10288   7  71
 7849 98028 172000 291.411682   5.971783   10288   8  71
 7849 98028 172000 271.901123   4.551138   10288   9  71
 7849 98028 172000 269.397491   3.381033   10288  10  71
 7849 98028 172000 264.993500   4.015846   10288  11  71
 7849 98028 172000 245.290222   2.863240   10288  12  71
 7849 98028 172000 281.580963   4.380967   10288  13  71
 7849 98028 172000 268.324371   2.998654   10288  14  71
 7849 98028 172000 244.256439   1.953310   10288  15  71
 7849 98028 172000 289.403198   4.248234   10288  16  71
 7849 98028 172000 298.493896   4.426011   10288  17  71
 7849 98028 172000 303.628387   5.490553   10288  18  71

 -- AREASTAT Done --

Average Differences.... (G8-G10)
     AVG Diff=    -2.0449        1
     AVG Diff=     -.9112        2
     AVG Diff=      .9378        3
     AVG Diff=     3.2641        4
     AVG Diff=      .7412        5
     AVG Diff=     1.5131        6
     AVG Diff=     1.5322        7
     AVG Diff=     1.3032        8
     AVG Diff=     4.2636        9
     AVG Diff=     1.7616       10
     AVG Diff=     2.2127       11
     AVG Diff=     3.2166       12
     AVG Diff=     9.3463       13
     AVG Diff=     7.4808       14
     AVG Diff=     9.7486       15
     AVG Diff=     2.4077       16
     AVG Diff=     1.3583       17
     AVG Diff=     1.7205       18

At one spot (20N, 75W):
GOES-10...
GIMD IAR,7848 AUTO,1  
time, dwell, step, dect, sat:   173048     1     0     2    10 
   NRDG   DRDG    MODE   MAXE  MINE   PRIM   SECN   PCWT    PCU
      0      0      3     13      0      7      1     50      0
   LINE   ELEM    LAT    LON   LZEN   SZEN   ELEV   SURF    VIS
   5811  11791   1998   7502   4280   3886     91      7     46
  CHAN1  CHAN2  CHAN3  CHAN4  CHAN5  CHAN6  CHAN7  CHAN8  CHAN9
  21578  21643  24101  25572  26721  28141  28292  28302  26219
  CHA10  CHA11  CHA12  CHA13  CHA14  CHA15  CHA16  CHA17  CHA18
  26887  26514  24495  26875  25927  23386  28195  29335  30359

GOES-8...
GIMD IAR,7849 AUTO,1
time, dwell, step, dect, sat:   172958     1     0     2     8
   NRDG   DRDG    MODE   MAXE  MINE   PRIM   SECN   PCWT    PCU
      0      0      3     13      0      7      1     50      0
   LINE   ELEM    LAT    LON   LZEN   SZEN   ELEV   SURF    VIS
   6097   8602   1998   7502   2309   3884     91      7     13
  CHAN1  CHAN2  CHAN3  CHAN4  CHAN5  CHAN6  CHAN7  CHAN8  CHAN9
  21604  21704  24236  25929  26920  28495  28782  28998  27179
  CHA10  CHA11  CHA12  CHA13  CHA14  CHA15  CHA16  CHA17  CHA18
  26902  26509  24706  28242  26811  24556  29183  30409  31206

The calculated brightness temperatures for the 18 sounder channels:

WFGIMNTX 1  18  SAT=8
  223.55  222.93  238.60  254.44  265.28  282.62  285.57  286.41  260.66
  257.55  246.19  231.40  275.07  261.13  239.72  280.92  285.88  286.33

WFGIMNTX 1  18  SAT=9
  223.44  222.60  237.93  254.37  264.41  282.63  285.54  286.44  260.72
  257.83  246.28  231.48  275.63  261.34  240.48  279.88  285.92  286.35

WFGIMNTX 1  18  SAT=10
  223.57  223.01  239.06  254.49  265.59  282.64  285.59  286.44  260.58
  257.67  245.83  231.27  272.07  259.80  236.82  280.77  285.96  286.35

GOES-10 Imager results