MPA: Meridian Photometer Array
Where_is_the_data
The location of data does not need to be known when using any of the MPA baseline software. A routine, FIND_MPA (see Software), is called by GET_PARAM (see Software) and looks for data in all the usual places (see BETA, below). In addition a caller may have data in another directory. This may be made known to the program by defining the logical D$OTHER_BETA. There are two levels of processed data on the system, ALPHA and BETA data. Most of the software requires BETA data, but if not available, and ALPHA data is, the access routine GET_BETA will create BETA data "on-the-fly". Provided of course the code can find the Alpha data. Here FIND_MPA also looks for the data in all the usual places (see ALPHA, below). If the Alpha data is in a different directory, this must be made known to the program by defining the logical D$OTHER_ALPHA. Additional information available: ALPHA BETA CAMPAIGN SOFTWARE This help file contains information on programs and subroutines related to the MPA, and provides help on how to use or run the code. In general, this help (except for the example) is an excerpt of the header in the source code of the mainline program or subroutine in question, but this source code is not routinely made available to the general user. The source code header always contains the most up to date information on the program. Sometime in the future, this header will always be a available as a corresponding .DOC file in MPA$SOFT. On-line help is also available for most public MPA software. This is called up from help files with the filetype .QUE located in [CANHELP.MPA], usually at time of parameter entry (see GET_PARAM). Executable images of these programs are located in MPA$EXE. The .OBJ files of the subroutines are found in MPA$SOFT:MPALIB.OLB, MPA$SOFT:STARLIB.OLB, the source code of data structures are located in MPA$SOFT:INCLUDE_FOR.TLB. Plotting programs are all written in IDL2 (except for those that have not been converted yet!). These are found in MPA$EXE. The support routines are in MPA$SOFT:MPA_IDL.TLB. Where mainline programs need to be linked locally, a .BLD file to link the program is provided. Additional information available: DARK_TIME GET_MPA GET_PARAM GET_BETA MPA_DATA PLOT_BETA RASTER READ_BETA
Cloud_Index
Estimation of Cloud Cover using MPA data.
F. Creutzberg, 30-JUL-1992
In the MPA data, cloud cover is estimated from the shape of the background channel scans, on the assumption that when the sky is clear, the measured brightness near the horizons is greater than the zenith brightness (van Rhijn effect); conversely, when the sky is overcast, the zenith brightness is greater than that near the horizons (Rayleigh or Mie scattering). There is a smooth monotonic change in going from the horizon to the zenith and back to the other horizon at least in a full meridian scan. This holds fairly well also for the binned data that constitute the MPA scans.
A number of factors can contribute to the failure of this strategy. If the filters are not pure background filters (and none of them are!), there will be enhanced emission where there is aurora during clear skies and in locations near the zenith when it is overcast and we donot have a simple second degree polynomial brightness curve. The same is true if the moon is crossing or near the scanner meridian. If we have broken cloud this concept also breaks down. So in short, an index for the cloud cover is a three-valued parameter: GOOD, BAD, DON'T KNOW.
We have to expand on this a little, because we have two background channels, which behave differently in situations where the concept breaks down. So for this reason we have created a four-valued index where the fourth value is PERHAPS (CAUTION), the case where one channel indicates clear sky and the other does not.
The cloud index described here is computed on a scan by scan basis. There are other ways of getting a handle of the degree of cloud cover. At switch-on/off the sky brightness often gives a positive indication of the presence of clouds based on the above criteria. At turn-on, clear skies show a decaying brightness which produces a << profile (darkest in the zenith), while a cloudy sky produces a >> profile (directions reversed at turn-off). Broken cloud often produces a skewed wave pattern, while high cirrus or ice crystals often cause "weeping", a spreading of the intensity towards the horizons where well confined arc boundaries would be expected. When aurora is active we expect to see structure, often moving equatorward or poleward. This may get washed out when haze is present. Bright arcs above the clouds show up as a bright band near the zenith. Extensive motion does not show up much, if at all. Another common feature is streaky bands running from horizon to horizon, particularly visible in H-Beta. H-Beta is a very low level emission and is very sensitive to haze. It is also corrected for background and the presence of such bands probably indicates cirrus drifting accross the meridian.
The subroutine (BG_LSQ) which computes the cloud indices does a least squares fit (2nd order polynomial) to the two background channels of each MPA scan and returns two background cloud indices and a composite cloud index.
The channel cloud index is a positive number which can assume five values: 1 - Clear: A significant second order constant >0; no rejected observations. 8 - Cloudy: A significant second order constant <0; no rejected observations. 2 - Marginal Viewing: A significant second order constant >0 after rejecting 1 or 2 observations in 1 cycle. 4 - Indeterminate: No significant second order or first order constant. 0 - No Valid Data to asses cloud index with. The Composite Index is evaluated as follows. Two indices the same (value I), CI = I C, O, !, ?, N One index 8, the other 2, 4 CI = 8 O the other 1 CI = 4 ? One index 1, the other 2 CI = 2 ! the other 4, 8 CI = 4 ? One index 2, the other 4 CI = 2 ! where C = Clear, O = Overcast, ! = Caution, ? = Don't Know, N = No Data In MPA RASTER plots, the cloud index is displayed in a color bar or grayscale bar. The colour values are assigned as follows.
0 White White No Data
1 Green White Clear
8 Red Black Cloudy
2 Yellow Light Grey Caution
4 Orange Dark Grey Don't Know
BIN_ANGLES
The step tables for the mirror driver of the four MPA are set up to provide data bins 0.5° wide, centered every even 0.5° for the low altitude emissions (4861Å, 5577Å, 4709Å) and bins 1.0° wide, centered every even 1.0° for the high altitude emisision (6300Å). The angles on which these computations are based, those of the bin centres, are shown together with the angles of the "Northern" and "Southern" bin boundaries. They are based on a mirror step size of 0.225° (1600 steps per revolution). The field of view of the instruments is 4°.
Rankin_110
Azimuth and Elevation Angles for RANKIN at 110.0 km
BIN Northern Bin Edge Southern Bin Edge Bin Centre
1 3.200 10.800 3.200 12.600 3.200 11.700
2 3.200 12.825 3.200 14.850 3.200 13.838
3 3.200 15.075 3.200 17.775 3.200 16.425
4 3.200 18.000 3.200 21.825 3.200 19.913
5 3.200 22.050 3.200 27.675 3.200 24.862
6 3.200 27.900 3.200 36.450 3.200 32.175
7 3.200 36.900 3.200 50.625 3.200 43.763
8 3.200 51.300 3.200 73.575 3.200 62.438
9 3.200 74.700 183.200 77.625 3.200 88.537
10 183.200 76.725 183.200 53.550 183.200 65.137
11 183.200 52.875 183.200 38.250 183.200 45.563
12 183.200 37.800 183.200 28.800 183.200 33.300
13 183.200 28.575 183.200 22.725 183.200 25.650
14 183.200 22.500 183.200 18.450 183.200 20.475
15 183.200 18.225 183.200 15.300 183.200 16.763
16 183.200 15.075 183.200 12.825 183.200 13.950
17 183.200 12.600 183.200 11.025 183.200 11.813
Rankin_230
Azimuth and Elevation Angles for RANKIN at 230.0 km
BIN Northern Bin Edge Southern Bin Edge Bin Centre
1 3.200 10.800 3.200 12.600 3.200 11.700
2 3.200 12.825 3.200 14.850 3.200 13.838
3 3.200 15.075 3.200 17.775 3.200 16.425
4 3.200 18.000 3.200 21.825 3.200 19.913
5 3.200 22.050 3.200 27.675 3.200 24.862
6 3.200 27.900 3.200 36.450 3.200 32.175
7 3.200 36.900 3.200 50.625 3.200 43.763
8 3.200 51.300 3.200 73.575 3.200 62.438
9 3.200 74.700 183.200 77.625 3.200 88.537
10 183.200 76.725 183.200 53.550 183.200 65.137
11 183.200 52.875 183.200 38.250 183.200 45.563
12 183.200 37.800 183.200 28.800 183.200 33.300
13 183.200 28.575 183.200 22.725 183.200 25.650
14 183.200 22.500 183.200 18.450 183.200 20.475
15 183.200 18.225 183.200 15.300 183.200 16.763
16 183.200 15.075 183.200 12.825 183.200 13.950
17 183.200 12.600 183.200 11.025 183.200 11.813
Gillam_110
Azimuth and Elevation Angles for GILLAM at 110.0 km
BIN Northern Bin Edge Southern Bin Edge Bin Centre
1 9.200 10.800 9.200 12.375 9.200 11.588
2 9.200 12.600 9.200 14.850 9.200 13.725
3 9.200 15.075 9.200 18.000 9.200 16.538
4 9.200 18.225 9.200 22.050 9.200 20.138
5 9.200 22.275 9.200 28.125 9.200 25.200
6 9.200 28.350 9.200 37.350 9.200 32.850
7 9.200 37.800 9.200 52.650 9.200 45.225
8 9.200 53.325 9.200 76.725 9.200 65.025
9 9.200 77.850 189.200 73.575 189.200 87.862
10 189.200 72.675 189.200 50.625 189.200 61.650
11 189.200 49.950 189.200 36.225 189.200 43.088
12 189.200 35.775 189.200 27.450 189.200 31.613
13 189.200 27.225 189.200 21.600 189.200 24.413
14 189.200 21.375 189.200 17.550 189.200 19.462
15 189.200 17.325 189.200 14.625 189.200 15.975
16 189.200 14.400 189.200 12.375 189.200 13.387
17 189.200 12.150 189.200 10.575 189.200 11.363
Gillam_230
Azimuth and Elevation Angles for GILLAM at 230.0 km
BIN Northern Bin Edge Southern Bin Edge Bin Centre
1 9.200 10.800 9.200 12.375 9.200 11.588
2 9.200 12.600 9.200 14.850 9.200 13.725
3 9.200 15.075 9.200 18.000 9.200 16.538
4 9.200 18.225 9.200 22.050 9.200 20.138
5 9.200 22.275 9.200 28.125 9.200 25.200
6 9.200 28.350 9.200 37.350 9.200 32.850
7 9.200 37.800 9.200 52.650 9.200 45.225
8 9.200 53.325 9.200 76.725 9.200 65.025
9 9.200 77.850 189.200 73.575 189.200 87.862
10 189.200 72.675 189.200 50.625 189.200 61.650
11 189.200 49.950 189.200 36.225 189.200 43.088
12 189.200 35.775 189.200 27.450 189.200 31.613
13 189.200 27.225 189.200 21.600 189.200 24.413
14 189.200 21.375 189.200 17.550 189.200 19.462
15 189.200 17.325 189.200 14.625 189.200 15.975
16 189.200 14.400 189.200 12.375 189.200 13.387
17 189.200 12.150 189.200 10.575 189.200 11.363
BIN_LATITUDES
Rankin_110
Geodetic and Geomagnetic Coordinates for RANKIN at 110.0 km
BIN GD Lat GD Lon EDFLat EDFLon L INLat
1 66.838 268.455 74.49 339.30 20.46 77.22
2 66.333 268.374 73.99 339.23 19.05 76.75
3 65.854 268.299 73.50 339.17 17.92 76.33
4 65.363 268.226 73.00 339.11 16.84 75.89
5 64.860 268.153 72.51 339.05 15.79 75.42
6 64.358 268.083 72.00 339.01 14.88 74.97
7 63.855 268.017 71.50 338.96 14.00 74.49
8 63.353 267.951 71.00 338.92 13.25 74.05
9 62.851 267.889 70.49 338.88 12.52 73.58
10 62.354 267.829 70.00 338.84 11.86 73.12
11 61.854 267.771 69.50 338.81 11.26 72.66
12 61.351 267.714 69.00 338.78 10.70 72.19
13 60.854 267.660 68.50 338.75 10.18 71.73
14 60.351 267.607 68.00 338.72 9.63 71.19
15 59.846 267.555 67.50 338.69 9.24 70.79
16 59.334 267.504 67.00 338.67 8.82 70.32
17 58.840 267.456 66.51 338.65 8.44 69.86
Rankin_230
Geodetic and Geomagnetic Coordinates for RANKIN at 230.0 km
BIN GD Lat GD Lon EDFLat EDFLon L INLat
1 70.178 269.095 77.90 339.84 35.19 80.28
2 69.394 268.927 77.11 339.66 30.67 79.58
3 68.608 268.771 76.32 339.51 26.84 78.86
4 67.761 268.614 75.47 339.36 23.65 78.11
5 66.853 268.458 74.57 339.23 20.69 77.28
6 65.905 268.307 73.62 339.12 18.24 76.44
7 64.917 268.162 72.64 339.01 16.10 75.55
8 63.905 268.023 71.63 338.92 14.29 74.64
9 62.878 267.893 70.61 338.83 12.72 73.70
10 61.862 267.773 69.61 338.77 11.42 72.77
11 60.850 267.660 68.61 338.71 10.31 71.83
12 59.860 267.557 67.64 338.67 9.39 70.94
13 58.914 267.464 66.71 338.63 8.61 70.06
14 58.000 267.379 65.82 338.60 7.94 69.21
15 57.123 267.301 64.97 338.57 7.38 68.39
16 56.280 267.229 64.15 338.55 6.89 67.61
17 55.507 267.166 63.40 338.53 6.50 66.89
Gillam_110
Geodetic and Geomagnetic Coordinates for GILLAM at 110.0 km
BIN GD Lat GD Lon EDFLat EDFLon L INLat
1 60.364 266.664 68.00 337.48 9.63 71.20
2 59.867 266.483 67.50 337.29 9.18 70.72
3 59.352 266.303 66.99 337.11 8.74 70.23
4 58.855 266.135 66.50 336.93 8.35 69.75
5 58.360 265.970 66.00 336.78 8.03 69.33
6 57.857 265.809 65.50 336.63 7.64 68.79
7 57.348 265.650 65.00 336.47 7.32 68.31
8 56.844 265.497 64.49 336.33 7.02 67.81
9 56.338 265.348 63.99 336.20 6.73 67.32
10 55.837 265.204 63.49 336.06 6.47 66.83
11 55.332 265.063 63.00 335.94 6.22 66.35
12 54.827 264.924 62.49 335.82 5.98 65.86
13 54.322 264.790 62.00 335.71 5.76 65.36
14 53.807 264.656 61.49 335.59 5.54 64.86
15 53.302 264.529 60.99 335.49 5.34 64.36
16 52.805 264.406 60.51 335.39 5.16 63.88
17 52.313 264.287 60.02 335.29 4.99 63.39
BIN_LATITUDES
Gillam_230
Geodetic and Geomagnetic Coordinates for GILLAM at 230.0 km
BIN GD Lat GD Lon EDFLat EDFLon L INLat
1 63.670 268.021 71.40 338.94 13.89 74.43
2 62.899 267.677 70.64 338.55 12.72 73.70
3 62.056 267.323 69.80 338.15 11.60 72.91
4 61.202 266.982 68.95 337.79 10.62 72.11
5 60.305 266.643 68.06 337.43 9.71 71.26
6 59.351 266.305 67.12 337.09 8.87 70.36
7 58.351 265.970 66.13 336.77 8.10 69.42
8 57.333 265.647 65.14 336.47 7.41 68.44
9 56.298 265.337 64.12 336.18 6.81 67.45
10 55.271 265.047 63.11 335.93 6.28 66.47
11 54.255 264.773 62.13 335.70 5.82 65.49
12 53.264 264.520 61.16 335.49 5.41 64.53
13 52.310 264.286 60.24 335.30 5.07 63.61
14 51.382 264.069 59.33 335.14 4.76 62.71
15 50.513 263.874 58.49 334.99 4.50 61.86
16 49.705 263.698 57.71 334.86 4.28 61.07
17 48.945 263.539 56.98 334.74 4.08 60.33
Pinawa_110
Geodetic and Geomagnetic Coordinates for PINAWA at 110.0 km
BIN GD Lat GD Lon EDFLat EDFLon L INLat
1 54.340 264.742 62.01 335.64 5.76 65.38
2 53.814 264.635 61.50 335.56 5.54 64.86
3 53.289 264.529 60.98 335.49 5.34 64.35
4 52.793 264.432 60.50 335.42 5.16 63.86
5 52.293 264.337 60.00 335.35 4.98 63.38
6 51.779 264.242 59.50 335.29 4.81 62.88
7 51.261 264.147 58.99 335.22 4.65 62.37
8 50.750 264.056 58.49 335.16 4.50 61.87
9 50.236 263.967 57.99 335.10 4.36 61.36
10 49.727 263.880 57.50 335.05 4.22 60.85
11 49.217 263.794 56.99 334.99 4.09 60.35
12 48.707 263.711 56.50 334.95 3.97 59.85
13 48.199 263.630 56.01 334.90 3.85 59.35
14 47.683 263.549 55.51 334.85 3.74 58.84
15 47.160 263.468 55.00 334.80 3.63 58.32
16 46.655 263.392 54.51 334.76 3.53 57.83
17 46.139 263.316 54.01 334.71 3.43 57.32
Pinawa_230
Geodetic and Geomagnetic Coordinates for PINAWA at 230.0 km
BIN GD Lat GD Lon EDFLat EDFLon L INLat
1 57.744 265.515 65.53 336.26 7.66 68.81
2 56.936 265.319 64.74 336.10 7.16 68.04
3 56.084 265.122 63.90 335.93 6.68 67.23
4 55.236 264.933 63.08 335.80 6.26 66.43
5 54.338 264.742 62.20 335.65 5.85 65.57
6 53.369 264.546 61.26 335.51 5.45 64.63
7 52.355 264.350 60.28 335.37 5.09 63.66
8 51.328 264.160 59.28 335.24 4.75 62.67
9 50.277 263.974 58.26 335.13 4.44 61.65
10 49.233 263.798 57.26 335.02 4.16 60.64
11 48.201 263.631 56.28 334.92 3.92 59.64
12 47.197 263.474 55.32 334.83 3.70 58.65
13 46.231 263.329 54.40 334.74 3.51 57.71
14 45.294 263.194 53.51 334.68 3.34 56.79
15 44.391 263.068 52.65 334.61 3.18 55.91
16 43.564 262.955 51.87 334.55 3.06 55.10
17 42.766 262.850 51.11 334.51 2.94 54.32
