Fig. 1. Contrastive diagrams of the traditional one-dimensional radiation model and the radiation model based on horizontally adjacent cells
Fig. 2. Schematic diagram of finitely adjacent-cloud in a vertical section of a three-dimensional space which contained clouds
Fig. 3. Schematic diagram of position and direction for the horizontal flux density
Fig. 4. Schematic diagram of optical thicknesses for the vertically and horizontally adjacent cells
Fig. 5. Spatial distribution of extinction coefficient for three-dimensional cumulus field
Fig. 6. Spectral radiance image under observing condition U-2 at solar zenith angle 30°
Fig. 7. Spectral radiance image under observing condition D-2 at solar zenith angle 30°
Fig. 8. Mean relative errors of intensity for IPA, EMSS and the proposed model under different solar zenith angles and observing conditions
Parameter | Numerical value |
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Grid size | 100×100×36 | Grid resolution/m | 66.7×66.7×40.0 | Horizontal domain size/km2 | 6.7×6.7 | Vertical domain range/km | 1.02~2.42 | Average extinction coefficient/km-1 | 73.9 | Cloud coverage/% | 5.7 |
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Table 1. Main parameters for three-dimensional cumulus field
Solar zenith angle/(°) | Source function | Mean relative error |
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IPA/% | EMSS/% | The proposed model /% | Improvement with EMSS/% |
---|
0 | USF | 58.76 | 53.38 | 28.27 | 25.11 | DSF | 34.03 | 32.75 | 17.36 | 15.39 | 15 | USF | 93.97 | 87.99 | 40.60 | 47.39 | DSF | 67.50 | 63.35 | 30.46 | 32.89 | 30 | USF | 120.85 | 111.60 | 67.56 | 44.04 | DSF | 100.27 | 90.97 | 57.04 | 33.93 | 45 | USF | 136.52 | 121.54 | 93.27 | 28.27 | DSF | 126.34 | 109.98 | 83.47 | 26.51 | 60 | USF | 120.05 | 103.41 | 95.21 | 8.20 | DSF | 120.54 | 99.77 | 89.12 | 10.65 |
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Table 2. Mean relative errors of USF and DSF for IPA, EMSS and the proposed model under different solar zenith angles
Solar zenith angle/(°) | Computational time |
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IPA/s | EMSS/s | The proposed model/s | SHDOM/s |
---|
0 | 5.9 | 8.7 | 8.6 | 147.4 | 15 | 6.3 | 8.9 | 9.0 | 155.1 | 30 | 6.4 | 9.2 | 9.1 | 155.0 | 45 | 6.6 | 9.2 | 9.5 | 160.0 | 60 | 6.7 | 9.5 | 9.4 | 108.9 | Mean | 6.4 | 9.1 | 9.1 | 145.3 |
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Table 3. Computational times of source function for IPA, EMSS, the proposed model and SHDOM under different solar zenith angles
Condition | Field of view/° | Zenith/° | Azimuth/° | X coordinate /km | Y coordinate /km | Altitude/km |
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U-1 | 1.441 | 0 | 180 | 3.375 | 3.375 | 402.420 | U-2 | 40 | -253.740 | 308.838 | D-1 | 15.363 | 180 | 3.375 | 0.050 | D-2 | 140 | 2.752 | 0.277 |
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Table 4. Observing conditions of the detector