ALOS-2
ALOS-2 / Calibration Result of JAXA standard products (ver. 2014.11.20, Initial calibration results)
(As of Nov. 20, 2014)
JAXA has conducted the calibration and validation of the PALSAR-2 and its standard products within the PALSAR-2 initial calibration phase (i.e., from Aug. 4, 2014 to Nov. 20, 2014), and we confirmed 1) that PALSAR-2 products have shown the very good radiometric and the geometric performances as requested from the product specification and as shown in the Table 1, and 2) PALSAR-2 has had good enough performance for monitoring the earth environment and the disaster status. While JAXA will start the data distribution officially on Nov. 25, 2014 as a result of the calibration review, we will continue the calibration and validation of the PALSAR-2 and its standard products for maintaining and further improvement of the PALSAR-2 image performances. Here, we will describe the calibration results of the PALSAR-2 in Table 1 and method to convert the PALSAR-2 data to radar backscatter of the target.
| Items | Results | Data | Requirement | |
|---|---|---|---|---|
| Geometry (RMSE) | High resolution/Spotlight mode | 5.34m (L1.1)/6.73m (L2.1) | 127/129 | 20m |
| ScanSAR mode | 60.77m (L1.1)/29.93m (L2.1) | 7/8 | 100m | |
| Radiometry | Corner reflector | 1.31 (CF: -81.60) | 120 | 1.0 dB |
| Amazon (forest) | 0.406 (CF: -82.34) | 30scenes | 1.0 dB: -6.84dB@Amazon | |
| NESZ (F/H/U) HH | -41.1 (F)/-36.0 (H)/-36.6 (U) | -26.0 (F)/-28.0 (H)/-24.0 (U) | ||
| HV | -49.2 (F)/-46.0(H) | |||
| Polarimetry | VV / HH | 1.0143 (σ: 0.06) | 6 | 1.047 |
| VV /HH phase (deg.) | 0.350 (σ: 0.286) | 5 deg. | ||
| Cross talk (dB) | -43.7 (σ: 6.65) hv/hh | -30 dB | ||
| -44.0 (σ: 7.10) vh/vv | -30 dB | |||
| -48.2 (σ: 6.05) corr | -30 dB | |||
| Resolution (m) Azimuth/Range | Spotlight | 0.79 (σ: 0.028)/1.66 (σ: 0.04) | 3 | 1.00×1.1/1.78 |
| High resolution [3m] | 2.81 (σ: 0.034)/1.70 (σ: 0.022) | 35 | 2.75×1.1/1.78 | |
| High resolution [6m] | 4.06 (σ: 0.108)/3.53 (σ: 0.317) | 28 | 3.75×1.1/3.57 | |
| High resolution [10m] | 5.05 (σ: 0.110)/5.36 (σ: 0.126) | 61 | 5.00×1.1/5.36 | |
| Sidelobes | PSLR (Azimuth) | -16.20 (σ: 2.53) | 124 | -13.26dB+2dB |
| PSLR (Range) | -12.59 (σ: 1.84) | -13.26dB+2dB | ||
| ISLR | -8.80 (σ: 3.23) | -10.16dB+2dB | ||
| Anbiguity | Azimuth | 23~14 (mean: 20) | 7scenes | More than20~25dB |
| Range | Invisible | More than25dB | ||
PSLR: Peak to Sidelobe Ratio, ISLR: Integrated Sidelobe Ratio.
U is High resolution [3m]、H for [6m]、F for [10m].
Standard dev. of CF is 1.31 will be tuned under 1.0 synchronized with Amazon calibration data.
U is High resolution [3m]、H for [6m]、F for [10m].
Standard dev. of CF is 1.31 will be tuned under 1.0 synchronized with Amazon calibration data.
Conversion from digital number (DN) to the backscattering coefficient (sigma-naught) (dB) can be done by the following equations.
(for L1.5, 2.1)
(for L1.1)
| CF | mean (dB) | std (dB) |
|---|---|---|
| CF1 | -83.0 | 0.406 |
| A | 32.0 | - |