=== versions === python 3.12.0 | pystac-client 0.9.0 | planetary-computer 1.0.0 | rasterio 1.5.2 | osmnx 2.1.1 | numpy 2.5.4 | pandas 3.0.6 === OpenStreetMap farmland polygons === 413 polygons of 3-100 ha inside the study area, median 10.5 ha, total 5,636 ha === CROME 2024 labels === 24,734 CROME hexagons; 413 polygons contain hexagons 247 fields are >= 80% one crop (the rest are mixed, or the OSM polygon spans several fields) fields median_ha crop Winter wheat 129 12.2 Spring barley 35 13.0 Winter oilseed rape 21 14.7 Winter barley 18 15.5 Grass 13 9.8 Winter field beans 8 8.5 Maize 8 15.2 Sugar beet 6 13.1 Fallow 4 15.0 Other 4 7.0 Temporary grass 1 7.0 === analysis grid === 1000 x 1040 pixels of 10 m (10.0 x 10.4 km), EPSG:32630 field cores: median 941 pixels per field (min 343, max 5119) === Sentinel-1 STAC search === 33 scenes from relative orbit 59 (ascending), 04 Sep 2023 to 22 Sep 2024 platforms: {'SENTINEL-1A': 33} example: S1A_IW_GRDH_1SDV_20230904T174210_20230904T174235_050181_060A2D_rtc | polarisations ['VV', 'VH'] read and field-averaged 33 scenes x 2 polarisations in 12 s === speckle: single pixels versus field averages === VH on 2024-03-26: median within-field pixel std 1.61 dB split-half test: std of (half A - half B) = 0.114 dB, so a whole-field mean is good to about 0.057 dB wrote 8,151 field-date rows to field_backscatter_timeseries.csv and 247 fields to fields_crome_2024.gpkg === crop signatures (median of field means, dB) === crop fields VH Nov-Dec VH Mar VH May-Jun VV May-Jun VH/VV May-Jun VH/VV Sep Winter wheat 129 -15.8 -16.7 -18.3 -14.7 -3.7 -8.0 Winter oilseed rape 21 -13.7 -13.7 -10.5 -6.4 -4.1 -8.8 Spring barley 35 -15.1 -17.3 -18.1 -12.8 -5.2 -8.3 Maize 8 -14.3 -16.5 -18.1 -10.2 -8.0 -6.8 Winter barley 18 -16.0 -16.5 -16.2 -11.8 -4.3 -8.2 Sugar beet 6 -13.9 -18.4 -16.5 -9.7 -6.6 -6.5 Winter field beans 8 -15.0 -17.3 -13.9 -8.4 -5.4 -8.3 Grass 13 -16.3 -16.4 -16.2 -11.1 -5.0 -5.7 largest all-field VV jumps: 10 Sep 2024 +3.8 dB, 22 Oct 2023 +2.4 dB, 13 May 2024 -2.3 dB Winter wheat: VH/VV highest -3.1 dB on 13 May 2024, lowest -10.3 dB on 26 Jan 2024; VV lowest -15.7 dB on 13 May 2024 Winter oilseed rape: VH/VV highest -3.6 dB on 13 May 2024, lowest -9.1 dB on 22 Sep 2024; VV lowest -10.2 dB on 04 Sep 2023 === Sentinel-2 over the same fields === 155 Sentinel-2 L2A acquisitions of tile 30UXC (any cloud cover), 03 Sep 2023 to 29 Sep 2024 read SCL (and red/NIR where useful) for 155 acquisitions in 8 s; 155 cover the fields fully acquisitions with >= 80% of field pixels clear: 17 of 155 (11%) acquisitions where at least one field is clear: 39 clear NDVI observations per field over 13 months: median 25, min 17, max 31 (Sentinel-1: 33 on every field) longest gap between clear views of the same field: median 43 days (range 30-90); clear views per field in March-April 2024: median 2 longest gap between >= 80%-clear Sentinel-2 dates: 90 days (12 Feb 2024 to 12 May 2024); longest Sentinel-1 gap: 12 days S1 scenes (orbit 59) S2 acquisitions S2 >= 80% clear Sep 2023 3 12 2 Oct 2023 2 12 2 Nov 2023 3 12 1 Dec 2023 2 12 1 Jan 2024 3 13 3 Feb 2024 2 11 1 Mar 2024 3 13 0 Apr 2024 2 12 0 May 2024 3 12 2 Jun 2024 3 12 2 Jul 2024 2 13 2 Aug 2024 3 12 1 Sep 2024 2 9 0 === NDVI versus VH/VV ratio (crop medians, dates within 3 days) === Winter wheat: 39 NDVI dates with >= 5 clear fields; 16 within 3 days of a radar date; Pearson r = 0.82 NDVI outliers (> 0.25 from the 5-date running median): 07 May 2024 (0.15) Winter oilseed rape: 34 NDVI dates with >= 5 clear fields; 13 within 3 days of a radar date; Pearson r = 0.48 NDVI outliers (> 0.25 from the 5-date running median): 25 Oct 2023 (0.09), 07 May 2024 (0.21) === nearest-centroid crop classification from Sentinel-1 alone (leave-one-out) === 219 fields, 66 features (33 dates x VV, VH); overall accuracy 87% predicted Winter wheat Winter oilseed rape Winter barley Spring barley Maize Winter field beans CROME label Winter wheat 111 0 5 12 1 0 Winter oilseed rape 0 21 0 0 0 0 Winter barley 0 0 14 2 2 0 Spring barley 1 0 0 31 3 0 Maize 0 0 1 1 6 0 Winter field beans 0 0 0 0 0 8 Winter wheat recall 86% (129 fields) Winter oilseed rape recall 100% (21 fields) Winter barley recall 78% (18 fields) Spring barley recall 89% (35 fields) Maize recall 75% (8 fields) Winter field beans recall 100% (8 fields) figures and outputs written to output/