A bank of synthetic methane plumes for injection into real hyperspectral scenes. Each sample is a GeoTIFF with the XCH4 enhancement (ppb) of one plume emitting 3000 kg/h, as seen from above with the sun at a given position. 279 physical plumes × 855 sun positions = 238 545 samples.
The plumes come from the WRF-LES 4.7.0 simulations of Gorroño et al. (2026), Atmos. Meas. Tech. 19, 1245-1257, with data on Zenodo (doi:10.5281/zenodo.18161182). The inner domain has 120 × 90 cells of 20 m and 49 vertical levels of 20 m, with one output every 30 s. There are two simulation types, multi (point sources p1 to p9) and area (area sources a1 to a9, from smallest to largest), each run at 11 wind speeds from 2 to 10 m/s.
The 5-cell relaxation band is removed on every side, which leaves a domain of 110 × 80 cells (2200 × 1600 m).
The wind always blows towards +x: the upwind edge is where it enters the domain and the downwind edge is where it leaves. A snapshot is included only if its vertical column map meets all of these conditions:
edge:downwind_width_m). One EMIT pixel is 60 m, so whatever leaves the domain is narrower than a pixel of the sensor and the cut cannot be seen once the plume is injected. 3. The upwind edge is clean. Its maximum is below 2% of the peak. This excludes tracer entering from the periodic outer WRF domain, where the same sources also emit. 4. The top and bottom edges are clean. Their maxima are below 2% of the peak, for the same reason. 5. Almost no methane from outside. The plume itself cannot reach the strip upwind of the source (from the upwind edge to 100 m before the source), so any tracer there comes from the outer WRF domain. Its mass per column, extended over the 110 columns of the domain, must be below 0.2% of the mass of the map (qa:foreign_mass_frac). Since the IME method gives Q proportional to the IME, this keeps the bias in Q below 0.2%, twice the budget accepted for the zeros. The estimate assumes the inflow is even along the domain, which it is not exactly: it comes in gusts.Up to three snapshots are kept per run: those closest to minutes 37.5, 45 and 52.5, at least 8 minutes apart. No snapshot of the three largest areas (a7 to a9) meets the conditions.
methane:source_width_m and H = methane:source_height_m. Point sources occupy a single 20 × 20 m cell (the source pixel). Area sources range from 60 × 80 m (a2) to 420 × 440 m (a6); they are always one cell taller than wide, so their centre falls on a pixel edge in y (array:source_row ends in .5).Use the row whose sun:sza and sun:raa are closest to those of the scene. The error of this choice grows with the height of the plume. Neighbouring sun positions, in both zenith and azimuth, shift the plume by 60 m × h / 330 m relative to each other, where h is methane:mean_height_m. The nearest position is therefore off by at most half the diagonal, about 42 m × h / 330 m: about 4 m for a plume close to the ground (30 m), and about 42 m (2 pixels) for the highest plumes (330 m).
Every value in the bank is the enhancement of a plume emitting 3000 kg/h. To use it at another emission Q, multiply the image by Q / 3000: at 1500 kg/h every value is halved, at 6000 kg/h every value is doubled.
The plume leaves the LES domain at its downwind edge, so it ends in a straight cut there. How much methane is left at that cut is edge:downwind_ppb, again at 3000 kg/h. The cut is invisible while it stays below the noise of the scene you inject into. So, for a scene with noise r (ppb), a plume can be used up to
Q = 3000 × r / edge:downwind_ppb [kg/h]
For example, a plume with 40 ppb at its downwind edge can be injected up to 3700 kg/h in a scene with 50 ppb of noise, but only up to 2000 kg/h in a quieter scene with 27 ppb. Select plumes with
python r = 50 # noise of your scene, ppb q = 3000 # emission you want, kg/h ok = t[3000 * r / t["edge:downwind_ppb"] >= q]
In this bank the median of that limit is about 2700 kg/h for r = 50 ppb.
Values below a threshold are set to 0. The threshold is the highest value that removes at most 0.1% of the plume mass, capped at 1e-4 of the maximum of the image. The cap applies in 84% of the images. Each image is then cropped to the bounding box of its non-zero values.
Values scale linearly with the emission rate: for a plume emitting Q kg/h, multiply the image and the _ppb columns by Q / 3000. The _frac columns do not change.
edge:downwind_frac: median 4%, up to 51% of the peak). With a low sun, this edge appears as a straight line inside the image. See "Choosing the emission rate" below to pick plumes whose cut stays hidden in the noise. - The images contain the enhancement only, with no noise and no background.Click on any region to view partition details
Hierarchical structure showing representative samples across levels. The "..." notation indicates additional samples following the same pattern. All samples at the same level share identical structure (RSUT constraint).
| Level | Types | Total Samples | Sample IDs (preview) |
|---|---|---|---|
| Level 0 | All FILE |
238,545 | Root level samples |
These fields are available for querying with SQL when using TacoReader.
| Field Name | Type | Description |
|---|---|---|
| id | string | Unique sample identifier within parent scope. Must be unique among siblings. |
| type | string | Sample type discriminator (FILE or FOLDER). |
| methane:plume_uid | string | Physical plume: emitter, wind speed and snapshot (e.g. a1_w02.0_s078). Shared by the 855 rows (sun positions) of the plume |
| methane:sim_type | string | LES simulation type: 'area' (area sources) or 'multi' (point sources) |
| methane:emitter | string | Emitter: a1 to a9 are area sources, from smallest to largest; p1 to p9 are point sources |
| methane:wind_speed | double | Wind speed of the LES run [m/s] |
| methane:snapshot_index | int64 | LES output index (one output every 30 s) |
| methane:snapshot_minute | double | Simulation minute of the snapshot (index / 2) |
| methane:scale_factor | double | Factor that converts the arbitrary WRF tracer to an emission of 3000 kg/h |
| methane:peak_ppb | double | Maximum of the plume with the sun overhead (SZA = 0) [ppb]. The same for all rows of a plume; the reference for every _frac column |
| methane:mean_height_m | double | Mass-weighted mean height of the methane [m]. The solar-path image of the plume shifts by about mean_height * tan(SZA); the nearest sun position in the bank is off by at most ~42 m * mean_height / 330 m |
| methane:width_max_m | double | Widest crosswind extent of the plume above 50 ppb on the vertical column map [m], at 3000 kg/h |
| methane:source_width_m | double | Size of the emitting rectangle along x, the wind direction [m]; 20 for point sources. The source at (0, 0) is its centre |
| methane:source_height_m | double | Size of the emitting rectangle along y [m]; 20 for point sources |
| sun:sza | double | Solar zenith angle [deg] |
| sun:raa | double | Azimuth of the sun relative to the wind direction [deg], counterclockwise from +x. The solar-path image of the plume is displaced towards raa + 180 |
| edge:upwind_ppb | double | Maximum along the upwind edge (column 5), where the wind enters [ppb]. Below 2% of the peak in every sample |
| edge:upwind_frac | double | edge:upwind_ppb / methane:peak_ppb. It does not change when the plume is rescaled to another emission rate |
| edge:downwind_ppb | double | Maximum along the downwind edge (column 114), where the wind leaves [ppb]. The plume is cut there; below edge:downwind_ref_ppb in every sample |
| edge:downwind_frac | double | edge:downwind_ppb / methane:peak_ppb. It does not change when the plume is rescaled to another emission rate |
| edge:downwind_slope | double | Slope of log(maximum per column) over the last 600 m before the downwind edge; a negative value means that the plume fades towards it. Negative in every sample |
| edge:downwind_ref_ppb | double | Reference for the downwind edge: the lowest value of the maximum per column in the middle of the domain, columns 40 to 84 [ppb]. Every sample has edge:downwind_ppb < edge:downwind_ref_ppb |
| edge:downwind_ref_frac | double | edge:downwind_ref_ppb / methane:peak_ppb. It does not change when the plume is rescaled to another emission rate |
| edge:downwind_width_m | double | Crosswind extent of the plume above 50 ppb at the downwind edge [m]. At most 60 m, one EMIT pixel, in every sample: the plume closes before leaving the domain |
| edge:top_ppb | double | Maximum along the top edge (row 84, columns 5 to 114, the +y side) [ppb]. Below 2% of the peak in every sample |
| edge:top_frac | double | edge:top_ppb / methane:peak_ppb. It does not change when the plume is rescaled to another emission rate |
| edge:bottom_ppb | double | Maximum along the bottom edge (row 5, columns 5 to 114, the -y side) [ppb]. Below 2% of the peak in every sample |
| edge:bottom_frac | double | edge:bottom_ppb / methane:peak_ppb. It does not change when the plume is rescaled to another emission rate |
| array:width | int64 | Image width [pixels of 20 m] |
| array:height | int64 | Image height [pixels of 20 m] |
| array:source_col | double | Column of the source pixel in the image (0 = upwind side) |
| array:source_row | double | Row of the source pixel in the image (0 = top, +y) |
| array:peak_ppb | double | Maximum of this image [ppb]. It changes with the sun and equals methane:peak_ppb when sza = 0 |
| array:grow_upwind_px | int64 | Number of pixels by which the image extends beyond (+) or falls short of (-) the 110 x 80 LES domain on the upwind, where the wind enters side |
| array:grow_downwind_px | int64 | Number of pixels by which the image extends beyond (+) or falls short of (-) the 110 x 80 LES domain on the downwind, where it leaves side |
| array:grow_top_px | int64 | Number of pixels by which the image extends beyond (+) or falls short of (-) the 110 x 80 LES domain on the top (+y) side |
| array:grow_bottom_px | int64 | Number of pixels by which the image extends beyond (+) or falls short of (-) the 110 x 80 LES domain on the bottom (-y) side |
| qa:threshold_ppb | double | Zero threshold of this image [ppb]: lower values were set to 0. It is the highest threshold that removes at most 0.1% of the mass, capped at 1e-4 of the image maximum |
| qa:threshold_rel | double | qa:threshold_ppb / array:peak_ppb; equal to 1e-4 when the cap applies |
| qa:ime_before | double | Sum of the image before zeroing [ppb x pixel] |
| qa:ime_after | double | Sum of the image after zeroing [ppb x pixel]; ime_after / ime_before is the fraction of mass kept |
| qa:foreign_mass_frac | double | Estimated fraction of the mass of the vertical column map that comes from the outer WRF domain: the mass in the strip upwind of the source, where the plume itself cannot reach, extended over the 110 columns of the domain. Below 0.002 in every sample |
| internal:current_id | int64 | Current sample position at this level (0-indexed). Enables O(1) random access and relational JOINs (ZIP, FOLDER, TACOCAT). |
| internal:parent_id | int64 | Foreign key referencing parent sample position in previous level (ZIP, FOLDER, TACOCAT). |
# pip install tacoreader
import tacoreader
# Load dataset
ds = tacoreader.load("/data/databases/METHANESET_TACOS/methaneset-bank/.tacocat")
# Basic info
print(f"ID: {ds.id}")
print(f"Version: {ds.version}")
print(f"Samples: {len(ds.data)}")If you use this dataset in your research, please cite:
No publications specified
@dataset{methaneset_bank1,
title = {MethaneSET bank},
author = {Unknown},
year = {2024},
version = {1.0.0},
publisher = {Unknown}
}