# Third-party notices

Air Time Machine's own code is MIT licensed (see `LICENSE`). It bundles or uses the third-party work listed below. Every item is public domain or under a permissive MIT/BSD-style licence. No Copernicus or Sentinel data is used. Keep this file when you redistribute the project.

## Summary

| Component | Where | Licence |
| --- | --- | --- |
| three.js r160 (`three.module.min.js`) and `OrbitControls.js` | `vendor/three/`, unmodified | MIT |
| Go fonts (Regular, Medium, Bold, Mono) by Bigelow & Holmes | `fonts/`, subset to Latin and converted to WOFF2 | BSD-3-Clause style (Go font licence) |
| Natural Earth 1:10m populated places | `data/cities.json`, fields selected and converted by `tools/build_cities.py` | Public domain |
| Natural Earth 1:50m land and lakes | `assets/basemap-4096.png`, `assets/basemap-2048.png`, rendered by `tools/build_basemap.py` | Public domain |
| Natural Earth 1:110m coastlines and land boundary lines | `data/reference-110m.json`, simplified and converted | Public domain |
| NASA satellite layers via GIBS (OMI NO₂, aerosol index and ozone; MODIS aerosol optical depth; AIRS carbon monoxide; OMPS SO₂), and each layer's GIBS colour map | loaded at run time by the visitor's browser, not stored in this repository | NASA data, no copyright in the US; acknowledgement requested |

Nothing is loaded from a CDN or font service. The only outside requests the app makes are to NASA GIBS.

## NASA nitrogen dioxide (OMI, via GIBS)

Nitrogen dioxide comes from NASA's Global Imagery Browse Services, layer `OMI_Nitrogen_Dioxide_Tropo_Column`: the tropospheric NO₂ column from the Ozone Monitoring Instrument (OMI) on NASA's Aura satellite, Level-3 daily product OMNO2d on a 0.25° grid, from 1 October 2004. No account or API key is needed. NASA's data and imagery policy allows free use; NASA asks for the acknowledgement below, which the app shows under **Credits**.

> We acknowledge the use of imagery provided by services from NASA's Global Imagery Browse Services (GIBS), part of NASA's Earth Science Data and Information System (ESDIS).

Data product: OMI/Aura NO₂ Cloud-Screened Total and Tropospheric Column L3 Global Gridded 0.25 degree x 0.25 degree V3 (OMNO2d), NASA Goddard Space Flight Center, distributed by the Goddard Earth Sciences Data and Information Services Center (GES DISC), doi:[10.5067/Aura/OMI/DATA3407](https://doi.org/10.5067/Aura/OMI/DATA3407). OMI was contributed to Aura by the Netherlands and Finland.

Endpoints used:

- Tiles: `https://gibs.earthdata.nasa.gov/wmts/epsg4326/best/OMI_Nitrogen_Dioxide_Tropo_Column/default/{date}/2km/{z}/{row}/{col}.png`
- Available days: `https://gibs.earthdata.nasa.gov/wmts/epsg4326/best/wmts.cgi?SERVICE=WMTS&REQUEST=DescribeDomains&VERSION=1.0.0&LAYER=OMI_Nitrogen_Dioxide_Tropo_Column&TILEMATRIXSET=2km`, read once and kept for six hours
- Fallback for days known to exist: the WMS endpoint `https://gibs.earthdata.nasa.gov/wms/epsg4326/best/wms.cgi`
- Colour map (legend and place values): `https://gibs.earthdata.nasa.gov/colormaps/v1.3/OMI_Nitrogen_Dioxide_Tropo_Column.xml`; if it cannot be read, the GIBS legend picture `https://gibs.earthdata.nasa.gov/legends/OMI_Nitrogen_Dioxide_Tropo_Column_H.svg` is shown instead.

## The other NASA layers (via GIBS)

The same terms, acknowledgement, endpoints (with the layer name swapped in) and fair-use limits apply to the other layers. Each has its own colour map under `https://gibs.earthdata.nasa.gov/colormaps/v1.3/`.

| In the app | GIBS layer | Instrument and satellite | Colour map |
| --- | --- | --- | --- |
| Particles | `MODIS_Terra_AOD_Deep_Blue_Combined` | MODIS on NASA's Terra: merged Dark Target and Deep Blue aerosol optical depth, land and ocean, from 24 February 2000 | `MODIS_VIIRS_AOD.xml` |
| Smoke & dust | `OMI_Aerosol_Index` | OMI on NASA's Aura: UV aerosol index, from 1 October 2004 | `OMI_Aerosol_Index.xml` |
| Carbon monoxide | `AIRS_L3_Carbon_Monoxide_500hPa_Volume_Mixing_Ratio_Daily_Day` | AIRS on NASA's Aqua: CO volume mixing ratio at 500 hPa, daily daytime Level 3, from 1 September 2002 | `AIRS_Carbon_Monoxide_Volume_Mixing_Ratio.xml` |
| Sulfur dioxide | `OMPS_SO2_Planetary_Boundary_Layer` | OMPS Nadir Mapper on the NASA/NOAA Suomi NPP satellite: SO₂ column in the planetary boundary layer, from 26 January 2012 | `OMPS_SO2_Planetary_Boundary_Layer.xml` |
| Ozone | `OMI_Ozone_TOMS_Total_Column` | OMI on NASA's Aura: TOMS-like total ozone column, from 1 October 2004 | `OMI_Ozone_TOMS_Total_Column.xml` |

Fair use of the service: a day of any layer is 15 pre-rendered tiles; switching layers loads that layer's list of days and colour map once; reading a place is one more tile; the list of available days is one small request, remembered for six hours, and no tiles are requested for days outside it. All requests go through one queue with at most 8 at a time and 40 per second (similar to an ordinary web map), are cancelled when no longer needed, and are cached by the browser.

Under NASA's media guidelines the app does not use the NASA insignia or logotype and does not suggest that NASA endorses it. Two display treatments are applied in the browser and described in the app: gaps may be filled, faded, from the 1–2 days before; and the lowest values may be drawn partly see-through. The legend reflects both settings. Neither changes the data values read for a place.

## Natural Earth

`data/cities.json` is converted from Natural Earth 1:10m `ne_10m_populated_places_simple` (name, ASCII name, region, country, coordinates rounded to 0.001°, population). The base map pictures are rendered from 1:50m `ne_50m_land` and `ne_50m_lakes`. Coastlines and borders in `data/reference-110m.json` are converted from 1:110m `ne_110m_coastline` and `ne_110m_admin_0_boundary_lines_land` (coordinates rounded to 0.01°). Source files: <https://github.com/nvkelso/natural-earth-vector>.

> All versions of Natural Earth raster + vector map data found on this website are in the public domain. You may use the maps in any manner, including modifying the content and design, electronic dissemination, and offset printing.
> — https://www.naturalearthdata.com/about/terms-of-use/

Made with Natural Earth. Free vector and raster map data @ naturalearthdata.com. Borders and place names are shown for orientation only; no position on any boundary or name is implied.

## three.js

`vendor/three/three.module.min.js` and `vendor/three/OrbitControls.js` come unmodified from the `three@0.160.0` npm package. The same licence text is in `vendor/three/LICENSE`.

```
The MIT License

Copyright © 2010-2023 three.js authors

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
```

## Go fonts

The four files in `fonts/` are subsets (Latin characters, WOFF2 format) of Go Regular, Go Medium, Go Bold and Go Mono from `golang.org/x/image/font/gofont/ttfs`. The same licence text is in `fonts/LICENSE`.

```
These fonts were created by the Bigelow & Holmes foundry specifically for the
Go project. See https://blog.golang.org/go-fonts for details.

They are licensed under the same open source license as the rest of the Go
project's software:

Copyright (c) 2016 Bigelow & Holmes Inc.. All rights reserved.

Distribution of this font is governed by the following license. If you do not
agree to this license, including the disclaimer, do not distribute or modify
this font.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

	* Redistributions of source code must retain the above copyright notice,
	  this list of conditions and the following disclaimer.

	* Redistributions in binary form must reproduce the above copyright notice,
	  this list of conditions and the following disclaimer in the documentation
	  and/or other materials provided with the distribution.

	* Neither the name of Google Inc. nor the names of its contributors may be
	  used to endorse or promote products derived from this software without
	  specific prior written permission.

DISCLAIMER: THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
```