Dry Atmospheric Deposition Dataset

700,709

Observations

525

Series

105

Subjects

1987–2026

Period covered

What this looks like

One real series from the dataset, and real rows from the head of its published extract. Neither is a mock-up: the rows below are the same rows, unchanged, that are in the file you would download.

Dry sulphate deposition at Oxford

The longest single series this dataset holds — 2,009 weekly values, one of 525. Drawn from 600 of them, evenly spaced across the record. The dataset is not this chart.

Drawn to show the shape and resolution of what the dataset contains, not to make a point about Oxford. Gaps are breaks, never interpolated.

View the data behind this chart

240 of 464 periods, evenly spaced across the record. Every value is in the download and the API; a table of all 464 would be longer than this page and unusable with a screen reader.
Period	Oxford (kg/ha)
1987.6666666666667	0.023
1987.8333333333333	0.0055
1988	0.024
1988.1666666666667	0.030
1988.3333333333333	0.043
1988.5	0.065
1988.6666666666667	0.027
1988.8333333333333	0.014
1988.9166666666667	0.016
1989.0833333333333	0.034
1989.25	0.048
1989.4166666666667	0.064
1989.5833333333333	0.068
1989.75	0.022
1989.9166666666667	0.023
1990.0833333333333	0.016
1990.25	0.038
1990.4166666666667	0.121
1990.5833333333333	0.083
1990.75	0.016
1990.9166666666667	0.0094
1991.0833333333333	0.030
1991.25	0.031
1991.4166666666667	0.079
1991.5	0.165
1991.6666666666667	0.048
1991.8333333333333	0.023
1992	0.020
1992.1666666666667	0.020
1992.3333333333333	0.069
1992.5	0.054
1992.6666666666667	0.062
1992.8333333333333	0.0099
1993	0.034
1993.1666666666667	0.056
1993.3333333333333	0.094
1993.5	0.086
1993.6666666666667	0.020
1993.8333333333333	0.019
1994	0.041
1994.0833333333333	0.022
1994.25	0.021
1994.4166666666667	0.086
1994.5833333333333	0.097
1994.75	0.020
1994.9166666666667	0.011
1995.0833333333333	0.023
1995.25	0.036
1995.4166666666667	0.079
1995.5833333333333	0.075
1995.75	0.022
1995.9166666666667	0.012
1996.0833333333333	0.026
1996.25	0.044
1996.4166666666667	0.075
1996.5833333333333	0.078
1996.6666666666667	0.025
1996.8333333333333	0.015
1997	0.023
1997.1666666666667	0.035
1997.3333333333333	0.056
1997.5	0.072
1997.6666666666667	0.048
1997.8333333333333	0.018
1998	0.0061
1998.1666666666667	0.019
1998.3333333333333	0.094
1998.5	0.064
1998.6666666666667	0.049
1998.8333333333333	0.018
1999	0.012
1999.1666666666667	0.015
1999.25	0.038
1999.4166666666667	0.088
1999.5833333333333	0.065
1999.75	0.034
1999.9166666666667	0.011
2000.0833333333333	0.015
2000.25	0.017
2000.4166666666667	0.037
2000.5833333333333	0.055
2000.75	0.035
2000.9166666666667	0.014
2001.0833333333333	0.021
2001.25	0.045
2001.4166666666667	0.074
2001.5833333333333	0.091
2001.75	0.027
2001.8333333333333	0.031
2002	0.018
2002.1666666666667	0.025
2002.3333333333333	0.058
2002.5	0.065
2002.6666666666667	0.057
2002.8333333333333	0.013
2003	0.010
2003.1666666666667	0.038
2003.3333333333333	0.050
2003.5	0.052
2003.6666666666667	0.084
2003.8333333333333	0.013
2004	0.022
2004.1666666666667	0.024
2004.3333333333333	0.044
2004.4166666666667	0.047
2004.5833333333333	0.055
2004.75	0.017
2004.9166666666667	0.021
2005.0833333333333	0.037
2005.25	0.043
2005.4166666666667	0.076
2005.5833333333333	0.056
2005.75	0.011
2005.9166666666667	0.013
2006.0833333333333	0.019
2006.25	0.031
2006.4166666666667	0.047
2006.5833333333333	0.073
2006.75	0.021
2006.9166666666667	0.0079
2007	0.0085
2007.1666666666667	0.034
2007.3333333333333	0.055
2007.5	0.030
2007.6666666666667	0.019
2007.8333333333333	0.019
2008	0.016
2008.1666666666667	0.025
2008.3333333333333	0.024
2008.5	0.052
2008.6666666666667	0.026
2008.8333333333333	0.0072
2009	0.011
2009.1666666666667	0.038
2009.3333333333333	0.036
2009.5	0.023
2009.5833333333333	0.037
2009.75	0.011
2009.9166666666667	0.011
2010.0833333333333	0.022
2010.25	0.025
2010.4166666666667	0.028
2010.5833333333333	0.044
2010.75	0.012
2010.9166666666667	0.016
2011.1666666666667	0.020
2011.3333333333333	0.034
2011.5	0.073
2011.6666666666667	0.019
2011.8333333333333	0.013
2012	0.0062
2012.1666666666667	0.021
2012.25	0.019
2012.4166666666667	0.030
2012.5833333333333	0.016
2012.75	0.0098
2012.9166666666667	0.0094
2013.0833333333333	0.014
2013.25	0.019
2013.4166666666667	0.022
2013.5833333333333	0.037
2013.75	0.012
2013.9166666666667	0.0083
2014.0833333333333	0.016
2014.25	0.020
2014.4166666666667	0.027
2014.5833333333333	0.030
2014.75	0.0090
2014.8333333333333	0.011
2015	0.011
2015.1666666666667	0.017
2015.3333333333333	0.018
2015.5	0.022
2015.6666666666667	0.012
2015.8333333333333	0.0025
2016	0.0051
2016.25	0.012
2016.4166666666667	0.015
2016.5833333333333	0.0094
2016.75	0.0056
2016.9166666666667	0.0062
2017.0833333333333	0.0098
2017.25	0.0070
2017.4166666666667	0.014
2017.5	0.012
2017.6666666666667	0.015
2017.8333333333333	0.0040
2018	0.0053
2018.1666666666667	0.0070
2018.3333333333333	0.019
2018.5	0.0088
2018.6666666666667	0.0096
2018.8333333333333	0.0055
2019	0.0096
2019.1666666666667	0.010
2019.3333333333333	0.014
2019.5	0.019
2019.6666666666667	0.013
2019.8333333333333	0.0067
2020	0.0036
2020.0833333333333	0.0056
2020.25	0.011
2020.4166666666667	0.013
2020.5833333333333	0.0097
2020.75	0.0037
2020.9166666666667	0.0036
2021.0833333333333	0.0097
2021.25	0.012
2021.4166666666667	0.011
2021.5833333333333	0.025
2021.75	0.0068
2021.9166666666667	0.0047
2022.0833333333333	0.0057
2022.25	0.011
2022.4166666666667	0.013
2022.5833333333333	0.011
2022.6666666666667	0.0075
2022.8333333333333	0.0056
2023	0.0051
2023.1666666666667	0.0078
2023.3333333333333	0.0062
2023.5	0.0092
2023.6666666666667	0.0061
2023.8333333333333	0.0049
2024	0.0034
2024.1666666666667	0.0070
2024.3333333333333	0.0085
2024.5	0.0068
2024.6666666666667	0.0038
2024.8333333333333	0.0045
2025	0.0045
2025.1666666666667	0.0078
2025.25	0.0066
2025.4166666666667	0.012
2025.5833333333333	0.0064
2025.75	0.0044
2025.9166666666667	0.0036
2026.0833333333333	0.0059
2026.25	0.011
2026.4166666666667	0.0087

Sample rows

12 of 1,432,422 rows Taken from the start of observations-atmospheric-us-epa-castnet.csv. These are sample rows, not the dataset.

Sample rows from the Dry Atmospheric Deposition Dataset extract
`metric_id`	`subject_id`	`subject_kind`	`value`	`censored`	`censor_operator`	`censor_threshold`	`censor_limit`	`censor_reported`	`unit`	`period_start`	`period_end`	`period_kind`	`basis`	`confidence`	`source_id`	`source_ref`	`qualifier`	`superseded`	`retrieved`
air-nitric-acid	castnet-abt147	geography	1.5911	—	—	—	—	—	µg/m³	1994-01-06	—	week	measured	high	us-epa-castnet	drychem.csv	—	—	2026-10-01
air-nitric-acid	castnet-abt147	geography	2.0533	—	—	—	—	—	µg/m³	1994-01-11	—	week	measured	high	us-epa-castnet	drychem.csv	—	—	2026-10-01
air-nitric-acid	castnet-abt147	geography	2.7979	—	—	—	—	—	µg/m³	1994-01-21	—	week	measured	high	us-epa-castnet	drychem.csv	—	—	2026-10-01
air-nitric-acid	castnet-abt147	geography	1.4102	—	—	—	—	—	µg/m³	1994-01-25	—	week	measured	high	us-epa-castnet	drychem.csv	—	—	2026-10-01
air-nitric-acid	castnet-abt147	geography	4.2669	—	—	—	—	—	µg/m³	1994-02-01	—	week	measured	high	us-epa-castnet	drychem.csv	—	—	2026-10-01
air-nitric-acid	castnet-abt147	geography	1.4562	—	—	—	—	—	µg/m³	1994-02-08	—	week	measured	high	us-epa-castnet	drychem.csv	—	—	2026-10-01
air-nitric-acid	castnet-abt147	geography	3.8997	—	—	—	—	—	µg/m³	1994-02-15	—	week	measured	high	us-epa-castnet	drychem.csv	—	—	2026-10-01
air-nitric-acid	castnet-abt147	geography	1.6216	—	—	—	—	—	µg/m³	1994-03-01	—	week	measured	high	us-epa-castnet	drychem.csv	—	—	2026-10-01
air-nitric-acid	castnet-abt147	geography	2.4045	—	—	—	—	—	µg/m³	1994-03-08	—	week	measured	high	us-epa-castnet	drychem.csv	—	—	2026-10-01
air-nitric-acid	castnet-abt147	geography	2.1742	—	—	—	—	—	µg/m³	1994-03-15	—	week	measured	high	us-epa-castnet	drychem.csv	—	—	2026-10-01
air-nitric-acid	castnet-abt147	geography	2.6266	—	—	—	—	—	µg/m³	1994-03-29	—	week	measured	high	us-epa-castnet	drychem.csv	—	—	2026-10-01
air-nitric-acid	castnet-abt147	geography	1.7103	—	—	—	—	—	µg/m³	1994-04-05	—	week	measured	high	us-epa-castnet	drychem.csv	—	—	2026-10-01

Download these rows as CSV — the same twelve, with the column header, for testing a loader before committing to the full file.

Methodology

Collected from the EPA CASTNET open data directory and stored as published. The flux is not measured: the publisher computes it as the measured weekly air concentration multiplied by a deposition velocity modelled from meteorology, land cover and surface properties, under the inferential method. Every value is therefore stored with basis modelled. The publisher reports what share of each week’s deposition velocity had to be substituted for missing inputs, and that share is not uniform through the record.

What this dataset cannot tell you

Read before relying on these figures

Modelled, not measured. The concentration was observed; the deposition velocity was not. The flux is their product and inherits every assumption in the velocity model.
The deposition velocity is substituted where the inputs to model it are missing. Across the record 38% of weeks are fully substituted, and in 2017 to 2021 that reaches 85 to 87% as on-site meteorology was reduced — so the series carries a change in how it was produced partway through, and a trend read across that change is partly a trend in method.
Dry deposition only. Wet deposition — what rain brings down, and often the larger share — is measured by a different programme and is not held, so nothing here is total deposition and total cannot be computed from it.
A flux at a site is not additive across sites. Adding two weekly fluxes from different places produces a number with no area behind it.
Deposition onto a monitoring site is not deposition onto a catchment. It is a point estimate for one surface, and real catchments vary in land cover, roughness and elevation, all of which change the velocity.
United States only.

Coverage

Subjects	United States CASTNET rural monitoring sites with a long record — 105 held
Period	1987–2026
Units	kg/ha
Update cadence	Weekly
Identifier	`dry-deposition` v1.0.0

Fields

Data dictionary →

Every metric this dataset carries, with the unit it is stored in and the geography level it is reported at. Full definitions are in the data dictionary.

Identifier	Field	Unit	Reported at
`sulphate-deposition-dry`	Dry sulphate deposition Modelled dry deposition of sulphate over one week, in kilograms per hectare.	kg/ha	monitoring-station
`sulphur-dioxide-deposition-dry`	Dry sulphur dioxide deposition Modelled dry deposition of sulphur dioxide over one week, in kilograms per hectare.	kg/ha	monitoring-station
`nitrate-deposition-dry`	Dry particulate nitrate deposition Modelled dry deposition of particulate nitrate over one week, in kilograms per hectare.	kg/ha	monitoring-station
`nitric-acid-deposition-dry`	Dry nitric acid deposition Modelled dry deposition of nitric acid over one week, in kilograms per hectare.	kg/ha	monitoring-station
`ammonium-deposition-dry`	Dry ammonium deposition Modelled dry deposition of ammonium over one week, in kilograms per hectare.	kg/ha	monitoring-station

Rights and access

Licence position

Open. Derivative use true; redistribution true; commercial reuse true.

Applies to material authored by US federal agencies. Third-party material carried within a federal product may be separately protected.

Permitted uses

Public display
Derived analysis
API delivery
Bulk download
Commercial use

Available to: Public, Developer, Research, Professional, Enterprise. These follow from the rights of the contributing publishers, not from a Hydrionis pricing decision — no access tier can widen what a publisher withheld.

Contributing sources

United States Environmental Protection Agency — Clean Air Status and Trends Network (US Government work — public domain)

Attribution and citation

Cite and reuse →

Two different obligations, deliberately kept apart. One is a condition of somebody else's licence; the other is a request Hydrionis has no standing to enforce.

Suggested citation for Hydrionis

Hydrionis (2026), Dry Atmospheric Deposition Dataset, version 1.0.0, accessed 2026-10-05, hydrionis.com/data/datasets/dry-deposition/

Cite Hydrionis where you rely on the compilation, the normalisation, the eligibility judgements or a chart. Where you use an unmodified published value, the publisher’s attribution is the one that is required; crediting Hydrionis as well is welcome and is not something Hydrionis can require of you.

Recommended, not required. Hydrionis does not claim rights over unmodified public data it relayed, and doing arithmetic on somebody else’s measurements does not make them Hydrionis’s. Cite the version and the access date: Dry Atmospheric Deposition Dataset changes as publishers release and as methods are revised, and a citation without both cannot be checked later. Full guidance is on cite and reuse.

None of the contributing licences requires attribution. Crediting the publishers is still good practice and they are listed above.

Changelog

Version 1.0.0 — 2026-08-28

First release.

Additions

Five modelled dry deposition fluxes at United States rural sites, from 1987.

Use this data

Download atmospheric observations from EPA CASTNET, part 1 of 2 (1,000,000 rows) (CSV)
Download atmospheric observations from EPA CASTNET, part 2 of 2 (432,422 rows) (CSV)
Machine-readable JSON /api/v1/datasets/dry-deposition.json
How to cite this, and who you must credit
How these figures were produced
Request this at a different scale, format or geography

Every bulk extract ships with a companion metadata file carrying this dataset’s version, its sources, their licences, the attribution you are required to give and the suggested citation — so the terms travel with the file rather than staying on this page.

About this data

The fields a professional user needs to judge whether this is fit for a particular purpose. Deliberately not a score.

About this data

Everything below is a property of the data rather than a rating of it. There is deliberately no single confidence score: how much a gap matters depends on what you are about to do with the series, and only you know that.

Source	United States Environmental Protection Agency — Clean Air Status and Trends Network · US Government work — public domain
How the values came to exist	Mixed across the series — the basis is recorded on every individual value.
Period held	1987–2026
Known gaps	Modelled, not measured. The concentration was observed; the deposition velocity was not. The flux is their product and inherits every assumption in the velocity model. The deposition velocity is substituted where the inputs to model it are missing. Across the record 38% of weeks are fully substituted, and in 2017 to 2021 that reaches 85 to 87% as on-site meteorology was reduced — so the series carries a change in how it was produced partway through, and a trend read across that change is partly a trend in method. Dry deposition only. Wet deposition — what rain brings down, and often the larger share — is measured by a different programme and is not held, so nothing here is total deposition and total cannot be computed from it.
Continuity	Version 1.0.0, released 2026-08-28. 1 recorded version; breaking changes and corrections are listed in the changelog above.
Last read from the publisher	2026-10-01 · publisher updates weekly
Redistribution	Permitted by the upstream licences
Commercial reuse	Permitted by the upstream licences. No Hydrionis access tier can widen this.
Methodology	How this was produced