ESA Snow Climate Change Initiative (Snow_cci): Snow Water Equivalent (SWE) level 3C daily global climate research data package (CRDP) (1979 – 2020), version 2.0

This dataset contains v2.0 of the Daily Snow Water Equivalent (SWE) product from the ESA Climate Change Initiative (CCI) Snow project, at 0.1 degree resolution.

Snow water equivalent (SWE) indicates the amount of accumulated snow on land surfaces, in other words the amount of water contained within the snowpack. The SWE product time series covers the period from 1979/01 to 2020/05. Northern Hemisphere SWE products are available at daily temporal resolution with alpine areas masked.

The product is based on data from the Scanning Multichannel Microwave Radiometer (SMMR) operated on National Aeronautics and Space Administration’s (NASA) Nimbus-7 satellite, the Special Sensor Microwave / Imager (SSM/I) and the Special Sensor Microwave Imager / Sounder (SSMI/S) carried onboard the Defense Meteorological Satellite Program (DMSP) 5D- and F-series satellites. The satellite bands provide spatial resolutions between 15 and 69 km. The retrieval methodology combines satellite passive microwave radiometer (PMR) measurements with ground-based synoptic weather station observations by Bayesian non-linear iterative assimilation. A background snow-depth field from re-gridded surface snow-depth observations and a passive microwave emission model are required components of the retrieval scheme.

The dataset is aimed to serve the needs of users working on climate research and monitoring activities, including the detection of variability and trends, climate modelling, and aspects of hydrology and meteorology.

The Finnish Meteorological Institute is responsible for the SWE product development and generation.

For the period from 1979 to May 1987, the products are available every second day. From October 1987 till May 2020, the products are available daily. Products are only generated for the Northern Hemisphere winter seasons, usually from beginning of October till the middle of May. A limited number of SWE products are available for days in June and September; products are not available for the months July and August as there is usually no snow information reported on synoptic weather stations, which is required as input for the SWE retrieval. Because of known limitations in alpine terrain, a complex-terrain mask is applied based on the sub-grid variability in elevation determined from a high-resolution digital elevation model. All land ice and large lakes are also masked; retrievals are not produced for coastal regions of Greenland.

This version 2 dataset has some notable differences compared to the v1 data. In v2, passive microwave radiometer data are obtained from the recalibrated enhanced resolution CETB ESDR dataset (MEaSUREs Calibrated Enhanced-Resolution Passive Microwave Daily EASE-Grid 2.0 Brightness Temperature (CETB) Earth System Data Record (ESDR) https://nsidc.org/pmesdr/data-sets/), the grid spacing is reduced from 25 km to 12.5 km, and spatially and temporally varying snow density fields are used to adjust SWE retrievals in post processing. The output grid spacing is reduced from 0.25-degree to 0.10-degree WGS84 latitude / longitude to be compatible with other Snow_cci products. The time series has been extended by two years with data from 2018 to 2020 added.

The ESA CCI phased product development framework allowed for a systematic analysis of these changes to the input data and snow density parameterization that occurred between v1 and v2 using a series of step-wise developmental datasets. In comparison with in-situ snow courses, the correlation and RMSE of v2 improved 18% (0.1) and 12% (5mm), respectively, relative to v1. The timing of peak snow mass is shifted two weeks later and a temporal discontinuity in the monthly northern hemisphere snow mass time series associated with the shift from the Special Sensor Microwave/Imager (SSM/I) and the Special Sensor Microwave Imager/Sounder (SSMIS) in 2009 is removed in v2.

Date (Publication): 2022-03-17T09:58:00

Date (Creation): 2022-03-17T09:58:00

Citation identifier: https://catalogue.ceda.ac.uk/uuid/4647cc9ad3c044439d6c643208d3c494

Citation identifier: NERC EDS Centre for Environmental Data Analysis / 4647cc9ad3c044439d6c643208d3c494

Citation identifier: doi / 10.5285/4647cc9ad3c044439d6c643208d3c494

Point of contact

Organisation name	Individual name	Electronic mail address	Role
Unavailable	Luojus, Kari	Unavailable	Author
Unavailable	Moisander, Mikko	Unavailable	Author
Unavailable	Pulliainen, Jouni	Unavailable	Author
Unavailable	Takala, Matias	Unavailable	Author
Unavailable	Lemmetyinen, Juha	Unavailable	Author
Unavailable	Derksen, Chris	Unavailable	Author
Unavailable	Mortimer, Colleen	Unavailable	Author
Unavailable	Schwaizer, Gabriele	Unavailable	Author
Unavailable	Nagler, Thomas	Unavailable	Author
Unavailable	Venäläinen, Pinja	Unavailable	Author
NERC EDS Centre for Environmental Data Analysis		support@ceda.ac.uk	Custodian
NERC EDS Centre for Environmental Data Analysis		support@ceda.ac.uk	Distributor
NERC EDS Centre for Environmental Data Analysis		support@ceda.ac.uk	pointofContact
NERC EDS Centre for Environmental Data Analysis		support@ceda.ac.uk	Publisher

Maintenance and update frequency: Not planned

Update scope: Dataset

Keywords

ESA
CCI
Snow
SWE

GEMET - INSPIRE themes, version 1.0

orthoimagery

Access constraints: Other restrictions

Other constraints: Public data: access to these data is available to both registered and non-registered users.

Use constraints: Other restrictions

Other constraints: Under the following licence https://artefacts.ceda.ac.uk/licences/specific_licences/esacci_snow_terms_and_conditions.pdf, appropriate use of these data may fall under any use. This message is intended as guidance, always read the full licence. When using these data you must cite them correctly using the citation given on the CEDA Data Catalogue record.

Spatial representation type: Grid

Language: English

Topic category

Imagery base maps earth cover

Begin date: 1979-01-02T00:00:00

End date: 2020-05-24T23:59:59

Unique resource identifier: WGS 84

Distribution format

Name	Version
This data product follows CCI Data Standards v2.3, 2021 and are distributed as NetCDF files conforming to Climate and Forecast (CF) convention version 1.9.

Distributor contact

Organisation name	Individual name	Electronic mail address	Role
NERC EDS Centre for Environmental Data Analysis		support@ceda.ac.uk	Distributor

OnLine resource

Protocol	Linkage	Name
	https://catalogue.ceda.ac.uk/uuid/4647cc9ad3c044439d6c643208d3c494	CEDA Data Catalogue Page

OnLine resource

Protocol	Linkage	Name
	http://data.ceda.ac.uk/neodc/esacci/snow/data/swe/MERGED/v2.0/	DOWNLOAD

OnLine resource

Protocol	Linkage	Name
	https://climate.esa.int/	ESA Climate Change Initiative website

OnLine resource

Protocol	Linkage	Name
	https://ieeexplore.ieee.org/document/763302	HUT Snow Emission Model and its Applicability to Snow Water Equivalent Retrieval. DOI: 10.1109/36.763302

OnLine resource

Protocol	Linkage	Name
	https://www.sciencedirect.com/science/article/abs/pii/S0034425706000241	Mapping of snow water equivalent and snow depth in boreal and sub-arctic zones by assimilating space-borne microwave radiometer data and ground-based observations. DOI: 10.1016/j.rse.2006.01.002

OnLine resource

Protocol	Linkage	Name
	https://doi.org/10.1016/j.rse.2011.08.014	Takala et al, 2011, Estimating northern hemisphere snow water equivalent for climate research through assimilation of space-borne radiometer data and ground-based measurements, Remote Sensing of Environment. DOI:10.1016/j.rse.2011.08.014

OnLine resource

Protocol	Linkage	Name
	https://climate.esa.int/projects/snow	Snow CCI webpages

OnLine resource

Protocol	Linkage	Name
	https://climate.esa.int/en/projects/snow/snow-key-documents/	Technical Documentation for Snow CCI

OnLine resource

Protocol	Linkage	Name
	https://doi.org/10.5194/tc-15-2969-2021	Impact of dynamic snow density on Globsnow snow water equivalent retrieval accuracy. DOI: 10.5194/tc-15-2969-2021

OnLine resource

Protocol	Linkage	Name
	https://climate.esa.int/media/documents/Snow_cci_D4.3_PUG_v3.1.pdf	Product User Guide

Hierarchy level: Dataset

Conformance result

Title: Commission Regulation (EU) No 1089/2010 of 23 November 2010 implementing Directive 2007/2/EC of the European Parliament and of the Council as regards interoperability of spatial data sets and services

Date (Publication): 2010-12-08

Statement: Data were produced by the project team and supplied for archiving at the Centre for Environmental Data Analysis (CEDA).

Metadata

File identifier: 4647cc9ad3c044439d6c643208d3c494 XML

Metadata language: English

Character set: UTF8

Hierarchy level: Dataset

Date stamp: 2026-03-16T03:20:05

Metadata standard name: UK GEMINI

Metadata standard version: 2.3

Metadata author

Organisation name	Individual name	Electronic mail address	Role
NERC EDS Centre for Environmental Data Analysis		support@ceda.ac.uk	Point of contact

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