@article{mortimer_benchmarking_2022,
	title = {Benchmarking algorithm changes to the Snow {CCI}+ snow water equivalent product},
	volume = {274},
	issn = {0034-4257},
	url = {https://www.sciencedirect.com/science/article/pii/S003442572200102X},
	doi = {https://doi.org/10.1016/j.rse.2022.112988},
	abstract = {The European Space Agency ({ESA}) Snow Climate Change Initiative ({CCI}+) provides long-term, global time series of daily snow cover fraction and snow water equivalent ({SWE}). The Snow {CCI}+ {SWE} Version 1 ({CCIv}1) product is built on the {GlobSnow} algorithm, which combines passive microwave ({PMW}) data with in situ snow depth ({SD}) measurements to estimate {SWE}. While {CCIv}1 remains algorithmically similar to the most recent {GlobSnow} product ({GlobSnow} Version 3), Snow {CCI}+ {SWE} Version 2 ({CCIv}2) incorporates two notable differences. {CCIv}2 uses updated {PMW} data from the {NASA} {MEaSUREs} Calibrated Passive Microwave Daily {EASE}-Grid 2.0 Earth Science Data Record and is generated in {EASE}-Grid 2.0 with 12.5 km grid spacing. It also adjusts {SWE} retrievals in post-processing by incorporating spatially and temporally varying snow density information. Due to the phased product development framework {CCI}+ employs, proposed changes between {CCIv}1 and {CCIv}2 were implemented in a series of step-wise developmental datasets. Using these developmental datasets, we analyze how changes to input {PMW} and {SD} data and the snow density parameterization affect the resulting {SWE} product. Using in situ snow courses as reference data, we demonstrate that the correlation and {RMSE} of the {CCIv}2 developmental product improved 18\% (0.10) and 12\% (5 mm), respectively, relative to {CCIv}1. 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) to the Special Sensor Microwave Imager/Sounder ({SSMIS}) in 2009 is also removed.},
	pages = {112988},
	journaltitle = {Remote Sensing of Environment},
	author = {Mortimer, C. and Mudryk, L. and Derksen, C. and Brady, M. and Luojus, K. and Venäläinen, P. and Moisander, M. and Lemmetyinen, J. and Takala, M. and Tanis, C. and Pulliainen, J.},
	date = {2022-06-01},
}