In:
Biogeosciences, Copernicus GmbH, Vol. 16, No. 2 ( 2019-01-21), p. 223-240
Abstract:
Abstract. The surface albedo time series, CLARA-A2 SAL, was used to study trends in the
snowmelt start and end dates, the melting season length and the albedo value
preceding the melt onset in Finland during 1982–2016. In addition, the melt
onset from the JSBACH land surface model was compared with the timing of
green-up estimated from Moderate Resolution Imaging Spectroradiometer (MODIS)
data. Moreover, the melt onset was compared with the timing of the greening
up based on MODIS data. Similarly, the end of snowmelt timing predicted by
JSBACH was compared with the melt-off dates based on the Finnish
Meteorological Institute (FMI) operational in situ measurements and the
Fractional Snow Cover (FSC) time-series product provided by the EU FP7
CryoLand project. It was found that the snowmelt date estimated using the
20 % threshold of the albedo range during the melting period corresponded
well to the melt estimate of the permanent snow layer. The longest period,
during which the ground is continuously half or more covered by snow, defines
the permanent snow layer (Solantie et al., 1996). The greening up followed
within 5–13 days the date when the albedo reached the 1 % threshold of
the albedo dynamic range during the melting period. The time difference
between greening up and complete snowmelt was smaller in mountainous areas
than in coastal areas. In two northern vegetation map areas (Northern
Karelia–Kainuu and Southwestern Lapland), a clear trend towards earlier
snowmelt onset (5–6 days per decade) and increasing melting season length
(6–7 days per decade) was observed. In the forested part of northern
Finland, a clear decreasing trend in albedo (2 %–3 % per decade in
absolute albedo percentage) before the start of the melt onset was observed.
The decreasing albedo trend was found to be due to the increased stem volume.
Type of Medium:
Online Resource
ISSN:
1726-4189
DOI:
10.5194/bg-16-223-2019
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2019
detail.hit.zdb_id:
2158181-2
