Investigation of Ice and Water Properties and Under-ice Light Fields in Fresh and Brackish Water Bodies

Leppäranta, Matti; Reinart, Anu; Erm, A.; Arst, Helgi; Hussainov, Medhat; Sipelgas, Liis

doi:10.2166/nh.2003.0006

Cited by 60 publications

(51 citation statements)

References 6 publications

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“…In our measurements, the values of K w always decreased with increasing depth. Such a vertical variation of this parameter is described as typical in the study [Leppäranta et al, 2003]. The authors also describe the opposite situation, when the minimum value of K w (0.8-1 m -1 ) was confined to a 0.2 m layer of under-ice water of mesotrophic Lake Ülemiste, and at the depth of 1.2 m, the coefficient values increased twofold.…”

Section: Methodssupporting

confidence: 53%

Optical Properties of Lake Vendyurskoe

Zdorovennov¹,

Гавриленко²,

Здоровеннова³

et al. 2016

GES

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ABSTRACT. We conducted a field study on light conditions in a small boreal Karelian Lake Vendyurskoe over two years. Albedo of ice-covered lake varied from 0.9 to 0.1, and the euphotic zone depth exceeded 3.5 m during the melting stage. The Secchi disc depth changed from 2.5 m after ice-break to 3.7 m at the stage of early summer. The vertical distribution of the photosynthetically active solar radiation (PAR) attenuation coefficient for water K w was characterized by high spatial (vertical) and temporal (seasonal and interannual) variability which can be connected with the dynamics of plankton cells. The highest values of K w reached 2-2.8 m -1 in the upper 0.5 m layer of a water column, and decreased to 0.5-1.5 m -1 with increasing depth. The highest values of K w were marked in the end of ice-covered period.

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Section: Methodssupporting

confidence: 53%

Optical Properties of Lake Vendyurskoe

Zdorovennov¹,

Гавриленко²,

Здоровеннова³

et al. 2016

GES

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“…The latter assumption may, however, be inappropriate for sea ice, which possibly has more forward scattering than backward scattering, but actually most studies have still treated sea ice as optically isotropic (Katlein et al, 2014). Moreover, internal melting makes sea ice more porous in summer, and as a result the geometric structure of ice becomes more irregular, which can favor isotropic scattering (e.g., Leppä ranta et al, 2003). Consequently, one may expect that the isotropic assumption is not badly biased for melting sea ice.…”

Section: Uncertainties In Pond-color Estimationmentioning

confidence: 99%

The color of melt ponds on Arctic sea ice

Lu¹,

Leppäranta²,

Cheng³

et al. 2017

Preprint

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Abstract.Pond color, which creates the visual appearance of melt ponds on Arctic sea ice in summer, is quantitatively investigated in this study. A two-stream radiative transfer model is used for ponded sea ice: the upwelling irradiance from the pond surface is determined, and then the upwelling spectrum is transformed into the RGB color space through a 10 colorimetric method. The dependence of pond color on various factors such as water and ice properties and incident solar radiation is investigated. The results reveal that increasing underlying ice thickness H i enhances both the green and blue components of pond color, whereas the red component is mostly sensitive to H i for thin ice (H i < 1.5 m) and to pond depth H p for thick ice (H i > 1.5 m), similar to the behavior of melt-pond albedo. The distribution of the incident solar spectrum F 0 with wavelength affects the pond color rather than its level. The pond color changes from dark blue to brighter blue with 15 increasing scattering in ice, but the influence of absorption in ice on pond color is limited. The pond color reproduced by the model agrees well with field observations on Arctic sea ice in summer, which supports the validity of this study. More importantly, pond color has been confirmed to contain information about meltwater and underlying ice, and therefore it can be used as an index to retrieve H i and H p . The results show that retrievals of H i for thin ice agree better with field measurements than retrievals for thick ice, but that retrievals of H p are not good. Color has been shown to be a new potential 20 method to obtain ice thickness information, especially for melting sea ice in summer, although more validation data and improvements to the radiative transfer model will be needed in future.

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“…Incident PAR increases from December to April; however, because of the properties of the ice cover, minimum values of under-ice PAR occur in February and March. According to investigations by Leppäranta et al (2003) that include Lake Võrtsjärv, the light field under snow and ice cover is more diffuse than the open water situation. Scalar irradiance is therefore higher than PAR measured conventionally by planar sensors.…”

Section: Winter Conditionsmentioning

confidence: 99%

Winter conditions in six European shallow lakes: a comparative synopsis

Dokulil

Herzig²,

Somogyi³

et al. 2014

Estonian J. Ecol.

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Abstract. This review summarizes winter conditions from six polymictic European shallow lakes. The lakes range from oligotrophic to hyper-eutrophic. Four of the lakes freeze regularly while ice cover is absent or rare in the two others. Ice duration and timing of ice-out are significantly influenced by climate signals in three of the lakes. Winter water temperature remains higher in nonice-covered lakes. No long-term trend in temperature is detectable except for one lake where winter water temperature began to increase in 1986. Secchi depth in winter is equal or greater than summer values in all six lakes indicating relatively better light conditions in winter. Total phosphorus concentration in winter ranges from 10 to 130 µg L -1 , which is equal or lower than summer values and is unrelated to chlorophyll a in five of the sites. Phytoplankton species composition during winter differs largely at the six sites. The winter assemblages largely depend on the trophic level and the conditions during the previous season. Winter chlorophyll a and phytoplankton biomass are usually lower than summer values because of reduced photosynthetic rates. Bacterial production often exceeds primary production. Epipelic algal assemblages tend to proliferate during winter in both ice-covered and non-ice-covered lakes. Primary production is low during winter because of insufficient light. Zooplankton abundances and biomass critically depend on conditions during the previous season and the winter situation and are quite variable from year to year, but their values correlate with the trophic status of the lakes. As a result, winter conditions are important to understand seasonal and annual changes in shallow lakes.

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Investigation of Ice and Water Properties and Under-ice Light Fields in Fresh and Brackish Water Bodies

Cited by 60 publications

References 6 publications

Optical Properties of Lake Vendyurskoe

Optical Properties of Lake Vendyurskoe

The color of melt ponds on Arctic sea ice

Winter conditions in six European shallow lakes: a comparative synopsis

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