Aircraft Measured Atmospheric Momentum, Heat and Radiation Fluxes Over Arctic Sea Ice

Hartmann, Jörg; Kottmeier, Christoph; Wamser, C.; Augstein, E.

doi:10.1029/gm085p0443

Cited by 23 publications

(13 citation statements)

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“…[] and Hartmann et al . [], which would have allowed to identify further topographical features, such as the edges of melt ponds, was not used due to uncertainties in the determination of errors in the filtering procedure. Later, a threshold of 0.8 m is used, as in Rabenstein et al .…”

Section: Methodsmentioning

confidence: 99%

“…Many of the available data sets were obtained in the marginal sea‐ice zones by both aircraft and shipborne observations. In particular, turbulence measurements were collected during the Arctic Ice Dynamics Joint Experiment (AIDJEX) in the seventies [ Untersteiner , ], during the Marginal Ice Zone Experiment (MIZEX) in 1983 [ Fairall and Markson , ; Guest and Davidson , ] and 1984 [ Anderson , ], during the Radiation and Eddy Flux Experiment (REFLEX) in 1991 [ Hartmann et al ., ] and 1993 [ Kottmeier et al ., ], and during the Arctic Radiation and Turbulence Interaction Study (ARTIST) in 1998 [ Garbrecht et al ., ; Vihma et al ., ]. Finally, the most comprehensive data set with drag coefficients for the inner Arctic was obtained during the SHEBA campaign in 1998.…”

Section: Methodsmentioning

confidence: 99%

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Variability of Arctic sea‐ice topography and its impact on the atmospheric surface drag

et al. 2014

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Over the polar oceans, near-surface atmospheric transport of momentum is strongly influenced by sea-ice surface topography. The latter is analyzed on the basis of laser altimeter data obtained during airborne campaigns between 1995 and 2011 over more than 10,000 km of flight distance in different regions of the Arctic Ocean. Spectra of height and spacing between topographic features averaged over 10 km flight sections show that typical values are 0.45 m for the mean height and about 20 m for the mean spacing. Nevertheless, the variability is high and the spatial variability is stronger than the temporal one. The total topography spectrum is divided into a range with small obstacles (between 0.2 m and 0.8 m height) and large obstacles ( 0.8 m). Results show that large pressure ridges represent the dominant topographic feature only along the coast of Greenland. In the Central Arctic, the concentration of large ridges decreased over the years, accompanied by an increase of small obstacles concentration and this might be related to decreasing multiyear ice. The application of a topography-dependent parameterization of neutral atmospheric drag coefficients reflects the large variability in the sea-ice topography and reveals characteristic differences between the regions. Based on the analysis of the two spectral ranges, we find that the consideration of only large pressure ridges is not enough to characterize the roughness degree of an ice field, and the values of drag coefficients are in most regions strongly influenced by small obstacles.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Variability of Arctic sea‐ice topography and its impact on the atmospheric surface drag

et al. 2014

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“…The second type of data set was obtained over the Arctic and Antarctic MIZ during observations from ship and aircraft in various seasons. Data are available for the Antarctic from Andreas et al [1984], and for the Arctic from the campaign MIZEX [ Guest and Davidson , 1987; Anderson , 1987] and Birnbaum and Lüpkes [2002], who compiled results from the campaigns REFLEX described in Mai et al [1996], Kottmeier et al [1994], and Hartmann et al [1992, 1994].…”

Section: Motivation and Goalsmentioning

confidence: 99%

“…Another reason for the scatter consists in the measurement errors, for example, of D i . As explained in more detail by Hartmann et al [1994], D i is not directly measured but derived from the measured edge length of floes in a domain of 10 km length and 60 m width. This process results in a mean error of roughly ±30%, as derived by Mai [1995] (shown by error bars in Figure 3).…”

Section: Physical Derivation Of CD Over Fractional Sea Icementioning

confidence: 99%

A parametrization, based on sea ice morphology, of the neutral atmospheric drag coefficients for weather prediction and climate models

et al. 2012

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Abstract.A hierarchy of parametrizations of the neutral 10 m drag coefficients over polar sea ice with different morphology regimes is derived on the basis of a partitioning concept that splits the total surface drag into contributions of skin drag and form drag. The new derivation, which provides drag coefficients as a function of sea ice concentration and characteristic length scales of roughness elements, needs fewer assumptions than previous similar approaches. It is shown that form drag variability can explain the variability of surface drag in the marginal sea ice zone (MIZ) and in the summertime inner Arctic regions. In the MIZ, form drag is generated by floe edges;in the inner Arctic, by edges at melt ponds and leads due to the elevation of the ice surface relative to the open water surface. It is shown that an earlier fit of observed neutral drag coefficients is obtained as a special case within the new concept when specific simplifications are made which concern the floe and melt pond geometry. Due to the different surface morphologies in the MIZ and summertime Arctic, different functional dependencies of the drag coefficients on the sea ice concentration result. These differences cause only minor differences between the MIZ and summertime drag coefficients in average conditions, but they might be locally important for atmospheric momentum transport to sea ice. The new parametrization formulae can be used for present conditions but also for future climate scenarios with changing sea ice conditions.

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“…Both empirical and physical-based parametrisations of surface drag have recently been developed. Andreas et al (2010) composited together all available MIZ C DN observations (primarily from Hartmann et al, 1994 andMai et al, 1996) with the vast number of summertime sea-ice pack C DN observations from the SHEBA project (Uttal et al, 2002) for A > 0.7. They argued that summertime sea ice, replete with melt ponds and leads, was morphologically similar to the MIZ and so these data sets could be combined.…”

Section: Introductionmentioning

confidence: 99%

Observations of surface momentum exchange over the marginal ice zone and recommendations for its parametrisation

et al. 2016

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Abstract. Comprehensive aircraft observations are used to characterise surface roughness over the Arctic marginal ice zone (MIZ) and consequently make recommendations for the parametrisation of surface momentum exchange in the MIZ. These observations were gathered in the Barents Sea and Fram Strait from two aircraft as part of the Aerosol-Cloud Coupling And Climate Interactions in the Arctic (ACCA-CIA) project. They represent a doubling of the total number of such aircraft observations currently available over the Arctic MIZ. The eddy covariance method is used to derive estimates of the 10 m neutral drag coefficient (C DN10 ) from turbulent wind velocity measurements, and a novel method using albedo and surface temperature is employed to derive ice fraction. Peak surface roughness is found at ice fractions in the range 0.6 to 0.8 (with a mean interquartile range in C DN10 of 1.25 to 2.85 × 10 −3 ). C DN10 as a function of ice fraction is found to be well approximated by the negatively skewed distribution provided by a leading parametrisation scheme (Lüpkes et al., 2012) tailored for sea-ice drag over the MIZ in which the two constituent components of drag -skin and form drag -are separately quantified. Current parametrisation schemes used in the weather and climate models are compared with our results and the majority are found to be physically unjustified and unrepresentative. The Lüpkes et al. (2012) scheme is recommended in a computationally simple form, with adjusted parameter settings. A good agreement holds for subsets of the data from different locations, despite differences in sea-ice conditions. Ice conditions in the Barents Sea, characterised by small, unconsolidated ice floes, are found to be associated with higher C DN10 values -especially at the higher ice fractions -than those of Fram Strait, where typically larger, smoother floes are observed. Consequently, the important influence of sea-ice morphology and floe size on surface roughness is recognised, and improvement in the representation of this in parametrisation schemes is suggested for future study.

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Aircraft Measured Atmospheric Momentum, Heat and Radiation Fluxes Over Arctic Sea Ice

Cited by 23 publications

References 20 publications

Variability of Arctic sea‐ice topography and its impact on the atmospheric surface drag

Variability of Arctic sea‐ice topography and its impact on the atmospheric surface drag

A parametrization, based on sea ice morphology, of the neutral atmospheric drag coefficients for weather prediction and climate models

Observations of surface momentum exchange over the marginal ice zone and recommendations for its parametrisation

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