New estimates of the pan-Arctic sea ice–atmosphere neutral drag coefficients from ICESat-2 elevation data

Abstract

Abstract. The effect that sea ice topography has on the momentum transfer between ice and atmosphere is not fully quantified due to the vast extent of the Arctic and limitations of current measurement techniques. Here we present a method to estimate pan-Arctic momentum transfer via a parameterization which links sea ice–atmosphere form drag coefficients with surface feature height and spacing. We measure these sea ice surface feature parameters using the Cloud and land Elevation Satellite-2 (ICESat-2) which, though it cannot resolve as well airborne surveys, has a higher along-track spatial resolution than other contemporary altimeter satellites. As some narrow obstacles are effectively smoothed out by the ICESat-2 ATL07 spatial resolution, we use near-coincident high-resolution Airborne Topographic Mapper (ATM) elevation data from NASA's Operation IceBridge (OIB) mission to scale up the regional ICESat-2 drag estimates. By also incorporating drag due to open water, floe edges and sea ice skin drag, we produced a time series of average total pan-Arctic neutral atmospheric drag coefficient estimates from October 2018 to May 2022. Here we have observed its temporal evolution to be unique and not directly tied to sea ice extent. By also mapping 3-month aggregates for the years 2019, 2020 and 2021 for better regional analysis, we found the thick multiyear ice area directly north of the Canadian Archipelago and Greenland to be consistently above 2.0 · 10−3 with rough ice ∼ 1.5 · 10−3 typically filling the full multiyear ice portion of the Arctic each spring.

Winter Arctic Sea Ice Surface Form Drag During 1999-2021: Satellite Retrieval and Spatiotemporal Variability

“…The highlights of this study include: 1) an improved surface feature detection algorithm that solves the problem of oversegmentation of surface features from OIB ATM data; 2) the novel 𝜎 𝑣𝑣 𝑜 -𝜎 ℎ -𝐶 𝑑𝑛,𝑓𝑟 regression model that extrapolates 𝐶 𝑑𝑛,𝑓𝑟 to the entire winter season using QSCAT and ASCAT backscatter observations; and 3) the time series of wintertime daily Arctic sea ice 𝐶 𝑑𝑛,𝑓𝑟 with the longest record (1999-2021) so far. The 𝐶 𝑑𝑛,𝑓𝑟 estimates have been shown to be reliable and robust, compared to previous estimates from OIB ATM [30], ASCAT [30], and ICESat-2 [32]. From an observational perspective, this study has revealed the spatiotemporal variability of 𝐶 𝑑𝑛,𝑓𝑟 over the last 20 years for the first time and also demonstrated the increasing contribution of sea ice deformation to 𝐶 𝑑𝑛,𝑓𝑟 since 2009.…”

“…Based on P2016, Petty, et al [30] (hereafter referred to as P2017) investigated the 𝐶 𝑑𝑛,𝑓𝑟 over sections of the Arctic sea ice using ATM data and extrapolated it across the Arctic for the late winter of 2009-2015 using Advanced Scatterometer (ASCAT) data, producing the first map of pan-Arctic 𝐶 𝑑𝑛,𝑓𝑟 to date. Recent studies have shown the potential to map pan-Arctic pressure ridges (and hence 𝐶 𝑑𝑛,𝑓𝑟 ) from ICESat-2 elevation profiles [31][32][33], e.g., Mchedlishvili, et al. [32] (hereafter referred to as M2023) derived a new monthly Arctic 𝐶 𝑑𝑛,𝑓𝑟 dataset using ICESat-2 elevation data and revealed the variability of the Arctic sea ice drag coefficient from November 2018 to May 2022.…”

“…Recent studies have shown the potential to map pan-Arctic pressure ridges (and hence 𝐶 𝑑𝑛,𝑓𝑟 ) from ICESat-2 elevation profiles [31][32][33], e.g., Mchedlishvili, et al. [32] (hereafter referred to as M2023) derived a new monthly Arctic 𝐶 𝑑𝑛,𝑓𝑟 dataset using ICESat-2 elevation data and revealed the variability of the Arctic sea ice drag coefficient from November 2018 to May 2022.…”

Fetch‐Limited, Strongly Forced Wind Waves in Waters With Frazil and Grease Ice – Spectral Modeling and Satellite Observations in an Antarctic Coastal Polynya

“…As they all cluster at the plateau of relatively constant values of C D , in the rest of this analysis we set, for the sake of simplicity, the open-water drag C Dw to C Dw = 2 ⋅ 10 3 . Studies on the surface drag over an ice-covered ocean concentrate mainly on the Arctic ice pack and the MIZ, that is, conditions where the surface morphology and the associated form drag play an important role (e.g., Garbrecht et al, 2002;Lüpkes & Birnbaum, 2005;Lüpkes et al, 2012;Mchedlishvili et al, 2023). Observations for frazil and grease ice are rare and limited to low-wind and mildly sloped wave conditions (see Guest, 2021b, and references there).…”

Linking scales of sea ice surface topography: evaluation of ICESat-2 measurements with coincident helicopter laser scanning during MOSAiC

“…The height of sea ice ridges above the surrounding level ice, known as the sail height, is required for the estimation of drag coefficients. These drag coefficients indicate the intensity of air-ice interactions in the momentum balance equation describing the ice motion in sea ice models (Tsamados et al, 2014;Castellani et al, 2014;Mchedlishvili et al, 2023). The geometry of ridges also plays a role in the distribution of snow on sea ice.…”