Higher ocean wind speeds during marine cold air outbreaks

Kolstad, Erik W.

doi:10.1002/qj.3068

Cited by 37 publications

(35 citation statements)

References 49 publications

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“…Our focus was limited to the North Atlantic sector of the Arctic. Hence, the results presented here do not necessarily translate to the entire Arctic climate system because the regional differences are too large (e.g., Cavalieri and Parkinson, 2012;Koyama et al, 2017). For example, sea ice coverage in the region was anomalously high and reached far south as a result of the strong southward drift during CP and, albeit weaker, still southward drifts during WP and NP.…”

Section: Summary and Concluding Remarksmentioning

confidence: 86%

Meteorological conditions during the ACLOUD/PASCAL field campaign near Svalbard in early summer 2017

et al. 2018

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Abstract. The two concerted field campaigns, Arctic CLoud Observations Using airborne measurements during polar Day (ACLOUD) and the Physical feedbacks of Arctic planetary boundary level Sea ice, Cloud and AerosoL (PASCAL), took place near Svalbard from 23 May to 26 June 2017. They were focused on studying Arctic mixed-phase clouds and involved observations from two airplanes (ACLOUD), an icebreaker (PASCAL) and a tethered balloon, as well as ground-based stations. Here, we present the synoptic development during the 35-day period of the campaigns, using near-surface and upper-air meteorological observations, as well as operational satellite, analysis, and reanalysis data. Over the campaign period, short-term synoptic variability was substantial, dominating over the seasonal cycle. During the first campaign week, cold and dry Arctic air from the north persisted, with a distinct but seasonally unusual cold air outbreak. Cloudy conditions with mostly low-level clouds prevailed. The subsequent 2 weeks were characterized by warm and moist maritime air from the south and east, which included two events of warm air advection. These synoptical disturbances caused lower cloud cover fractions and higher-reaching cloud systems. In the final 2 weeks, adiabatically warmed air from the west dominated, with cloud properties strongly varying within the range of the two other periods. Results presented here provide synoptic information needed to analyze and interpret data of upcoming studies from ACLOUD/PASCAL, while also offering unprecedented measurements in a sparsely observed region.

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Section: Summary and Concluding Remarksmentioning

confidence: 86%

Meteorological conditions during the ACLOUD/PASCAL field campaign near Svalbard in early summer 2017

et al. 2018

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“…Due to the temperature deficit of CAO air masses with respect to the sea surface temperature (SST), intense upward fluxes of sensible heat ensue (e.g., Brümmer, 1997;Renfrew & Moore, 1999;Wacker et al, 2005). Furthermore, as a result of their initial dryness, the rapid warming by sensible heat fluxes, and the typically high wind speeds (Kolstad, 2017), CAO air masses pick up substantial amounts of moisture via evaporation from the ocean surface, which for intense and large-scale CAOs can exceed 5% of the hemispheric water content poleward of 40 • N and are, thus, an important element of the high-latitude atmospheric water budget (Aemisegger & Papritz, 2018;Papritz & Sodemann, 2018). Consequently, CAO air masses are rapidly transformed from anomalously cold and dry into much warmer and moist air masses.…”

Section: Introductionmentioning

confidence: 99%

On the Thermodynamic Preconditioning of Arctic Air Masses and the Role of Tropopause Polar Vortices for Cold Air Outbreaks From Fram Strait

et al. 2019

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Fram Strait is a hot spot of Arctic cold air outbreaks (CAOs), which typically occur within the northerly flow associated with a strong low tropospheric east‐west pressure gradient between Svalbard and Greenland. This study investigates the processes in the inner Arctic that thermodynamically precondition air masses associated with CAOs south of Fram Strait where they lead to negative potential temperature anomalies often in excess of 15 K. Kinematic backward trajectories from Fram Strait are used to quantify the Arctic residence time and to analyze the thermodynamic evolution of these air masses. Additionally, the study explores the importance of cyclonic tropopause polar vortices (TPVs) for CAO formation south of Fram Strait. Results from a detailed case study and the climatological analysis of the 100 most intense CAOs from Fram Strait in the ERA‐Interim period reveal that (i) air masses that cause CAOs (CAO air masses) reside longer in the inner Arctic compared to those that do not (NO‐CAO air masses), and they originate from climatologically colder regions; (ii) the 10‐day accumulated cooling is very similar for CAO and NO‐CAO air masses indicating that the transport history and northerly origin of the air masses is more decisive for the formation of an intense negative temperature anomaly south of Fram Strait than an enhanced inner Arctic diabatic cooling; (iii) 40% (29%) of the top 40 (100) CAOs are related to a TPV in the vicinity of Fram Strait; (iv) TPVs confine anomalously cold air masses within their associated low tropospheric cold dome leading to enhanced accumulated radiative cooling.

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“…air outbreaks near the Antarctic continent (see e.g. Kolstad, 2017). High surface wind speed in extratropical cyclones is often associated with the cold front, but can occur in both the warm and cold sector of the cyclone and shows a complex mesoscale structure (see e.g.…”

Section: Lv3 -Meridional Cold and Warm Air Advectionmentioning

confidence: 99%

Biogeochemistry and Physics of the Southern Ocean-Atmosphere System Explored With Data Science

Landwehr¹,

Volpi²,

Haumann³

et al. 2021

Preprint

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Abstract. The Southern Ocean is a critical component of Earth’s climate system, but its remoteness makes it challenging to develop a holistic understanding of its processes from the small to the large scale. As a result, our knowledge of this vast region remains largely incomplete. The Antarctic Circumnavigation Expedition (ACE, austral summer 2016/2017) surveyed a large number of variables describing the dynamic state of the ocean and the atmosphere, the freshwater cycle, atmospheric chemistry, ocean biogeochemistry and microbiology. This circumpolar cruise included visits to twelve remote islands, the marginal ice zone, and the Antarctic coast. Here, we use 111 of the observed variables to study the latitudinal gradients, seasonality, shorter term variations, the geographic setting of environmental processes, and interactions between them over the duration of 90 days. To reduce the dimensionality and complexity of the dataset and make the relations between variables interpretable, we applied a sparse Principal Component Analysis (sPCA), which describes environmental processes through 14 latent variables. To derive a robust statistical perspective on these processes and to estimate the uncertainty in the sPCA decomposition, we have developed a bootstrap approach. We identified temporal patterns from diurnal to seasonal cycles, as well as geographical gradients and “hotspots” of interaction. Our results establish connections of oceanic, atmospheric, biological and terrestrial processes in an innovative way, while confirming many well known relations of the Southern Ocean system. More specifically, we identify: the important role of the oceanic circulations, frontal zones, and islands in shaping the nutrient availability that controls biological community composition and productivity; that sea ice predominantly controls sea water salinity, dampens the wave field, and is associated with increased phytoplankton growth and net community productivity possibly due to iron fertilization and reduced light limitation; and clear regional patterns of aerosol characteristics emerged, stressing the role of the sea state, atmospheric chemical processing, as well as source processes near “hotspots” for the availability of cloud condensation nuclei and hence cloud formation. A set of key variables and their combinations, such as the difference between the air and sea surface temperature, atmospheric pressure, sea surface height, geostrophic currents, upper ocean layer light intensity, surface wind speed and relative humidity, played an important role in the majority of latent variables, highlighting their importance for a large variety of processes and the necessity for Earth System Models to represent them adequately. In conclusion, our study highlights the use of sPCA to identify key ocean-atmosphere interactions across physical, chemical, and biological processes and their associated spatio-temporal scales. The sPCA processing code is available as open-access and we believe that our approach is widely applicable to other environmental field studies.

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Higher ocean wind speeds during marine cold air outbreaks

Cited by 37 publications

References 49 publications

Meteorological conditions during the ACLOUD/PASCAL field campaign near Svalbard in early summer 2017

Meteorological conditions during the ACLOUD/PASCAL field campaign near Svalbard in early summer 2017

On the Thermodynamic Preconditioning of Arctic Air Masses and the Role of Tropopause Polar Vortices for Cold Air Outbreaks From Fram Strait

Biogeochemistry and Physics of the Southern Ocean-Atmosphere System Explored With Data Science

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