Poleward moisture transport and its influence on precipitation in the Arctic: From case studies to long-term statistics

2020 ◽  
Author(s):  
Melanie Lauer ◽  
Annette Rinke ◽  
Irina Gorodetskaya ◽  
Susanne Crewell
Keyword(s):  
Sea Ice ◽  
Case Studies ◽  
Water Vapour ◽  
Moisture Transport ◽  
Longwave Radiation ◽  
The Arctic ◽  
Vapour Transport ◽  
Water Vapour Transport ◽  
Downward Longwave Radiation

<p>There are many factors which could contribute to the Arctic warming: feedback processes like the lapse rate and ice-albedo feedback, the increasing downward longwave radiation caused by clouds and water vapour, and the reduction of sea ice in summer that leads to absorption of solar radiation and increase in local evaporation and more clouds. But also the atmospheric moisture transport from the lower latitudes can contribute to the surface warming in high-latitudes. This poleward moisture transport is mostly accomplished by extra-tropical cyclones, with especially strong contribution by the Atmospheric Rivers (ARs). ARs are long, narrow bands of enhanced water vapour transport which are responsible for over 90% of the poleward water vapour transport in and across mid-latitudes. Furthermore, they are responsible for producing significant levels of rain and snow. In addition, the greenhouse effect of water vapour and the formation of clouds increase the downward longwave radiation which can cause a thinning and melting of Arctic sea ice and snow.</p><p>In this study, we investigate the contribution of ARs to Arctic precipitation. Firstly, we look into different case studies for which observational data from the campaigns within the Collaborative Research Center “Arctic Amplification: Climate Relevant Atmospheric and Surface Processes, and Feedback Mechanisms (AC)<sup>3</sup>” exist. The data include enhanced observations at/around Svalbard performed during the ACLOUD and the AFLUX campaigns.</p><p>Previous studies have shown that ARs reaching into the Arctic have different origins, including the Atlantic and the Pacific pathways and also Siberia. Here we examine which pathway is more common and which one transports more moisture into the Arctic for these case studies by using existing AR catalogues from global and polar-specific algorithms. Furthermore, the variability of precipitation influences the surface mass and energy balance of polar sea ice and ice sheets. Therefore, we will analyse the influence of ARs on precipitation in terms of frequency, intensity, and type of precipitation (rain or snow) for the different case studies. For this purpose, we will use reanalyses and observational data for the water vapour transport, total precipitation, rain and snow profiles.The occurrence of ARs and its influence on precipitation will be extended from case studies to the long-term statistics (for at least 10 years).</p>

scholarly journals Mechanism of Seasonal Arctic Sea Ice Evolution and Arctic Amplification

2016 ◽  
Author(s):  
Kwang-Yul Kim ◽  
Benjamin D. Hamlington ◽  
Hanna Na ◽  
Jinju Kim
Keyword(s):  
Heat Flux ◽  
Sea Ice ◽  
Air Temperature ◽  
Surface Air Temperature ◽  
Longwave Radiation ◽  
The Arctic ◽  
Turbulent Heat ◽  
Arctic Amplification ◽  
Ice Melting ◽  
Downward Longwave Radiation

Abstract. Sea ice melting is proposed as a primary reason for the Artic amplification, although physical mechanism of the Arctic amplification and its connection with sea ice melting is still in debate. In the present study, monthly ERA-interim reanalysis data are analyzed via cyclostationary empirical orthogonal function analysis to understand the seasonal mechanism of sea ice melting in the Arctic Ocean and the Arctic amplification. While sea ice melting is widespread over much of the perimeter of the Arctic Ocean in summer, sea ice remains to be thin in winter only in the Barents-Kara Seas. Excessive turbulent heat flux through the sea surface exposed to air due to sea ice melting warms the atmospheric column. Warmer air increases the downward longwave radiation and subsequently surface air temperature, which facilitates sea surface remains to be ice free. A 1 % reduction in sea ice concentration in winter leads to ~ 0.76 W m−2 increase in upward heat flux, ~ 0.07 K increase in 850 hPa air temperature, ~ 0.97 W m−2 increase in downward longwave radiation, and ~ 0.26 K increase in surface air temperature. This positive feedback mechanism is not clearly observed in the Laptev, East Siberian, Chukchi, and Beaufort Seas, since sea ice refreezes in late fall (November) before excessive turbulent heat flux is available for warming the atmospheric column in winter. A detailed seasonal heat budget is presented in order to understand specific differences between the Barents-Kara Seas and Laptev, East Siberian, Chukchi, and Beaufort Seas.

Long-term Arctic homogenized radiosondes

2020 ◽  
Author(s):  
Michael Blaschek ◽  
Federico Ambrogi ◽  
Leopold Haimberger
Keyword(s):  
Weather Prediction ◽  
The Arctic ◽  
Radiosonde Data ◽  
Observation System ◽  
Vapour Transport ◽  
Water Vapour Transport ◽  
First Time ◽  
Adjustment Scheme ◽  
Stable Measurement

<p>Radiosonde measurements are potentially valuable indicators of upper air climate change because of their unique long-term availability and their high vertical extent and resolution. The radiosonde network, however, is not a long-term stable measurement system, since it was designed for operational use. Changes in the observation system are frequent and surf the purpose of competitive daily weather prediction, but result in more or less clear breakpoints in the observed long-term time series. These artificial biases need to be removed. We apply a bias adjustment scheme for radiosonde temperatures and humidity based on departures from a recent reanalysis, ERA5 potentially back to 1950. Newly digitized and recovered radiosonde data have been used within ERA5 for the first time. We present long-term bias adjustments and trends as preliminary results. In particular, we focus on the water vapour transport into the Arctic as a result of polar amplification and meridional heat exchange.</p>

scholarly journals Suppression of Arctic sea ice growth by winter clouds and snowfall

2021 ◽  
Author(s):  
Won-il Lim ◽  
Hyo-Seok Park ◽  
Andrew Stewart ◽  
Kyong-Hwan Seo
Keyword(s):  
Sea Ice ◽  
Longwave Radiation ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Ice Thickness ◽  
Sea Ice Thickness ◽  
Ice Growth ◽  
Downward Longwave Radiation ◽  
Arctic Sea ◽  
The Impact

Abstract The ongoing Arctic warming has been pronounced in winter and has been associated with an increase in downward longwave radiation. While previous studies have demonstrated that poleward moisture flux into the Arctic strengthens downward longwave radiation, less attention has been given to the impact of the accompanying increase in snowfall. Here, utilizing state-of-the art sea ice models, we show that typical winter snowfall anomalies of 1.0 cm, accompanied by positive downward longwave radiation anomalies of ~5 W m-2 can decrease sea ice thickness by around 5 cm in the following spring over the Eurasian Seas. This basin-wide ice thinning is followed by a shrinking of summer ice extent in extreme cases. In the winter of 2016–17, anomalously strong warm/moist air transport combined with ~2.5 cm increase in snowfall decreased spring ice thickness by ~10 cm and decreased the following summer sea ice extent by 5–30%. Projected future reductions in the thickness of Arctic sea ice and snow will amplify the impact of anomalous winter snowfall events on winter sea ice growth and seasonal sea ice thickness.

Evaluating atmospheric rivers and their influence on precipitation in the Arctic - comparing observational with reanalysis data

2021 ◽  
Author(s):  
Melanie Lauer ◽  
Annette Rinke ◽  
Irina Gorodetskaya ◽  
Susanne Crewell
Keyword(s):  
Sea Ice ◽  
Water Vapour ◽  
Moisture Transport ◽  
Collaborative Research ◽  
Surface Processes ◽  
Research Center ◽  
The Arctic ◽  
Arctic Amplification ◽  
Feedback Mechanisms ◽  
Atmospheric Rivers

<p>The Arctic as a whole has been experiencing significant warming and moistening with several potential factors at play. In general, the warming amplifies the Arctic hydrological cycle. There are two processes which could affect the water vapour content in the Arctic. These are the enhanced local evaporation due to reduced sea-ice concentration and extent and the modified poleward moisture transport from lower latitudes due to changing circulation patterns. An important contribution to the total poleward moisture transport comes from Atmospheric rivers (ARs). ARs have rare occurrence but are associated with anomalously high moisture transport compared to tropical cyclones. ARs are typically associated with not only moisture but also with significant heat advection. They can bring precipitation as rain and/or snow. Moreover, additional feedbacks can occur: the warming effect of the ARs on the surface, coupled with rain lowering surface albedo, can cause thinning and melting of Arctic sea ice and snow. This, in turn, could increase the relative role of the local evaporation compared to the moisture transported from lower latitudes.</p><p>In this study, we investigate the relationship between the poleward moisture transport by ARs and the precipitation in the Arctic. The focus is on AR events during the ACLOUD (May/June 2017) and AFLUX (March/April 2018) campaign within the Collaborative Research Center “Arctic Amplification: Climate Relevant Atmospheric and Surface Processes, and Feedback Mechanisms (AC)<sup>3</sup>”. For these campaigns, existing AR catalogues with the input of ERA5 reanalyses are used to detect AR events. Six ARs are detected: two coming from Siberia and four from the Atlantic.</p><p>These AR events are analysed in terms of the macro- and microphysical precipitation properties, including frequency, intensity, and type of precipitation (rain or snow).  For this purpose, we use ERA5 reanalyses data for the water vapour transport, precipitation amount and type, rain and snow profiles (convective, large-scale, total), as well as vertical profile of hydrometeors. Reanalysis products are evaluated using a set of observational data (satellite data and ground-based remote sensing measurements). This new multi-parameter, multi-dataset set will allow to investigate the occurrence of ARs and its influence on precipitation in the Arctic for the last decades.</p><p> </p><p>“We gratefully acknowledge the funding by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) –Projektnummer 268020496 –TRR 172, within the Transregional Collaborative Research Center “ArctiC Amplification: Climate Relevant Atmospheric and SurfaCe Processes, and Feedback Mechanisms (AC)3.“</p>

scholarly journals Warm and moist atmospheric flow caused a record minimum July sea ice extent of the Arctic in 2020

2021 ◽  
Author(s):  
Yu Liang ◽  
Haibo Bi ◽  
Haijun Huang ◽  
Ruibo Lei ◽  
Xi Liang ◽  
...  
Keyword(s):  
Sea Ice ◽  
Large Scale ◽  
Extreme Event ◽  
Longwave Radiation ◽  
Decisive Role ◽  
High Energy ◽  
The Arctic ◽  
Sea Ice Extent ◽  
Atmospheric Flow ◽  
Downward Longwave Radiation

Abstract. The satellite observations unveiled that the July sea ice extent of the Arctic shrank to the lowest value in 2020 since 1979, with a major ice retreat in the Eurasian shelf seas including Kara, Laptev, and East Siberian Seas. Based on the ERA-5 reanalysis products, we explored the impacts of warm and moist air-mass transport on this extreme event. The results reveal that anomalously high energy and moisture converged into these regions in the spring months (April to June) of 2020, leading to a burst of high moisture content and warming within the atmospheric column. The convergence is accompanied by local enhanced downward longwave radiation and turbulent fluxes, which is favorable for initiating an early melt onset in the areas with severe ice loss. Once the melt begins, solar radiation played a decisive role in leading to further sea ice depletion due to ice-albedo positive feedback. The typical trajectories of the synoptic cyclones that occurred on the Eurasian side in spring 2020 agree well with the path of atmospheric flow. Assessments suggest that variations in characteristics of the spring cyclones are conducive to the severe melt of sea ice. We argue that large-scale atmospheric circulation and synoptic cyclones act in concert to trigger the exceptional poleward transport of total energy and moisture from April to June to cause this new record minimum of sea ice extent in the following July.

Effect of Test Methods on Apparent Moisture Vapour Transmission of P/V and P/C Fabrics

2014 ◽  
Vol 18 (1) ◽  
pp. 71-79
Author(s):  
Subhasis Das ◽  
V. K. Kothari
Keyword(s):  
Water Vapour ◽  
Transmission Rate ◽  
Test Methods ◽  
Test Method ◽  
Transport Rate ◽  
Vapour Transport ◽  
Vapour Permeability ◽  
Water Vapour Transport ◽  
Moisture Vapour

The moisture vapour permeability properties of a series of almost similar polyesterviscose (P/V) and polyester-cotton (P/C) blended fabrics are investigated. The water vapour transport rate greatly differs depending on the principle of the test methods, even when other parameters are nearly identical, such as air permeability, areal density, porosity and thickness. The water absorption characteristics of fibre seem to be the most important in determining the overall water vapour transport rate. Substitution of polyester for viscose and cotton in P/V and P/C blended fabrics respectively, reduces the water transport rate of the fabrics in a long term method. It is found that the P/C blended fabrics show greater water vapour transport than the corresponding P/V fabrics when a long term test method is used; however, the P/V fabrics show relatively higher water vapour permeability than the P/C fabrics when short duration tests are carried out by using the Permetest and moisture vapour transmission rate (MVTR) cell methods

scholarly journals Strong Dependence of Wintertime Arctic Moisture and Cloud Distributions on Atmospheric Large-Scale Circulation

2019 ◽  
Vol 32 (24) ◽  
pp. 8771-8790 ◽  
Author(s):  
Tiina Nygård ◽  
Rune G. Graversen ◽  
Petteri Uotila ◽  
Tuomas Naakka ◽  
Timo Vihma
Keyword(s):  
North Atlantic ◽  
Moisture Transport ◽  
Large Scale ◽  
Strong Dependence ◽  
Longwave Radiation ◽  
The Arctic ◽  
Large Scale Circulation ◽  
The North ◽  
Downward Longwave Radiation ◽  
The Impact

Abstract This study gives a comprehensive picture of how atmospheric large-scale circulation is related to moisture transport and to distributions of moisture, clouds, and surface downward longwave radiation in the Arctic in winter. Anomaly distributions of the abovementioned variables are compared in 30 characteristic wintertime atmospheric circulation regimes, which are allocated from 15 years (2003–17) of mean sea level pressure data of ERA-Interim reanalysis applying the self-organizing map method. The characteristic circulation regimes are further related to known climate indices—the North Atlantic Oscillation (NAO), the Arctic Oscillation (AO), and Greenland blocking index—as well as to a frequent high pressure pattern across the Arctic Ocean from Siberia to North America, herein called the Arctic bridge. Effects of large-scale circulation on moisture, cloud, and longwave radiation are to a large extent occurring through the impact of horizontal moisture transport. Evaporation is typically not efficient enough to shape those distributions, and much of the moisture evaporated in the Arctic is transported southward. The positive phase of the NAO and AO increases moisture and clouds in northern Europe and the eastern North Atlantic Ocean, and a strong Greenland blocking typically increases those in the southwest of Greenland. When the Arctic bridge is lacking, the amount of moisture, clouds, and downward longwave radiation is anomalously high near the North Pole. Our results reveal a strong dependence of moisture, clouds, and longwave radiation on atmospheric pressure fields, which also appears to be important from a climate change perspective.

Extreme Sea Ice Loss over the Arctic: An Analysis Based on Anomalous Moisture Transport

2016 ◽  
Author(s):  
Marta Vázquez ◽  
Raquel Nieto ◽  
Anita Drumond ◽  
Luis Gimeno
Keyword(s):  
Sea Ice ◽  
Moisture Transport ◽  
The Arctic

The implications of selected processing methods on satellite altimetry derived sea ice thickness state and trends in the seasonal ice zone

2021 ◽  
Author(s):  
Isolde Glissenaar ◽  
Jack Landy ◽  
Alek Petty ◽  
Nathan Kurtz ◽  
Julienne Stroeve
Keyword(s):  
Sea Ice ◽  
Snow Depth ◽  
Satellite Altimetry ◽  
Region Of Interest ◽  
The Arctic ◽  
Ice Thickness ◽  
Sea Ice Thickness ◽  
Baffin Bay ◽  
The Impact

<p>The ice cover of the Arctic Ocean is increasingly becoming dominated by seasonal sea ice. It is important to focus on the processing of altimetry ice thickness data in thinner seasonal ice regions to understand seasonal sea ice behaviour better. This study focusses on Baffin Bay as a region of interest to study seasonal ice behaviour.</p><p>We aim to reconcile the spring sea ice thickness derived from multiple satellite altimetry sensors and sea ice charts in Baffin Bay and produce a robust long-term record (2003-2020) for analysing trends in sea ice thickness. We investigate the impact of choosing different snow depth products (the Warren climatology, a passive microwave snow depth product and modelled snow depth from reanalysis data) and snow redistribution methods (a sigmoidal function and an empirical piecewise function) to retrieve sea ice thickness from satellite altimetry sea ice freeboard data.</p><p>The choice of snow depth product and redistribution method results in an uncertainty envelope around the March mean sea ice thickness in Baffin Bay of 10%. Moreover, the sea ice thickness trend ranges from -15 cm/dec to 20 cm/dec depending on the applied snow depth product and redistribution method. Previous studies have shown a possible long-term asymmetrical trend in sea ice thinning in Baffin Bay. The present study shows that whether a significant long-term asymmetrical trend was found depends on the choice of snow depth product and redistribution method. The satellite altimetry sea ice thickness results with different snow depth products and snow redistribution methods show that different processing techniques can lead to different results and can influence conclusions on total and spatial sea ice thickness trends. Further processing work on the historic radar altimetry record is needed to create reliable sea ice thickness products in the marginal ice zone.</p>

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