ID:15 Arctic sea ice changes: Causes and their effect on weather and climate in lower latitudes

22 February 2023 | 08:30 - 10:00 (GMT+1) 
22 February 2023 | 10:30 - 12:30 (GMT+1) 

Open Session - HYBRID

 

Room: Hörsaal 1

 

Session Conveners: Avinash Kumar (National Centre for Polar and Ocean Research, Ministry of Earth Sciences, India); Rohit Srivastava (National Centre for Polar and Ocean Research, Ministry of Earth Sciences, India); Seong-Joong Kim (Korea Polar Research Institute, Republic of Korea)

 

Session Description: 

The Arctic is linked to the global system through a variety of direct and indirect mechanisms. There are many causes by which Arctic sea ice is changing rapidly. Anthropogenic activities have a significant impact on Arctic sea ice changes. The rapid increase in Greenhouse gases and aerosols can have an important role in warming over the Arctic region. The warming of the Arctic is leading to the dramatic thinning and retreat of sea ice, glaciers, the thawing of permafrost, and the significant warming of the Arctic Ocean surface. Together, Arctic sea ice and atmosphere regulate complex physical and biological processes and occurrences on a global scale. Presently, the majority of climate change studies conducted by scientists and researchers focus on Arctic warming and its relationship to lower latitude regions. This session invites observational and model-based studies on Arctic ocean-atmosphere processes and its teleconnection with lower latitudes, with an emphasis on the following topics:

• Arctic sea ice variabilities over the paleo-present and future timescales
• Arctic sea ice variability linkages with the mid-latitude precipitation and temperature patterns;
• Synergistic effects of Arctic Amplification on the summer circulation in mid-latitudes and favouring in the extreme heatwaves/cold waves event, heavy rainfall, and frequent cyclones;
• Intermittency of teleconnections between Arctic and lower-latitude: how the climatic oscillations (NAO, AO, PDO, AMO and ENSO) are influenced through the lower to upper-level atmospheric pathways;
• Low Arctic sea ice cover is linked to the changes in mid-latitude pressure and wind patterns and resulting in increased PM10 concentration events;
• Arctic Aerosols variability: sources, transport, and sinks of Greenhouse gases and aerosols over the Arctic;
• Arctic Aerosols impacts: on Arctic warming, sea-ice changes, and the association with the low latitude weather patterns.

 

Presentations: 

• unfold_moreThe role of the Scandinavian blocking for pathways of Arctic-midlatitude linkages

  Dörthe Handorf¹; Raphael Köhler¹; Ines Höschel¹; Johannes Riebold¹; Sara Khosravi¹; Ralf Jaiser^{1
  1}Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research

  Abstract:

  Despite an improved understanding of mechanisms underlying Arctic-midlatitude linkages over recent years, there is still no consensus, if and how much Arctic amplification contributes to the observed winter cooling over Eurasia. Observational studies have shown that negative temperature anomalies over Eurasia occur more frequently in winters with deep warming over the Barents‐Kara Seas. Our analysis of atmospheric circulation regimes over the North-Atlantic Eurasian region shows that deep warming over the Barents‐Kara Seas is related to a high probability of the occurrence of the Scandinavian-Ural blocking regime (SUB), and subsequent large positive anomalies of meridional energy transport into the Arctic via the North-Atlantic pathway. CMIP/AMIP model simulations miss deep warming trends since 1980. We investigate the critical role of the representation of the SUB in model simulations with the global atmospheric model ECHAM6 forced by sea surface temperature (SST) and sea-ice anomalies representing recent past, present and future conditions. We detect a nonlinear response in terms of changes of the frequency of occurrence of SUB in early winter for the recent past and for the future that is either related to SST or sea ice changes. Furthermore, we analyze the sensitivity of vertical propagation of planetary waves related to these SUB blocking changes, which is critical for the initiation of a stratospheric pathway of Arctic-midlatitude linkages.

• unfold_moreRole of lower atmosphere air temperature on decadal sea-ice variability in the Arctic

  Arnab Mukherjee¹; M Ravichandran²; Nuncio Murukesh^{1
  1}National Centre for Polar and Ocean Research; ²Ministrey of Earth Science

  Abstract:

  In our study, we have investigated the role of recent decadal change (decade of 2010–2019 and 2000–2009) of lower atmosphere air temperature (LaAT) on decadal sea-ice variability in the Arctic using a global sea-ice couple model, known as Modular Ocean Model of Sea Ice Simulator (MOM-SIS). Our model MOM-SIS successfully simulates decadal change of sea-ice concentration (SIC) at all four seasons of Arctic, which includes winter (December–February), spring (March–May), summer (June–August) and autumn (September–November).In the order to quantify the role of LaAT, we have performed a model experiment by replacing Arctic (north of 55 o N) real-time LaAT forcing in the model to its daily climatological values. We have observed decadal increase of LaAT in the Arctic. Our model analysis shows that decadal variability of LaAT forcing play a significant role for decadal decrease of SIC in the Arctic during summer and autumn seasons. During winter and spring seasons, the impact of LaAT mostly restricted in the Norwegian, Barents and Kara sea regions of the Arctic. Using mixed layer heat budget analysis, we have found that increased change of net heat flux during summer and autumn seasons after removing decadal variability of LaAT forcing play a most significant role related to decadal weakening of SIC during above two seasons.

• unfold_moreMISR Arctic and Antarctic Sea Ice Albedo 2000-2022 Product Creation and Trend Analysis

  Jan-Peter Muller
  University College London

  Abstract:

  Sea ice albedo is a key climate variable that affects the Earth’s radiation budget. Spatio-temporal variation of sea ice albedo can be retrieved from pre existing satellite observation processing chains such as the CLARA2-SAL product. However, currently there is only one albedo product which is derived from instantaneous multi-angle measurements and that is from MISR. In this study, we present a data fusion method using the high accuracy near simultaneous sampling of the Multiangle Imaging SpectroRadiometer (MISR) generated at the Langley Research Center applying a Rayleigh atmospheric correction, with the MOD35 cloud mask which is part of the MOD29 Surface Temperature and Ice Extent product derived from the Moderate Imaging Spetroradiometer (MODIS), both onboard the Terra satellite. As the accuracy of MOD29 cloud mask is assessed at >90%, this synergistic method can retrieve an improved BHR of the Arctic sea ice between April and September of each year from 2000 to 2022, and of the Antarctic sea ice between September and March of each year from 2000 to 2022. For both polar regions, we create four daily sea ice products consisting of different averaging time window (±1 day, ±3 days, ±7 days and ±15 days), each containing the number of samples, mean and standard deviation. For all four MISR cloud-free daily sea ice products, we derive 1km, 5km and 25km spatial resolutions. We perform an assessment of the day-of-year trend of sea ice BHR between 2000 and 2022 for the Arctic and the Antarctic, confirming a continuing decline of sea ice shortwave albedo in the Arctic depending on the day of year and length of observed time window, and providing a novel sea ice shortwave albedo product analysis for the Antarctic.

• unfold_moreRelationship between Azores High and Indian summer monsoon

  Ramesh Kumar Yadav
  Indian Institute of Tropical Meteorology

  Abstract:

  The interannual variation of Indian summer monsoon (ISM) not only affects millions of people in India, but also the global weather and climate. The teleconnections of this variation are not stable. A dominant mode of the recent four decades ISM rainfall shows west-east dipole pattern with above normal rainfall towards west and central India and subdued rainfall towards the east and northeast India, and is related to the vigorous Azores High. The vigorous Azores High is accompanied by enhanced subsidence resulting in well-built widespread upper-troposphere convergence. This forms the meridional vorticity dipole consisting of anomalous cyclonic and anti-cyclonic circulation at 30ºN and 50ºN, respectively. The meridional vorticity dipole increases the Asian jet at its entrance. In addition, the widespread North Atlantic convergence boosts the Rossby wave source. The cascading down Rossby wave train imposes successive negative, positive and negative Geopotential height (GPH) anomalies over north Mediterranean, northwest of India and northeast of India, respectively. The negative GPH anomaly at the north Mediterranean further increases the Asian jet towards the Caspian Sea. The increased Asian jet strengthens the monsoon circulation through the 'silk-road' pattern. While, the dipole GPH anomalies north of India shift the core of the Tibetan High westward triggering monsoon activity towards the west and central India and subdued monsoon over east and northeast India, forming an anomalous west-east dipole rainfall pattern and vice-versa. Future work should examine the extent to which these teleconnections are represented in the climate forecast models to aid the seasonal prediction of ISM rainfall.

• unfold_moreInvestigating the Passive Microwave Sea Ice Edge Estimation in Baffin Bay, 2013-2021

  Armina Soleymani¹; K. Andrea Scott^{1
  1}Norwegian Meteorological Institute

  Abstract:

  Sea ice along Baffin Island is one of the primary sections of the Northwest Passage. Sea ice retreat and increased shipping traffic may increase pollution, threatening wildlife and biodiversity. Therefore, it is of interest to monitor sea ice in this region. Passive microwave (PM) products are essential for long-term planning for ship navigation, wildlife studies, and climate monitoring. The ASI, NT2, and BT, three PM algorithms, are used in this study to determine the daily and monthly sea ice edge (SIE). In order to compare the PM SIEs (daily and monthly) with the daily ice charts from Canadian Ice Service, we introduced an edge-length-based displacement measure called edge displacement error (EDE). Results indicated that the EDE has the highest value and greatest day-to-day variability in November for all three PM algorithms since the ice edge is diffused in November as thin ice is emerging (freeze-up period). The ice edge location from the ice chart does not vary significantly on a day-to-day basis in January. The EDE has the lowest value in January for all three PM algorithms. According to our assessment, daily ice charts (available at a higher temporal frequency than regional/weekly ice charts) are helpful in SIE monitoring during the freeze-up period when SIE locations fluctuate frequently and can provide insight into these fluctuations. This study can assist in selecting an appropriate PM SIC product or in bias-correcting a PM product for fusion with ice charts or other SAR-based products.

• unfold_moreCohesive influence of Greenland Sea ice, Eurasian snow and ENSO on the diverse nature of South and East Asian Monsoons

  Amita Prabhu¹; Govindan Pandithurai^{1
  1}Indian Institute of Tropical Meteorology

  Abstract:

  Mutual impacts of Greenland Sea ice, Eurasian Snow, and ENSO (El Niño–Southern Oscillation) on out-of-phase relationship between Indian Summer Monsoon (ISM) and Korean Summer Monsoon (KSM) have been investigated through observational and numerical experiments. Results reveal that non-linear responses of Indian and Korean summer rainfall to ENSO and Greenland Sea ice forcing prevail when both the events co-occur. Above normal Greenland Sea ice along with a con-current La Niña showed a distinct in-phase relationship with ISM while having an out-of-phase relationship with KSM. Further, below (above) normal Greenland sea ice during boreal autumn causes anomalous low (high) pressure surrounding Greenland, which may be associated with barotropic +west/−east or –west/+east dipole pattern, respectively, over Eurasia during subsequent winter and spring seasons. Further, this pattern leads to positive (negative) snow depth anomaly over western Eurasia while having an opposite snow tendency over eastern Eurasia in subsequent spring. Furthermore, this variability in Eurasian snow pattern may play a crucial role on the contrasting pattern of ISM and KSM. Furthermore, co-occurrence of ENSO variability also generates high- and low-pressure anomaly patterns over the Indian Ocean that may be related to unfavourable or favourable ISM, respectively, while influencing negative or positive phases of a Pacific Japan (PJ)-like teleconnection pattern that may be related to unfavourable or favourable KSM, respectively. Therefore, coexisting ENSO forcing may play a dominant role in ISM and KSM, but Greenland Sea ice forcing and Eurasian snow variation intensify an out-of-phase relationship between the south and East Asian summer monsoons.

• unfold_moreInfluence of Arctic Sea Ice Extent on South Asian Monsoon during Mid-Piacenzian Warm Period

  Manish Tiwari¹; Padmasini Behera¹; Vikash Kumar^{1
  1}National Centre for Polar and Ocean Research

  Abstract:

  Arctic sea ice extent (SIE) is decreasing at an alarming rate as a result of global warming, with observations surpassing model estimates. A few short-term time-series studies have found that reducing Arctic SIE can impact the monsoon via atmospheric routes. With similar CO2 concentrations, the late Pliocene, particularly the Mid-Piacenzian Warm Period (MPWP, roughly 3 million years ago), is considered the closest approximation to the present climate. We used geochemical proxies in sediment collected during IODP Expedition 355 from the eastern Arabian Sea to reconstruct South Asian monsoon variability during the late Pliocene. During the MPWP and at 2.9 Ma, we identify two distinct phases of monsoon intensification. Various dynamical and thermodynamic processes, including Arctic SIE variability, affect the South Asian monsoon. Comparison with an Arctic SIE record from the late Pliocene shows that lower SIE results in a stronger South Asian monsoon while higher SIE is linked with a weaker monsoon. Our findings contribute to a better understanding of how the South Asian monsoon could behave in the face of global warming, as well as how the Arctic SIE might impact it.

• unfold_moreArctic to tropics, whether a two way teleconnection mechanism exists?

  Nuncio Murukesh¹; Sourav Chatterjee^{1
  1}National Centre for Polar and Ocean Research

  Abstract:

  This study explore the role of tropical- polar teleconnection in the northern hemisphere. In the first place we examine a strong heat flux event in Ny Alesund Svalbard. The reason for the unusual high temperature during winter was strong southerlies associated with a high pressure system over Northern Europe. Coincidentaly, MJO was active in the Western Pacific and maritime continent. During the event Rossby wave trains emanating from western Pacific was traced all the way to the northern Europe, accentuating the high pressure anomalies over Europe. On the other hand, it has been noted that Barents and Kara sea loss sea-ice. There is an intra-decadal out-of-phase co-variability between JJA sea-ice extent in the Kara Sea and frequency of extreme Indian summer Monsoon Rainfall over India. Large scale circulation anomalies associated with decadal sea-ice loss in the Barents-Kara sea strengthen the subtropical high over Asia, a major feature influencing the Indian summer monsoon. Further analysis reveal rossbywave trains induced by the sea-ice decline impact the circulation anomalies over Asia. Thus, there seems to be a two way teleconnection mechanism between the Arctic and tropics. We explore the details in the study.

• unfold_moreRole of Arctic Oscillation and North Atlantic Oscillation in modulating Arctic Sea Ice Concentration

  Shravan Kumar¹; Pranab Deb^{1
  1}Indian Institute of Technology Kharagpur

  Abstract:

  The rapid decline of Arctic sea ice in recent decades is one of the main concerns for climate science community. The study of Arctic sea ice variability has emerged as a major focus of climate research, primarily because of its impact on atmospheric circulations and the climate change in mid-latitudes as well as on the global energy balance. This study focused on two main atmospheric circulations in Arctic: Arctic Oscillation and North Atlantic oscillation. The role on these two oscillations on the Arctic sea ice is studied using composite analysis technique during the melt season (June-July-August) for the period 1979-2020. We examine the thermodynamical and dynamical effect of positive/negative phases of AO and NAO on Arctic sea ice, and demonstrated that the dynamical effect has more influence on sea ice concentration by using sea ice budget equation by Holland and Kimura(2016) . The sea ice motion and surface winds are accountable for the increase in the sea ice concentration when the temperatures are high and vice-versa. The temperature is high during positive phase of AO also the sea ice concentration is high whereas during negative phase of NAO the opposite effect takes place. During these phases the accumulation of sea ice is due the sea ice drift and the surface winds which is independent of the surface temperature.

• unfold_morePossible linkages between spring Arctic Sea ice and Indian summer monsoon rainfall

  Juhi Yadav¹; Rohit Srivastava¹; Avinash Kumar¹; Seong Joong Kim²; Rahul Mohan¹; M Ravichandran^{3
  1}National Centre for Polar Ocean Research; ²Korea Polar Research Institute; ³Ministry of Earth Sciences

  Abstract:

  The Arctic sea ice is one of the most rapidly changing components of the global climate system. The substantial changes in the Arctic have a profound impact on the climatic patterns of the Earth through the interrelated atmospheric and ocean system. This study investigated the relationship between Arctic Sea ice loss and Indian summer monsoon rainfall (ISMR) using singular value decomposition (SVD), Empirical Orthogonal Function (EOF) and regression/composite analysis. Using SVD, it is revealed that spring Arctic Sea ice concentration (SIC) and ISMR accounts for 68.2% of the total covariance. The leading ISMR EOF pattern has a significant positive correlation with spring SIC in the Central Arctic and a negative correlation in the Barents Kara Sea. These findings imply that more (less) spring Arctic SIC plays a crucial role in determining the increase (decrease) in the ISMR. In addition, possible pathways from preceding Arctic SIC to ISMR are examined and discussed. The sea ice has a long memory, which is responsible for the variations in the intensity of jet streams and upper atmospheric circulation. Further these variations result in atmospheric instability conducive to a weak or strong Indian monsoon.

• unfold_moreInvestigation of aerosols properties over the Arctic region using a regional climate model

  Rohit Srivastava
  National Centre for Polar Ocean Research

  Abstract:

  Arctic amplification is the faster increase in the mean surface temperature of the Arctic region than the global mean value. It could be due to the complex feedback mechanism such as the decrease in sea ice extent, which can influence the global radiation balance by reducing the surface albedo. The positive feedback can lead to more rapid ice loss. Aerosols play a crucial role in the global climate system, including the Arctic. Aerosols can perturb the radiative balance by scattering and absorbing the incoming solar and outgoing terrestrial radiation and by altering the cloud scattering and lifetime. Black Carbon (BC) (which is generated by biomass and fossil fuel burning) can trap radiation and warm the atmosphere; and are the second strongest contributor to global warming after carbon dioxide. The simulations of the Weather Research and Forecasting model coupled with Chemistry (WRF-CHEM) were investigated and compared with the aerosol observations over the Arctic regions. The model simulations were performed at a horizontal grid resolution of 30 km × 30 km. BC and Organic Carbon (OC) mass were found to be higher over the Arctic region during January-February-March, while lower during September-October. Higher BC mass can be attributed to transport from nearby (mid-latitude) regions during winter. The enhancement of anthropogenic aerosols over the highly reflecting snow surface can lead to positive forcing and result in more warming in the region and hence reducing the ice more rapidly. The detailed results on aerosol properties in recent years over the Arctic will be presented and discussed.