GNSS transpolar earth reflectometry exploriNg system (G-TERN): mission concept

The global navigation satellite system (GNSS) Transpolar Earth Reflectometry exploriNg system (G-TERN) was proposed in response to ESA's Earth Explorer 9 revised call by a team of 33 multi-disciplinary scientists. The primary objective of the mission is to quantify at high spatio-temporal resolution crucial characteristics, processes and interactions between sea ice, and other Earth system components in order to advance the understanding and prediction of climate change and its impacts on the environment and society. The objective is articulated through three key questions. 1) In a rapidly changing Arctic regime and under the resilient Antarctic sea ice trend, how will highly dynamic forcings and couplings between the various components of the ocean, atmosphere, and cryosphere modify or influence the processes governing the characteristics of the sea ice cover (ice production, growth, deformation, and melt)? 2) What are the impacts of extreme events and feedback mechanisms on sea ice evolution? 3) What are the effects of the cryosphere behaviors, either rapidly changing or resiliently stable, on the global oceanic and atmospheric circulation and mid-latitude extreme events? To contribute answering these questions, G-TERN will measure key parameters of the sea ice, the oceans, and the atmosphere with frequent and dense coverage over polar areas, becoming a “dynamic mapper”of the ice conditions, the ice production, and the loss in multiple time and space scales, and surrounding environment. Over polar areas, the G-TERN will measure sea ice surface elevation (<;10 cm precision), roughness, and polarimetry aspects at 30-km resolution and 3-days full coverage. G-TERN will implement the interferometric GNSS reflectometry concept, from a single satellite in near-polar orbit with capability for 12 simultaneous observations. Unlike currently orbiting GNSS reflectometry missions, the G-TERN uses the full GNSS available bandwidth to improve its ranging measurements. The lifetime would be 2025-2030 or optimally 2025-2035, covering key stages of the transition toward a nearly ice-free Arctic Ocean in summer. This paper describes the mission objectives, it reviews its measurement techniques, summarizes the suggested implementation, and finally, it estimates the expected performance.Peer ReviewedPostprint (published version

GNSS transpolar earth reflectometry exploriNg system (G-TERN): Mission concept

The global navigation satellite system (GNSS) Transpolar Earth Reflectometry exploriNg system (G-TERN) was proposed in response to ESA's Earth Explorer 9 revised call by a team of 33 multi-disciplinary scientists. The primary objective of the mission is to quantify at high spatio-temporal resolution crucial characteristics, processes and interactions between sea ice, and other Earth system components in order to advance the understanding and prediction of climate change and its impacts on the environment and society. The objective is articulated through three key questions. 1) In a rapidly changing Arctic regime and under the resilient Antarctic sea ice trend, how will highly dynamic forcings and couplings between the various components of the ocean, atmosphere, and cryosphere modify or influence the processes governing the characteristics of the sea ice cover (ice production, growth, deformation, and melt)? 2) What are the impacts of extreme events and feedback mechanisms on sea ice evolution? 3) What are the effects of the cryosphere behaviors, either rapidly changing or resiliently stable, on the global oceanic and atmospheric circulation and mid-latitude extreme events? To contribute answering these questions, G-TERN will measure key parameters of the sea ice, the oceans, and the atmosphere with frequent and dense coverage over polar areas, becoming a "dynamic mapper" of the ice conditions, the ice production, and the loss in multiple time and space scales, and surrounding environment. Over polar areas, the G-TERN will measure sea ice surface elevation (&lt;10 cm precision), roughness, and polarimetry aspects at 30-km resolution and 3-days full coverage. G-TERN will implement the interferometric GNSS reflectometry concept, from a single satellite in near-polar orbit with capability for 12 simultaneous observations. Unlike currently orbiting GNSS reflectometry missions, the G-TERN uses the full GNSS available bandwidth to improve its ranging measurements. The lifetime would be 2025-2030 or optimally 2025-2035, covering key stages of the transition toward a nearly ice-free Arctic Ocean in summer. This paper describes the mission objectives, it reviews its measurement techniques, summarizes the suggested implementation, and finally, it estimates the expected performance

Preparing for the unprecedented : Moving towards quantitative understanding of oil spill impacts on Arctic marine biota

The risk of a major oil spill in the Arctic has become a matter of global concern, since climate change is extending the ice-free period and bringing more shipping to the area. The Arctic is already under great pressure from climate change, and an oil spill in this unique and sensitive environment could be a catastrophe for its biota. Fortunately, no major oil spill has happened in the true Arctic yet, but as the probability of one is increasing, we need to prepare for the potential consequences. Understanding the likely impacts of Arctic oil spills could greatly benefit conservation of the area as, for example, spatially and temporally varying risk could be taken into account when selecting shipping routes. Hence, comprehensive knowledge about the impacts of oil spills on Arctic ecosystems is needed. So far, however, knowledge about the likely impacts of oil on Arctic biota is scarce and insufficient for comprehensive risk assessment. The thesis constructs and applies a probabilistic framework for assessing the environmental risk oil spills pose for marine biota in the data-poor Arctic. The work consists of the summary and four research papers. Paper I brings together the current understanding about Arctic oil spills and their environmental impacts, and conceptualizes that knowledge as a probability-based framework that can guide further risk assessment. It further identifies the key Arctic marine functional groups that environmental risk assessment should focus on. Paper II carries out an expert elicitation to quantify the acute oil spill -induced mortality of adult and offspring individuals belonging to each functional group. Paper III develops a vulnerability index describing the acute mortality and the longer-term recovery potential of the functional groups based on scientific and grey literature. Paper IV uses the information collected in papers I–III and combines it with estimates of oil spreading and species distributions to compare the spatiotemporally varying mortality risk for polar bears, ringed seals and walrus in a case study area, the Kara Sea. The results of the thesis suggest that, in general, polar bears and marine birds are most at risk from spilled oil in the Arctic, but there is great variation in the risk depending on the timing of the spill and the type of oil spilled. Moreover, the distribution of biota in relation to shipping routes can have a major impact on the risk the spilled oil poses to them. Furthermore, the amount of ice present at the spill site can alter the risk to biota, as ice cover affects both the spreading of oil and the abundance of species in the vicinity of the oil spill. On an acute scale, medium density oil spilled when ice concentration are relatively low seems to be the worst-case accident scenario when considering the joint impact on all biota, but determining the safest shipping route may prove to be challenging. This thesis offers new insights into the risk that oil spills pose to Arctic biota, and is a step on the way towards a comprehensive understanding of the impact of Arctic oil spills. However, there are still great knowledge gaps, which this thesis both identifies and aims to minimize by suggesting different methods for efficient data collection to benefit risk management related to Arctic shipping. Additional research is needed to evaluate the longer-term impacts of spilled oil and the persistence of oil in cold environments in particular. Furthermore, the need for a valuing method to guide both risk assessment and management is recognized.Arktinen öljyonnettomuus on globaali huoli. Kun ilmastonmuutos pidentää pohjoisen jäätöntä kautta, lisääntyy alueen meriliikenne. Ilmastonmuutos itsessään aiheuttaa suurta painetta arktiselle luonnolle, ja öljyonnettomuus tällä ainutlaatuisella ja herkällä alueella voi johtaa ympäristökatastrofiin. Alueella ei ole toistaiseksi sattunut suurta öljyvuotoa, mutta koska sellaisen todennäköisyys kasvaa laivaliikenteen lisääntyessä, myös seurauksiin tulee varautua. Öljyonnettomuuden seurauksien ymmärtäminen voi hyödyttää arktisen luonnon suojelua jos esimerkiksi ajallisesti ja alueellisesti vaihteleva öljyvuodon aiheuttama riski voidaan huomioida laivareittien valinnassa. Tämä kuitenkin vaatii kattavaa tietoa öljyvuodon vaikutuksista arktiselle ekosysteemille. Toistaiseksi tieto on hajanaista ja riittämätöntä kattavaan riskianalyysiin. Väitöskirja rakentaa todennäköisyyspohjaisen viitekehyksen, jonka avulla voidaan tutkia arktisten öljyvuotojen aiheuttamaa riskiä arktiselle merilajistolle tilanteessa, jossa kovaa dataa on vähän eikä perinteisiä öljymalleja siten voida käyttää. Väitöskirja myös käyttää rakentamaansa viitekehystä riskin kvantifioimiseksi. Työ koostuu tiivistelmästä ja neljästä tutkimusartikkelista. Artikkeli I koostaa nykyisen tiedon arktisista öljyonnettomuuksista ja niiden ympäristövaikutuksista, sekä rakentaa viitekehyksen, jota voidaan käyttää riskianalyysissä. Lisäksi artikkeli identifioi tärkeimmät funktionaaliset lajiryhmät, joihin meriympäristöön keskittyvän riskianalyysin tulisi kohdistua. Artikkeli II suorittaa asiantuntijaelisitaation kvantifioidakseen öljyvuotoihin liittyvää merilajiston akuuttia kuolleisuutta. Artikkeli III kehittää haavoittuvuusindeksin, joka kuvaa sekä merilajiston akuuttia kuolleisuutta että populaatioiden pidemmän aikavälin elpymistä. Artikkeli IV käyttää artikkeleissa I–III kerättyä tietoa ja yhdistää sen arvioihin öljyn leviämisestä sekä lajien levinneisyydestä. Tulosten perusteella verrataan merinisäkkäisiin kohdistuvaa, ajallisesti ja alueellisesti vaihtelevaa riskiä tapaustutkimusalueella, Karanmerellä. Väitöskirjan tulokset osoittavat, että jääkarhut ja merilinnut ovat suurimmassa riskissä öljyonnettomuuden sattuessa, mutta riski vaihtelee suuresti riippuen vuodon ajoituksesta ja vuotaneen öljyn ominaisuuksista. Lisäksi lajien levinneisyys suhteessa laivareittien sijaintiin vaikuttaa riskiin suuresti. Myös jään määrä vuotokohdan läheisyydessä muokkaa eliöstölle kohdistuvaa riskiä koska se vaikuttaa sekä öljyn leviämiseen että lajien levinneisyyteen. Akuutilla aikavälillä vaarallisin onnettomuus näyttäisi olevan keskitiheän öljyn vuotaminen jääpeitteen ollessa kohtalaisen pieni. Turvallisimman laivareitin määrittäminen voi kuitenkin olla vaikeaa, koska eri reitit ja onnettomuusskenaariot aiheuttavat erilaisen riskin eri lajeille. Väitöskirja tuottaa uutta tietoa öljyonnettomuuksien aiheuttamista riskeistä arktiselle eliöstölle, ja on askel kohti öljyvuotojen ympäristövaikutusten kokonaisvaltaista hahmottamista. Aiheeseen liittyy kuitenkin vielä paljon epävarmuutta, ja väitöskirja sekä tunnistaa näiden epävarmuuksien lähteitä että ehdottaa erilaisia keinoja tiedonkeruun tehostamiseksi ja riskinhallinnan parantamiseksi. Tulevaisuudessa lisätietoa tarvitaan erityisesti öljyn pidemmän aikavälin ympäristövaikutuksista sekä öljyn säilymisestä luonnossa kylmissä olosuhteissa. Lisäksi väitöskirja tunnistaa tarpeen arvonmääritysmenetelmälle, joka voi auttaa päätöksentekijöitä vertaamaan ja arvottamaan eri lajeihin kohdistuvaa riskiä

Status of the Global Observing System for Climate

Status of the Global Observing System for Climat

Macrophysical properties and a climatology of Arctic coastal fog in East Greenland

Arctic summer fog is a major transportation hazard and has implications for the cryospheric energy balance. In this thesis, the climatology and macrophysical properties of fog along the coast of East Greenland are explored, and local to mesoscale environmental conditions studied to explain regional differences. Using a combination of long-term synoptic weather observations and Integrated Global Radiosonde Archive data, novel automated methods were developed to classify liquid fog thermodynamic structure and calculate fog top elevation. Six fog types were identified; several of which could be associated with advection fog formation and dissipation processes. Temperature inversions during fog were deeper and stronger compared to non-fog conditions. At Low-Arctic locations fog was geometrically thin and occurred below the temperature inversion. Fog was thicker in the High-Arctic, often penetrating the inversion layer. The radiosonde data analysis and automated methods presented are applicable to any synoptic Arctic weather station with present weather codes.Natural Sciences and Engineering Research Council of Canada; Alberta Innovates Technology Futures