Extreme marine heatwaves and cold-spells events in the Southern North Sea: classifications, patterns, and trends

In this study, we examined the long-term spatiotemporal trend of marine heatwaves (MHW) and marine cold spells (MCS) characteristics in the southern North Sea over the last four decades (1982-2021). We then estimated the difference between their annual mean values and the possible relationship with the large-scale climate modes of natural sea surface temperature (SST) and atmospheric variability using satellite SST data. The SST warming rate was 0.33 ± 0.06°C/decade and was associated with an increase in MHW frequency (0.85 ± 0.39 events/decade) and a decrease in MCS frequency (-0.92 ± 0.40 events/decade) over the entire period. We found a distinct difference between the annual mean values of MHW and MCS characteristics, with a rapid increase in total MHW days (14.36 ± 8.16 days/decade), whereas MCS showed an opposite trend (-16.54 ± 9.06 days/decade). The highest MHW frequency was observed in the last two decades, especially in 2014 (8 events), 2020 (5 events), and 2007 (4 events), which were also the warmest years during the study period. Only two years (2010 and 2013) in the last two decades had higher MCS frequency, which was attributed to the strong negative phase of the North Atlantic Oscillation (NAO). Our results also show that on the annual scale, both the East Atlantic Pattern (EAP) and the Atlantic Multidecadal Oscillation (AMO) play a more important role in the formation of the MHW in the southern North Sea than the other teleconnections (e.g., the NAO). However, the NAO made the largest contribution only in the winter. Strong significant (p < 0.05) positive/negative correlations were found between oceanic and atmospheric temperatures and the frequency of MHW/MCS. This suggests that with global warming, we can expect an increase/decrease in MHW/MCS occurrences in the future

Symposium on Advances in Ocean Observation

The Symposium on Advances in Ocean Observation was held in Terceira, Azores from 3–7 July 2022 to bridge the gap between computational and robotic sciences and ocean sciences by bringing together physical, biological, chemical oceanographers, ocean modelers remote sensing experts, marine robotics and autonomous platform experts, sensor technologists, experts in AI, adaptive sampling, and spatial statistics

Assimilation of sea surface temperature, sea ice concentration and sea ice drift in a model of the Southern Ocean

Current ocean models have relatively large errors and biases in the Southern Ocean. The aim of this study is to provide a reanalysis from 1985 to 2006 assimilating sea surface temperature, sea ice concentration and sea ice drift. In the following it is also shown how surface winds in the Southern Ocean can be improved using sea ice drift estimated from infrared radiometers. Such satellite observations are available since the late seventies and have the potential to improve the wind forcing before more direct measurements of winds over the ocean are available using scatterometry in the late nineties. The model results are compared to the assimilated data and to independent measurements (the World Ocean Database 2009 and the mean dynamic topography based on observations). The overall improvement of the assimilation is quantified, in particular the impact of the assimilation on the representation of the polar front is discussed. Finally a method to identify model errors in the Antarctic sea ice area is proposed based on Model Output Statistics techniques using a series of potential predictors. This approach provides new directions for model improvements

Observación de oportunidad de un Giro argelino al sur de Cabo de Palos (Mediterráneo sudoccidental)

Large anticyclonic eddies can detach from the Algerian Current, forming open-sea Algerian Eddies. These mesoscale structures have been intensively studied by means of sea surface temperature and altimetry data, and using numerical models. However, few studies describe an in situ sampling of their whole vertical structure. Furthermore, the area extending from Cape La Nao (western edge of the Balearic Channels) to the Almería-Orán Front has received very little attention, and it could be considered that there is a gap in our present oceanographic knowledge of this part of the western Mediterranean. An Algerian Eddy lasting for several months was detected in December 2021 to the south of Cape Palos. In order to analyse this eddy, an opportunity sampling was designed taking advantage of the periodic monitoring campaign RADMED 0222. This sampling revealed that the eddy had a baroclinic character, affecting the whole water column. These results suggest that this eddy was generated at the Algerian Current, finally affecting an area close to the eastern Spanish coast. The presence of these structures in this region of the western Mediterranean could alter the southward progression of the Northern Current and even the presence and structure of the Almería-Orán Front.Giros anticiclónicos de gran tamaño pueden desprenderse de la Corriente Argelina, llegando a formar giros en mar abierto. Estas estructuras de mesoescala han sido estudiadas intensamente mediante datos de temperatura superficial del mar, datos de altimetría, y modelos numéricos. Sin embargo, hay pocos trabajos que describan mediante medidas in situ la estructura vertical de estos giros. Al margen de esta circunstancia, la zona que se extiende desde el Cabo La Nao (en el extremo occidental de los Canales Baleares) hasta el Frente Almería-Orán, ha recibido poca atención, pudiéndose considerar que existe una laguna en nuestro conocimiento sobre la oceanografía de esta zona. Un giro anticiclónico fue detectado en diciembre de 2021 al sur de Cabo de Palos, pudiéndose observar durante varios meses. Para analizar este giro se diseñó un muestreo de oportunidad, aprovechando la campaña rutinaria RADMED0222. Este muestreo mostró la estructura baroclina del giro, la cual afectaba a toda su extensión vertical. Los resultados obtenidos también sugieren que el giro se formó en la Corriente Argelina, afectando finalmente a una zona próxima a la costa española. La presencia de este tipo de estructuras en esta región del Mediterráneo Occidental podría afectar a la progresión hacia el sur de la Corriente Septentrional, e incluso a la presencia y estructura del Frente Almería-Orán

Monitoring Black Sea environmental changes from space: New products for altimetry, ocean colour and salinity. Potentialities and requirements for a dedicated in-situ observing system

21 pages, 13 figures, 2 tables, supplementary material https://www.frontiersin.org/articles/10.3389/fmars.2022.998970/full#supplementary-material.-- Data availability statement: The datasets generated for this study can be found on the web interface (http://www.eo4sibs.uliege.be/) and on Zenodo under data doi: 10.5281/zenodo.6397223 with a full documentation that include Products User Manuals (PUM) and Algorithm Theoretical Basis Document (ATBD). All these products are distributed in netCDF files Grégoire et al. (2022). SMOS SSS and CDM products are also available at https://bec.icm.csic.es/bec-ftp-service/In this paper, satellite products developed during the Earth Observation for Science and Innovation in the Black Sea (EO4SIBS) ESA project are presented. Ocean colour, sea level anomaly and sea surface salinity datasets are produced for the last decade and validated with regional in-situ observations. New data processing is tested to appropriately tackle the Black Sea’s particular configuration and geophysical characteristics. For altimetry, the full rate (20Hz) altimeter measurements from Cryosat-2 and Sentinel-3A are processed to deliver a 5Hz along-track product. This product is combined with existing 1Hz product to produce gridded datasets for the sea level anomaly, mean dynamic topography, geostrophic currents. This new set of altimetry gridded products offers a better definition of the main Black Sea current, a more accurate reconstruction and characterization of eddies structure, in particular, in coastal areas, and improves the observable wavelength by a factor of 1.6. The EO4SIBS sea surface salinity from SMOS is the first satellite product for salinity in the Black Sea. Specific data treatments are applied to remedy the issue of land-sea and radio frequency interference contamination and to adapt the dielectric constant model to the low salinity and cold waters of the Black Sea. The quality of the SMOS products is assessed and shows a significant improvement from Level-2 to Level -3 and Level-4 products. Level-4 products accuracy is 0.4-0.6 psu, a comparable value to that in the Mediterranean Sea. On average SMOS sea surface salinity is lower than salinity measured by Argo floats, with a larger error in the eastern basin. The adequacy of SMOS SSS to reproduce the spatial characteristics of the Black Sea surface salinity and, in particular, plume patterns is analyzed. For ocean colour, chlorophyll-a, turbidity and suspended particulate materials are proposed using regional calibrated algorithms and satellite data provided by OLCI sensor onboard Sentinel-3 mission. The seasonal cycle of ocean colour products is described and a water classification scheme is proposed. The development of these three types of products has suffered from important in-situ data gaps that hinder a sound calibration of the algorithms and a proper assessment of the datasets quality. We propose recommendations for improving the in-situ observing system that will support the development of satellite productsThis work has been carried out as part of the European Space Agency contract Earth Observation data For Science and Innovations in the Black Sea (EO4SIBS, ESA contract n° 4000127237/19/I-EF). MG received fundings from the Copernicus Marine Service (CMEMS), the European Union’s Horizon 2020 BRIDGE-BS project under grant agreement No. 101000240 and by the Project CE2COAST funded by ANR(FR), BELSPO (BE), FCT (PT), IZM (LV), MI (IE), MIUR (IT), Rannis (IS), and RCN (NO) through the 2019 “Joint Transnational Call on Next Generation Climate Science in Europe for Oceans” initiated by JPI Climate and JPI Oceans. The research on SMOS SSS has been also supported in part by the Spanish R&D project INTERACT (PID2020-114623RB-C31), which is funded by MCIN/AEI/10.13039/501100011033, funding from the Spanish government through the “Severo Ochoa Centre of Excellence” accreditation (CEX2019-000928-S) and the CSIC Thematic Interdisciplinary Platform TeledetectPeer reviewe

Enhanced SMOS Sea Surface Salinity in the Western Mediterranean Sea: accuracy and mesoscale structures description

European Geosciences Union (EGU) General Assembly 2018, 8-13 April 2018, Vienna, Austria.-- 1 pageThe Mediterranean Sea is a hot spot for climate change. The water balance in the basin is characterized by anexcess of evaporation over precipitation and river runoff, which is compensated by the entrance of fresher waterfrom the Atlantic. This Atlantic water, AW, which spreads through the Mediterranean Sea, determines the surfacecirculation.In the Algerian Basin, AW forms an unstable current that generates fresh-core coastal eddies that propa-gate downstream, eventually offshore. The eddy activity in the region enhances the mixing of the recently enteredAW with the saltier resident water, strongly affecting the spatial distribution of salinity and, therefore, playinga major role in the surface circulation of the Mediterranean Sea. Besides, during winter, in the North WesternMediterranean, deep water convection occurs under the influence of dry and cold northerly winds.In such a context, data from Soil Moisture and Ocean Salinity (SMOS) European Space Agency (ESA)’smission spanning more than 8 years can help to gain a better understanding of the Sea Surface Salinity (SSS)dynamics in the Mediterranean Sea. Unfortunately, this critical area is strongly affected by Radio FrequencyInterference and systematic biases due to the coast contamination (also called Land-Sea contamination). Botheffects impair SMOS SSS retrieval in these areas.A new methodology using a combination of debiased non-Bayesian retrieval, DINEOF (Data InterpolatingEmpirical Orthogonal Functions) and multifractal fusion has been used to improve to improve SMOS SSS fieldsover the North Atlantic Ocean and the Mediterranean Sea. The debiased non-Bayesian retrieval mitigates thesystematic errors produced by the Land-Sea contamination. Besides, this retrieval improves the coverage bymeans of multiyear statistical filtering criteria. This methodology allows obtaining SMOS SSS fields in theMediterranean Sea. However, the resulting SSS suffers from a seasonal (and other time-dependent) bias. Thistime-dependent bias has been characterized by means of specific Empirical Orthogonal Functions (EOFs). Finally,high resolution remotely-sensed Sea Surface Temperature (SST) maps have been used for improving the spatialand temporal resolution of the SMOS SSS maps.The presented methodology practically reduces the error of the previous SMOS SSS in the MediterraneanSea by half. As a result, the SSS dynamics described by the new SMOS maps in the Algerian Basin and theBalearic Front agree with the one described by the TRANSMED in situ SSS time series, and the mesoscalestructures described by SMOS in the Alboran Sea and in the Gulf of Lion coincide with the ones described by thehigh resolution SST satellite imagesPeer Reviewe

Local ensemble assimilation scheme with global constraints and conservation

International audienc