Error attribution and validation of SMOS high-level salinity products with Argo data

European Geosciences Union General Assembly 2015 (EGU2015), 12-17 April 2015, Vienna, Austria.-- 1 pageIn the context of the E-AIMS project (7FP Project No. 284391), the role and suggested improvements of the Argo array in the validation of SMOS sea surface salinity (SSS) have been investigated. Here, a summary of the main results is shown and discussed. The Argo array continues to be the sole component of the ocean observing system to provide routine observations of temperature and salinity profiles at global scale with a time sampling period of about ten days. The observations provided by an Argo profiler are publicly available a few days from being taken (Real Time Mode) after application of automatic quality control filters. Scientific quality data (Delayed Mode) is generated after a human supervised quality control. In this study, the highest quality, delayed mode, near-the-surface data are being used to validate the SSS Level 3 and Level 4 products generated by the SMOS Barcelona Expert Centre (http://cp34-bec.cmima.csic.es). The products being validated here are the weighted binned average (L3), an Optimal Interpolation (OI), and a data fused product exploiting the spatial variability of OSTIA SST. An Argo profile is considered if its quality flags of position and time are equal to one (good), two (probably good), five (value changes) or eight (value interpolated). However, temperature, salinity and pressure data are used only if their quality flags are equal to one (good). The uppermost (but deeper than 0.5 m) salinity measurement is taken as an approximation of the in-situ SSS, but only if the salinity profile allows a robust interpolation of the salinity at 7.5 m (this additional requirement is introduced to ensure that the salinity profile is properly sampled near the surface). At the moment of performing this study, the main drawbacks have been the lag in the Delayed Mode processing, and the lack of salinity observations in the first five meters below the ocean surface. While 5500 profiles in Delayed Mode were available for January 2011, about 1000 were available for December 2013. Valid observations in the top five meters have been 2600 and 235, respectively. Comparison between Argo data and SMOS illustrates some of the systematic deficiencies of the salinity retrieval approach. Among them, land-sea contamination and model deficiencies at low and high temperatures. Moreover, Argo data may illustrate some deficiencies one of the auxiliary fields, namely the Sea Surface Temperature, used in the retrieval approach. When the Argo and SMOS match-up pairs data are properly filtered, the mean and standard deviation of the differences in the latitudinal band of 60S-60N are (L3/OI/L4): -0.00/-0.01/-0.06 and 0.49/0.29/0.28. When match-up pairs are limited to the 30S-30N band the mean and standard deviation are -0.02/-0.03/-0.12 and 0.37/0.23/0.23. While these figures have been found to be robust when Argo observations are taken deeper than five meters, their differ when Argo data is restricted to the first four meters of the ocean. However, more upper-surface measurements are required to elucidate the robustness of these changesPeer Reviewe

El papel de la velocidad oceánica en la variabilidad de la clorofila. Un estudio de modelado en el mar de Alborán

In this work we focus on the Alboran Sea (western Mediterranean) to relate wind field and ocean velocity variability with chlorophyll a (Chl a) behaviour, using a 2-km resolution, coupled 3D ocean circulation-NPZD model (ROMS). The analysis is done in three steps. First, we split the seasonal and residual contribution for the fields under study. Second, we calculate the corresponding empirical orthogonal functions (EOFs) for the seasonal and residual parts. Finally, we relate each pair of variables for both seasonal and residual contribution EOFs. The results reported here allow the links between wind and Chl a to be quantified. We explain these links in terms of the ocean velocity field acting as a driver of Chl a variability. The results show that, although the seasonal part of the Chl a field is modulated by the vertical velocity, the residual component is modulated by the horizontal velocity components. Vertical velocities are responsible, through coastal upwelling, for Chl a bloom enhancement, while horizontal velocities spread coastal Chl a surface blooms off-shore.En este trabajo nos centramos en el mar de Alborán (Mediterráneo Occidental) para relacionar los campos de velocidad del viento y del océano con la variabilidad de la clorofila a (Chl a), utilizando un modelo de circulación 3D-NPZD (ROMS-Fennel) con una resolución de 2 km. El análisis se realiza en tres pasos. En primer lugar, separamos la contribución estacional y el residuo para todos los campos de estudio. En segundo lugar, calculamos las correspondientes funciones ortogonales empíricas (EOFs) para las components estacionales y residuales. Por último, relacionamos cada par de variables para ambos, EOFs estacionales y residuales. Los resultados permiten la cuantificación de las relaciones entre el viento y la clorofila. Explicamos estas relaciones en términos del campo de velocidades del océano que actúa como motor de la variabilidad de la Chl a. Los resultados muestran que, aunque la parte estacional de campo Chl a es modulada por la velocidad vertical, la componente residual es modulada por las componentes de la velocidad horizontal. Las velocidades verticales son responsables, a través de la surgencia costera, de incrementar el valor de la proliferación de Chl a, mientras que las velocidades horizontales extienden estas proliferaciones costeras superficiales a mar abierto

Salinity & Temperature Data assimilation

15 diapositivas.-- SMOS-BEC: Barcelona Expert Centre on Radiometric Calibration and Ocean Salinity.Peer reviewe

The contribution of the Barcelona World Race to improved ocean surface information. A validation of the SMOS remotely sensed salinity

12 pages, 14 figures[EN] The oceans not only cover about three quarters of the Earth’s surface but they also constitute the most relevant climate driver. However, our present knowledge about the oceans is by no means comparable to that of terrestrial or atmospheric systems. Salinity and temperature are key parameters to understand the dynamics of the oceans; but a global network of observations is lacking in spite of valuable data on the oceans that are being accumulated through oceanographic campaigns and by using automated devices, fixed moorings, drifting instrumented buoys, and ships of opportunity. In addition, during the last 40 years, remotely sensed data from satellites have offered almost synoptic information describing the Earth’s surface. This information includes sea surface temperature, which has been routinely monitored; by contrast, ocean surface salinity was not remotely measured until very recently. The Soil Moisture and Ocean Salinity (SMOS) satellite, launched in November 2009, has been the first attempt to obtain remotely sensed surface salinity data. In this context, the Barcelona World Race has provided new opportunities not only to obtain a worldwide sequence of sea surface temperature and salinity data, through one of the participating ships, but also to validate the first salinity data obtained by the SMOS[CAT] Els oceans no solament cobreixen aproximadament tres quartes parts de la superfície de la Terra, sinó que constitueixen el controlador més rellevant del clima. Així i tot, el coneixement que es té actualment dels oceans no es pot comparar amb el que es té dels sistemes terrestres o atmosfèrics. La salinitat i la temperatura són factors clau per entendre la dinàmica dels oceans, però encara no existeix una xarxa global d’observacions. Així i tot, s’estan obtenint dades molt valuoses dels oceans mitjançant campanyes oceanogràfiques i l’ús de dispositius automatitzats, ancoratges o boies a la deriva instrumentades i vaixells d’oportunitat. A més, durant els darrers quaranta anys, les dades obtingudes per teledetecció per satèl·lits han ofert informació gairebé sinòptica sobre la superfície de la Terra, que inclou la temperatura de la superfície del mar, monitoritzada de manera rutinària. En canvi, la salinitat superficial de l’oceà no s'ha pogut obtenir remotament fins fa molt poc. El satèl·lit SMOS (per les sigles en anglès de «humitat del sòl i salinitat oceànica»), llançat el novembre del 2009, n’ha estat el primer intent satisfactori. En aquest context, la Barcelona World Race ha ofert noves oportunitats per obtenir una seqüència de temperatura i salinitat superficials a escala global, a través d’un dels vaixells participants, així com per validar les primeres dades sobre salinitat obtingudes amb l’SMOSThis work was performed with the support of the MIDAS-6 project of the Spanish R+D+I National Plan (AYA2010-22062-C05) and is a contribution of the SMOS Barcelona Expert Centre (SMOS-BEC, CSIC/UPC)Peer reviewe

Energia i societat

El present article inaugura una secció de la revista destinada a utilitzar eines i raonaments familiars als físics per analitzar problemes relacionats amb les interaccions entre energia i societat. Pretenem aportar algunes anàlisis de problemes d'actualitat en aquest camp, sense entrar excessivament en els detalls i les derivacions matemàtiques, però anant més enllà de la pura divulgació. Amb aquest article encetem, doncs, una sèrie que vol donar algunes idees sobre com la formació en física pot aportar una base sòlida per donar sortida laboral als estudiants actuals en un futur mercat que, amb les perspectives actuals i segons les previsions, es presenta canviant i amb uns escenaris notablement diferents del que havia estat fins ara

Energia i societat

El present article inaugura una secció de la revista destinada a utilitzar eines i raonaments familiars als físics per analitzar problemes relacionats amb les interaccions entre energia i societat. Pretenem aportar algunes anàlisis de problemes d'actualitat en aquest camp, sense entrar excessivament en els detalls i les derivacions matemàtiques, però anant més enllà de la pura divulgació. Amb aquest article encetem, doncs, una sèrie que vol donar algunes idees sobre com la formació en física pot aportar una base sòlida per donar sortida laboral als estudiants actuals en un futur mercat que, amb les perspectives actuals i segons les previsions, es presenta canviant i amb uns escenaris notablement diferents del que havia estat fins ara

Evaluation of soil and vegetation response to drought using SMOS soil moisture satellite observations

European Geosciences Union General Assembly 2014 (EGU2014), 27 april - 2 may 2014, Vienna, Austria.-- 1 pageSoil moisture plays an important role in determining the likelihood of droughts and floods that may affect an area. Knowledge of soil moisture distribution as a function of time and space is highly relevant for hydrological, ecological and agricultural applications, especially in water-limited or drought-prone regions. However, measuring soil moisture is challenging because of its high variability; point-scale in-situ measurements are scarce being remote sensing the only practical means to obtain regional- and global-scale soil moisture estimates. The ESA’s Soil Moisture and Ocean Salinity (SMOS) is the first satellite mission ever designed to measuring the Earth’s surface soil moisture at near daily time scales with levels of accuracy previously not attained. Since its launch in November 2009, significant efforts have been dedicated to validate and fine-tune the retrieval algorithms so that SMOS-derived soil moisture estimates meet the standards required for a wide variety of applications. In this line, the SMOS Barcelona Expert Center (BEC) is distributing daily, monthly, and annual temporal averages of 0.25-deg global soil moisture maps, which have proved useful for assessing drought and water-stress conditions. In addition, a downscaling algorithm has been developed to combine SMOS and NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) data into fine-scale (< 1km) soil moisture estimates, which permits extending the applicability of the data to regional and local studies. Fine-scale soil moisture maps are currently limited to the Iberian Peninsula but the algorithm is dynamic and can be transported to any region. Soil moisture maps are generated in a near real-time fashion at BEC facilities and are used by Barcelona’s fire prevention services to detect extremely dry soil and vegetation conditions posing a risk of fire. Recently, they have been used to explain drought-induced tree mortality episodes and forest decline in the Catalonia region. These soil moisture products can also be a useful tool to monitor the effectiveness of land restoration management practices. The aim of this work is to demonstrate the feasibility of using SMOS soil moisture maps for monitoring drought and water-stress conditions. In previous research, SMOS-derived Soil Moisture Anomalies (SSMA), calculated in a ten-day basis, were shown to be in close relationship with well-known drought indices (the Standardized Precipitation Index and the Standardized Precipitation Evapotranspiration Index). In this work, SSMA have been calculated for the period 2010-2013 in representative arid, semi-arid, sub-humid and humid areas across global land biomes. The SSMA reflect the cumulative precipitation anomalies and is known to provide ’memory’ in the climate and hydrological system; the water retained in the soil after a rainfall event is temporally more persistent than the rainfall event itself, and has a greater persistence during periods of low precipitation. Besides, the Normalized Difference Vegetation Index (NDVI) from MODIS is used as an indicator of vegetation activity and growth. The NDVI time series are expected to reflect the changes in surface vegetation density and status induced by water-deficit conditions. Understanding the relationships between SSMA and NDVI concurrent time series should provide new insight about the sensitivity of land biomes to droughtPeer Reviewe

The Impact of Satellite Sea Surface Salinity for Prediction of the Coupled Indo-Pacific System

We assess the impact of satellite sea surface salinity (SSS) observations on seasonal to interannual variability of tropical Indo-Pacific Ocean dynamics as well as on dynamical ENSO forecasts. Our coupled model is composed of a primitive equation ocean model for the tropical Indo-Pacific region that is coupled with the global SPEEDY atmospheric model (Molteni, 2003). The Ensemble Reduced Order Kalman Filter is used to assimilate observations to constrain dynamics and thermodynamics for initialization of the coupled model. The baseline experiment assimilates satellite sea level, SST, and in situ subsurface temperature and salinity observations. This baseline is then compared with experiments that additionally assimilate Aquarius (version 4.0) and SMAP (version 2.0) SSS. Twelve-month forecasts are initialized for each month from Sep. 2011 to Dec. 2016. We find that including satellite SSS significantly improves NINO 3.4 sea surface temperature anomaly validation after 1 out to 12 month forecast lead times. For initialization of the coupled forecast, the positive impact of SSS assimilation is brought about by surface freshening near the eastern edge of the western Pacific warm pool and density changes that lead to shallower mixed layer between 10 degrees South latitude-5 degrees North latitude. SST differences at initialization force wide-spread downwelling favorable curl over most of the tropical Pacific. Over an average forecast, SST remains warmer with SSS assimilation at the eastern edge of the warm pool. This warm SST propagates into the eastern Pacific and drags westerly wind anomalies eastward into the NINO 3.4 region. In addition, salting near the ITCZ (Intertropical Convergence Zone) leads to a deepening of the mixed layer and thermocline near 8 degrees North latitude. These patterns together lead to a funneling effect that provides the background state to amplify equatorial Kelvin waves. We show that the downwelling Kelvin waves are amplified by assimilating satellite SSS and lead to significantly improved forecasts particularly for the 2015 El Nino

Marine heat waves detection in climate warming seas: their evolution in the NW Mediterranean sea

Ponencia presentada en: XII Congreso de la Asociación Española de Climatología celebrado en Santiago de Compostela entre el 19 y el 21 de octubre de 2022.[ES]El aumento extremo y prolongado de la temperatura del mar, una ola de calor marina (MHW), se detecta por comparación con los valores históricos en cada localización y época del año. Así, el correcto establecimiento de los valores de referencia es una tarea clave en la detección de MHW. Al comparar diferentes épocas es necesario considerar dos contribuciones a la evolución de los episodios extremos: la tendencia subyacente de la temperatura y los cambios súbitos de la misma. Siguiendo la definición de Hobday (2016), comparamos las MHW detectadas en caso de corregir o no la tendencia climatológica en la definición de los valores de referencia. Para ello empleamos 38 años de temperatura superficial del mar Mediterráneo proporcionados por el servicio Copernicus. El trabajo se centra alrededor de la reserva marina de las islas Columbretes, donde existe una estación costera de medición de la temperatura del mar integrada en la red T-MedNet. Esto permite vislumbrar el efecto a diferentes profundidades aunque con series temporales más cortas. El resultado es que no corregir la tendencia al definir la referencia subestima el número de eventos detectados en los primeros años de la serie y los sobreestima en los últimos, independientemente de la longitud de la serie. La influencia del cambio climático en la alteración de los ecosistemas marinos debido a las MHW no parece deberse al incremento en la frecuencia de las mismas, sino a que éstas tienen lugar en un mar cada vez más caliente, actuando sobre sistema biológicos con mayor estrés térmico.[EN]Extreme and prolonged increases in the sea temperature, a marine heatwave (MHW), are detected by comparison with historical values at each location and time of year. Thus, the correct estimation of reference values is key in detecting marine heatwaves. In temporally separated epochs comparison, it is necessary to consider two contributions to the evolution of extreme events: the underlying trend in temperature and its sudden changes. Following the definition of Hobday (2016), we compare the detected MHW in case of correcting or not the climatological trend in the definition of the reference values. We use 38 years of the surface temperature of the Mediterranean Sea provided by the Copernicus service. This work is centered around the Columbretes Islands marine reserve, where there is a coastal sea temperature measurement station integrated into the T-MedNet network. This allows us to have a glimpse of the effect at different depths but with shorter time series. The results show that if the long-term trend is not removed from the reference, then the number of events is underestimated in the first years of the series and overestimated in the last ones regardless of the length of the series. The influence of climate change on the alteration of marine ecosystems caused by the MHWs does not seem to be caused by the increased frequency of MHWs, but rather by the fact that the MHWs take place in an increasingly hot sea, acting on biological systems having greater thermal stress.This is a contribution made with the support of the MPA-Engage project (Grant:5216 | 5MED18_3.2_M23_007) and MINKE project (Grant: 101008724). The authors would like to thank the institutional support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S)

Decadal time-series of SeaWiFS retrieved CDOM absorption and estimated CO₂ photoproduction on the continental shelf of the eastern United States

Published algorithms were employed to convert SeaWiFS images of normalized water-leaving-radiance to absorption images of CDOM (chromophoric dissolved organic matter). The best performing algorithm was employed to produce decadal time-series of CDOM monthly composites from 1998 through 2007. Deficits in CDOM absorption coefficient for surface waters across the shelf over the summer were then acquired relative to the uniformly mixed waters prior to and following stratification (spring and fall, respectively). Estimates were attained of the photochemical oxidation of carbon to CO₂ on and beyond the shelf of the Middle Atlantic Bight. Approximately 3–7 × 10¹⁰ g C as CO₂ were estimated to be produced via photooxidation of CDOM over the summertime, highlighting the significance of CDOM photochemistry and pointing out the importance of CO₂ photoproduction at a global scale. In principle, this approach could be applied to global ocean color data