scholarly journals Major improvement of altimetry sea level estimations using pressure derived corrections based on ERA-interim atmospheric reanalysis

2016 ◽  
Author(s):  
L. Carrere ◽  
Y. Faugère ◽  
M. Ablain
Keyword(s):  
Shallow Water ◽  
Sea Level ◽  
Positive Impact ◽  
Regional Scale ◽  
Atmospheric Correction ◽  
Deep Ocean ◽  
Global Ocean ◽  
Strong Impact ◽  
Residual Variance ◽  
The Impact

Abstract. New Dynamic Atmospheric Correction (DAC) and Dry Tropospheric (DT) correction derived from the ERA-Interim meteorological reanalysis have been computed on the 1992-2013 altimeter period. Using these new corrections improves significantly sea-level estimations for short temporal signals (< 2 months); the impact is stronger if considering old altimeter missions (ERS-1, ERS-2, TP), for which DAC_ERA allows reducing the residual variance at crossovers by more than 10 cm2 in the Southern Ocean and in some shallow water regions. The impact of DT_ERA is also significant in the southern high latitudes for these missions. Using the ERA-interim forcing has the greatest positive impact on the first decade of altimetry, then this impact diminishes until giving similar results as the operational forcing from year 2002. Concerning more recent missions (Jason-1, Jason-2, and Envisat), results are very similar between ERA-Interim and ECMWF based corrections: on average on global ocean, the operational DAC becomes slightly better than DAC_ERA only from year 2006, likely due to the switch to a higher resolution of operational forcing. At regional scale, both DACs are similar in deep ocean but DAC_ERA raises the residual crossovers variance in some shallow water regions. On the second decade of altimetry, unexpectedly DT_ERA still gives better results compared to the operational DT. Concerning climate signals, both DAC_ERA and DT_ERA have a low impact on global MSL trend, but they can have a strong impact on long-term regional trends estimation, until several mm/yr locally.

scholarly journals Major improvement of altimetry sea level estimations using pressure-derived corrections based on ERA-Interim atmospheric reanalysis

Ocean Science ◽  
2016 ◽  
Vol 12 (3) ◽  
pp. 825-842 ◽  
Author(s):  
Loren Carrere ◽  
Yannice Faugère ◽  
Michaël Ablain
Keyword(s):  
Shallow Water ◽  
Sea Level ◽  
Regional Scale ◽  
Atmospheric Correction ◽  
Deep Ocean ◽  
Global Ocean ◽  
Strong Impact ◽  
Global Mean Sea Level ◽  
Along Track ◽  
The Impact

Abstract. The new dynamic atmospheric correction (DAC) and dry tropospheric (DT) correction derived from the ERA-Interim meteorological reanalysis have been computed for the 1992–2013 altimeter period. Using these new corrections significantly improves sea level estimations for short temporal signals (< 2 months); the impact is stronger if considering old altimeter missions (ERS-1, ERS-2, and Topex/Poseidon), for which DAC_ERA (DAC derived from ERA-Interim meteorological reanalysis) allows reduction of the along-track altimeter sea surface height (SSH) error by more than 3 cm in the Southern Ocean and in some shallow water regions. The impact of DT_ERA (DT derived from ERA-Interim meteorological reanalysis) is also significant in the southern high latitudes for these missions. Concerning more recent missions (Jason-1, Jason-2, and Envisat), results are very similar between ERA-Interim and ECMWF-based corrections: on average for the global ocean, the operational DAC becomes slightly better than DAC_ERA only from the year 2006, likely due to the switch of the operational forcing to a higher spatial resolution. At regional scale, both DACs are similar in the deep ocean but DAC_ERA raises the residual crossovers' variance in some shallow water regions, indicating a slight degradation in the most recent years of the study. In the second decade of altimetry, unexpectedly DT_ERA still gives better results compared to the operational DT. Concerning climate signals, both DAC_ERA and DT_ERA have a low impact on global mean sea level rise (MSL) trends, but they can have a strong impact on long-term regional trends' estimation, up to several millimeters per year locally.

On the impact of sea ice in a global ocean circulation model

1997 ◽  
Vol 25 ◽  
pp. 111-115 ◽  
Author(s):  
Achim Stössel
Keyword(s):  
Southern Ocean ◽  
Sea Ice ◽  
Ocean Circulation ◽  
General Circulation ◽  
Thermohaline Circulation ◽  
Circulation Model ◽  
Deep Ocean ◽  
Global Ocean ◽  
Convective Activity ◽  
The Impact

This paper investigates the long-term impact of sea ice on global climate using a global sea-ice–ocean general circulation model (OGCM). The sea-ice component involves state-of-the-art dynamics; the ocean component consists of a 3.5° × 3.5° × 11 layer primitive-equation model. Depending on the physical description of sea ice, significant changes are detected in the convective activity, in the hydrographic properties and in the thermohaline circulation of the ocean model. Most of these changes originate in the Southern Ocean, emphasizing the crucial role of sea ice in this marginally stably stratified region of the world's oceans. Specifically, if the effect of brine release is neglected, the deep layers of the Southern Ocean warm up considerably; this is associated with a weakening of the Southern Hemisphere overturning cell. The removal of the commonly used “salinity enhancement” leads to a similar effect. The deep-ocean salinity is almost unaffected in both experiments. Introducing explicit new-ice thickness growth in partially ice-covered gridcells leads to a substantial increase in convective activity, especially in the Southern Ocean, with a concomitant significant cooling and salinification of the deep ocean. Possible mechanisms for the resulting interactions between sea-ice processes and deep-ocean characteristics are suggested.

scholarly journals Consistency of the current global ocean observing systems from an Argo perspective

Ocean Science ◽  
2014 ◽  
Vol 10 (3) ◽  
pp. 547-557 ◽  
Author(s):  
K. von Schuckmann ◽  
J.-B. Sallée ◽  
D. Chambers ◽  
P.-Y. Le Traon ◽  
C. Cabanes ◽  
...  
Keyword(s):  
Sea Level ◽  
Heat Content ◽  
Deep Ocean ◽  
Global Ocean ◽  
Regional Variability ◽  
Tropical Ocean ◽  
Steric Sea Level ◽  
Ocean Observing ◽  
Ocean Observing Systems ◽  
Observing Systems

Abstract. Variations in the world's ocean heat storage and its associated volume changes are a key factor to gauge global warming and to assess the earth's energy and sea level budget. Estimating global ocean heat content (GOHC) and global steric sea level (GSSL) with temperature/salinity data from the Argo network reveals a positive change of 0.5 ± 0.1 W m−2 (applied to the surface area of the ocean) and 0.5 ± 0.1 mm year−1 during the years 2005 to 2012, averaged between 60° S and 60° N and the 10–1500 m depth layer. In this study, we present an intercomparison of three global ocean observing systems: the Argo network, satellite gravimetry from GRACE and satellite altimetry. Their consistency is investigated from an Argo perspective at global and regional scales during the period 2005–2010. Although we can close the recent global ocean sea level budget within uncertainties, sampling inconsistencies need to be corrected for an accurate global budget due to systematic biases in GOHC and GSSL in the Tropical Ocean. Our findings show that the area around the Tropical Asian Archipelago (TAA) is important to closing the global sea level budget on interannual to decadal timescales, pointing out that the steric estimate from Argo is biased low, as the current mapping methods are insufficient to recover the steric signal in the TAA region. Both the large regional variability and the uncertainties in the current observing system prevent us from extracting indirect information regarding deep-ocean changes. This emphasizes the importance of continuing sustained effort in measuring the deep ocean from ship platforms and by beginning a much needed automated deep-Argo network.

Vulnerability of coastal areas to increased aquifer saturation due to climate change

2021 ◽  
Author(s):  
Alexandre Gauvain ◽  
Ronan Abhervé ◽  
Jean-Raynald de Dreuzy ◽  
Luc Aquilina ◽  
Frédéric Gresselin
Keyword(s):  
Climate Change ◽  
Sea Level ◽  
Large Scale ◽  
Regional Scale ◽  
Drainage System ◽  
Hydrological Regime ◽  
Coastal Areas ◽  
Western Coast ◽  
Study Sites ◽  
The Impact

&lt;p&gt;Like in other relatively flat coastal areas, flooding by aquifer overflow is a recurring problem on the western coast of Normandy (France). Threats are expected to be enhanced by the rise of the sea level and to have critical consequences on the future development and management of the territory. The delineation of the increased saturation areas is a required step to assess the impact of climate change locally. Preliminary models showed that vulnerability does not result only from the sea side but also from the continental side through the modifications of the hydrological regime.&lt;/p&gt;&lt;p&gt;We investigate the processes controlling these coastal flooding phenomena by using hydrogeological models calibrated at large scale with an innovative method reproducing the hydrographic network. Reference study sites selected for their proven sensitivity to flooding have been used to validate the methodology and determine the influence of the different geomorphological configurations frequently encountered along the coastal line.&lt;/p&gt;&lt;p&gt;Hydrogeological models show that the rise of the sea level induces an irregular increase in coastal aquifer saturations extending up to several kilometers inland. Back-littoral channels traditionally used as a large-scale drainage system against high tides limits the propagation of aquifer saturation upstream, provided that channels are not dominantly under maritime influence. High seepage fed by increased recharge occurring in climatic extremes may extend the vulnerable areas and further limit the effectiveness of the drainage system. Local configurations are investigated to categorize the influence of the local geological and geomorphological structures and upscale it at the regional scale.&lt;/p&gt;

scholarly journals Data assimilation of SMOS observations into the Mercator Ocean operational system: focus on the Nino 2015 event

2018 ◽  
Author(s):  
Benoît Tranchant ◽  
Elisabeth Remy ◽  
Eric Greiner ◽  
Olivier Legalloudec
Keyword(s):  
Data Assimilation ◽  
Ocean Circulation ◽  
Positive Impact ◽  
Atmospheric Precipitation ◽  
Sea Surface ◽  
Sea Surface Salinity ◽  
Global Ocean ◽  
Data Sets ◽  
The Impact ◽  
Over The Top

Abstract. Monitoring Sea Surface Salinity (SSS) is important for understanding and forecasting the ocean circulation. It is even crucial in the context of the acceleration of the water cycle. Until recently, SSS was one of the less observed essential ocean variables. Only sparse in situ observations, most often closer to 5 meters deep than the surface, were available to estimate the SSS. The recent satellite missions of ESA's SMOS, NASA's Aquarius, and now SMAP have made possible for the first time to measure SSS from space. The SSS drivers can be quite different than the temperature ones. The model SSS can suffer from significant errors coming not only from the ocean dynamical model but also the atmospheric precipitation and evaporation as well as ice melting and river runoff. Satellite SSS can bring a valuable additional constraint to control the model salinity. In the framework of the SMOS Nino 2015 ESA project (https://www.godae-oceanview.org/projects/smos-nino15/), the impact of satellite SSS data assimilation is assessed with the Met Office and Mercator Ocean global ocean analysis and forecasting systems with a focus on the Tropical Pacific region. This article presents the analysis of an Observing System Experiment (OSE) conducted with the 1/4° resolution Mercator Ocean analysis and forecasting system. SSS data assimilation constrains the model SSS to be closer to the observations in a coherent way with the other data sets already routinely assimilated in an operational context. Globally, the SMOS SSS assimilation has a positive impact in salinity over the top 30 meters. Comparisons to independent data sets show a small but positive impact. The sea surface height (SSH) has also been impacted by implying a reinforcement of TIWs during the El-Niño 2015/16 event. Finally, this study helped us to progress in the understanding of the biases and errors that can degrade the SMOS SSS performance.

scholarly journals Assessment of the Accuracy of Recent Empirical and Assimilated Tidal Models for the Great Barrier Reef, Australia, Using Satellite and Coastal Data

2019 ◽  
Vol 11 (10) ◽  
pp. 1211 ◽  
Author(s):  
Fardin Seifi ◽  
Xiaoli Deng ◽  
Ole Baltazar Andersen
Keyword(s):  
Great Barrier Reef ◽  
Sea Level ◽  
Root Mean Square ◽  
Tide Gauge ◽  
Bottom Topography ◽  
Deep Ocean ◽  
Mean Square ◽  
Barrier Reef ◽  
In Situ Data ◽  
The Impact

The latest satellite and in situ data are a fundamental source for tidal model evaluations. In this work, the satellite missions TOPEX/Poseidon, Jason-1, Jason-2 and Sentinel-3A, together with tide gauge data, were used to investigate the performance of recent regional and global tidal models over the Great Barrier Reef, Australia. Ten models, namely, TPXO8, TPXO9, EOT11a, HAMTIDE, FES2012, FES2014, OSUNA, OSU12, GOT 4.10 and DTU10, were considered. The accuracy of eight major tidal constituents (i.e., K1, O1, P1, Q1, M2, S2, N2 and K2) and one shallow water constituent (M4) were assessed based on the analysis of sea-level observations from coastal tide gauges and altimetry data (TOPEX series). The outcome was compared for four different subregions, namely, the coastline, coastal, shelf and deep ocean zones. Sea-level anomaly data from the Sentinel-3A mission were corrected using the tidal heights predicted by each model. The root mean square values of the sea level anomalies were then compared. According to the results, FES2012 compares more favorably to other models with root mean square (RMS) values of 10.9 cm and 7.7 cm over the coastal and shelf zones, respectively. In the deeper sections, the FES2014 model compares favorably at 7.5 cm. In addition, the impact of sudden fluctuations in bottom topography on model performances suggest that a combination of bathymetric variations and proximity to the coast or islands contributes to tidal height prediction accuracies of the models.

scholarly journals Application of remote sensing and GIS for assessing the level of change of land use status in the coast of Ngoc Hien district (Ca Mau province) due to the impact of sea level rise

2019 ◽  
Vol 19 (3B) ◽  
pp. 227-237
Author(s):  
Pham Viet Hong ◽  
Tran Anh Tuan ◽  
Nguyen Thi Anh Nguyet
Keyword(s):  
Climate Change ◽  
Remote Sensing ◽  
Land Use ◽  
Natural Disasters ◽  
Sea Level Rise ◽  
Sea Level ◽  
Human Life ◽  
Regional Scale ◽  
Great Influence ◽  
The Impact

Today, environmental hazards and challenges are no longer confined to the national or regional scale but on the global scale. One of the biggest challenges for humanity is the natural disasters, global warming and sea level rise. The natural disasters causing serious consequences for human life, such as: Storms, floods, earthquakes, tsunamis, desertification, high tides... increase in frequency, intensity and scale. In recent years, Ca Mau province as well as coastal provinces of Vietnam is under great influence due to the impacts of climate change. One of the most affected districts in Ca Mau province is Ngoc Hien district. The district has a geographic location with three sides bordering the sea, one side bordering the river, a completely isolated terrain. The terrain is flat, strongly divided by the system of natural rivers and canals and intertwined canals, so it is constantly flooded by the sea. Ngoc Hien district is characterized by a sub-equatorial monsoon climate, directly affected by irregular semi-diurnal regime. The main purpose of the paper is to assess coastal vulnerability due to the impact of climate change over time with GIS-based remote sensing images. Remote sensing data with multi-time characteristics, collected in many periods and covering a wide area is an effective tool for monitoring shoreline fluctuations in particular and land use status of the study area in general.

scholarly journals DO TAGLINES HAVE A POSITIVE IMPACT ON BUILDING THE BRAND PERCEPTION? A CASE STUDY ON KIT KAT

2016 ◽  
Vol 12 (1) ◽  
Author(s):  
Farooq-E Azam Cheema ◽  
Keyword(s):  
Brand Management ◽  
Positive Impact ◽  
Geographical Area ◽  
Strong Impact ◽  
Brand Associations ◽  
Brand Perception ◽  
Relationship Of ◽  
The Impact ◽  
The Relationship

Purpose: This study, focusing on the relationship of tagline and brand image, finds the impact of the Kit-Kat’s tagline on the product’s popularity. Methodology: For the purpose, a correlational test and regression analysis have been conducted. The data was collected by preselected enumerator through shoppers’ intercepts method by collecting the responses of 378 consumers of KitKat. Findings: Findings of the study suggest that taglines not only have strong impact on brand perception, but they also help in creating strong brand associations. Kit Kat is a famous brand that has various attributes and has gained popularity among the customers not just because of its tagline but because of various other elements. The Study has concluded that the tagline of the brand has a strong impact on building positive brand perception about Kit Kat. Practical Implications: This study contributes to knowledge development on brand management, and it might be helpful to other companies in designing their products’ taglines around correct parameters. However, limitation of this research is that it is based on the respondents of one area of Karachi. Hence, results may differ if this study is conducted in a wider geographical area with bigger sample size.

scholarly journals Impact of frontal ablation on the ice thickness estimation of marine-terminating glaciers in Alaska

2019 ◽  
Vol 13 (10) ◽  
pp. 2657-2672 ◽  
Author(s):  
Beatriz Recinos ◽  
Fabien Maussion ◽  
Timo Rothenpieler ◽  
Ben Marzeion
Keyword(s):  
Sea Level ◽  
Thickness Distribution ◽  
Regional Scale ◽  
Ice Thickness ◽  
Potential Contribution ◽  
Volume Estimate ◽  
Tidewater Glaciers ◽  
Thickness Estimation ◽  
The Impact ◽  
Frontal Ablation

Abstract. Frontal ablation is a major component of the mass budget of calving glaciers, strongly affecting their dynamics. Most global-scale ice volume estimates to date still suffer from considerable uncertainties related to (i) the implemented frontal ablation parameterization or (ii) not accounting for frontal ablation at all in the glacier model. To improve estimates of the ice thickness distribution of glaciers, it is thus important to identify and test low-cost and robust parameterizations of this process. By implementing such parameterization into the ice thickness estimation module of the Open Global Glacier Model (OGGM v1.1.2), we conduct a first assessment of the impact of accounting for frontal ablation on the estimate of ice stored in glaciers in Alaska. We find that inversion methods based on mass conservation systematically underestimate the mass turnover and, therefore, the thickness of tidewater glaciers when neglecting frontal ablation. This underestimation can amount to up to 19 % on a regional scale and up to 30 % for individual glaciers. The effect is independent of the size of the glacier. Additionally, we perform different sensitivity experiments to study the influence of (i) a constant of proportionality (k) used in the frontal ablation parameterization, (ii) Glen's temperature-dependent creep parameter (A) and (iii) a sliding velocity parameter (fs) on the regional dynamics of Alaska tidewater glaciers. OGGM is able to reproduce previous regional frontal ablation estimates, applying a number of combinations of values for k, Glen's A and fs. Our sensitivity studies also show that differences in thickness between accounting for and not accounting for frontal ablation occur mainly at the lower parts of the glacier, both above and below sea level. This indicates that not accounting for frontal ablation will have an impact on the estimate of the glaciers' potential contribution to sea-level rise. Introducing frontal ablation increases the volume estimate of Alaska marine-terminating glaciers from 9.18±0.62 to 10.61±0.75 mm s.l.e, of which 1.52±0.31 mm s.l.e (0.59±0.08 mm s.l.e when ignoring frontal ablation) are found to be below sea level.

scholarly journals A Global Ocean Observing System for Measuring Sea Level Atmospheric Pressure: Effects and Impacts on Numerical Weather Prediction

2017 ◽  
Vol 98 (2) ◽  
pp. 231-238 ◽  
Author(s):  
Luca Centurioni ◽  
András Horányi ◽  
Carla Cardinali ◽  
Etienne Charpentier ◽  
Rick Lumpkin
Keyword(s):  
Sea Level ◽  
Surface Pressure ◽  
Numerical Weather Prediction ◽  
Atmospheric Pressure ◽  
Weather Prediction ◽  
Global Ocean ◽  
Numerical Weather ◽  
Observation Impact ◽  
The Impact

Abstract Since 1994 the U.S. Global Drifter Program (GDP) and its international partners cooperating within the Data Buoy Cooperation Panel (DBCP) of the World Meteorological Organization (WMO) and the United Nations Education, Scientific and Cultural Organization (UNESCO) have been deploying drifters equipped with barometers primarily in the extratropical regions of the world’s oceans in support of operational weather forecasting. To date, the impact of the drifter data isolated from other sources has never been studied. This essay quantifies and discusses the effect and the impact of in situ sea level atmospheric pressure (SLP) data from the global drifter array on numerical weather prediction using observing system experiments and forecast sensitivity observation impact studies. The in situ drifter SLP observations are extremely valuable for anchoring the global surface pressure field and significantly contributing to accurate marine weather forecasts, especially in regions where no other in situ observations are available, for example, the Southern Ocean. Furthermore, the forecast sensitivity observation impact analysis indicates that the SLP drifter data are the most valuable per-observation contributor of the Global Observing System (GOS). All these results give evidence that surface pressure observations of drifting buoys are essential ingredients of the GOS and that their quantity, quality, and distribution should be preserved as much as possible in order to avoid any analysis and forecast degradations. The barometer upgrade program offered by the GDP, under which GDP-funded drifters can be equipped with partner-funded accurate air pressure sensors, is a practical example of how the DBCP collaboration is executed. Interested parties are encouraged to contact the GDP to discuss upgrade opportunities.

Sign in / Sign up

Export Citation Format

Share Document