High‐Resolution Numerical Modelling of Barotropic Global Ocean Tides for Satellite Gravimetry

Abstract. A consistently calibrated 40-year length dataset of visible channel remote sensing reflectance has been derived from the Advanced Very High Resolution Radiometer (AVHRR) sensor global time-series. The dataset uses as its source the Pathfinder Atmospheres – Extended (PATMOS-x) v5.3 Climate Data Record (CDR) for top-of-atmosphere (TOA) visible channel reflectances. This paper describes the theoretical basis for the atmospheric correction procedure and its subsequent implementation, including the necessary ancillary data files used and quality flags applied, in order to determine remote sensing reflectance. The resulting dataset is produced at daily, and archived at monthly, resolution, on a 0.1° × 0.1° grid at https://doi.pangaea.de/10.1594/PANGAEA.892175. The primary aim of deriving this dataset is to highlight regions of the global ocean affected by highly reflective blooms of the coccolithophorid Emiliania Huxleyi over the past 40 years.

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Evaluation of global ocean tide models based on tidal gravity observations in China

10.5194/egusphere-egu2020-3297 ◽

2020 ◽

Author(s):

Hongbo Tan ◽

Chongyong Shen ◽

Guiju Wu

Keyword(s):

High Precision ◽

Earth Tide ◽

Global Ocean ◽

Ocean Tide ◽

Ocean Tides ◽

Ocean Tide Model ◽

Tidal Forces ◽

The Earth ◽

Gravity Observation ◽

Ocean Tide Models

Solid Earth is affected by tidal cycles triggered by the gravity attraction of the celestial bodies. However, about 70% the Earth is covered with seawater which is also affected by the tidal forces. In the coastal areas, the ocean tide loading (OTL) can reach up to 10% of the earth tide, 90% for tilt, and 25% for strain (Farrell, 1972). Since 2007, a high-precision continuous gravity observation network in China has been established with 78 stations. The long-term high-precision tidal data of the network can be used to validate, verifying and even improve the ocean tide model (OTM).In this paper, tidal parameters of each station were extracted using the harmonic analysis method after a careful editing of the data. 8 OTMs were used for calculating the OTL. The results show that the Root-Mean-Square of the tidal residuals (M0) vary between 0.078-1.77 &#956;gal, and the average errors as function of the distance from the sea for near(0-60km), middle(60-1000km) and far(>1000km) stations are 0.76, 0.30 and 0.21 &#956;gal. The total final gravity residuals (Tx) of the 8 major constituents (M2, S2, N2, K2, K1, O1, P1, Q1) for the best OTM has amplitude ranging from 0.14 to 3.45 &#956;gal. The average efficiency for O1 is 77.0%, while 73.1%, 59.6% and 62.6% for K1, M2 and Tx. FES2014b provides the best corrections for O1 at 12 stations, while SCHW provides the best for K1 ,M2and Tx at 12,8and 9 stations. For the 11 costal stations, there is not an obvious best OTM. The models of DTU10, EOT11a and TPXO8 look a litter better than FES2014b, HAMTIDE and SCHW. For the 17 middle distance stations, SCHW is the best OTM obviously. For the 7 far distance stations, FES2014b and SCHW model are the best models. But the correction efficiency is worse than the near and middle stations&#8217;.The outcome is mixed: none of the recent OTMs performs the best for all tidal waves at all stations. Surprisingly, the Schwiderski&#8217;s model although is 40 years old with a coarse resolution of 1&#176; x 1&#176; is performing relative well with respect to the more recent OTM. Similar results are obtained in Southeast Asia (Francis and van Dam, 2014). It could be due to systematic errors in the surroundings seas affecting all the ocean tides models. It's difficult to detect, but invert the gravity attraction and loading effect to map the ocean tides in the vicinity of China would be one way.

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A global high-resolution data set of ice sheet topography, cavity geometry and ocean bathymetry

10.5194/essd-2016-3 ◽

2016 ◽

Cited By ~ 4

Author(s):

Janin Schaffer ◽

Ralph Timmermann ◽

Jan Erik Arndt ◽

Steen Savstrup Kristensen ◽

Christoph Mayer ◽

...

Keyword(s):

High Resolution ◽

Continental Shelf ◽

Ice Sheet ◽

The Arctic ◽

Global Ocean ◽

Data Set ◽

Antarctic Ice Sheet ◽

Ice Shelves ◽

Surface Topographies ◽

The Antarctic

Abstract. The ocean plays an important role in modulating the mass balance of the polar ice sheets by interacting with the ice shelves in Antarctica and with the marine-terminating outlet glaciers in Greenland. Given that the flux of warm water onto the continental shelf and into the sub-ice cavities is steered by complex bathymetry, a detailed topography data set is an essential ingredient for models that address ice-ocean interaction. We followed the spirit of the global RTopo-1 data set and compiled consistent maps of global ocean bathymetry, upper and lower ice surface topographies and global surface height on a spherical grid with now 30-arc seconds resolution. We used the General Bathymetric Chart of the Oceans (GEBCO_2014) as the backbone and added the International Bathymetric Chart of the Arctic Ocean version 3 (IBCAOv3) and the International Bathymetric Chart of the Southern Ocean (IBCSO) version 1. While RTopo-1 primarily aimed at a good and consistent representation of the Antarctic ice sheet, ice shelves and sub-ice cavities, RTopo-2 now also contains ice topographies of the Greenland ice sheet and outlet glaciers. In particular, we aimed at a good representation of the fjord and shelf bathymetry surrounding the Greenland continent. We corrected data from earlier gridded products in the areas of Petermann Glacier, Hagen Bræ and Sermilik Fjord assuming that sub-ice and fjord bathymetries roughly follow plausible Last Glacial Maximum ice flow patterns. For the continental shelf off northeast Greenland and the floating ice tongue of Nioghalvfjerdsfjorden Glacier at about 79° N, we incorporated a high-resolution digital bathymetry model considering original multibeam survey data for the region. Radar data for surface topographies of the floating ice tongues of Nioghalvfjerdsfjorden Glacier and Zachariæ Isstrøm have been obtained from the data centers of Technical University of Denmark (DTU), Operation Icebridge (NASA/NSF) and Alfred Wegener Institute (AWI). For the Antarctic ice sheet/ice shelves, RTopo-2 largely relies on the Bedmap-2 product but applies corrections for the geometry of Getz, Abbot and Fimbul ice shelf cavities. The data set is available in full and in regional subsets in NetCDF format from the PANGAEA database at https://doi.pangaea.de/10.1594/PANGAEA.856844.

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EnOI-Based Data Assimilation Technology for Satellite Observations and ARGO Float Measurements in a High Resolution Global Ocean Model Using the CMF Platform

Communications in Computer and Information Science - Supercomputing ◽

10.1007/978-3-319-55669-7_5 ◽

2016 ◽

pp. 57-66 ◽

Cited By ~ 4

Author(s):

Maxim Kaurkin ◽

Rashit Ibrayev ◽

Alexandr Koromyslov

Keyword(s):

High Resolution ◽

Data Assimilation ◽

Ocean Model ◽

Satellite Observations ◽

Global Ocean ◽

Argo Float

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Decadal changes in the Atlantic Meridional Overturning Circulation in high-resolution simulations of the subpolar North Atlantic

10.5194/egusphere-egu21-7789 ◽

2021 ◽

Author(s):

Claus W. Böning ◽

Arne Biastoch ◽

Klaus Getzlaff ◽

Patrick Wagner ◽

Siren Rühs ◽

...

Keyword(s):

High Resolution ◽

North Atlantic ◽

Deep Convection ◽

Alternative Interpretation ◽

Meridional Overturning Circulation ◽

Global Ocean ◽

Labrador Sea ◽

Overturning Circulation ◽

First Results ◽

Meridional Overturning

A series of global ocean - sea ice model simulations is used to investigate the spatial structure and temporal variability of the sinking branch of the meridional overturning circulation (AMOC) in the subpolar North Atlantic. The experiments include hindcast simulations of the last six decades based on the high-resolution (1/20&#176;) VIKING20X-model forced by the CORE and JRA55-do reanalysis products, supplemented by sensitivity studies with a 1/4&#176;-configuration (ORCA025) aimed at elucidating the roles of variations in the wind stress and buoyancy fluxes. The experiments exhibit different multi-decadal trends in the AMOC, reflecting the well-known sensitivity of ocean-only models to subtle details in the configuration of the subarctic freshwater forcing. All experiments, however, concur in that the dense, southward branch of the overturning is mainly fed by &#8220;sinking&#8221; (in density space) in the Irminger and Iceland Basins, in accordance with the first results of the OSNAP observational program. Remarkably, the contribution of the Labrador Sea has remained small throughout the whole simulation period, even during the phase of extremely strong convection in the early 1990s: i.e., the rate of deep water exported from the subpolar North Atlantic by the DWBC off Newfoundland never differed by more than O(1 Sv) from the DWBC entering the Labrador Sea at Cape Farewell. The model solutions indicate a particular concentration of the sinking along the deep boundary currents south of the Denmark Straits and south of Iceland, pointing to a prime importance for the AMOC of the outflows from the Nordic Seas and their subsequent enhancement by the entrainment of intermediate waters. Since these include the water masses formed by deep convection in the Labrador and southern Irminger Seas, our study offers an alternative interpretation of the dynamical role of decadal changes in Labrador Sea convection intensity in terms of a remote effect on the deep transports established in the outflow regimes.

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High-Resolution Sea Surface Temperature and Salinity in the Global Ocean from Raw Satellite Data

Remote Sensing ◽

10.3390/rs11192191 ◽

2019 ◽

Vol 11 (19) ◽

pp. 2191 ◽

Cited By ~ 7

Author(s):

Encarni Medina-Lopez ◽

Leonardo Ureña-Fuentes

Keyword(s):

Neural Network ◽

High Resolution ◽

Satellite Data ◽

Google Earth ◽

Sea Surface ◽

Global Ocean ◽

The Neural Network ◽

Wide Range ◽

Sentinel 2

The aim of this work is to obtain high-resolution values of sea surface salinity (SSS) and temperature (SST) in the global ocean by using raw satellite data (i.e., without any band data pre-processing or atmospheric correction). Sentinel-2 Level 1-C Top of Atmosphere (TOA) reflectance data is used to obtain accurate SSS and SST information. A deep neural network is built to link the band information with in situ data from different buoys, vessels, drifters, and other platforms around the world. The neural network used in this paper includes shortcuts, providing an improved performance compared with the equivalent feed-forward architecture. The in situ information used as input for the network has been obtained from the Copernicus Marine In situ Service. Sentinel-2 platform-centred band data has been processed using Google Earth Engine in areas of 100 m × 100 m. Accurate salinity values are estimated for the first time independently of temperature. Salinity results rely only on direct satellite observations, although it presented a clear dependency on temperature ranges. Results show the neural network has good interpolation and extrapolation capabilities. Test results present correlation coefficients of 82 % and 84 % for salinity and temperature, respectively. The most common error for both SST and SSS is 0.4 ∘ C and 0 . 4 PSU. The sensitivity analysis shows that outliers are present in areas where the number of observations is very low. The network is finally applied over a complete Sentinel-2 tile, presenting sensible patterns for river-sea interaction, as well as seasonal variations. The methodology presented here is relevant for detailed coastal and oceanographic applications, reducing the time for data pre-processing, and it is applicable to a wide range of satellites, as the information is directly obtained from TOA data.

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The INALT family – a set of high-resolution nests for the Agulhas Current system within global NEMO ocean/sea-ice configurations

Geoscientific Model Development ◽

10.5194/gmd-12-3329-2019 ◽

2019 ◽

Vol 12 (7) ◽

pp. 3329-3355 ◽

Cited By ~ 6

Author(s):

Franziska U. Schwarzkopf ◽

Arne Biastoch ◽

Claus W. Böning ◽

Jérôme Chanut ◽

Jonathan V. Durgadoo ◽

...

Keyword(s):

High Resolution ◽

Boundary Conditions ◽

Current System ◽

Western Boundary Current ◽

Global Ocean ◽

Western Boundary ◽

Boundary Current ◽

The South ◽

Agulhas Current ◽

Mesoscale Dynamics

Abstract. The Agulhas Current, the western boundary current of the South Indian Ocean, has been shown to play an important role in the connectivity between the Indian and Atlantic oceans. The greater Agulhas Current system is highly dominated by mesoscale dynamics. To investigate their influence on the regional and global circulations, a family of high-resolution ocean general circulation model configurations based on the NEMO code has been developed. Horizontal resolution refinement is achieved by embedding “nests” covering the South Atlantic and the western Indian oceans at 1/10∘ (INALT10) and 1/20∘ (INALT20) within global hosts with coarser resolutions. Nests and hosts are connected through two-way interaction, allowing the nests not only to receive boundary conditions from their respective host but also to feed back the impact of regional dynamics onto the global ocean. A double-nested configuration at 1/60∘ resolution (INALT60) has been developed to gain insights into submesoscale processes within the Agulhas Current system. Large-scale measures such as the Drake Passage transport and the strength of the Atlantic meridional overturning circulation are rather robust among the different configurations, indicating the important role of the hosts in providing a consistent embedment of the regionally refined grids into the global circulation. The dynamics of the Agulhas Current system strongly depend on the representation of mesoscale processes. Both the southward-flowing Agulhas Current and the northward-flowing Agulhas Undercurrent increase in strength with increasing resolution towards more realistic values, which suggests the importance of improving mesoscale dynamics as well as bathymetric slopes along this narrow western boundary current regime. The exploration of numerical choices such as lateral boundary conditions and details of the implementation of surface wind stress forcing demonstrates the range of solutions within any given configuration.

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High-resolution numerical modelling of convective precipitation over Northern Italy

Meteorology and Atmospheric Physics ◽

10.1007/bf01025510 ◽

1992 ◽

Vol 50 (1-3) ◽

pp. 143-163 ◽

Cited By ~ 14

Author(s):

T. Paccagnella ◽

S. Tibaldi ◽

R. Buizza ◽

S. Scoccianti

Keyword(s):

High Resolution ◽

Numerical Modelling ◽

Northern Italy ◽

Convective Precipitation

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Compact Modeling Framework v3.0 for high-resolution global ocean-ice-atmosphere models

10.5194/gmd-2017-294 ◽

2018 ◽

Cited By ~ 1

Author(s):

Vladimir V. Kalmykov ◽

Rashit A. Ibrayev ◽

Maxim N. Kaurkin ◽

Konstantin V. Ushakov

Keyword(s):

High Resolution ◽

Global Ocean ◽

Optimal Interpolation ◽

Compact Modeling ◽

Software Environment ◽

Modeling Framework ◽

Coupled Models ◽

High Resolution Models ◽

High Level ◽

Parallel Supercomputers

Abstract. We present new version of the Compact Modeling Framework (CMF3.0) developed for providing the software environment for stand-alone and coupled models of the Global geophysical fluids. The CMF3.0 designed for implementation high and ultra-high resolution models at massive-parallel supercomputers. The key features of the previous CMF version (2.0) are mentioned for reflecting progress in our researches. In the CMF3.0 pure MPI approach with high-level abstract driver, optimized coupler interpolation and I/O algorithms is replaced with PGAS paradigm communications scheme, while central hub architecture evolves to the set of simultaneously working services. Performance tests for both versions are carried out. As addition a parallel realisation of the EnOI (Ensemble Optimal Interpolation) data assimilation method as program service of CMF3.0 is presented.

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