Section 8 development of and advances in ocean modelling and. Toward a data assimilation system for seamless sea ice. The role of atmospheric uncertainty in arctic summer sea. International leadership in data assimilation, from theory to stateoftheart applications within ocean and climate. Future work will be focused on developing sea ice data assimilation techniques to incorporate observations of sea ice concentration and thickness into the coupled assimilation procedure, and investigating the impact of sea ice model physics on prediction skill.
Forward modeling of polar ice caps using largescale, highresolution, multiphysics, multimodel based finite element ice flow. Data assimilation is a mathematical discipline that seeks to optimally combine theory usually in the form of a numerical model with observations. Impacts of the assimilation of these thickness data on sea ice simulations have been reported in several studies, e. Thus, a multivariate data assimilation that integrates sea ice observations to generate realistic and skillful model initialization is needed to improve predictive skill of arctic sea ice. Snow data assimilation system snodas national snow and ice. The purpose of this framework is to facilitate the evaluation of different data assimilation. Dasim comes as the natural fusion between the recent achievements in lagrangian data assimilation lada and sea ice modelling. Impacts of assimilating satellite sea ice concentration and. Sea ice outlook for september 20 july report nasa global. Both observation data sets and forcing fields have been updated as well. Sea ice data assimilation for nwp and operational ice services at ecmwf workshop on observations and analysis of sea surface temperature and sea ice for nwp and climate applications mark buehner, alain caya, alex komarov meteorological research division lynn pogson, michael ross canadian ice service 2225 january 2018.
Efficient ensemble data assimilation for coupled models with the. Overview of sea ice data assimilation activities at environment canada mark buehner, alain caya and michael ross meteorological research division. Adjoint model code generation via automatic differentiation and its application to ocean sea ice state estimation patrick heimbach and dimitris menemenlis. An ensemblebased lestkf is employed to assimilate satellite sea ice data and is. Ncep sea ice analysis nceps sea ice team works on sea ice analysis from satellite, sea ice modeling, a. Towards reliable arctic sea ice prediction using multivariate. An important novelty in oras5 is a generic ensemble generation scheme for perturbing both observations and forcing fields. Insights on sea ice data assimilation from perfect model observing system simulation experiments osses yongfeizhang and cecilia bitz1 jeffrey anderson, nancy collins, jonathan hendricks, tim hoar, and kevin raeder2 1university of washington, seattle. One of the main goals of soca is to make use of surfacesensitive radiances to constrain sea ice and upper ocean fields e. The group collaborates with the data assimilation and ocean forecasting and global ocean and seaice modeling groups of the oda division, as well as with other cmcc divisions, in particular with the ocean prediction and applications opa division on the oceanvar development for the black sea and the reanalysis production. On the assimilation of ice velocity and concentration data.
The data used to force the wave models, such as data on wind speed, seaair temperature difference, sea ice. The assimilation procedure can also help to identify biases between the model and data. Snow data assimilation system snodas data products at nsidc, version 1 snodas is a modeling and data assimilation system developed by nohrsc to provide the best possible estimates of snow cover and associated parameters to support hydrologic modeling and analysis. Dasim comes as the natural fusion between the recent achievements in lagrangian data assimilation lada and seaice modelling. Sea ice variability, prediction and impacts bsccns. For all methods used in this report, the analysis can be expressed as a linear regression in observation space. Monthly images show sea ice extent with an outline of the 30year 1981. It is a source for consistently processed ice extent and concentration images and data values since 1979. The sea ice assimilation system used by giops is based on the 3d. Data assimilation nansen environmental and remote sensing. Ensemble data assimilation using the cesm model integrating the cesm with the dart ensemble filter cesm tutorial key cgd personnel. Alicia karspeck, gokhan danabasoglu, svetlana karol, steve yeager, joe tribbia key cisl personnel. Analysis and forecasting of sea ice conditions with three. This data set contains snow pack properties, such as depth and snow water equivalent swe, from the noaa national weather services national operational.
Snodas is a modeling and data assimilation system developed by nohrsc to provide the best possible estimates of snow cover and associated. Hiwppnggps program meeting oceanwavessea ice team projects page 17 of 27 umd. General topics considered appropriate for this workshop include. Analyse the sea ice reanalysis to understand the proximate causes of sea ice change.
This data set contains snow pack properties, such as depth and snow water equivalent swe, from the noaa national weather services national operational hydrologic remote sensing center nohrsc snow data assimilation system snodas. The position is based in the department of meteorology, university of reading. Oras5 also includes a prognostic thermodynamicdynamic sea ice model with assimilation of sea ice concentration data. The model is complemented with the parallel data assimilation framework to assimilate observations in the oceanice component with an. The 3 assimilation systems thought certain coastal grid points had sea ice. Two sets of seasonality numbers for antarctic sea ice volume are shown for comparison in b, one derived from a sea iceocean model simulation. A multivariate data assimilation experiment was conducted in order to improve the global representation of both the ocean and sea ice fields through the inclusion of sea ice concentration sic data. Previous sea ice concentration assimilation studies have employed either direct insertion or initialization from a prescribed sea ice concentration field e.
Towards an increased reliance on automated prediction systems. Although sea ice values are simulated by the seaice model, sea ice data is not assimilated. In the antarctic, though the overall sea ice extent is slightly. A data assimilation system is developed for seamless sea ice prediction on a climate model equipped with an unstructured ocean ice component the system performance is examined based on experiments. Most existing models treat the sea ice as a viscoplastic and are unable to describe important features such as cracks, leads, and ridges. Only recently has seaice motion been described with lagrangian dynamics. Seaice ocean and coupled assimilation soca the soca project focuses on meshing atmospheric and marine data assimilation efforts to create innovative data assimilation systems. Arctic sea ice predictions geophysical fluid dynamics. Started migrating sea ice and sst analyses into the modular software framework. The model is effectively a random simulation of sea ice dynamics.
The ice analysis system uses a 6 h window centred at 0000, 0600, 1200. The arcticsubarctic sea ice system is entering a seasonal. Ocean data assimilation experiment an improved ocean state product the main goal of this project is to develop a stateoftheart data assimilation system that incorporates nearrealtime data with which we can provide the community a high quality ocean state product. Insights on sea ice data assimilation from perfect model observing system simulation experiments osses yongfeizhang and cecilia bitz1 jeffrey anderson, nancy collins, jonathan hendricks, tim hoar, and kevin raeder2 1university of washington, seattle, wa 2national center for atmospheric sciences, boulder, co. The model comes with a data assimilation class and a few driver programs for conducting twin experiments. Sea ice ocean and coupled assimilation soca the soca team works to merge atmospheric and marine data assimilation efforts for the design of both weakly coupled, and strongly coupled, data assimilation systems. Oras5 also includes a prognostic thermodynamicdynamic seaice model with assimilation of seaice concentration data. Icoads global surface marine data from 1800 to near the present summarized in monthly gridded formats 2x2 boxes, or 1x1 boxes from 1960 forward, and offering a variety of statistics. The iceocean model used in this study is the community iceocean model ciom as described by yao et al. For example, for subseasonal predictions submitted to the 67. Ice grows as a function of the thickness, concentration, and a random variable. Insights on sea ice data assimilation from perfect model. Sea ice forecast verification in the canadian global ice. Jeff anderson, nancy collins, tim hoar, helen kershaw, kevin raeder cgd software engineering participants.
Optimising assimilation of sea ice concentration in an. The problem was traced back to the new seaice analyses. Snow data assimilation system snodas data products at nsidc. The role of atmospheric uncertainty in arctic summer sea ice. The improvement of sea ice initialization for global climate forecasts from timescales of the season to the decade and beyond. The computational core of the system consists of wind wave models with open source software. Optimising assimilation of sea ice concentration in an earth. Overview of sea ice data assimilation activities at. The generation of realistic sea ice reconstructions for a better understanding of past sea ice variability, using advanced data assimilation techniques. Snow data assimilation system snodas data products at. Yu polar science center, applied physics laboratory, college of ocean and fishery sciences, university of washington, seattle, washington, usa r. The met office coupled atmospherelandoceanseaice data. Towards an increased reliance on automated prediction systems on free shipping on qualified orders sea ice analysis and forecasting. Toward a data assimilation system for seamless sea ice prediction based on the awi climate model article pdf available in journal of advances in modeling earth systems 124.
For example, iceocean models have difficulty estimating the ice thickness distribution accurately. Optimising assimilation of sea ice concentration in an earth system. Toward a data assimilation system for seamless sea ice prediction. Assimilation method data assimilation refers to optimization methods that seek the true state of a system by optimally combining observations with a physical representation of that system. The goddard earth system integrated ocean data assimilation system geos iodas.
Downward longwave irradiance dli and surface solar irradiance ssi, sea ice concentration, edge, type, emissivity, drift. Data assimilation of sea ice concentration into a global. Sea ice concentration and motion assimilation in a sea ice. The ocean and sea ice analyses used in the seasonal forecast are. Emc, incois india, nasa gmao, nrlssc and inpebrazil codebase available on repository for restricted access baseline oceanletkf data assimilation systems have. Our work supports the alaska region of the national weather service, the great lakes marine forecasting group in the cleveland nwsfo, and ncep numerical modeling systems.
The iodas is a sequential ensemble assimilation software system that includes a wide range of algorithm. The ice thickness from the ice mass balance buoy program is used here. Var method developed for regional applications at cmc buehner et al. Abstract a threedimensional variational data assimilation 3dvar system has been developed to provide analyses of the iceocean state and to initialize a coupled iceocean numerical model for for. Data assimilation is a method used in numerical modeling to assure that model results are close to observations.
Several existing sea ice aps described in chapter 5 use data assimilation. Sea ice ocean and coupled assimilation soca the soca project focuses on meshing atmospheric and marine data assimilation efforts to create innovative data assimilation systems. At one time, both analyses were produced by the same system. Toward reanalysis of the arctic climate system sea ice and ocean. An integrative data assimilation for the arctic system idaas has been recommended for development by a special interagency research program a study of.
The latest assimilation results are obtained once in five days, and the targeted term of the analysis is 37 days before the assimilation is carried out. The osi saf also offers climatological data records. Sea ice data assimilation for nwp and operational ice. The assimilation of ice concentration data can also help in improving the model behavior, but it has to be handled with care because of the strong connection between ice concentration and ice thickness. The focus of the workshop is to discuss crosscutting issues in sea ice modelling and data assimilation and how deficiencies of current systems can be more efficiently diagnosed and addressed. It is composed of the princeton ocean model blumberg and mellor 1987. Assimilation of ice motion observations and comparisons. However, the code then thought the sea ice was inconsistent with the current sst so true and promptly rejected both the sst and seaice analyses. Assimilation of ice motion observations and comparisons with submarine ice thickness data jinlun zhang, d. One of the main goals of soca is to make use of surfacesensitive radiances to constrain seaice and upper ocean fields e. A data assimilation method capable of constraining the sea ice of an earth.
Ncoda navy coupled ocean data assimilation deliverables end of next year an end to end data assimilation system for the global model a near real time data assimilation system for the global model and. A fully coupled ocean seaice or atmospheresea ice data assimilation may not be feasible at the present time, but the application of the ensemble information from the fully coupled model forecast guess fields should be very useful, because ensemble forecasts will be used from the coupled model, sea ice assimilation can also be ensemble based. Introduction sea ice is a key element of the climate system as it affects the radiative surface balance and strongly restricts exchanges of momentum, heat and moisture between the ocean and the atmosphere. Seaice ocean and coupled assimilation soca the soca team works to merge atmospheric and marine data assimilation efforts for the design of both weakly. Hadley sea ice sst monthly global gridded sst and sea ice from 1870 to the near present. End to end data assimilation cycle for the gulf of mexico using canned data sets near real time gom assimilation system using ncep data streams hiwppnggps program meeting nggps meeting, ncwcp aug 2016 oceanwavessea ice team projects page 12 of 27.
Argo is a global array of 3,000 freedrifting profiling floats that measures the temperature and salinity of the upper 2000 m of the ocean. The objectives of the sea ice variability, prediction and impacts research line are. Hiwppnggps program meeting nggps meeting, ncwcp aug 2016oceanwavessea ice team projects page 12 of 27 emc. Data assimilation refers to optimization methods that seek the true state of a system by optimally combining observations with a physical representation of that system. Data assimilation for forecast improvements in the north sea and baltic sea losa et al. Monthly images show sea ice extent with an outline of the 30year 19812010 median extent for that month magenta line.
Section 8 development of and advances in ocean modelling. To help improve model forecasts, data assimilation is used to combine observational data with model forecasts and produce more accurate estimates. Yu polar science center, applied physics laboratory, college of ocean and fishery sciences, university of. Most existing models treat the seaice as a viscoplastic and are unable to describe important features such as cracks, leads, and ridges. There may be a number of different goals sought, for exampleto determine the optimal state estimate of a system, to determine initial conditions for a numerical forecast model, to interpolate sparse observation data using e. Assimilation of ice motion observations and comparisons with. A data assimilation method capable of constraining the sea ice of an. The monthly sea ice index provides a quick look at arcticwide changes in sea ice. Insights on sea ice data assimilation from perfect model observing system simulation experiments yongfei zhang and cecilia m. Datadriven regularization and uncertainty estimation to. Ocean data assimilation geophysical fluid dynamics.
A marked improvement in the data assimilations skill is seen when the argo observational data is included chang et al. Sea ice data assimilation methods and results sea ice observations and uncertainties. Only recently has sea ice motion been described with lagrangian dynamics. Bitz department of atmospheric sciences, university of washington, seattle, washington jeffrey l. By using a data assimilation system, we can obtain analysis fields, which are a set of ocean and sea ice variables optimally combining observations and a model. Pdf toward a data assimilation system for seamless sea ice. Projections of sealevel rise using dynamically consistent earth models, constrained by satellite data. In the southern ocean, however, apart from the aspect observations worby, 1999, the satellite sit data are even more limited. Adjoint model code generation via automatic differentiation. We demonstrate that the quality of the reanalysis changes when different sea surface temperature products are assimilated, or when insitu pro. Sea ice data assimilation chapter 4 sea ice analysis and. Sea ice data assimilation is a relatively new research area. The data used to force the wave models, such as data on wind speed, sea air temperature difference, sea ice concentration, are taken from output products of several weather forecasting systems.
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