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. Bitz department of atmospheric sciences, university of washington, seattle, washington jeffrey l. However, the improvement is larger when the uncertainty in atmospheric forcing data is taken into account in the data assimilation. Toward reanalysis of the arctic climate system sea ice and ocean. The modelagnostic structure of the assimilation software ensures a separation. The ocean and sea ice analyses used in the seasonal forecast are. Both observation data sets and forcing fields have been updated as well. Pdf toward a data assimilation system for seamless sea ice. Dasim comes as the natural fusion between the recent achievements in lagrangian data assimilation lada and sea ice modelling. Snow data assimilation system snodas data products at. To help improve model forecasts, data assimilation is used to combine observational data with model forecasts and produce more accurate estimates. A marked improvement in the data assimilations skill is seen when the argo observational data is included chang et al.
Datadriven regularization and uncertainty estimation to. Assimilation of ice motion observations and comparisons with submarine ice thickness data jinlun zhang, d. The monthly sea ice index provides a quick look at arcticwide changes in sea ice. 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. Towards an increased reliance on automated prediction systems on free shipping on qualified orders sea ice analysis and forecasting. The role of atmospheric uncertainty in arctic summer sea ice. One of the main goals of soca is to make use of surfacesensitive radiances to constrain seaice and upper ocean fields e. Projections of sealevel rise using dynamically consistent earth models, constrained by satellite data. Var method developed for regional applications at cmc buehner et al. Sea ice data assimilation chapter 4 sea ice analysis and. The objectives of the sea ice variability, prediction and impacts research line are.
Ocean data assimilation geophysical fluid dynamics. 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. 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 model is complemented with the parallel data assimilation framework to assimilate observations in the oceanice component with an. 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. 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. Ice grows as a function of the thickness, concentration, and a random variable. A data assimilation method capable of constraining the sea ice of an. Toward a data assimilation system for seamless sea ice prediction.
The model is effectively a random simulation of sea ice dynamics. Started migrating sea ice and sst analyses into the modular software framework. Overview of sea ice data assimilation activities at. International leadership in data assimilation, from theory to stateoftheart applications within ocean and climate. Sea ice forecast verification in the canadian global ice. Alicia karspeck, gokhan danabasoglu, svetlana karol, steve yeager, joe tribbia key cisl personnel. Yu polar science center, applied physics laboratory, college of ocean and fishery sciences, university of washington, seattle, washington, usa r. Data assimilation of remote sensing observations into projections of ice sheet mass balance and sea level rise. Snow data assimilation system snodas data products at nsidc. 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.
Data assimilation nansen environmental and remote sensing. An integrative data assimilation for the arctic system idaas has been recommended for development by a special interagency research program a study of. Previous sea ice concentration assimilation studies have employed either direct insertion or initialization from a prescribed sea ice concentration field e. Dasim comes as the natural fusion between the recent achievements in lagrangian data assimilation lada and seaice modelling. Analysis and forecasting of sea ice conditions with three. Insights on sea ice data assimilation from perfect model. Ensemble data assimilation using the cesm model integrating the cesm with the dart ensemble filter cesm tutorial key cgd personnel.
On the assimilation of ice velocity and concentration data. Emc, incois india, nasa gmao, nrlssc and inpebrazil codebase available on repository for restricted access baseline oceanletkf data assimilation systems have. 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. Analyse the sea ice reanalysis to understand the proximate causes of sea ice change. The osi saf team focuses on scatterometer winds and soon microwave winds, sea surface temperature sst and sea ice surface temperature ist, radiative fluxes. The met office coupled atmospherelandoceanseaice data. 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. Yu polar science center, applied physics laboratory, college of ocean and fishery sciences, university of. 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. Most existing models treat the seaice as a viscoplastic and are unable to describe important features such as cracks, leads, and ridges. Optimising assimilation of sea ice concentration in an. 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. Sea ice concentration and motion assimilation in a sea ice. For all methods used in this report, the analysis can be expressed as a linear regression in observation space.
We demonstrate that the quality of the reanalysis changes when different sea surface temperature products are assimilated, or when insitu pro. 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. 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. Insights on sea ice data assimilation from perfect model observing system simulation experiments yongfei zhang and cecilia m. Adjoint model code generation via automatic differentiation. Data assimilation for forecast improvements in the north sea and baltic sea losa et al.
A data assimilation method capable of constraining the sea ice of an earth. The 3 assimilation systems thought certain coastal grid points had sea ice. Arctic sea ice predictions geophysical fluid dynamics. 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. Section 8 development of and advances in ocean modelling. Sea ice outlook for september 20 july report nasa global. 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.
The purpose of this framework is to facilitate the evaluation of different data assimilation. Toward a data assimilation system for seamless sea ice. Impacts of assimilating satellite sea ice concentration and. In the southern ocean, however, apart from the aspect observations worby, 1999, the satellite sit data are even more limited. Sea ice data assimilation methods and results sea ice observations and uncertainties. The sea ice assimilation system used by giops is based on the 3d. Towards reliable arctic sea ice prediction using multivariate. Optimising assimilation of sea ice concentration in an earth. In the antarctic, though the overall sea ice extent is slightly. 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. 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.
Assimilation of ice motion observations and comparisons with. Overview of sea ice data assimilation activities at environment canada mark buehner, alain caya and michael ross meteorological research division. Seaice ocean and coupled assimilation soca the soca team works to merge atmospheric and marine data assimilation efforts for the design of both weakly. The generation of realistic sea ice reconstructions for a better understanding of past sea ice variability, using advanced data assimilation techniques. 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. Data assimilation is a method used in numerical modeling to assure that model results are close to observations.
Two sets of seasonality numbers for antarctic sea ice volume are shown for comparison in b, one derived from a sea iceocean model simulation. The model comes with a data assimilation class and a few driver programs for conducting twin experiments. It is a source for consistently processed ice extent and concentration images and data values since 1979. The iceocean model used in this study is the community iceocean model ciom as described by yao et al.
The computational core of the system consists of wind wave models with open source software. The assimilation procedure can also help to identify biases between the model and data. 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. Snow data assimilation system snodas national snow and ice. 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.
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. Hiwppnggps program meeting oceanwavessea ice team projects page 17 of 27 umd. For example, for subseasonal predictions submitted to the 67. The goddard earth system integrated ocean data assimilation system geos iodas. 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. Ncep sea ice analysis nceps sea ice team works on sea ice analysis from satellite, sea ice modeling, a. Monthly images show sea ice extent with an outline of the 30year 19812010 median extent for that month magenta line.
It is composed of the princeton ocean model blumberg and mellor 1987. Although sea ice values are simulated by the seaice model, sea ice data is not assimilated. Only recently has seaice motion been described with lagrangian dynamics. Sea ice variability, prediction and impacts bsccns. Several existing sea ice aps described in chapter 5 use data assimilation. Data assimilation is a mathematical discipline that seeks to optimally combine theory usually in the form of a numerical model with observations. Assimilation of ice motion observations and comparisons. Monthly images show sea ice extent with an outline of the 30year 1981. Adjoint model code generation via automatic differentiation and its application to ocean sea ice state estimation patrick heimbach and dimitris menemenlis. 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.
Forward modeling of polar ice caps using largescale, highresolution, multiphysics, multimodel based finite element ice flow. Oras5 also includes a prognostic thermodynamicdynamic seaice model with assimilation of seaice concentration data. 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. Towards an increased reliance on automated prediction systems. Sea ice data assimilation for nwp and operational ice. Most existing models treat the sea ice as a viscoplastic and are unable to describe important features such as cracks, leads, and ridges. The improvement of sea ice initialization for global climate forecasts from timescales of the season to the decade and beyond.
Efficient ensemble data assimilation for coupled models with the. Seaice ocean and coupled assimilation soca the soca project focuses on meshing atmospheric and marine data assimilation efforts to create innovative data assimilation systems. The problem was traced back to the new seaice analyses. The ice analysis system uses a 6 h window centred at 0000, 0600, 1200. 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. This data set contains snow pack properties, such as depth and snow water equivalent swe, from the noaa national weather services national operational. Jeff anderson, nancy collins, tim hoar, helen kershaw, kevin raeder cgd software engineering participants. At one time, both analyses were produced by the same system. The role of atmospheric uncertainty in arctic summer sea. Hiwppnggps program meeting nggps meeting, ncwcp aug 2016oceanwavessea ice team projects page 12 of 27 emc. The ice thickness from the ice mass balance buoy program is used here. The position is based in the department of meteorology, university of reading. General topics considered appropriate for this workshop include.
The osi saf also offers climatological data records. Only recently has sea ice motion been described with lagrangian dynamics. Section 8 development of and advances in ocean modelling and. For example, iceocean models have difficulty estimating the ice thickness distribution accurately. 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. The arcticsubarctic sea ice system is entering a seasonal. 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. An important novelty in oras5 is a generic ensemble generation scheme for perturbing both observations and forcing fields. Impacts of the assimilation of these thickness data on sea ice simulations have been reported in several studies, e. An ensemblebased lestkf is employed to assimilate satellite sea ice data and is. 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.
Snodas is a modeling and data assimilation system developed by nohrsc to provide the best possible estimates of snow cover and associated. 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. The data used to force the wave models, such as data on wind speed, seaair temperature difference, sea ice. The iodas is a sequential ensemble assimilation software system that includes a wide range of algorithm.
Hadley sea ice sst monthly global gridded sst and sea ice from 1870 to the near present. Oras5 also includes a prognostic thermodynamicdynamic sea ice model with assimilation of sea ice concentration data. Data assimilation of sea ice concentration into a global. Sea ice data assimilation is a relatively new research area. 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.