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