the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 26 Jan 2023
A new high-resolution Coastal Ice-Ocean Prediction System for the East Coast of Canada
Abstract. This paper describes the Coastal Ice Ocean Prediction System for the East Coast of Canada (CIOPS-E) running operationally at Environment and Climate Change Canada (ECCC). CIOPS-E uses a one-way downscaling technique on a 1/36° horizontal grid (~2 km) to simulate high-resolution ice and ocean conditions over the northwest Atlantic Ocean and the Gulf of St. Lawrence (GSL). CIOPS-E is forced at its lateral boundaries with ECCC’s Regional Ice-Ocean Prediction System (RIOPS) and tidal conditions from the Oregon State University TPXO model. The three-dimensional temperature and salinity fields are spectrally nudged towards the RIOPS solution offshore of the 1500 m isobath to, effectively constrain mesoscale features in the Gulf Stream area. Over the continental shelf and the GSL, the CIOPS-E solution is free to develop fully according to model dynamics.
CIOPS-E is evaluated over one year from March 2019 to February 2020. Overall, the CIOPS-E improves the representation of tides compared to ECCC’s lower resolution systems: RIOPS (1/12°) and the Regional Marine Prediction System – Gulf of St. Lawrence (RMPS-GSL, 5 km). The accuracy of the tides are comparable to the TPXO at most coastal tide gauges. Sub-tidal water levels from CIOPS-E agree well with the observed seasonal variability and show improved errors statistics at all stations compared to RIOPS and RMPS-GSL. Improvements are especially noted for the GSL.
Sea surface temperatures (SSTs) from CIOPS-E are lower (higher) in spring (fall) over most of the GSL compared to satellite-derived analyses and RIOPS. Comparison with in-situ observations of SST show significant improvement in CIOPS-E with respect to the RMPS-GSL. Lastly, sea ice conditions in the GSL are compared with the Canadian Ice Service (CIS) charts and the RMPS-GSL model. The sea ice cover and thickness from the pseudo-analysis component (without data assimilation) shows an overestimation compared to the CIS estimates, which is subsequently corrected in the forecast phase through the direct insertion of a Radarsat image analysis product.
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Interactive discussion
Status: closed
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RC1: 'Comment on egusphere-2023-42', Anonymous Referee #1, 03 Apr 2023
This manuscript describes the development of the new high-resolution (~2 km) Coastal Ice-Ocean Prediction System for the East Coast of Canada (CIOPS-E) model. CIOPS-E lateral boundary conditions are provided by a regional model (RIOPS) forecast, tidal components from University of Oregon TPXO model and spectral nudging is applied. The manuscript evaluates the performance of the high-resolution CIOPS-E by comparison with various models and observations. The manuscript, in it current form, is not suitable for publication in Ocean Science.
Major Comments
- The manuscript is poorly organised and does not adequately or clearly describe and explain the model development, improvements or how it fits into the suite of models operated by the Canadian Centre for Meteorology and Environmental Prediction (CCEMP) and the wider communities coastal and marine forecasting efforts currently being developed. For example, it would be more appropriate if Section 3. was presented before Section 2. and some components of Section 2 should be included in the description of the CIOPS-E System to enable the reader to understand the construction and steps of the modelling system more easily. Currently figure 4 is provides a confusing schematic of the CIOPS-E execution pathway. A schematic that accurately supports the information should be developed.
- Section 2 essentially provides information on CCEMP products that are used to validate the CIOPS-E pseudo-analysis. However, it does not include information on all data used in the validation of the model. This section should include information of all data used for validation.
- Section 4 model evaluation does not provide enough information to assess the improvement and advances in using the CIOPS-E system. The section should, within the text, quantify the CIOPS-E improvement (or not) against observations and other model systems. Difference plots should be used where appropriate.
- Section 4.5 refers the reader to Figure 13 to support statements. However, the same figure appears to be shown in both panels.
- All manuscript figures and captions need to be revised. x-, y- axis labels should be included on all figure, color bar labels should be provided, and units need to be added. Appropriate map projections should be considered; land masses should be colored. The figures do not support the text, for example the reader is unable to assess the improvement or not of the CIOPS-E system against other models as it is not known where places and regions such as Labrador Current, Orphan Basin, Magdalen Shallows are found.
Citation: https://doi.org/10.5194/egusphere-2023-42-RC1 -
RC2: 'Comment on egusphere-2023-42', Anonymous Referee #2, 12 Apr 2023
In my view the study needs improvement and the manuscript needs revision in order to be accepatable for publication. The narrative needs strengthening with a stronger scientific focus. The description of the system as well as the assessment of its performance also need improvement. The ocean tides receive the most attention in the verification of the system, however, the sea-ice component is given little attention. I hope my detailed comments below are helpful and illustrate this.
L80 What is a pseudo-analysis?
L90 It’s a bit unclear what parts are reduced-order EnKF or 3DVar analysis or even the reasons why these different methods are used
L99 …that was providing….
Lots of system descriptions - its hard work for the reader, could any of this be captured pictorially?
The scientific problem, importance of this study is not a strong part of the narrative
L115 …solves the “governing equations of ocean circulation and hydrography…” is an unscientific description of these equations
L170-175 RIOPS SSH on the open boundary is detided – then the tide is added to CIOPS-E – what was the reason this step was taken, which seems at a glance to be avoidable. Was the tide error in RIOPS too large to use?
L177 – How are the self-attraction and loading terms used? Is this an additional step to improve accuracy over TPX0?
L195 How do we know they are “well-constrained” or just mainly frozen to the input data?
L195 I suggest avoid the language like ‘the sophisticated data assim…”. Using these qualifiers is not great scientific writing practice. In reality, it’s a method used today but may be not used in the future.
L196 If spectral nudging truly worked, then why would spatial restriction to >1500m depths be necessary?
L197 Freely evolving ‘in practice’ but perhaps not in theory.
L200 Nudging the state using a forcing term in the model equations is non-conservative and a source of imbalance that the model needs to reorganise. Do you also nudge the velocity as this is part of the state as well? Need to acknowledge the method can introduce imbalances that can interact non-linearly with other scales within the model. In practice discontinuities are introduced by both nudging and data assimilation.
L300 Complex differences – mixes amplitude and phase, which have different dimensions L and T. Doesn’t appear to have much to do with a complex number. Can’t find this in the reference to Foreman at al 1995. Figure 7 units of ‘complex difference’ are not m, aren’t they m/s according to the equation for D?
L340-345 Getting lost on the direction this goes and its relevance, towards an issued related to operational products?
L345 Lost the relevance of the CIOPS-E pseudo analysis
L375 Here the system needs to be evaluated at least against daily SST super-observations not against gridded products or where there is not independence between the model and the observations. The seasonal component of the error is one part but it would also be important to evaluate the finer scales for which CIOPS-E was designed.
F2 and F3 - there is no clear evidence of the additional variability that CIOPS-E provides over RIOPS. In the spectrally nudged deeper region aren’t we still meant to see additional variance? Perhaps an additional figure using a different variable such as vorticity would be useful.
F9 Panels need labels and plots don’t highlight difference between CIOPS-E and RIOPS RMSE very well.
F10 Panels need labels. All these products have relatively large SST bias over the period shown. The figures show CIOPS-E has the largest. Shouldn’t there be better agreement in the boundaries with RIOPS. If same atmospheric forcing what explains the mean differences on shelf.
F13 Not sure what the message is in this plot
F14 It looks like the errors are related to shallow coastal regions in CIOPS-E, which may mean that the model becomes more sensitive to errors in either atmospheric or river fluxes than the lower resolution counterpart.
Citation: https://doi.org/10.5194/egusphere-2023-42-RC2
Interactive discussion
Status: closed
-
RC1: 'Comment on egusphere-2023-42', Anonymous Referee #1, 03 Apr 2023
This manuscript describes the development of the new high-resolution (~2 km) Coastal Ice-Ocean Prediction System for the East Coast of Canada (CIOPS-E) model. CIOPS-E lateral boundary conditions are provided by a regional model (RIOPS) forecast, tidal components from University of Oregon TPXO model and spectral nudging is applied. The manuscript evaluates the performance of the high-resolution CIOPS-E by comparison with various models and observations. The manuscript, in it current form, is not suitable for publication in Ocean Science.
Major Comments
- The manuscript is poorly organised and does not adequately or clearly describe and explain the model development, improvements or how it fits into the suite of models operated by the Canadian Centre for Meteorology and Environmental Prediction (CCEMP) and the wider communities coastal and marine forecasting efforts currently being developed. For example, it would be more appropriate if Section 3. was presented before Section 2. and some components of Section 2 should be included in the description of the CIOPS-E System to enable the reader to understand the construction and steps of the modelling system more easily. Currently figure 4 is provides a confusing schematic of the CIOPS-E execution pathway. A schematic that accurately supports the information should be developed.
- Section 2 essentially provides information on CCEMP products that are used to validate the CIOPS-E pseudo-analysis. However, it does not include information on all data used in the validation of the model. This section should include information of all data used for validation.
- Section 4 model evaluation does not provide enough information to assess the improvement and advances in using the CIOPS-E system. The section should, within the text, quantify the CIOPS-E improvement (or not) against observations and other model systems. Difference plots should be used where appropriate.
- Section 4.5 refers the reader to Figure 13 to support statements. However, the same figure appears to be shown in both panels.
- All manuscript figures and captions need to be revised. x-, y- axis labels should be included on all figure, color bar labels should be provided, and units need to be added. Appropriate map projections should be considered; land masses should be colored. The figures do not support the text, for example the reader is unable to assess the improvement or not of the CIOPS-E system against other models as it is not known where places and regions such as Labrador Current, Orphan Basin, Magdalen Shallows are found.
Citation: https://doi.org/10.5194/egusphere-2023-42-RC1 -
RC2: 'Comment on egusphere-2023-42', Anonymous Referee #2, 12 Apr 2023
In my view the study needs improvement and the manuscript needs revision in order to be accepatable for publication. The narrative needs strengthening with a stronger scientific focus. The description of the system as well as the assessment of its performance also need improvement. The ocean tides receive the most attention in the verification of the system, however, the sea-ice component is given little attention. I hope my detailed comments below are helpful and illustrate this.
L80 What is a pseudo-analysis?
L90 It’s a bit unclear what parts are reduced-order EnKF or 3DVar analysis or even the reasons why these different methods are used
L99 …that was providing….
Lots of system descriptions - its hard work for the reader, could any of this be captured pictorially?
The scientific problem, importance of this study is not a strong part of the narrative
L115 …solves the “governing equations of ocean circulation and hydrography…” is an unscientific description of these equations
L170-175 RIOPS SSH on the open boundary is detided – then the tide is added to CIOPS-E – what was the reason this step was taken, which seems at a glance to be avoidable. Was the tide error in RIOPS too large to use?
L177 – How are the self-attraction and loading terms used? Is this an additional step to improve accuracy over TPX0?
L195 How do we know they are “well-constrained” or just mainly frozen to the input data?
L195 I suggest avoid the language like ‘the sophisticated data assim…”. Using these qualifiers is not great scientific writing practice. In reality, it’s a method used today but may be not used in the future.
L196 If spectral nudging truly worked, then why would spatial restriction to >1500m depths be necessary?
L197 Freely evolving ‘in practice’ but perhaps not in theory.
L200 Nudging the state using a forcing term in the model equations is non-conservative and a source of imbalance that the model needs to reorganise. Do you also nudge the velocity as this is part of the state as well? Need to acknowledge the method can introduce imbalances that can interact non-linearly with other scales within the model. In practice discontinuities are introduced by both nudging and data assimilation.
L300 Complex differences – mixes amplitude and phase, which have different dimensions L and T. Doesn’t appear to have much to do with a complex number. Can’t find this in the reference to Foreman at al 1995. Figure 7 units of ‘complex difference’ are not m, aren’t they m/s according to the equation for D?
L340-345 Getting lost on the direction this goes and its relevance, towards an issued related to operational products?
L345 Lost the relevance of the CIOPS-E pseudo analysis
L375 Here the system needs to be evaluated at least against daily SST super-observations not against gridded products or where there is not independence between the model and the observations. The seasonal component of the error is one part but it would also be important to evaluate the finer scales for which CIOPS-E was designed.
F2 and F3 - there is no clear evidence of the additional variability that CIOPS-E provides over RIOPS. In the spectrally nudged deeper region aren’t we still meant to see additional variance? Perhaps an additional figure using a different variable such as vorticity would be useful.
F9 Panels need labels and plots don’t highlight difference between CIOPS-E and RIOPS RMSE very well.
F10 Panels need labels. All these products have relatively large SST bias over the period shown. The figures show CIOPS-E has the largest. Shouldn’t there be better agreement in the boundaries with RIOPS. If same atmospheric forcing what explains the mean differences on shelf.
F13 Not sure what the message is in this plot
F14 It looks like the errors are related to shallow coastal regions in CIOPS-E, which may mean that the model becomes more sensitive to errors in either atmospheric or river fluxes than the lower resolution counterpart.
Citation: https://doi.org/10.5194/egusphere-2023-42-RC2
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