The paper presents an overview of the status of operational ocean forecasting systems in 8 key regions in the world ocean :  the West Pacific and Marginal Seas of South and East Asia, the Indian Ocean, the African Seas, the Mediterranean and Black Sea, the North-East Atlantic, the South and Central America Seas, the North America and the Arctic.  This is not an easy task but the paper provides a useful summary of the existing operational oceanography offer.   The  paper needs, however, to be improved in several ways before it can be accepted :

1. A general introduction is needed where the authors should explain how the international ocean prediction community is organized at global level through the OceanPredict international programme and the role now played by the UN OceanPrediction DCC (e.g. DCC regional teams, DCC atlas that will provide up to date information on the different systems including operational readiness level information) .   Explain also the scope of the paper : physical systems including wave and sea ice ? BGC systems ?  real time and reanalyses ?  and the methodology used to gather this information and its limitation (you cannot be comprehensive in particular for coastal systems).   You should also limit the scope to operational systems for which data are readily available.   
2. Global systems should be described in a specific section as they all serve the 8 regions. Explain in addition the role of global systems to provide boundary conditions to regional and coastal systems.  
3. There is strong need to homogenize the description of the different systems (including for tables that should all have the same content).  Provide core information to all systems you describe (eg model resolution, assimilated data sets, physics or physics + BGC) .   A recent and an up to date reference should also be provided for all systems you mention and the way to access products (e.g. URL).   

 Specific comments :

Abstract : physical peculiarities ? What do you mean ?  What about biogeochemical ?

Abstract : Authors => authors

Abstract : is the scope limited to physical systems ?   

Abstract : « and the ways forward to improve the essential ocean variables predictability from regional to coastal scales, products reliability and accuracy ».  This is not or barely discussed in the paper

Line 57 : « we explore the collaborative efforts and international initiatives aimed at enhancing global ocean forecasting ».  Where ?

Need consistent information for all tables and all regions, e.g.  model resolution, assimilated data sets, URL to access forecasts.

Use Copernicus Marine / Copernicus Marine Service instead of CMEMS everywhere in the paper

Table 4.  2.3 degree => 2.3 km ?

Line 283.  From the GLORYS Copernicus Marine reanalyses producted by Mercator Ocean International.

Line 459.   Figure 5 should be removed.  It is no more up to date and includes operational and non operational systems.   The main message should be operational systems are organized through the Copernicus marine service and are interfaced to a series of downstream coastal systems organized a national level

Page 12.  IBI MFC developed by Mercator Ocean International (MOi) and operated by NOLOGIN as part of the EU Copernicus Marine Service.     

Line 342.  MFS INGV is the Med Sea Copernicus Marine MFC described above.  To be removed.

Line 425.  The Copernicus Marine Service (CMEMS) (CMS is not the right acronym for Copernicus Marine.  When an acronym is needed,  CMEMS should be used)

Section 9.1  add the Mercator Ocean global model 1/12° here (part of Copernicus Marine)

Line 697.  Suggest to remove this paragraph on statistical model (out of scope – or you should do it in the other sections, eg AI based forecasts). 

Explain that all European operational ocean prediction activities in global and regional operational oceanography are federated as part of the Copernicus Marine Service (marine.copernicus.eu) implemented by Mercator Ocean International and are available through a common marine data store and a common user service component.   

The manuscript lists and provides a short description of the existing operational ocean forecasting systems around the Globe focusing in particular on 8 different regions. I found the manuscript very interesting and personally discovered many ocean products I did not know about. It is a reference for any reader who need ocean forecasts for specific applications and provide a clearer picture of the ocean products available. I still believe the list is partial, but it is a good starting point and there could be new updates every year or so.

Have said that, the manuscript requires mayor corrections before I can support the publication.  As it stands, the manuscript is chaotic and heterogeneous, the products are described without precise guidelines: some products are carefully written with detailed references, some others are described with few inaccuracies, for others it is not even clear whether they are operational and which are the forecasted variables. Moreover the same product can have multiple descriptions and different acronyms, some operational systems are listed in the tables but do not have a description in the text, several links are misplaced and/or do not work. I would add also a section “conclusion” as recommended by the Journal although I will not insist on this last point.

MAJOR COMMENTS

-) The description of each ocean product should be systematic and homogenised. A list of required info to be provided for each product could be the following:

• Resolution of the product
• Availability of the product
• All variables are forecasted
• Whether the products are freely available or not
• Whether they are operational or not
• Whether they include a data assimilation scheme
• Link to a webpage

Optional info can be

• Info on initial condition
• Quality of the forecasts and link to quality documents

-) In several regions the Authors list global products together with regional ones. It would be probably better to have a section on global ocean forecasts and remove them from the regional description. For global ocean forecasts the Authors can refer to the OceanPredict website  https://oceanpredict.org/science/operational-ocean-forecasting-systems/ocean-models/#section-model-characteristics

-) Since there are plenty of acronyms, it can be probably worth to include a “table of acronyms” at the beginning.

MINOR COMMENTS

Line 105

This is the only product with an exact value for RMSE. I do not find it particularly useful since it cannot be compared to any other products. The Authors can safely remove it.

Line 129-132

Is this the DREAMS system described in the table 1?

Figure 2

This Figure is too crowded, can be replotted?

Line 159,161

Rather then SSH (sea surface height) the system probably assimilates SLA (sea level anomaly). SSH is used many times instead of SLA in the text, please double check it.

Line 161: “it assimilates daily data of […] SST (e.g., AVHRR SST, RTG-SST and OSTIA) “

The SST list is a mix of L3 and L4 products, I am not sure the system assimilates all these products every day, please double check

Line 164: “Mercator provides […] their website (http://bulletin.mercator-ocean.fr/)”

Is this a different product with respect to the global ocean analysis and forecast available from CMEMS website?

Line 165

The Authors list also products at eddy-permitting resolution. In this case also FOAM (Blockey et al, 2014, 10.5194/gmd-7-2613-2014) provides the global forecasts at a similar resolution, but there are also other global ocean forecasts at higher resolution (please check the OceanPredict website).

Line 166/174:

Is NOAA-GFS different from GFS?

Line 206:

Why the Indian Ocean Forecasting System (INDOFOS) is listed for the African Seas and not for the Indian Ocean?

Line 211 and 213

GFS and ECMWF are listed but I believe those are atmospheric products.

Line 212:

is this different from Bluelink?

Line 259:

The link seems not related to GLOSSIS

Line 269: “the Global Ocean Analysis and Forecasts system provided by Copernicus Marine Service “

Is this the same product of MOI line 164?

Line 275:

Two different atmopheric forcings are used in this product?

Line 282:

The Authors mentioned GLORYS, but this is a reanalysis product. I believe the system uses the corresponding CMEMS analysis product, that should be the same of  line 164 and 269.

Line 286: “nature based solutions (NBS)“

This acronym is not used elsewhere.

Line 329: “The systems assimilate in situ and satellite data”.

Which satellite data?

Line 343:” based on NEMO and implementing a data assimilation scheme”

Which data assimilation scheme?

Line 362:” NEMO model integrated with a data assimilation scheme.”

Which data assimilation scheme? Are, the systems described in this paragraph, operational?

Line 425: Copernicus Marine Service component (CMS)

The acronym CMEMS is used previously, please choose between CMEMS or CMS.

Line 544:

GLORYS is mentioned here, is the reanalysis used or the operational analysis?

Line 604: Ocean boundary conditions are from Mercator and river run-offs from 35 point sources are used based on the FLOW products.

Is “Mercator” referring to the CMEMS global ocean analysis and forecast product? What is FLOW product?

Table 7 :

Not all the systems have a description in the text.

Line 985:

where are the references for North America?

LINKS that do not work or point to a wrong webpage:

• Page 4, footnote 5
• Table 2, Table 3, Table 4
• Line 270-271

TYPOS:

Line 55: “w e” ->”we”

Line 64: “activities ,” -> “activities,”

Line 82: “Princeton Ocean Model” misses the acronyms  (POM) that is used in the rest of the text

Table 4: 2.3 degree -> probably 2.3km

Line 261:INAM31 -> INAM

Line 263: (SAWS)38 ->(SAWS)

Line 282-283: GLORIS -> GLORYS

Line 497/499: km2->km²

Line 583 and others: 1/12o -> 1/12^° , 1/24o -> 1/24^° , 1/60o -> 1/60^°

Line 585: include -> includes