Historic records for currents at depth

Challenge ID

C-CORE_OFF1.4

Title

Historic records for currents at depth

Challenge originator:

General Description

What data/products do you use?

Historical ocean currents data for currents at depth are available via different agencies. They are either based on reanalysis, hindcast model data or derived from satellite observations. Quality is lower than for the surface currents due to fewer observations.

Data from Global models:
HYCOM+NCODA model system
Three Global reanalysis from MERCATOR, University of Reading and  CMCC via MyOcean
Data from regional models:
Mediterranean Sea: MEDSEA (MyOcean)
Iberian, Biscay and Irish Seas: IBI MFC model, limited in time.
European NW Shelf: FOAM

Currents derived from satellite:
Global geostrophic currents analysis from MyOcean derived from satellite observations
Global geosptrophic currents from NOAA: derived from sea surface height, wind speed and sea surface temperature satellite observations

When do you use this kind of dataset?

Historical ocean current data at depth are used to great extent in all phases of the O&G cycle, except strictly operational tasks.

The data set is used to assist in qualifying and quantifying the means and extremes of ocean currents in the area of interest. In addition ocean data are important for environmental impact studies, oil spill trajectory modeling, modeling of drilling cuttings etc.

During the early stages, field assessment/seismics etc. the data are mostly used to assess the operability of the area during different seasons and to assess financial risk and first draft of development costs.

During planning of new fields and operations data are used to assess the climatic limitations local/regional weather would have on safety in order to reduce risk for operations, personnel and environment. 
 

Finally surface current data are important to design of structures that can withstand the local conditions and take into account the risk of the extreme situations of the area.

What are your actual limitations and do you have a work around? 

Same as for wind and wave, only that data of sufficient quality is very rare. Most of this is due to the limited access to observations of currents at dept. Most current observations are made at the surface. In addition data of sufficient quality can be even harder to come by in coastal and remote/less developed areas. Modelled data has low quality for on shorter time scales, while climatology is of sufficient quality. These data rarely catch short lived and small scale extremes.

There are important spatial and temporal limitations of historical surface-based and remotely-sensed ocean current observations that make the analyses of extreme values very challenging (e.g., most extremes at sea were probably not observed or sampled).

Vertical resolution, often to large, does not catch variations in shallow coastal areas. Bottom dynamics not well described.
Update frequency:
Generally to slow, and not extended to real-time. And observations for "patching" often not available.
Temporal resolution:
Not by far sufficient, often daily snapshots, and averages, does not catch important events.
Spatial resolution:
Not by far sufficient, should have at least 4 km resolution to resolve small scale features and coastal areas.
NOTE. High resolution and high update resolution does not equal quality, hence documentation of verification is equally important!!

Time consuming to work with these data series, makes accurate analyses expensive.

Needs and expectations on EO data

EO cannot be used for this today.

Long (10 years +) observed time series of high quality from gliders, ADCPs etc., in all areas.

Specific need: Long time series of ocean current data.

Challenge classification

Pre license

3

Exp.

4

Dev.

4

Prod.

3

Decom.

3

Geographic context/ restrictions

Applies to all six areas of interest, except for the cautionary notes about tropical cyclones, which only applies to South China Sea, West of Ireland, and Myanmar.

Seasonality: Applies to all seasons.

Topographic classification / Offshore classification

Ocean

Activity impacted/concerned

Technology Urgency

Short term (2-5 years)

Information requirements

Update frequency

Available today:

Temporal resolution

Data should be at least 1-3 hourly resolution depending on area and phenomena needed to be resolved.

Available today:
OSCAR: 5-day moving mean.

HYCOM+NCODA system: Daily snapshot at 00Z
MyOcean global reanalysis: Monthly (all), weekly (MERCATOR) , daily (CMCC) from 1993
Regional models:
Mediterranean Sea: MEDSEA (MyOcean): Monthly, daily from 1987
Iberian, Biscay and Irish Seas: IBI MFC model: Daily means (and hourly means) from 20110401
European NW Shelf: FOAM: Daily means from 1985

Currents, temperature and SST derived from satellite:
Global geostrophic currents and SST analysis based on satellite observations: Weekly and monthly means

Spatial resolution

Around 4 km, maybe less in coastal areas.

Available:
OSCAR: 1/3°

HYCOM+NCODA system: 1/12°
MyOcean global reanalysis: 0.25°
Regional models:
Mediterranean Sea: MEDSEA (MyOcean) :6-7 km
Iberian, Biscay and Irish Seas: IBI MFC model: ~2km
European NW Shelf: FOAM: 7 km

Currents, temperature and SST derived from satellite:
Global geostrophic currents and SST analysis based on satellite observations: 1/4°

Data quality

The selected sources in this document are selected because they are known to have sufficient quality (after some work around/adaptation). In general separate indepth verification studies has to be made for each source planned to be used for analysis, and the analysis has to be repeated for each geographical area (since sources might be of sufficient quality in one area but not another).

Data Coverage and extent

Regional.

Example format

CSV and/or netCDF

Timeliness

Normally needed urgently, possibly before assessing, planning, or exploring a new field. Hence the data source used for analysis needs to be frequently updated to avoid unnecessary waiting. Daily, weekly or monthly updates of data sets are sufficient, depending on the analysis required.

Existing standards

In addition, DNV-RP-C205, ISO-19001-1, and DNV-OS-J001 contain cautionary notes regarding the treatment of waves in areas that experience tropical cyclones, such as South China Sea, West of Ireland, and Myanmar.