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Dimensions used by variables in the data request
| Attribute | Value |
|---|---|
| cf_category | coordinate |
| cf_standard_name | sea_water_sigma_t_difference |
| description | Coordinate variable for use with ocean_mixed_layer_thickness_defined_by_sigma_t standard name. |
| grid_class | fixedScalar |
| name | deltasigt |
| output_name | dsigmat |
| title | sigma_t criterion that determines layer thickness. The method to calculate the mixed layer depth (mlotst) is documented in Griffies et al. 2016 ( https://doi.org/10.5194/gmd-9-3231-2016 ). It is the depth at which density is larger than the density of the first model level+ a threshold of 0.03 kg.m-3 (appendix H24). For CMIP7, we propose to make the reference depth 10 m instead of the first model level (note than some modelling groups already did it that way for CMIP6). A recent study based on OMIP (Treguier et al. 2023, https://doi.org/10.5194/gmd-16-3849-2023 )discusses the fact that using the first model level as a reference makes mlotst less comparable with obs (obs-based datasets reference the MLD to 10m because the diurnal cycle is not well-sampled by observations). Furthermore, the difference of the depth of the first model level between different models makes a significant difference in the computed MLDs in some seasons/regions (Treguier et al., 2023). |
| type | double |
| units | kg m-3 |
| value | 0.03 |
| uid | 966ba436-a816-11ef-851e-c9d2077e3a3c |