A thermobaric instability of Lagrangian vertical coordinate ocean models

Abstract. Sensitivities of the oceanic biological pump within the GISS climate modeling system are explored here. Results are presented from twin control simulations of the air-sea CO2 gas exchange using two different ocean models coupled to the same atmosphere. The two ocean models (Russell ocean model and Hybrid Coordinate Ocean Model, HYCOM) use different vertical coordinate systems, and therefore different representations of column physics. Both variants of the GISS climate model are coupled to the same ocean biogeochemistry module (the NASA Ocean Biogeochemistry Model, NOBM) which computes prognostic distributions for biotic and abiotic fields that influence the air-sea flux of CO2 and the deep ocean carbon transport and storage. In particular, the model differences due to remineralization rate changes are compared to differences attributed to physical processes modeled differently in the two ocean models such as ventilation, mixing, eddy stirring and vertical advection. The Southern Ocean emerges as a key region where the CO2 flux is as sensitive to biological parameterizations as it is to physical parameterizations. Mixing in the Southern Ocean is shown to be a~good indicator of the magnitude of the biological pump efficiency regardless of physical model choice.

Download Full-text

On the impact of vertical coordinate choice for innovation when assimilating hydrographic profiles into isopycnal ocean models

Ocean Modelling ◽

10.1016/j.ocemod.2021.101917 ◽

2021 ◽

pp. 101917

Author(s):

F.B. Costa ◽

C.A.S. Tanajura

Keyword(s):

Vertical Coordinate ◽

Ocean Models ◽

The Impact

Download Full-text

Development of an Adaptive Vertical Coordinate Capability for Community Ocean Models

10.21236/ada625354 ◽

2001 ◽

Author(s):

Y. T. Song ◽

Yi Chao

Keyword(s):

Vertical Coordinate ◽

Ocean Models

Download Full-text

Impact Assessment of Dynamic Characteristics on the Hydraulic Driven Machinery Operation

Mechanical Engineering and Computer Science ◽

10.24108/0418.0001354 ◽

2018 ◽

pp. 1-12

Author(s):

A. D. Terenteva

Keyword(s):

Dynamic Error ◽

Total Error ◽

Soil Layer ◽

Hydraulic Drive ◽

Hydraulic Cylinder ◽

Working Mechanism ◽

Automated Control ◽

Vertical Coordinate ◽

Construction Machinery ◽

The Difference

In civil engineering in Russia, trenching for utilities is currently under digging. To perform such works, it is necessary to use high-precision construction machinery, because inaccurate performance of works can lead to the break down of existing utilities, thereby affecting the residents of nearby houses and demanding the additional works for renewal.The most universal labour saver to perform construction works is hydraulic driven single-bucket excavators, which provide up to 38% of works. Therefore, to improve technical characteristics that affect the accuracy of the work performed is an important task.High requirements for the performance of works are defined by existing construction regulations: an allowable soil layer to remain is at most 0.05 m. To fulfil such requirements, an exact assessment of the working mechanism position and a trench profile is necessary.Examination of a manually operated digging process shows that an operator provides operations untimely, however an automated control system can solve this problem. Dynamic phenomena in the working mechanism have the greatest impact on the accuracy of the works performed.To assess the bucket digging edge position accuracy, a mathematical model of the working mechanism has been created. Based on the cycle scheme of the working process, the excessive displacements of the hydraulic cylinder rods under the load are taken into account. By the end of the cycle, the difference between the specified and obtained positions along the vertical coordinate has been 0.0892 m.A dynamic error of the hydraulic drive system of the working mechanism is considered as a sum of the error due to excessive displacements of the hydraulic cylinder rods and the error due to delay of the hydraulic drive, with the latter being calculated for the average time of delay taking into account the data available in the literature. The total error of the bucket digging edge position of the working mechanism is 0.1176 m, which is 2 times more than the value of 0.05 mConformity of all the links with specification requirements does not guarantee compliance with the required displacement accuracy of the bucket digging edge, and, thus, the soil layer to remain in the base of the trench can exceed the regulated value of 0.05 m.

Download Full-text