Estimation of impact of nonlinear barotropic and baroclinic tidal effect into formation and long-period variability of sea level, current circulation, and thermohaline structure of Euro-Arctic Seas water
Grantee: Ruslan May, State Oceanographic Institute of Roshydromet, St.Petersburg Branch
PI from St.Petersburg State University: Prof. Dr Viktor Foux
PI from NPI: Dr Vladimir Pavlov
The hydrological regime of Euro-Arctic Seas is important for human life, since just it defines navigation, fisheries activity, opportunity of production of oil on shelf, and it essentially influences on climate in the region. Recently the hydrological regime of Norwegian and Barents Seas investigated enough due model accounts and in situ measurements.
However, despite plenty of in situ observations and perfection of numerical models there is unknown following important aspects until now:
Being of internal tidal waves in the Arctic seas. The generation, redistribution and dissipation of internal tidal wave energy. The internal waves influence of in formation thermohaline structure of Euro-Arctic Seas.
The residual tidal current impact into general circulation of Norwegian and Barents Sea.
The influence of tidal nonlinearity (include nonlinearity of long-period tides) on fluctuations of sea level in various spectral diapason.
Nonlinear interaction barotropic and baroclinic tides with background currents, with phenomena caused by atmosphere forcing, and with frontal zones.
The listed problems require careful study, because they determine variability of hydrological regime of Barents and Norwegian seas in spectral diapasons from tidal and synoptical to low-frequency range.
For study this questions in this project conducted joint research of data (in situ and satellite) by mathematical statistics and experiments on nonlinear three-dimensional thermohydrodynamic model.
The model, in situ and satellite data will undergo spectral, harmonically, pPCSP (poli Periodically Correlated Stohostical Processes) and wavelet analysis. The harmonical constant of tidal currents including barotropic and baroclinic component will be calculated. The following methods of separations of barotropic and baroclinic component currents used:
by the joint analysis of results of 2D modeling of flow and in situ observations
by method modal analysis of vertical distribution of speed tidal currents
by average of the basic characteristics tidal flow on depth
by filtration barotropic current of style at quasibimodal stratification
In this project conduct verification and numerical experiments on three-dimensional thermohydrodynamic model. On grids with spatial step 5 and 10km the results of following experiments will be received:
realization of model with the complete conditions (predictions of tidal level on open borders, meteorological forces of reanalysis data, year-average drain of the main rivers of region)
realization of model without rivers and atmosphere forcing.
realization of model without convective accelerations in basic equations.
realization of model with various types of waters stratification.
realization of model without rotation of the Earth, and with constant parameter of Coriolis (estimation of influence of Rossby waves on results).
realization of model with constant depth considerably exceeding fluctuations of sea level and with constant depth comparable with amplitude of sea level.
realization of model with various constants of the square-law bottom friction.
The simulation time of model is 18,6 years for elimination of tidal inequalities. For definition residual tidal currents and residual tidal level the results of modeling will be averaged for all period of realization. Results of model experiments (level, current on various horizons, temperature, salinity and density) and their variability will be mapped in terms of statistical moments of first and second order. The contributions in general long-period variability of various nonlinear effects estimated also.
The final of research work will include the spectral and correlation analysis of fields of sea level, currents, temperature and salinity of Norwegian and Barents Seas. In this research work will be defined general three-dimensional quasi-constant circulation of the Euro-Arctic Seas. Relative contributions in this circulation by the various factors will be estimated and the variability of currents, level and thermohaline structure, reasons of the variability will be found.
Assessment of sea ice cover parameters within the area of Fram expedition in 1893-96 including Nansen sledge trip to North Pole
Investigators: Dr Vasily Smolyanitsky and Dr Sergey Frolov, AARI
To assess sea ice cover parameters (total concentration, old ice concentration, ice thickness or volume, surface features likely snow on ice, hummocks, ice drift vectors) and their short term variance for the high-latitude area of Fram expedition in 1893-96 including Nansen sledge trip to North Pole and
To simulate possible drift tracks with various starting years with different Arctic general drift pattern
General tasks and strategy of the work include:
Select and acquire optimal data sources;
Select possible sea ice cover parameters and construct databases;
Assess statistics for selected sea ice cover parameters;
Define types of Arctic general drift pattern;
Find possible analogue years from the second part of XX century for the period of Fram drift;
Simulate possible drift tracks with various starting years;
It is proposed to acquire following data sources:
WMO “Global Digital Sea Ice Data Bank” project sea ice charts including AARI 10-days period ice charts for 1950…1992 period and NIC (USA National Ice Center) 7-days ice charts for 1972-1994 in WMO SIGRID format;
Passive microwave Nimbus-7 and DMSP SSMR-SSM/I daily ice parameter patterns for 1978-2004 period and AQUA AMSR daily ice parameters patterns for 2003-2004 from USA NSIDC;
Combined data base of sea ice drift measurements from USA and USSR manned stations, DARMS and IABP for 1953…1997 period (from EWG USA-Russian Joint Arctic Ocean Sea Ice Atlas on CD);
Shipborne visual measurements during high-latitude cruises of icebreakers and icebreaking vessels during 1977-2002 period;
Data from publication, including Fram log-books.
Ice cover parameter:
It is proposed to assess statistics, generally in seasonal cycle with monthly step for the following ice cover parameters:
Total concentrationStages of ice development (up to 11 according to WMO nomenclature, old ice partial concentration) and ice thickness/volume of level ice, possibly corrected by means of visual shipborne observations.
Short term variance of sea ice total concentration based on SSMR-SSM/I and AMSR dataIce drift variances in seasonal cycle and simulation of possible FRAM drift with various starting years.
Surface features including snow on ice, hummocks etc based on visual shipborne observationsAll ice cover parameters will be presented in mapped form in standard polar projections with superimposed Fram drift tracks.