Climate variations in the Northern Hemisphere based on the use of an atmosphere-ocean IPCC model

Forced and natural variability of modelled and observed Atlantic Ocean temperature and Atlantic Meridional Overturning Circulation (AMOC) is studied. In the observations and in a forced climate model run, we find increasing temperature at 1000m in the Atlantic (20N). SVD analysis shows that, for both model data and observations, a high index of North Atlantic Oscillation (NAO) corresponds to negative temperature anomaly at 1000m to the north of 55N, although geographical details of temperature anomaly distribution are different for the model and observations. Particular attention has been paid to the influence of the fresh water flux due to the present global warning on the slowing down of the AMOC. It is shown that fresh water flux change is only a secondary cause of reduced AMOC in global warming conditions, while heat flux change is probably the main reason. Finally, it is shown that internal model AMOC variability is positively correlated with the near-surface air temperature in Atlantic-European Arctic sector on a 10-year time scale

Моделирование разливов нефти в море для планирования мероприятий по обеспечению экологической безопасности при реализации нефтегазовых проектов. Часть 2. Особенности реализации прикладных задач

In the second part of the article, peculiarities of the oil spills modeling for applied problems are marked, and some examples of simulation results are submitted. As an example of a oil spill model, which able to ensure the needs of information support of applied problems, the description of model SPILLMOD is presented in the final part of the article. Also a set of parameterizations allowing to take into account the role of hydrometeorological conditions for use skimmers and booms in oil spill response operations are described.Во второй части статьи отмечены особенности постановки задачи моделировании разливов нефти для (подготовки планов ликвидации разливов нефти в море (ПЛАРН), анализа совокупной экологической выгоды при выборе стратегий реагирования на разливы (АСЭВ) и оценки воздействия на окружающую среду (ОВОС), представлены примеры результатов моделирования. В качестве примера модели нефтяного разлива, обеспечивающей потребности информационного обеспечения ПЛАРН и АСЭВ, в заключительной части статьи приведено описание модели SPILLMOD с набором параметризаций, позволяющих учитывать роль гидрометеорологических условий при использовании в операции ЛАРН скиммеров и боновых заграждени

Upper mixed layer temperature anomalies at the North Atlantic storm-track zone

Synoptic sea surface temperature anomalies (SSTAs) were determined as a result of separation of time scales smaller than 183 days. The SSTAs were investigated using daily data of ocean weather station "C" (52.75°N; 35.5°W) from 1 January 1976 to 31 December 1980 (1827 days). There were 47 positive and 50 negative significant SSTAs (lifetime longer than 3 days, absolute value greater than 0.10 °C) with four main intervals of the lifetime repetitions: 1. 4–7 days (45% of all cases), 2. 9–13 days (20–25%), 3. 14–18 days (10–15%), and 4. 21–30 days (10–15%) and with a magnitude 1.5–2.0 °C. An upper layer balance model based on equations for temperature, salinity, mechanical energy (with advanced parametrization), state (density), and drift currents was used to simulate SSTA. The original method of modelling taking into account the mean observed temperature profiles proved to be very stable. The model SSTAs are in a good agreement with the observed amplitudes and phases of synoptic SSTAs during all 5 years. Surface heat flux anomalies are the main source of SSTAs. The influence of anomalous drift heat advection is about 30–50% of the SSTA, and the influence of salinity anomalies is about 10–25% and less. The influence of a large-scale ocean front was isolated only once in February-April 1978 during all 5 years. Synoptic SSTAs develop just in the upper half of the homogeneous layer at each winter. We suggest that there are two main causes of such active sublayer formation: 1. surface heat flux in the warm sectors of cyclones and 2. predominant heat transport by ocean currents from the south. All frequency functions of the ocean temperature synoptic response to heat and momentum surface fluxes are of integral character (red noise), though there is strong resonance with 20-days period of wind-driven horizontal heat advection with mixed layer temperature; there are some other peculiarities on the time scales from 5.5 to 13 days. Observed and modelled frequency functions seem to be in good agreement

Upper mixed layer temperature anomalies at the North Atlantic storm-track zone

Synoptic sea surface temperature anomalies (SSTAs) were determined as a result of separation of time scales smaller than 183 days. The SSTAs were investigated using daily data of ocean weather station "C" (52.75°N; 35.5°W) from 1 January 1976 to 31 December 1980 (1827 days). There were 47 positive and 50 negative significant SSTAs (lifetime longer than 3 days, absolute value greater than 0.10 °C) with four main intervals of the lifetime repetitions: 1. 4–7 days (45% of all cases), 2. 9–13 days (20–25%), 3. 14–18 days (10–15%), and 4. 21–30 days (10–15%) and with a magnitude 1.5–2.0 °C. An upper layer balance model based on equations for temperature, salinity, mechanical energy (with advanced parametrization), state (density), and drift currents was used to simulate SSTA. The original method of modelling taking into account the mean observed temperature profiles proved to be very stable. The model SSTAs are in a good agreement with the observed amplitudes and phases of synoptic SSTAs during all 5 years. Surface heat flux anomalies are the main source of SSTAs. The influence of anomalous drift heat advection is about 30–50% of the SSTA, and the influence of salinity anomalies is about 10–25% and less. The influence of a large-scale ocean front was isolated only once in February-April 1978 during all 5 years. Synoptic SSTAs develop just in the upper half of the homogeneous layer at each winter. We suggest that there are two main causes of such active sublayer formation: 1. surface heat flux in the warm sectors of cyclones and 2. predominant heat transport by ocean currents from the south. All frequency functions of the ocean temperature synoptic response to heat and momentum surface fluxes are of integral character (red noise), though there is strong resonance with 20-days period of wind-driven horizontal heat advection with mixed layer temperature; there are some other peculiarities on the time scales from 5.5 to 13 days. Observed and modelled frequency functions seem to be in good agreement

NATURAL VARIABILITY OF THE ATLANTIC MERIDIONAL OVERTURNING CIRCULATION IN THE INMCM3.0 MODEL

Natural variability of the Atlantic Meridional Overturning Circulation (AMOC) in a 720-year pre-industrial simulation from the coupled climate model INMCM3.0 is analyzed. In the model, AMOC has the strongest spectral maximum at a period of 15 years. On the basis of a 5-year running mean AMOC index it is shown that the transition from negative to positive AMOC phase corresponds with high water density at 35-60N and low density at 15-25N, while during the positive AMOC phase, density anomalies are weaker. A correspondence between the positive AMOC phase and positive Arctic Oscillation is identified. Positive, negative and delayed feedbacks between AMOC and surface heat and fresh water fluxes, and heat and salinity transport in the ocean are studied. The meridional oceanic fresh water flux is found to be mainly responsible for a positive feedback, while the meridional heat flux is a main factor for a delayed negative feedback for the AMOC variability