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Hydrographic monitoring - neva bight


The objective was to conduct a study on the relationship between the Gulf of Finland waters and the Neva Bight, using historical and actual optical remote sensing data. This study had the objective to understand the external impact on the Neva Bight. The study also included the usage of in-situ measurements and SAR remote sensing data, which are part of the contribution of the other HYMNE partners. A literature study of the hydro-meteorological situation was carried out and found that satellite remote sensing data were seldom used. Therefore, NOAA-AVHRR satellite images were selected for analysis of Sea Surface Temperature. The AVHRR instrument is available on two satellite platforms and the spectral bands of the AVHRR are dedicated to provide the sea surface temperature. For studying the temperature pattern in different areas, the Neva Bay and the Gulf of Finland were divided into 10 boxes. The detailed results of the statistical analysis can be found in the Report on the External Impact. The typical distribution of the average SST within the Neva Bay in the different boxes can be summarised as follows: - In 83 of 145 cases investigated (57 %) the SST around the dam is warmer than in adjacent waters during the ice-free months. Divided into the seasons a clear differentiation can be observed: Spring: 77,5% of all spring cases; Summer: 64% of all summer cases; Autumn: 5% of all autumn cases. - In 103 of 145 cases investigated (71%) the average SST northwest of the dam is higher then in the southwestern part during the ice-free months. Divided into seasons: Spring 55%; Summer: 83%; Autumn: 80%. - In 112 of 145 cases investigated (82%) the SST increases from St. Petersburg towards the dam. - In 110 of 145 cases investigated (76 %) the SST decreases proportionally to the distance away from the dam in a western direction during the ice-free months. Divided into the seasons: Spring: 96%; Summer: 88%; Autumn: 15%. - In 94 of 145 cases investigated (65%) the SST west of the dam is warmer than that in the east during the ice-free months. Divided into seasons: Spring: 46%; Summer: 65%; Autumn: 99%. - In 120 of 179 cases investigated (67%) the northern section of the Gulf of Finland is colder than the southern part.
The overall objective of HYMNE was to provide the environmental administration of Saint Petersburg a low cost tool, which is well enough validated to monitor and to predict key parameters for the description of the environmental situation in the Neva Bight. It is possible to solve this task only when considering the Neva Bight as a part of the Neva-Ladoga Lake water system and by taking into account the current hydrographical monitoring system in the Gulf of Finland and also the improvement of the system on the basis of the last achievements of Baltic Sea countries. Modern hydrographical monitoring systems are built on a complex collection, processing and analysis of heterogeneous distant and in-situ hydrometeorological information. The hydrological regime of the Neva Bight and the water quality are determined for the first by Neva river run-off, ice conditions in the Gulf of Finland and the Ladoga Lake (in winter) and synoptic processes which could result in some cases in anomaly hydrological phenomenon (such as floods) dangerous for the Saint Petersburg and populated area in the Neva Bight near shore. Preceding this, the participants of the project developed the directions of monitoring system improvement for information ability increase in different season and hydrometeorological conditions. The standard actual and forecast hydrometeorological data from the European Centre for Medium-Range Weather Forecasts and network of observation posts of Leningrad Regional Centre for Hydrometeorology and Monitoring of Environment constitutes the base information. This data allows to plan and process data collection from distant measuring systems (first of all take into consideration the closing of the water area by clouds creating obstacles for satellite observations in visual and infrared bands) and to serve as the initial information for modelling of water and ice dynamics. The characteristics of ice situations are determined by the data from shore posts of Leningrad Regional Centre for Hydrometeorology and Monitoring of Environment (bearing point measurements) and satellite optical information which are collected and analysed in Satellite Information Department of the Centre of the Ice and Hydrometeorological Information of the Arctic and Antarctic Research Institute (AARI). Satellite radar data is used to get the area information in any meteorological conditions. The special methods were developed by University of Dundee for this task. The charts of actual ice situation are prepared on the base of this data in Centre of the Ice and Hydrometeorological Information of the AARI. They serve as the initial information for the modelling of water and ice dynamics together with meteorological forecast charts. 2D and 3D models for common water and ice dynamics developed in AARI allow forecasting the main hydrological and icing characteristics in the Neva Bight and in the Gulf of Finland. The ground radars and special methods for radar data analysis were developed by GKSS Research Centre and Saint Petersburg Electrotechnical University and used for area measurements of sea surface currents and ice drift in any time, hard weather and orographic (mountainous) conditions. This information is also used for the verification of the models for water and ice dynamics. Russian State Hydro-Meteorological University conducted the measurements of the vertical profiles of currents in some water area points and the establishment of their peculiarities. The data allows to verify the hydrological models and ground radar measurements of currents. The Finnish Institute of Marine Research conducted hydrological measurements on the open water area of the Gulf of Finland. The output data of 3D hydrological model is the initial information for ecological modelling in the Neva Bight and the Gulf of Finland. The ecological models of the Independent Consulting & Investigation Centre (ICIC) allowed determining the main characteristics of water quality. Brockmann Consulting used the special methods for satellite data processing for estimations of chlorophyll concentration in water of the Gulf of Finland. Such data could be used for verification of ecological models as well. The AARI's Service for Automated Data Collection and Transmission (SADC&T) allows the operational collection and transmission of all initial hydrometeorological data as well as standard network hydrochemical information. From the other side the SADC&T is connected with Leningrad Regional Centre for Hydrometeorology and Monitoring of Environment that is official state responsible organization for hydrographical and ecological monitoring in the Neva Bight and the Gulf of Finland.
The spreading and mixing of the river Neva waters in the eastern Gulf of Finland was of interest in HYMNE. A 3-D hydrodynamic-numerical model by Andrejev and Sokolov was used in simulations of the river flume flow to the eastern gulf. The model simulation showed strong mixing of the water masses already in the easternmost gulf. The river flume tends to separate from the coast. Current stability calculations have previously shown that the westward net outflow in the gulf is most stabile outside the coastal boundary layer slightly northward from the centre line of the gulf.
In the frame of the project the ecosystem module, based on a biogeochemical model of Savchuk and Wulff (1996) has been adopted for the region of interest. Simulated water dynamics is used in a system of transport equations for ecosystem variables, where the Biogeochemical module describes nitrogen and phosphorus cycling among 8 pelagic variables (phytoplankton, zooplankton, nitrogen and phosphorus detritus, ammonium, nitrate, phosphate, and oxygen) and two benthic variables (bioavailable nitrogen and phosphorus in the sediments). For the project needs the hydrological model and the ecological model are presently being combined into one system. The results obtained imply that the model simulates the principal features of the real situation in the Neva Bay and Gulf of Finland including their seasonal variability. Coupled model algorithms adopted for the project needs and ported to the common program environment. Common programming environment includes Unix platform (Linux, Irex6.2) and Fortran 95 compiler. Data exchange format is the text file and the output format could be text or graphic image presenting typical scenarios of environmental situation in the Neva Bay.
The HYMNE project created a low-cost hydrosphere monitoring tool for the prediction and control of key hydrological variables in the Neva Bight and Gulf of Finland (GOF) which are of major concern to the St. Petersburg administration. A ground-based X-band radar complex with two radar stations was used as one of the tools for measuring marine surface parameters, surface currents and observing ice conditions. The mobile monitoring radar post was developed for the present experiments. The mobile post was installed on the automobile "GAZEL". The advantages of using a ground based radar system can be seen by the possibilities of acquiring constant and real-timed data at a rather small cost and the exploitation and matching of these data with satellite systems are independence of the weather conditions. Furthermore, the high spatial resolution allows measurements to be made with a very small grid resolution. The radar complex ETU has two radar stations: the pseudo-coherent navigational pulse radar "LOZIA" (transmitter pick power 6kW), experimental coherent radar "ALPHA" with very low pick power transmitter (10W) and phase modulated sounding waveform (Barker code 13 bits). A slotted wave guide antenna with electronic switching vertical and horizontal polarisation was especially manufactured for the marine surfaces remote sensing. This allowed the use of the polarisation effect when electromagnetic wave reflects from a marine surface or ice. The hardware-software structure of the radar complex for the realisation of hydrological measurements with the help of radars of ground level basing of microwave-range was determined.
The project fulfilled the improvement of the radar system towards a complete system for observing and predicting the sea surface state. The development of software for processing was accomplished. Radar antennae were optimised for the hydrographic application (vertical polarisation and programmable azimutal positioning). The optimal position for a fixed radar station was designated. A mobile station was prepared to be easily installed at the observation point on the coast (to the south of the dyke). The control software to operate multiple radar systems was set up. The software for acquiring and archiving the data in real time and to correct the model during operations was upgraded. The information transfer between the measurement hardware and the model was optimised taking the operational requirement into account. The design of a strategy of the remote sensing radar (radar monitoring); realisation by ground-level radar stations is intended to apply to the present systems of the Gulf of Finland monitoring was accomplished. The radar measurement techniques of hydrological parameters used in hydrological models were designed. Special attention deserted a method of the surface current measurement by a single radar, as ensuring maximum mobility and effectiveness of the information obtaining. The theoretical error analysis of the velocity vector measurement of the surface current was conducted. It was demonstrated that defining the minimum error of the current velocity is reached at values of angles between measured radial components of a current vector of about 50-150 degrees. This also determines the selection of radar locations for remote sensing.
The numerical model for common water and ice dynamics is intended for the calculation of the main hydrological characteristics in the Neva Bight and the Gulf of Finland. The system of the equations includes the two-dimensional model for forecast of the storm surges taking into account the friction between the water and ice and the ice cover dynamics that take the slopes of the water surface into account. The model was constructed at three levels. The first level covers the entire Baltic Sea with a 30km grid size. The second level covers the Gulf of Finland with a grid resolution of 5km. The third level model with a grid resolution of 1km covers the Neva Bight and the eastern part of the Gulf of Finland. The relations that had been obtained during the work on model calibration calculated the speed and direction of sea level wind and the tangential stresses on the sea and ice surface. The model for water and ice common dynamics allow to determine the following parameters: sea level fluctuations; current direction and speed; ice drift direction and speed; ice compaction; ice distribution; atmospheric pressure; direction and speed of sea level wind. A quality analysis of the prognostic results for the level prediction compared to level observations at a series of stations at the Gulf of Finland demonstrated a high efficiency of the model. The mean absolute error of the predicted rise of level was 10-20cm, the mean quadratic error was 15-25cm and the correlation coefficient was 0,70-0,90.
The aim of this block of the ecological model was to give a very rough estimation of the controls measures costs in the scope of the entire region. Initially cost functions are standardized for 2000 Russia conditions. When costs for pollution control are calculated, the model adds up all the investment-related costs to estimate the total investment costs per source of polluting process, and adds up all the variable costs to calculate the total variable costs per source of polluting process. Preliminary estimations for the region of interest shows that "Good Housekeeping and Waste Prevention" programs control might have beneficial economic effects on the productivity of the industry beyond their effects on pollution reduction.
The objective was to conduct a study on the relationship between the Gulf of Finland waters and the Neva Bight, using historical and actual optical remote sensing data. This study had the objective to understand the external impact on the Neva Bight. The study also included the usage of in-situ measurements and SAR remote sensing data, which are part of the contribution of the other HYMNE partners. A literature study of the hydro-meteorological situation was carried out and found that satellite remote sensing data were seldom used. Therefore, SeaWifs data (together with NOAA-AVHRR satellite images for anaylsing Sea Surface Temperature) were selected to quantify the distribution and concentration of suspended material, particularly algae. The SeaWiFS (Sea-viewing Wide Field-of-view Sensor) is an optical scanner with a resolution of 1km at nadir (LAC: local area resolution, which is used here). The radiation is separated into four wavelength regions. Spectral bandpass filters are used to narrow these regions to the 20nm requirements of the 8 SeaWiFS spectral bands. The processing of the SeaWiFS data included the RGB presentation of the data, the geo-referencing and the calculation of the chlorophyll concentration from the spectral information using the standard SeaDas software package as well as a phenomenological analysis of RGB and Chl images. The spatial resolution of the data (1km at Nadir, 4km at the edge of the swath) is at the lower limit for the investigation of the Neva Bight. However, the general trend of the chlorophyll concentration agrees with the in-situ measurements made. Further, some images do show patterns in the Neva Bay, however only in an image from 16th May 2000, a structure similar to a river plume could be detected. This structure indicates the Neva flowing to the south of the Neva Bay and passing the dam in the southern part, following the dredged shipping lane. Other images show a relative even distribution of material in the Neva Bay, where no current can be identified.
Three-dimensional model for water dynamics having the connection with the ice dynamics model was developed for calculation of the hydrological regime parameters in the Neva Bight and the Gulf of Finland. A description of the vertical profile for current speed was chosen in the form of the sum of the modes determined by the analytical functions. Such an approach permits the execution of calculations quickly, which is necessary for the operational use of the model during hydrographical monitoring. The Navier-Stokes equation was transformed and the currents' vertical profile was parameterised with the use of basic functions that were chosen depending on the physical notions on the currents' nature. The number of improvements was introduced in comparison to the analogous Devise model that allowed obtaining satisfactory results for the basins with different depths. A three-dimensional model for water dynamics was combined with the ice dynamics model. This allows using it for calculations during the whole year. The spatial resolution of the third level model grid (up to 500m) was improved during the model adaptation for correct modelling of the Neva Bight. The open boundary was laid on the meridian that passes through the Stirsuden Cape on the north bank and the Ustinskiy Cape on the south bank. The results of the numerical calculations showed the satisfactory quality correlation between calculation and in-situ observations as well as conforming to the information from published sources on the character of water mass dynamics. At the same time the results allow the enlargement of the notions on hydrologic conditions of this water area to provide more details.
R/V Aranda did two research cruises in the Gulf of Finland. The purposes of the cruises were to obtain ground truth data from sea temperature, salinity density, oxygen and nutrients in the gulf. The first cruise was done in 23-27 April 2001 just after the disappearance of the ice cover from the gulf. That time represented winter conditions before the spring bloom. It covered the eastern Gulf of Finland only. The second cruise was conducted in 3-9 June 2001 and it covered the whole Gulf of Finland. This cruise was aimed at the season when the annual river discharge is at its maximum. Temperature, conductivity and oxygen profiles were measured with a CTD-sonde and water samples were taken and analysed for determination of nutrient constituents along several sections across the gulf.
The regime-reference textbook "Hydrometeorological conditions of the Neva Bight" was prepared on the basis of analysis and generalization of published data. The textbook includes the overall complex of hydrometeorological information which must be taken into account when plan the economic activity, organize the monitoring system, long-term forecasts and to develop the methods for forecasting of individual hydrological characteristics. The textbook consists from introduction, eight parts and conclusion, the list of used literature. The last spread to 150 issues. In the first part of the textbook the data are adduced about physic-geographical location of researched region namely Neva river, Neva river delta and Neva Bight. In the second part the climate conditions of the Neva Bight are characterized. The data are adduced about average characteristics and change of atmospheric pressure, wind, temperature and humidity of air, at-mospheric precipitations, snow cover, clouds, mists and solar radiation. The third part includes the data about Neva river discharge as a factor that has the strong influence on hydrological regime in the Neva Bight. The forth part is devoted to the regime of sea level fluctuations in Neva Bight. There the data adduced on of long standing, seasonal and daily level fluctuations. The main characteristics are given for surges, high tides, negative surges, surges and floods that had been seen in Neva Bight. In the fifth part the systems are described of flows that are formed in the different areas of Neva Bight under the influence of different factors. The wind, flowing, slopes of surfaces and ice cover is attributed to the main factors. The sixth part includes the brief information about rough sea on the water area of the Neva Bight. In the seventh part the ice conditions of the Neva Bight during the winter period are described. In the eighth part the data are adduced on average characteristics and change of temperature and salty.
As the river Neva is the largest fresh water supply to the entire Baltic Sea, we could expect to see the clear effect of variability of discharges in the variability of coastal salinity conditions along the northern coast of the Gulf of Finland. This assumption is a direct consequence from the general dynamics of the gulf. Most factors affecting the circulation, like winds, Coriolis and density distributions, favour cyclonic circulation pattern in the gulf. Thus long term resultant mass flow circulates counter-clockwise in the gulf. However, the real dynamics are more complicated. Meso-scale eddies with horizontal scales of kilometres to some tens of kilometres are common features. Stability of the flow, determined as the ratio of vector mean velocity to mean current speed, is generally lower than 50% except during late autumn and some places like the northwestern coast of Estonia. This means that the direction of the instantaneous current is rather variable in most of the gulf. Co-analysis of Neva river discharge and coastal salinity along the Finnish coast shows correlation between these, but it is sometimes low. The propagation speed of the signal seems to correspond to the earlier estimates on resultant mass transport along the coast.
The model was designed to produce a pollution load data for transport models. Pollution loads resulting from emissions in water are calculated by multiplying the levels of production by the corresponding emission factors and by corresponding reduction factors if a control technology (reduction measure) is adopted. Emission factors are average values that take into account the type of process used in that industry, input or other technological characteristics that are relevant for emission levels (e.g. quality of fuel used), and the presence (or absence) of waste prevention programs. Comparison of the model results against statistical data shows that these estimations are suitable to form model input for any operation year with certain accuracy based on the available production levels.
The complex hydrodynamic module is based on a 3-D ocean circulation-sea ice model of Neelov (1996). The distinctive features of the Neelov model are a numerical scheme without the numerical diffusion for advective terms in the heat, salt and tracer transport equations and a large time step (0.5-1.5 hours) owing to using implicit difference schemes in equations for the turbulent kinetic energy and sea level elevation. The model is driven by daily atmospheric forcing taken from the re-analysis of NCEP/NCAR, daily values for water flows, temperature and salinity in the Danish Straits, mean monthly water discharges for all major rivers flowing in the Baltic Sea and the Gulf of Finland and mean monthly concentrations of nutrients and organic matter at river mouths. Model runs are carried out in two stages. First, the model is integrated on a 10x5km grid for the whole Baltic Sea. After that the solution for the Gulf is obtained on a finer grid (with grid size of 3.7km), the conditions at the boundary with the Baltic Proper being taken from the solution for the whole Baltic Sea. Simulated water dynamics can be used in a system of transport equations for physical transports of toxic pollutants.
One innovative component of the HYMNE system is the complex radar acquiring data on a high-resolution grid. The hardware consists of ground based X-band radar, which was tuned to detect movements at the water surface level by the Doppler effect. The Doppler measurement is based on the phase detection of the individual radar beam. By inverse modelling hydrodynamic parameters, such as the surface current during the ice-free season, and ice floe mobility during winter conditions can be detected. Using a shored base mounted radar it was shown, that during low wind speed conditions (u<5m/s) the sea surface current could be detected from the radar signal Doppler shift. For the calculation of the full current vector radar data must be acquired from two different positions. The frequency shift acquired from both positions must be corrected for the effects due to the local wind and wave impact. Under known stratification the vertical current profile will be assessed by means of the numeric model run by AARI and thus transport rates can be estimated. To observe the ice-floe mobility, time series of the radar images were Fourier decomposed. Arial structures due to stationary ice fields were recognised to induce a signal with low frequency. Signals with higher frequencies were detected over moving ice fields. It was shown that the number of floes and their speed correlates with the detected frequency.