Integrated ground-based remote sensing stations for atmospheric profiling

Ziel

A.BACKGROUND

A long-term trend in meteorology is to study and forecast atmospheric phenomena at increasingly finer scales, both in research and operational activities. Hence, aerological measurements with adequate resolution in space and time are needed. With respect to wind profiling COST-76 has realised significant improvements, in particular in data quality and data availability, as demonstrated during different experiments like CWINDE-97 and CWINDE-99.

However, apart from wind, there still is a lack in measurements of vertical profiles of other essential meteorological parameters, in particular of temperature and water (solid, liquid and vapour). This particularly impacts short-range forecasts and nowcasting, which includes boundary-layer evolution and pollution dispersion. Although there are already instruments providing this type of information (see C-1), and also some of the instruments are being developed or improved in the frame of COST actions, there is nevertheless a need to:

- integrate the various techniques into one profiling station, which will enable the improvement of the quality control procedures and the derivation of additional parameters

- improve signal processing algorithms and data availability in order to enhance data quality under all atmospheric and environmental conditions

- reduce the efforts and cost of manual service and maintenance of the stations, in particular under operational conditions, which would also allow cost-effective operation in remote areas

- push the industry to reduce the costs of remote-sensing instruments for profiling stations in order to promote a broader implementation in the national weather services.

Ground-based remote-sensing techniques are, and will remain, complementary to already existing observing systems, because:

- while radiosondes can provide high-resolution vertical profiles, they cannot economically provide the high-time resolution data needed for the new fine-scale models and very short-range forecasts

- while commercial aircraft measurements may provide high-time resolution data, they are limited in profiling to regions around airfields

- while geostationary-satellite measurements can meet timeliness and areal requirements, they cannot supply profiles with sufficient vertical resolution and accuracy, particularly in the critical lower 2 km. Moreover, in most cases satellite sounding instruments have poor performance under cloudy conditions. Polar-orbiting satellites have better sounding capacities than geostationary ones but provide poor temporal resolution.

Integrated remote-sensing stations can be used for synoptic-scale numerical weather prediction (NWP), mesoscale NWP, boundary-layer research and air-pollution monitoring, and air-traffic control. For most types of use, the full benefit of these stations can only be obtained by establishing (international) networks. For the definition of such a network, impact studies will be done, where participation of experts in the particular field of use is of vital importance. As for synoptic-scale NWP, the outcomes of these studies will be the indispensable prerequisite for the evaluation of the possibility of future inclusion in the EUMETNET Composite Observing System (EUCOS) of a network of such integrated remote-sensing stations, and in case of a positive decision, also for the network design (density) and implementation. While the demonstration of the technical feasibility, including quality assessment, is part of this action; it is anticipated that any future development into networks and operational use would be undertaken in other programmes, such as the EUMETNET programme for synoptic- and mesoscales.

As well as the benefits mentioned above, the data can also be used as reference data in developing the data assimilation procedures of numerical models and in evaluating new space- or ground-based measuring techniques.

In practice, remote-sensing tools are often exploited by institutions that have specific knowledge and expertise in a limited number of techniques. Moreover, cooperation between data users (e.g numerical modellers) and the instrumental community is currently rather weak. This COST action, inter alia, addresses this weakness through proposing a well-structured international project, in which experts from National Weather Services, Universities and Industry cooperate.

B.OBJECTIVES AND BENEFITS

The main objective of the action is the development of cost-effective integrated ground-based remote-sensing stations for atmospheric profiling and the assessment of their use for meteorological analysis and forecast as well as climate research and climate monitoring.

Nowadays, atmospheric numerical modelling (operational and research) at increasingly finer scales requires high-quality measurements with high temporal and spatial resolution. In this respect, ground-based remote-sensing techniques are best suited to complement existing measurement techniques with satellites, commercial aircraft and radiosondes. Further improvement and integration of the various existing remote-sensing techniques will lead to several benefits:

- the security of the airports operations demands real-time profiles of the lower atmosphere for production of warnings of dangerous conditions;

- substantial improvement of the description of the vertical atmospheric structure, taking full advantage of the synergy resulting from the integration of different techniques;

- substantial improvement of the description of the time evolution of the vertical atmospheric structure, which is especially beneficial for planetary boundary-layer (PBL) research and for fine scale modelling, in the view of ongoing development of 4-dimensional variation analysis (4D-VAR), e.g. for limited area models;

- standardisation of methods for precise measurements and quality control of wind, temperature and humidity profiles leading to potential networking of such stations;

- improved cooperation between European institutions and feedback to the industry, which is a prerequisite for future cost-effective European networking;

- enhanced European competitiveness in science and technology.

To achieve these benefits, the action is structured into the following major topics:

- Identification of needs for operational meteorology and atmospheric research in the fields of NWP, PBL (including air quality and dispersion modelling), and climatology.

- Assessment of existing remote-sensing techniques and selection in view of their applicability in an integrated station and their capability of fulfilling the user needs.

- Optimisation of the chosen techniques where necessary in view of operational applicability.

- Integration in a station and development of integrated quality-control procedures

- Development of additional parameter derivation.

- Development of data coding and data exchange procedures.

- Data quality assessment in view of use within a network, including impact studies such as Observing System Simulation Experiments (OSSEs).

- Documentation and dissemination of results.

C.SCIENTIFIC PROGRAMME

The scientific programme falls logically into five areas. After identification of suitable basic techniques and improvements of the corresponding basic algorithms, the main work will be the integration of the individual systems, allowing the derivation of basic meteorological parameters (e.g. temperature instead of virtual temperature) as well as additional meteorological parameters (e.g. mixing height, covariances, etc.); quality control will be performed at each stage, using the advantage of the simultaneous availability of various parameters; eventually the operational aspects, including impact studies, will receive attention in the view of future possible network deployment.

The programme indispensably prerequisites a comprehensive identification of user needs for both operational meteorology and atmospheric research in order to reduce the gap between users and instrumental community. It is divided into the following five major working fields, where the bullets summarise main activities:

C-1Basic techniques

- Identification of user needs. Here, four different user groups can be identified:
- Meso-scale NWP,
- Synoptic-scale NWP,
- boundary-layer research and air-pollution monitoring, and
- air-traffic control;

- assessment of existing techniques in view of the user needs (as regards vertical resolution, accuracy and availability under operational conditions), for instance:
- active systems: Wind Profilers (wind), Sodars (PBL winds with enhanced vertical resolution), Doppler Lidars (wind), Radio-Acoustic Sounding Systems (RASS: virtual temperature; having enhanced vertical resolution with Sodar), Raman Lidar and Differential Absorption Lidar (water vapour, mixing height), Cloud radar and Ceilometer
- passive systems: Microwave Radiometer Profiler (MRP: temperature, liquid water and water vapour), Fourier-Transform Infrared Radiometer (temperature and water vapour), GPS

C-2Basic Algorithms

- review and improvement of algorithms, both theoretically and experimentally, for profiling of wind, temperature, and humidity, like e.g. multi-peak signal processing of Doppler spectra, Wavelet transform, the fuzzy-logic technique or neural networks concerning wind profiling, new range corrections for RASS temperatures or improved neural network applications for MRP humidities.

C-3Integration of Techniques

- assessment of the usefulness and practical operational applicability of different system configurations of an integrated remote-sensing station in view of optimised data quality, temporal and spatial resolution, and cost;

- development of methods for combination of measurements provided by different systems for wind, temperature and humidity profiling; this covers both treatment of redundant information (composite profiling), retrieval of basic information from different sounders (e.g. temperature from humidity profiles and virtual temperatures measured by RASS), and data assimilation aspects in liaison with the NWP community;

- development of methods to derive meteorological information of higher order, such as mixing heights, turbulent fluxes, etc.(e.g. for boundary-layer research and air-pollution monitoring);

- automation of the systems in cooperation with industry, including remote monitoring and remote control;

- development of recommendations on systems suitable for different users and applications, and of specifications for the industry.

C-4Quality Control

- development of instrument-level quality-control procedures(self-consistency statistics etc.) in cooperation with industry;

- development and test of multi-instrument quality-control procedures;

- systematic comparison of measured data with those obtained from numerical models (analysis or first guess) and operational standard observing systems.

C-5Impact Studies and Networking Aspects

- impact studies as Observing System Simulation Experiments (OSSEs), where the needs of user categories will be taken into account in collaboration with the NWP community in order to assess the usefulness of a potential network for the different categories of users especially in view of the data emerging from the station synergy;

- recommendation for an observing network and data provision in particular for numerical weather prediction on synoptic and mesoscale.

The risks associated to the scientific programme are comparatively small. This is due to the comparative maturity of both, the individual remote-sensing instruments and the algorithms. Moreover, the well-established contacts with the industry simplifies the incorporation of developed improvements. The risk is furthermore comparatively small due to the fact, that most parts of the programme can be investigated independently or without the need to have all systems available at one or more sites (C-1, C-2, C-5 and partly C-4). There are already many European sites having at least one specific remote-sensing system and where one can work on assessments of their techniques, improvement of algorithms and/or on enhancements of quality assessment in the frame of this action. Concerning complete integrated remote-sensing stations (C-3 and partly C-4), there is already now one station available (Lindenberg, Germany) measuring winds, temperatures and humidity, and it is expected to have at least two more stations in Europe within the next two years (KNMI and UKMO). To minimise the risk of availability for the observational period, this period is intended to be started 30 months after the start of the action and will be run up to the end of the action. The main innovation in this action will be the integration of the individual measurements. The degree of interdisciplinarity will prolong to the one experienced in previous COST actions.

D.ORGANISATION AND TIMETABLE

The management of this COST meteorological action will follow the established guidelines of the other meteorological actions, taking into account the increased emphasis on project management, progress assessment, tangible deliverables and visibility that the COST Senior Officials are requiring. A Management Committee will be established from the signatories and they will be jointly responsible for planning and carrying out this action. They will also be responsible for ensuring, within national constraints, that the planned countries activities are matched by appropriate resources and will endeavour to resolve conflicts. This area tends to be the biggest risk in the successful completion of a COST action. This Management Committee will elect a Chairperson, who will attend, as necessary, and routinely submit summary reports to the Meteorological Technical Committee as required. It is also anticipated that the Met TC will be invited to propose an ex officio member.

The detailed work programme, planning and production of the deliverables will be undertaken by Working Groups. The Chairpersons of the Working Groups will be elected from or become members of the Management Committee. It is anticipated that there will be three Workings Groups, whose major tasks are defined in brackets according to the Scientific Programme above. The Working Groups are:

D-1Working Groups

Working Group 1 "Basic Techniques and Integration"(C1, C3)
Working Group 2 "Algorithms"(C2)
Working Group 3 "Impact studies and Quality Assessment"(C4, C5)

The key deliverables of the different working groups are:

- WG-1:

- Recommendations for individual remote-sensing techniques for use in a cost-effective integrated profiling station based on the needs of the different user communities, in comparison with a review of the operational efficiency of existing individual remote-sensing techniques.

- Recommendation and realisation of improvements for an automation and enhanced reliability of integrated profiling stations in cooperation with industry. This deliverable will be derived mainly from operational experience during the observational period of the action.

- Recommendation of methods for derivation of meteorological parameters of higher order from integrated profiling stations derived from theoretical and experimental investigations.

- WG-2:

- Recommendation of basic algorithms for each individual remote-sensing techniques in view of the user needs. The recommendation will be based on a review of existing algorithms, i.e. results from comparisons of all available and currently improved signal-processing algorithms by using a reference data set and by comparing quality and data availability. This work will make use of the experience and expertise of all different research communities already working with new algorithms in Europe.

- WG-3:

- Recommendation/Definition of quality control procedures from experimental experience (comparison with standard observing systems as well as numerical model output) and sensor synergy.

- Recommendations for the necessary data quality of integrated profiling stations and definition of requirements for a future observing network. This deliverable will be derived from OSSEs on the base of the capabilities of integrated profiling stations.

The Chairpersons of the Working Groups and the Management Committee will be responsible for the smooth running of the action, co-ordination of meetings, timely reports and particularly the flow of management information between the Working Groups, the Management Committee and the Meteorological Technical Committee. The Action Chairperson will also be responsible for preparing and managing the COST part of the budget.

Milestones, Deliverables and Schedule

An overall schedule is appended as a simple bar chart. A task of the Management Committee will be the detailing of such a chart and its maintenance during the action. The action Chairperson, should in his report identify any significant changes and the options for corrective action, if required.

Meetings will be approximately 6 monthly and the minutes should become available on the dedicated web-site within the following four weeks.

Two workshops are envisaged. The first workshop (after year 1) will be on the state of the art and user needs. The second workshop after 4 years, will present the findings of the action and recommendations for future network operations.

The key deliverables are the reports indicated by an "R" and the data from the single-site trials and the impact assessment experiment.

D-2Dissemination Plan

All reports, minutes, working papers and data products will be made available through a dedicated web site. It is envisaged that as for CWINDE experimental profile data will also be available over the internet in near real time probably during the last 24 months of the action.

Key technical papers and workshop reports will also be submitted to peer reviewed journals.

D-3Cooperation with other organisations

The action Chairperson will ensure suitable liaison and coordination with the other meteorological actions through regular meetings with the other Chairpersons at the Technical Committee Meetings and on an individual basis for a specific topic. The Technical Committee, itself, and the TC representative for the action should take the lead role in the broader context (e.g. EUMETNET, WMO).

With respect to other meteorological COST actions, a relatively close link regarding humidity profiling derived from GPS methods and related OSSEs is directed to the action COST-716. Also action COST-717 on the assimilation of radar data in NWP models is related to this action.

E.ECONOMIC DIMENSIONS

Interest in participation has been indicated e.g. by Austria, Denmark, Finland, France, Germany, Greece, Italy, the Netherlands, Spain, Switzerland and the United Kingdom. The overall cost of the activities to be carried out under the Action has been estimated at 1999 prices at EUR 7,8 million.

Programm/Programme

IC-COST - European cooperation in the field of scientific and technical research (COST), 1971-

Thema/Themen

10 - Meteorology

Aufforderung zur Vorschlagseinreichung

Data not available

Finanzierungsplan

Data not available

Koordinator

N/A

EU-Beitrag

Keine Daten

Adresse

Belgien

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