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THE OPTIMISING OF REGIONAL RADIOSONDE NETWORKS Oleg Pokrovsky Main Geophysical Observatory, Karbyshev str.7, St. Petersburg, 194021, Russian Federation
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Outlines: (a) Identify statistically homogeneous areas; (b) Calculate the statistical weights of the information of each RAOB station ; (c) Derive an optimized network configuration for the upper-air stations, including GUAN stations; (d) Calculate error fields for main meteorological parameters (Z500, T500, U700, V700, relative air humidity Q850 used in NWP models) related to the optimized network configuration.
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Approach
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Kalman Filter (1) where where:
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Kalman Filter (2)
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Information Weights of Sites Statistical Invariant: Information weight of i-th site
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Optimization Criteria function - Optimization: Criteria examples: 1) A: 2) D:
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Part 1 Siberian RAOB network of Roshydromet
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A set of RAOB stations presented in WMO list
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Soviet Time
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October, 1999
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Catastrophic Flood in Siberia River Lena, May, 2001
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Persisted Atmospheric Circulation Regime during February-May, 2001 Source: SATOB data
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Z 700 field anomaly,March-April, 2001
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РАЙОНИРОВАНИЕ АТР (СРОЧНЫЕ ДАННЫЕ)
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Sufficient RAOB network
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Optimal interpolation H500 RMS error field
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Responded to Jan-March, 2007, RAOB
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Table. Comparison of the optimal and operational RAOB network configurations in Siberia with account for Z500 objective analysis error (m). Contribution of measurement data in covariance matrix reduction RAOB –40 (non- regular, Jan-Mar, 2007) RAOB-34 (Jan-Mar, 0Z&12Z, 2007) RAOB-42 (Optimal design ) Mean STD (60-80 N) 58.757.627.8 Mean STD (40-60 N) 42.346.942.5 Mean STD51.052.634.7
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Conclusions (Part 1): -Number of Siberian RAOB sites was increased during last years -Most of recovered stations are located in southern part of Siberia close to China border provided by many vertical profiles from Chinese RAOB -Few stations were added in medium latitude belt and in high latitudes -Present configuration of Siberian RAOB network does not provide necessary accuracy in analysis of height, temperature and, particularly, wind fields in in high latitudes
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Part 2 A CASE STUDY: RA I - AFRICA
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RAOB network in RA-I: red-operational (2004); black-nominal in WMO list
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Statistical Regionning due to zonal wind U700
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Information content weights attributed to existed operational sites
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Relative error (with account for seasonal variability) fields for Z500 objective analysis
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Relative error (with account for seasonal variability) fields for U700 objective analysis
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Scenario for RA-I RAOB extension with account for maximization of information content: red-new 13 stations; black-operational network (46 stations)
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Relative error (with account for seasonal variability) fields for Z500 objective analysis: extended network
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Relative error (with account for seasonal variability) fields for U700 objective analysis: extended network
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Minimal GUAN network due to U700
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Relative error (with account for multi-year variability) monthly fields attributed to GUAN for U700
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Conclusions (Part 2) -Missing data areas with respect to operational RAOB station list for RA-I are very significant. Only 46 from nominal 262 sites carried out measurements in January-April, 2004. -Error fields corresponding to major meteorological variables reveal many gap regions, where the relative errors of meteorological field representation reach 0.7-0.8 levels. -Search algorithm allows us to develop a scenario for existed operational RAOB network extension from 46 to 59 stations by recover measurements at 13 stations, which provide a substantial improvement of error fields for all meteorological variables in missing data areas -Existing GUAN network has some gaps in Central Africa, which are a reason of anomaly in objective analysis error fields. An alternative set of ten GUAN sites provides more uniform information coverage of Africa with respect to monthly fields.
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