THE OPTIMISING OF REGIONAL RADIOSONDE NETWORKS Oleg Pokrovsky Main Geophysical Observatory, Karbyshev str.7, St. Petersburg, , Russian Federation

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.

Approach

Kalman Filter (1) where where:

Kalman Filter (2)

Information Weights of Sites Statistical Invariant: Information weight of i-th site

Optimization Criteria function - Optimization: Criteria examples: 1) A: 2) D:

Part 1 Siberian RAOB network of Roshydromet

A set of RAOB stations presented in WMO list

Soviet Time

October, 1999

Catastrophic Flood in Siberia River Lena, May, 2001

Persisted Atmospheric Circulation Regime during February-May, 2001 Source: SATOB data

Z 700 field anomaly,March-April, 2001

РАЙОНИРОВАНИЕ АТР (СРОЧНЫЕ ДАННЫЕ)

Sufficient RAOB network

Optimal interpolation H500 RMS error field

Responded to Jan-March, 2007, RAOB

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) Mean STD (40-60 N) Mean STD

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

Part 2 A CASE STUDY: RA I - AFRICA

RAOB network in RA-I: red-operational (2004); black-nominal in WMO list

Statistical Regionning due to zonal wind U700

Information content weights attributed to existed operational sites

Relative error (with account for seasonal variability) fields for Z500 objective analysis

Relative error (with account for seasonal variability) fields for U700 objective analysis

Scenario for RA-I RAOB extension with account for maximization of information content: red-new 13 stations; black-operational network (46 stations)

Relative error (with account for seasonal variability) fields for Z500 objective analysis: extended network

Relative error (with account for seasonal variability) fields for U700 objective analysis: extended network

Minimal GUAN network due to U700

Relative error (with account for multi-year variability) monthly fields attributed to GUAN for U700

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, Error fields corresponding to major meteorological variables reveal many gap regions, where the relative errors of meteorological field representation reach 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.