VSA Proposal Summary
VSA title / Testing of dual-polarization processing algorithms for radar rainfall estimation in Tropical scenariosVSA proposal ID: / H_VS17_01 / Objective category (if applicable):
VSA Host institute: / Department of Civil Protection - Rome / Related SAF products:
VSA supervisor: / Gianfranco Vulpiani / Related SAF WP: / WP6100, WPO6145, WP6300, WP6400
Expected start date: / February 2017 / Related SAF (review) processes:
Expected end date: / September 2017 / VSA costs: / 12.000 Euros (estimated as 3.7 working months at 3220 € (calculated as 50% of the average manpower rate inside the H-SAF consortium (6.440 € per month))
VS candidate: / Assigned by open call / VS / AS:
Document Approval Table
Name / Function / DatePrepared by: / Gianfranco Vulpiani / Validation Cluster member / 28/11/2016
Reviewed by:
Approved by:
Document Change Record
Issue / Revision / Date / DCN. No / Summary of ChangesV0.1 / 28/11/2016 / Initial version sent to the Science Manager
V1.0
V2.0
V3.0
1Objectives and RationalE
The VS activity has to be intended as the integral part of the Federated Activity proposal entitled “Assessment of ground-reference data in Brazil and validation of the H-SAF precipitation products in the perspective of CDOP-3”that is aimed at setting up the framework for the validation of the H-SAF precipitation products on Full Disk, being a crucial task of CDOP-3.
In this contest, the main objective is to verifythe robustness of the radar rainfall algorithms currently implemented by the mobile X-band radar system managed byCPTEC/INPE used during the CHUVA field campaign. Detailed information on the mentioned campaign are available on
Quantitative precipitation estimation requires accurate evaluation of the main error sources, including calibration, ground clutter, anomalous propagation, beam blockage, W-LAN interferences, and rain path attenuation (e.g., Bringi and Chandrasekar 2001).
Dual-polarization technology has greatly improved the quality of radar precipitation measurements and reduced the gap between the qualitative and quantitative use of radar observations.
Several operational S- and C-band radar networks have been upgraded to adopt dual-polarization technology. In the past decade, many studies have been undertaken to explore the benefit of polarimetry for quantitative precipitation estimation (QPE) using X-band radars (Anagnostou et al., 2004; Matrosov et al., 2005; Wang and Chandrasekar, 2010; Matrosov et al., 2013, Koffi et al., 2014; Vulpiani et al., 2015), which are de facto very appealing systems due to their compact size, transportability and, generally, affordable cost.
However, attenuation remains the major impairment for the quantitative use of X-band radar systems, despite the availability of robust correction methods and rainfall algorithms based on a specific differential phase that is immune to attenuation.
In the presence of heavy rain and hail mixtures, partial attenuation can be further enhanced, leading to signal extinction (Tabary et al., 2009).
Furthermore, Drop Size Distribution (DSD) variability also plays a relevant role in the determining the uncertainty related to rainfall retrieval process.
In addition to the radar reflectivity factor, the use of differential reflectivity (ZDR) and specific differential phase (KDP) can potentially reduce the DSD dependency of the radar rainfall algorithms.
Notwithstanding, ZDR can be heavily affected by miscalibration, rain path attenuation, wet-radome attenuation, interferences. KDP is immune to radar calibration and partial beam blockage but is not directly measured. It has to be derived by the Differential Phase DP that is affected by measurements noise, back scattering effects, and system offset (Bringi and Chandrasekar, 2001).
For these reasons, the present VS activity is devoted tocritically evaluate the algorithms framework currently implemented within the manufacturer software package with the aim to optimize in the light of the recent advancement in the field.
A special focus will be devoted to the optimal processing of DP in order to correct for attenuation, on one side, and estimate precipitation, on the other side.
2TASKS and Methods
The tasks and methods will be defined by the candidates’ proposals, they will be considered one of the criteria of selection for the open call.
3Deliverables
- The main deliverable will be the VS Intermediate Report at the end of Task 1 (T0+2 months) and Final Report at the end of the VS, documenting arguments and results from the project activity and recommendations for future activities;
- Presentation of the results at the EUMETSAT Meteorological Satellite Conference and the H-SAF Validation meeting.
4Expected Benefits for The SAF
The proposed work is preparatory and beneficial for the assessment of the precipitation products on Full Disk, as required by the CDOP-3 proposal.
5Relation to SAF Products / Workpackages / Processes
In the CDOP2 VSA proposals are foreseen to support the Product Validation Group.
H-SAF products related to VSA: H01, H02 and H18
H-SAF CDOP-2 Work Packages: WP6100, WPO6145, WP6300, WP6400
6Dependencies
Availability of the user manuals documenting the manufacturer software package. Availability of the radar data in any standard format (i.e., HDF, NetCDF) and/or on any conversion software.
7VSA Host Institute and Supervisor
People responsible from SAF side to manage the VSA:
Gianfranco Vulpiani (Validation cluster member)
Host Institute:Department of Civil ProtectionRome, Italy
8VSA Milestones and Schedule
T0 (tentative date February 15, 2017): start of the VS
T0+2 months: Delivery of the Intermediate Report,
T0+3.7 months: End of the VS activity and Delivery of the Final Report.
9Summary financial information
The total cost of the VSA activity is estimated as € 12000.
10ConclusionS
A cumbersome task of CDOP-3 is dealt with through this VSA activity: the validation on full Disk of the H-SAF precipitation products. This requires the access to ground-reference data on extra European areas, their preliminary assessment via the implementation of a suitable processing chain.
Additionally, this VSA proposal would provide the opportunity to establish acooperation with the CHUVA field-experiment team that might be useful also for the optimization of precipitation product optimization on the Tropics.
The H-SAF SG is invited to approve this VSA proposal and to task the Project Team with its implementation.
References
Alcoba M and M Gosset, 2015 :Verification study over West Africa of PMW precipitation products using X-pol radar observations and rain gauges ; H-SAF ASSOCIATED SCIENTIST ACTIVITY SAF_AS15_03 ; FINAL REPORT.
Anagnostou, E. N., Anagnostou, M. N., Krajewski, W. F.,Kurger, A., and Mirovsky, B. J.: High-resolution rainfall estimation from X-band polarimetric radar measurements, J. Hydrometeorol., 5, 110–128, 2004.
Bringi, V. N. and Chandrasekar, V.: Polarimetric doppler weather radar, Cambridge University Press, Cambridge, UK, 636 pp., 2001.
Koffi, A.K., M. Gosset, E.P. Zahiri, A.D. Ochou, M. Kacou, F. Cazenave, and P. Assamoi, 2014: Evaluation of X-band polarimetric radar estimation of rainfall and rain drop size distribution parameters in West Africa. Atmospheric Research 143, 438–461. doi:10.1016/j.atmosres.2014.03.009
Matrosov, S. Y., Kingsmill, D. E., and Martner, B. E.: The utility of X-band polarimetric radar for quantitative estimates of rainfall parameters, J. Hydrometeorol., 6, 248–262, 2005.
Matrosov, S. Y., Cifelli, R., and Gochis, D.: Measurements of heavy convective rainfall in the presence of hail in flood-prone areas using an X-band polarimetric radar, J. Appl. Meteorol. Clim., 52, 395–407, 2013.
Rinollo, A., G. Vulpiani, S. Puca, P. Pagliara, J. Kaňák, E. Lábό, Ł. Okon, E. Roulin, P. Baguis, E. Cattani, S. Laviola, and V. Levizzani, 2013: Definition and impact of a quality index for radar-based reference measurements in the H-SAF precipitation product validation. Nat. Hazards Earth Syst. Sci., 13, 2695-2705;
Tabary, P., Vulpiani, G., Gourley, J. J., Illingworth, A. J., Thompson, R. J., and Bousquet, O.: Unusually high differential attenuation at C-band: Results from a two-year analysis of the French Trappes polarimetric radar data, J. Appl. Meteorol. Clim., 48, 2037–2053, 2009.
Wang, Y. and Chandrasekar, V.: Quantitative precipitation estimation in the CASA X-band dual-polarization radar network, J. Atmos. Ocean. Tech., 27, 1665–1676, 2010.
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