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Quality indicators in an operational precipitation product. IPWG meeting 4 Beijing, 13-17 October 2008. Presented by: Thomas Heinemann Meteorological Operations Division EUMETSAT [email protected] Overview. News from METOP/HRPT

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Quality indicators in an operational precipitation product

Quality indicators in an operational precipitation product

IPWG meeting 4

Beijing, 13-17 October 2008

Presented by: Thomas Heinemann

Meteorological Operations Division

EUMETSAT

[email protected]


Overview
Overview

  • News from METOP/HRPT

  • The Multi Sensor precipitation Estimate (MPE), a real-time precipitation algorithm

  • Why shall we provide quality information

  • The MPE quality indicators (QI)

  • How useful are the MPE QIs

  • Outlook


News from metop a hrpt
News from METOP-A HRPT

  • METOP-A was launched on 19 October 2006

  • LRPT direct data transmission was not activated

  • HRPT direct data transmission service failed soon after activation

  • Root cause was heavy ion radiation causing the failure of a component of the AHRPT Solid State Power Amplifier (SSPA)

  • To minimise the risk of failure to the HRPT-B unit a "partial" HRPT service in those areas where the risk of damage from heavy ions is reduced, has been implemented. 

  • For southbound passes over Europe and the North Atlantic, HRPT side B will be activated starting around 60°N.

  • First activation was on 29 September 2008  (2 month trial)


Mpe a real time precipitation algorithm
MPE: a real-time precipitation algorithm

  • Combines passive microwave from polar orbiting satellites with IR data from geo-stationary satellites.

  • Algorithm is based on the classical blending approach.

  • Instantaneous rain rate data are produced every 15/30min in original Geo-satellite pixel resolution (MET-7 INDOEX, MET-8 RSS, MET-9 0°) in the operational environment of the MSG groundsegment.

  • Processing is done in near-real time mode with a time delay of < 10 minutes between image acquisition and data dissemination.

  • Data are provided on the internet and via EUMETCAST in GRIB-2 data format and in addition visualised on the EUMETSAT web-page.



Who are the (designated) users of real-time precipitation algorithms ?

  • NRT or RT precipitation data are

  • essential for:

  • Short term weather forecasts and nowcasting

  • Operational short term hydrological and acricultural applications

Photos: WFP

In large areas of the world methods based on ground measurements or polar orbiting satellite products cannot fulfil the NRT requirements and a dense radar network is not available ( Africa, Asia !!!)


Why still a blending algorithm
Why (still) a blending algorithm ? algorithms ?

  • EUMETSAT ‘s and its users requirements for the rain-rate algorithm are:

  • To provide a real-time product in high temporal and spatial resolution.

  • To use a scientifically mature algorithm which has been proven to work operationally.

  • Most other algorithm types cannot be used in real-time.

  • Other real-time algorithm’s are either very similar to the used one or still in development phase.

  • But tests with other algorithms were done:

  • Hydro-estimator implemented for South Africa, CMORPH version tested, co-operation with H-SAF and NOAA …


Mpe and hydro estimator in south africa
MPE and Hydro-Estimator in South Africa algorithms ?

MPE results (left) and Hydroestimator results (right) of the instantaneous rain rate (mm/hour) based on the 10:00 UTC MSG image of 6 November 2007.



Mpe validation by the european pehrpp site1
MPE validation by the European PEHRPP site algorithms ?

Courtesy: Chris Kidd


Why quantitative quality indicators
Why (quantitative) quality indicators? algorithms ?

  • Users trust data only if they have a clear vision how accurate they are.

  • Most algorithms perform in some conditions better than in others (especially combined algorithms).

  • Algorithm developers have more a-priori information available and know their algorithm better than the users.

  • Many algorithms depend on the results of previous data analysis (eg. cloud mask). The quality of the previous steps affects the quality of the final product.

  • All this information should be provided to the users.

  • Different applications need different QI’s!


Continuous re adjustment of luts as source for mpe quality indicators
Continuous re-adjustment of LUTs as source for algorithms ?MPE quality indicators

  • Blending principle:

  • Co–located microwave rain-rates and IR brightness temperature for a specific region and time-span are used to derive a monotonic relation between IR BT and rain rate.


Definition of mpe qis
Definition of MPE QIs algorithms ?

  • QI1 := Correlation coefficient between MPE rain-rates for the

  • co-located IR data and the microwave data rain-rates

  • QI2 := Standard deviation between MPE rain-rates for the

  • co-located IR data and the microwave data rain-rates


Mpe correlation qi
MPE Correlation QI algorithms ?



Test strategy for qis
Test strategy for QIs algorithms ?

  • Purpose : Test if MPE rain-rates in areas with high QI are really better.

  • Method: Compare MPE rain rates ffrom the real-time algorithm with microwave rain-rates.

  • Precondition: None of the microwave rain rates used for the comparison are included in the co-locations.

  • Limitation: Not a real validation of rain-rates but of the matching-algorithm.






Summary
Summary algorithms ?

  • EUMETSAT committed to continue the operational service for a disk-wide real-time rain-rate product

  • The current algorithm should be updated to a mature, state-of-the-art algorithm which fulfils the requirements.

  • The EUMETSAT Hydrology SAF is developing additional algorithms for various applications

  • Effective and adapted Quality Indicators are essential for the optimal application of precipitation products, especially in models.

  • The MPE QIs based on the co-location statistics are useful indicators to identify the areas where the MPE algorithm should not be used.


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