1 / 28

Kazumasa Aonashi (MRI/JMA) Takuji Kubota (Osaka Pref. Univ.) Nobuhiro Takahashi (NICT)

Oct.24, 2006. 3rd IPWG Workshop. Developnemt of Passive Microwave Precipitation Retrieval Algorithm Towards the GPM Era. Kazumasa Aonashi (MRI/JMA) Takuji Kubota (Osaka Pref. Univ.) Nobuhiro Takahashi (NICT). Main Satellite DPR GMI. Constellation Sat MWRs (8?).

paige
Download Presentation

Kazumasa Aonashi (MRI/JMA) Takuji Kubota (Osaka Pref. Univ.) Nobuhiro Takahashi (NICT)

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Oct.24, 2006 3rd IPWGWorkshop Developnemt of Passive Microwave Precipitation Retrieval Algorithm Towards the GPM Era Kazumasa Aonashi (MRI/JMA) Takuji Kubota (Osaka Pref. Univ.) Nobuhiro Takahashi (NICT)

  2. Main Satellite DPR GMI Constellation Sat MWRs (8?) GPM （Global Precipitation Measurement:） （2013～） 3hourly Observation Satellite Microwave Radiometers Aqua AMSR-E TRMM TMI PR DMSP SSM/I ADEOS-II AMSR MWRs with window channels

  3. Passive Microwave Precipitation Retrieval GSMaP Retrieval Algorithm • Global Satellite Mapping of Precipitation Project started in 2003. • Leader: Prof. Ken’ich Okamoto (Osaka Pref. Univ.) • Funded by JST/CREST • The goal is to produce accurate precip map using mainly satellite microwave radiometer. • Passive microwave precip retrieval algorithm is based on Aonashi and Liu (2000).

  4. Outline • Introduction • GSMaP MW Retrieval Algorithm • Retrieval Algorithm (V4.7.2) • Validation using radar and gauge data • Improvement of the Scattering part

  5. GSMaP MW Retrieval Algorithm Retrieval Algorithm (V4.7.2)

  6. GSMaP Precip Retrieval Algorithm • Over Land: Scattering by frozen particles (TBs at 37 & 85GHz) • Over Ocean: Scattering (37 & 85GHz) + Radiation from Rain (TBs at 10 & 19 GHz)

  7. Passive microwave precipitation retrieval Forward calculation Retrieval Calculation parameters Observed TBs Look-up Table FLH Precip Profiles DSD inhomogeneity Precip.

  8. Forward Calculation • Liu’s RTM (1998) is used to calculate TBs • Mixed-phase precip is parameterized with Takahashi & Awaka (2005). • Parameters (FLH, precip profiles) are given as the a priori information.

  9. On the basis of the filed experiment, the following parameters are modeled Volume liquid water fraction （Pw) shape parameter of the dielectric constant (U) DSD parameter (B) is a function of Pw Density ρ=√Pw Fall velocity Magono-Nakamura(1965) for snow and Foot and Du Toit for rain Implicitly including break-up/coalescence processes Nishitsuji Model (N model) Pw and U profile Relationship between B and Pw B

  10. Lookup table (TB-R) for variable Freezing Level Height (FLH) • Melting layer model shows slightly better representation than rain only model. Procedure: Rain rate from PR is integrated within TMI’s 10 GHz footprint weighted by the antenna pattern.

  11. Forward Calculation • Liu’s RTM (1998) is used to calculate TBs • Mixed-phase precip is parameterized with Takahashi & Awaka (2005). • Parameters (FLH, precip profiles) are given as the a priori information.

  12. Parameters used in the Algorithm:Precipitation Types and Profiles (TRMM PR) Classification of types Database for types 2.5 deg. grid Seasonal 8types（Sea 3, Land 5） Type-1 Profile for each Types Height　（km） Database for Profile For precip. types surface precip. Precip [mm/h] Precipitation profiles for Type 1 0.5, 1, 2, 3, 4, 6, 8, 10, 15, 20, 30, 40, 60, 80, 120, 160, 200 mm/h

  13. Parameters used in the Algorithm:Atmospheric variables (GANAL) • Atmospheric variables (FLH, SSW, SST) are derived from the Global Analysis data of JMA

  14. Basic Idea of the Retrieval Algorithm Forward calculation Retrieval Calculation parameters Observed TBs Look-up Table FLH Precip Profiles DSD inhomogeneity Precip. To find the optimal precipitation that gives RTM-calculated TBs fitting best with the observed TBs.

  15. Observed TBs Precipitation Retrival Algorithm Screening of Precip Areas LOOK-UP TABLE (LUT) rain flag Scatter-based Precip Estimation rain37 PCT37+LUT rain85 PCT85+LUT sigma (inhomogeneity) First-guess of over-sea Precipitation rain10V  TB10V+LUT (sigma) rain19V TB19V+LUT (sigma) Minimization of Σ(TBc-TBo)**2 Retrivals

  16. Validation using Radar & gauges • Comparison with • PR.2A25 • Ground radar (Okinawa, KWAJ) • GPCC (rain gauge)

  17. Error=100 × |TMI – PR|/PR % Average over （1998～2004） Relative Error with PR (1998-2004) Tropic （15S～15N） Mid （<15S or > 15N）

  18. Zonal Mean Precip over Ocean(1998～2004) PR3G68, GPROF.v6, GSMaP.v4.7.2 3G68 V6 PR GPROFV6 TMI GSMaP V4.7 GSMaP V4.7.2 3G68 V6 PR GPROFV6 TMI GSMaP V4.7 GSMaP V4.7.2 3G68 V6 PR GPROFV6 TMI GSMaP V4.7 GSMaP V4.7.2 3G68 V6 PR GPROFV6 TMI GSMaP V4.7 GSMaP V4.7.2

  19. Zonal Mean Precip over Land (1998～2004) PR3G68, GPROF.v6, GSMaP.v4.7.2 3G68 V6 PR GPROFV6 TMI GSMaP V4.7 GSMaP V4.7.2 3G68 V6 PR GPROFV6 TMI GSMaP V4.7 GSMaP V4.7.2 3G68 V6 PR GPROFV6 TMI GSMaP V4.7 GSMaP V4.7.2 3G68 V6 PR GPROFV6 TMI GSMaP V4.7 GSMaP V4.7.2

  20. Comparison with ground-based radar COBRA(Okinawa) KWAJ Corretation：0.79（No:253） RMSE：1.46 mm/hr Correlation：0.65（No:1139） RMSE：1.78 mm/hr

  21. Integrated 6-hour Microwave radiometer Precipitation Map(TMI+AMSR+AMSR-E+F13,F14,F15 SSM/I; Jul., 2003) Missing Values

  22. GSMaP_MWR：monthly mean preciptation (1x1 deg) GPCC Monthly Precipitation (Monitoring) Product（Rudolf et al. 2006）： Comparison with GPCC data Correlation：0.80 （Number：5974)

  23. Improvement of the Scattering part Retrieval Algorithm (V5.1)

  24. (rainsurf/rain.4.7.2).vs.stdlgpr and Toplev over Tropical Land, July, 1998 STDLGPR (inhomo) Precip. Top level

  25. Scattering part (V5.1) Sigma85 vs STDLGPR PCT85 vs Precip. top • Dual-frequency (37,85GHz) • Retrieval of rain37 uses parameters from rain85 • Horizontal inhomogeneity • Precipitation top level

  26. Comparison with PR 3G68 over Land (July, 1998) V4.7.2 V5.1

  27. Summary • GSMaP passive microwave precipitation retrieval algorithm. • The retrieved precipitation agreed well with PR, radar data over ocean. • The over-land algorithm underestimated the strong precipitation. • Introduction of the retrieved inhomogeneity alleviated the underestimation.

  28. END Thank you.

More Related