1 / 16

Envisat RA-2 rain flagging

Envisat RA-2 rain flagging. Graham Quartly & Meric Srokosz. Heritage. Rain flagging for TOPEX (Ku,C). Envisat RA-2 (Ku,S). Sigma0 monitoring. Periods when S-band sigma0 values are ~23 dB too high. Comparison to MWR. All points. Points with BT 36 >200K.

wanda
Download Presentation

Envisat RA-2 rain flagging

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. Envisat RA-2 rain flagging Graham Quartly & Meric Srokosz

  2. Heritage Rain flagging for TOPEX (Ku,C)

  3. Envisat RA-2 (Ku,S)

  4. Sigma0 monitoring Periods when S-band sigma0 values are ~23 dB too high

  5. Comparison to MWR All points Points with BT36 >200K Correspondence between attenuation events and high BT values

  6. Global pattern

  7. << Rain Flagging >> Detection of rain Estimation of rain rate (storm studies,      climatologies etc.) Finding anomalous / contaminated data (Automatic removal of bogus ssh, Hs values)

  8. Case study

  9. Automatic detection 1. One-point anomaly filter 2. Look at sh, sHs 3. Dual-frequency rain flag

  10. Flagging on sh & sHs Threshold: mn + 3 s.d. = 0.12 + 0.007 Hs2 Threshold: mn + 3 s.d. = 0.60 + 0.04 Hs2

  11. Dual-frequency rain flag Rain-contaminated if ‘significantly’ below mean relationship Here 0.5 dB and s0S ≤ 15 dB — Could use smaller threshold. — Could use 2.5 x Std. Dev. — Could extend over all s0 Also require MWR confirmation?

  12. Effect on Hs Attenuation near leading edge leads to higher Hs and shift in range …

  13. Effect on ssh

  14. Effect on sigma_Hs and sigma_h

  15. Co-variation with peakiness

  16. Conclusions Differential attenuation can be used for ‘rain flagging’. Threshold of 0.5 dB picks out most Hs and ssh spikes. Apart from when S-band goes AWOL, there is good s0 stability (track-to-track variation ~ 0.1 dB). Will make a contribution to ‘rain studies’ (Use of many DF altimeters give better climatology; synergistic use of RA-2 with MERIS and AATSR.)

More Related