FN Archimer Export Format
PT J
TI Validation of the TOPEX rain algorithm: Comparison with ground-based radar - art. no. 4038
BT 
AF MCMILLAN, A
   QUARTLY, G
   SROKOSZ, M
   TOURNADRE, Jean
AS 1:;2:;3:;4:;
FF 1:;2:;3:;4:PDG-DRO-DOPS-LOS;
C1 Southampton Oceanog Ctr, Southampton SO14 3ZH, Hants, England.
   Inst Francais Rech Exploitat Mer, DRO OS, F-29280 Brest, France.
C2 SOUTHAMPTON OCEANOG CTR, ENGLAND
   IFREMER, FRANCE
SI BREST
SE PDG-DRO-DOPS-LOS
IN WOS Ifremer jusqu'en 2018
   copubli-europe
TC 8
UR https://archimer.ifremer.fr/doc/2002/publication-695.pdf
LA English
DT Article
DE ;Attenuation;Validation;Rain;Satellite remote sensing;TOPEX
AB [1] Recently developed algorithms have shown the potential recovery of rainfall information from spaceborne dual-frequency altimeters. Given the long mission achieved with TOPEX and the prospect of several other dual-frequency altimeters, we need to validate the altimetrically derived values so as to foster their integration with rain information from different sensors. Comparison with some alternative climatologies shows the bimonthly means for TOPEX to be low. Rather than apply a bulk correction we investigate individual rain events to understand the cause of TOPEX's underestimation. In this paper we compare TOPEX with near-simultaneous ground-based rain radars based at a number of locations, examining both the detection of rain and the quantitative values inferred. The altimeter-only algorithm is found to flag false rain events in very low wind states (<3.8 m s(-1)); the application of an extra test, involving the liquid water path as sensed by the microwave radiometer, removes the spurious detections. Some false detections of rain also occur at high wind speeds (>20 m s(-1)), where the empirical dual-frequency relationship is less well defined. In the intermediate range of wind speeds, the TOPEX detections are usually good, with the instrument picking up small-scale variations that cannot be recovered from infrared or passive microwave techniques. The magnitude of TOPEX's rain retrievals can differ by a factor of 2 from the ground-based radar, but this may reflect the uncertainties in the validation data. In general, over these individual point comparisons TOPEX values appear to exceed the "ground truth.'' Taking account of all the factors affecting the comparisons, we conclude that the TOPEX climatology could be improved by, in the first instance, incorporating the radiometric test and employing a better estimate of the melting layer height. Appropriate corrections for nonuniform beam filling and drizzle fraction are harder to define globally.
PY 2002
PD FEB
SO Journal of Geophysical Research Atmospheres
SN 0747-7309
PU American Geophysical Union
VL 107
IS D4
UT 000178891200004
DI 10.1029/2001JD000872
ID 695
ER

EF