variable lo freq. cal. analysis lo at 2min from 23-2-2012 to 23-3-2012
DESCRIPTION
Variable LO freq. Cal. analysis LO at 2min from 23-2-2012 to 23-3-2012. BEC team SMOS Barcelona Expert Centre Pg. Marítim de la Barceloneta 37-49, Barcelona SPAIN E-mail: [email protected] URL: www.smos-bec.icm.csic.es. ZONES. Tropics and mid-latitudes 60S:60N. Equatorial Ocean - PowerPoint PPT PresentationTRANSCRIPT
SMOS-BEC – Barcelona (Spain)
Variable LO freq. Cal. analysis
LO at 2min from 23-2-2012 to 23-3-2012
BEC team
SMOS Barcelona Expert CentrePg. Marítim de la Barceloneta 37-49, Barcelona SPAINE-mail: [email protected]: www.smos-bec.icm.csic.es
SMOS-BEC – Barcelona (Spain) 2/9
ZONES
Tropics and mid-latitudes60S:60N
Tropics and mid-latitudes60S:60N
Equatorial Ocean10S:10NZone 126
Equatorial Ocean10S:10NZone 126Southern Pacific
30S:0N – 150W:120WZone 122
Southern Pacific30S:0N – 150W:120W
Zone 122
SMOS-BEC 3/9
SMOS – ARGO 2012 VS 2011
LO = 2 MIN -> 201220120223 - 20120324
LO=10 MIN -> 201120110223 - 20110324
SMOS-BEC 4/9
MEAN/STD/RMS 2011 VS 2012
122 ZONE 126
ZONE 6060
ZONE 122
mea
nm
ean
mea
n
std
std
std
RMS
RMS
RMS
23/1-22/2
23/2-22/3
24/3-22/4
LO=2min
SMOS-BEC 5/9
SMO
S m
easu
rem
ents
ARGO measurements
AREA 122 : 30S – 0N /150W-120W
LO = 10 min20120123 - 20120223
LO = 2 min20120223 - 20120323
LO = 10 min20120323 - 20120424
SMOS-BEC 6/9
AREA 126 10º S – 10º N
LO = 10 min20120123 - 20120223
LO = 2 min20120223 - 20120323
LO = 10 min20120323 - 20120424
SMOS-BEC 7/9
AREA 60º S – 60º N
LO = 10 min20120123 - 20120223
LO = 2 min20120223 - 20120323
LO = 10 min20120323 - 20120424
SMOS-BEC
CHI 2 after convergence
LO=10min
LO=10minLO=2min
SMOS-BEC
CHI 2 after convergence
LO=10min
LO=10minLO=2min
SMOS-BEC
• Analysis of the impact of the change of calibration frequency near the coast. Comparison before and after setting the variable LO cal. freq.
10
No evident impact on coastal areasWhen using a variable LO cal. frequency
Effects on the coastal areas
SMOS-BEC
Difference due to a large wind event
Effects on the coastal areas
No evident impact on coastal areasWhen using a variable LO cal. frequency
• Analysis of the impact of the change of calibration frequency near the coast. Comparison before and after setting the variable LO cal. freq.
SMOS-BEC
Analysis LO cal. freq. =2min
23/2-23/3 2011 LO=10minSMOS - ARGO
23/2-23/3 2012 LO=2minSMOS - ARGO
Mean (SMOS–ARGO)
Std (SMOS–ARGO)
LO=2min
SMOS-BEC 13
Conclusions - From QWG-5
Conclusions from decimated study:
The present LO calibration frequency has a clear impact on TB (larger in V-pol) and SSS.
TB differences between LO-10min and LO-2min have a global STD of 0.47 K (1.1K in N. Atlantic, 0.21 K in Pacific)
Differences in SSS (filtered by good retrieval flag): global STD 0.48 psu (0.94 psu in N. Atlantic, 0.20 psu in Pacific)
Accuracy requirement for L2 SSS is 1.2 psu. We don’t know yet the actual retrieval error, but the low calibration freq can represent in average 0.5 psu of additional error!!
SMOS SSS requirements will likely never be met with LO being calibrated at 10 min intervals
SMOS-BEC
During 10 minutes 500 SMOS snapshots are acquired. In every calibration event 5 snapshots are lost.
When calibrating LO every 10 min, the error in building an L3 map by averaging L2 products (wrt no calibration) increases by sqrt (500)/sqrt(495) = 1.005
Calibrating every 2 min, 25 snapshots maximum are lost, the L3 error increases by sqrt(500)/sqrt(475) = 1.026
Then the increase of usable snapshots @10 min compared to @2 min implies an error reduction of sqrt(495)/ sqrt(475) = 1.021
This 2.1% reduction on the current SSS accuracy (0.4 psu approx. results in 0.008 psu
We showed that calibrating @2 min instead of @10 min implies an error reduction by 0.48 psu in global average
SMOS-BEC