rémy roca laurence picon laboratoire de météorologie dynamique, paris, france and
DESCRIPTION
Free Tropospheric Humidity from GEO - a long time series perspective-. Rémy Roca Laurence Picon Laboratoire de Météorologie Dynamique, Paris, France and Hélène Brogniez LATMOS, Guyancourt, France. Climate and humidity in the troposphere. Scales of interest to the relative humidity ?. - PowerPoint PPT PresentationTRANSCRIPT
Rémy Roca, FTH from GEO, GEWEX Globvapour Workshop, 8-10 March 2011, Frascati, Italy
Rémy Roca
Laurence Picon
Laboratoire de Météorologie Dynamique, Paris, France
and
Hélène Brogniez
LATMOS, Guyancourt, France
Free Tropospheric Humidity from GEO - a long time series perspective-
Rémy Roca, FTH from GEO, GEWEX Globvapour Workshop, 8-10 March 2011, Frascati, Italy
RelativeHumidity (%)
Mixing of extra-tropical / tropical air is taking place at short time scale (synoptic to intraseasonal) And explain the variability of the FTH distribution
Humidity is influenced by thermodynamics AND dynamics
The high frequency variation is key to our better understanding of moisture and its links to climate
Scales of interest to the relative humidity ?
Climate and humidity in the troposphere
Rémy Roca, FTH from GEO, GEWEX Globvapour Workshop, 8-10 March 2011, Frascati, Italy
Outline of the presentation
• What do we get from the « water vapor » channel on board the METEOSAT spacecraft ?– Free tropospheric humidity
• The FCDR from LMD: – Homogeneous Clear Sky Radiance record
• The TCDR from LMD: FTH– Climatology and variability
• Current work and perspectives for space/time extension
Rémy Roca, FTH from GEO, GEWEX Globvapour Workshop, 8-10 March 2011, Frascati, Italy
What do we get from the METEOSAT WV channel ?
bTapRH
m
3.60
cosln
Interpretation of the clear sky scene of the 6.3 microns channel in terms of layer averaged relative humidity (Soden and Bretherton, 1993; Stephens et al., 1996)
Assumption is valid in the Tropics ! Much complicated in the mid latitudes
How bad is it to use ECMWF to compute p0 ?What should the <> operator should be ?
Rémy Roca, FTH from GEO, GEWEX Globvapour Workshop, 8-10 March 2011, Frascati, Italy
What do we get from the METEOSAT WV channel ?
Picon et al., JGR, 2003
Rémy Roca, FTH from GEO, GEWEX Globvapour Workshop, 8-10 March 2011, Frascati, Italy
Moist case Dry case
weighting function f() [Stephens et al, 1996]
local Jacobian
mean curve [Soden and Bretherton, 1996]
[Brogniez et al, 2004]
No/Weak contribution from the lower levels
What do we get from the METEOSAT WV channel ?
Which operator for the vertical average ?
Rémy Roca, FTH from GEO, GEWEX Globvapour Workshop, 8-10 March 2011, Frascati, Italy
What do we get from the METEOSAT WV channel ?
Rémy Roca, FTH from GEO, GEWEX Globvapour Workshop, 8-10 March 2011, Frascati, Italy
From Brogniez et al., 2006
Improved sampling by keeping the scenes with low levels clouds (following the UTH product approach of EUMETSAT)
Daily average built from 8xdaily imagery provides a better spatial characterization and estimates
What do we get from the METEOSAT WV channel ?
Rémy Roca, FTH from GEO, GEWEX Globvapour Workshop, 8-10 March 2011, Frascati, Italy
What do we get from the METEOSAT WV channel ?
A broad layer of the troposphere over the intertropical belt
-belongs to GEWEX not to SPARC
High time resolution-good sampling-access to shorter time scales (which are relevant)
A long term record ?
Rémy Roca, FTH from GEO, GEWEX Globvapour Workshop, 8-10 March 2011, Frascati, Italy
MET2 MET3 MET4
MET5
4 3
ISCCP DX Normalized Instead of nominal
The FCDR from LMD: 1983-2005
Upgrade of calibration technique (van de Berg, et al., 95)
Upgrade of calibration technique (Schmetz, 1989)
•Two upgrades corrected according to the work of Picon et al., JGR, 2003 but with ERA40 instead of ERA15.
•The DX data change of implementation corrected thanks to interaction with ISCCP people (V. Golea)
Original
Rémy Roca, FTH from GEO, GEWEX Globvapour Workshop, 8-10 March 2011, Frascati, Italy
MET2 MET3 MET4
MET5
4 3
Homogenized
Original
The FCDR from LMD: 1983-2005
Rémy Roca, FTH from GEO, GEWEX Globvapour Workshop, 8-10 March 2011, Frascati, Italy
MET2 MET3 MET4
MET5
4 3
Homogenized
Original
The FCDR from LMD: 1983-2005
Brogniez et al.,JCLIM, 2009
Rémy Roca, FTH from GEO, GEWEX Globvapour Workshop, 8-10 March 2011, Frascati, Italy
The TCDR from LMD: FTH 1983-2005
Brogniez et al.,JCLIM, 2009
Brogniez et al.,JCLIM, 2009
0.625°3 hourly
Rémy Roca, FTH from GEO, GEWEX Globvapour Workshop, 8-10 March 2011, Frascati, Italy
AMIP2: Comparing summer 1984-1995And the GCMs ?Brogniez et al., 2005, GRL
Rémy Roca, FTH from GEO, GEWEX Globvapour Workshop, 8-10 March 2011, Frascati, Italy
Current work and perspectivesExtension in SPACE and TIME of both the FCDR and the TCDRWork on METEOSAT nominal to extend it into the MSG era in cooperation with CMSAF
Example #1: Two METEOSAT spacecrafts 1998-nowadays
Rémy Roca, FTH from GEO, GEWEX Globvapour Workshop, 8-10 March 2011, Frascati, Italy
The Megha-Tropiques Mission
• Clear Sky Radiance using a modified version of the SAFNWC cloud classification
MTSAT 0300GMT 4 channels
GOES-W 2100GMT 3 channelsGOES-E 1500GMT 3 channels
Example of SAF NWC cloud mask run onto various platforms (Courtesy of G Sèze, LMD)
•Inter calibration of the WV channels accross platforms from the GEO from GSICS
Example #2: Towards the GEO ring FTH product
Rémy Roca, FTH from GEO, GEWEX Globvapour Workshop, 8-10 March 2011, Frascati, Italy
• Thank you !
Rémy Roca, FTH from GEO, GEWEX Globvapour Workshop, 8-10 March 2011, Frascati, Italy
July 1980-1998
What do we get from the METEOSAT WV channel ?
NOAA based Upper Tropospheric Humidity
Data from Bates et al., 2001
The driest zone in the world is located over the Eastern Mediterranean sea Is in the METEOSAT area !