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 !