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View Full Version : Latent Heat Flux (LHF) computation using satellite data


rocksea
13th March 2005, 09:10 AM
Which is the best algorithm to compute LHF using Satellite data,
like satellite data from TMI

I know about the Latent Heat Flux as calculated by Didier Jourdan
& Catherine Gautier (1995) where they use the water vapor, SST and
wind speed to calculate LHF.
[Illustrated example for those who are interested :
http://www.crseo.ucsb.edu/esrg/lh/lh.12.gif]

Is their algorithm the best (and verified) used at present?
Are their any modified versions?

Also, if anyone has a pdf/online copy of the Jourdan & Gautier 1995 work,
will you please forward it to me?
The paper is referred as:

Jourdan D, Gautier C (1995) Comparison between Global Latent Heat Flux
Computed from Multisensor (SSM/I and AVHRR) and from In Situ Data. Journal
of Atmospheric and Oceanic Technology 12(1): 46 DOI: 10.1175/1520-0426
(1995)012<0046:CBGLHF>2.0.CO;2.

praveen
17th March 2005, 02:22 PM
hi roxy

Sorry to say that I couldn't found out your paper here in library. They have Atm& ocean Tech issues from 2001 onwards only

Praveen

rocksea
7th April 2005, 03:14 PM
Well, I decided to use the readily available surface latent heat flux
by ECMRWF. HOAPS, is also another option for readily available LHF.

rajeshj
8th April 2005, 08:59 AM
roxy,
that is the best thing to use. the data is reliable also. good luck.

rocksea
8th April 2005, 09:08 AM
Vecchi and Harrison, 2002 in the study on "Monsoon Breaks and Subseasonal
Sea Surface Temperature Variability in the Bay of Bengal" mention about
LHF from ECMWF:

"Even our ability to estimate the air–sea heat fluxes is limited by the fact that
the NCEP–National Center for Atmospheric Research (NCAR) (Kalnay et al.
1996) and ECMWF (ECMWF 1989) global atmospheric analyses use the NCEP
SST product as a boundary condition, and this SST product has been found
to greatly underestimate BoB SST variability on subseasonal timescales
(see Sengupta and Ravichandran 2001; Premkumar et al. 2000; the present
paper). Depending on the depth over which the temperature changes
occurred, the observed variability in surface heat flux could be sufficient
to explain the oceanic thermal variability. The uncertainties in the amplitude
of the surface heat fluxes in the operational products in this region are large
enough that we do not attempt to quantify the role of heat flux in the SST
changes."

Anyways, the ECMWF LHF is pretty useful for variability studies, that is, if
you are not worried about the amplitude. So at present I think this
is the best option. If anyone knows about better options, please tell.
Rajesh, Thank you for mentioning about the data quality.


Reference:
Vecchi, G.A. and D.E. Harrison, Monsoon Breaks and subseasonal sea surface
temperature variability in the Bay of Bengal, J. Climate, 15(12), 1485-1493, 2002