Earth Space Research Group

Latent Heat Flux

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Movie of January 88 as the world turns

Authors

Latent Heat Flux as calculated by Didier Jourdan & Catherine Gautier @ ESRG, UCSB

Description

The LHF is one of the two dominant components of the air-sea energy exchange. It mostly balances energy from shortwave solar flux which is the other important component. LHF first occurs as a tranfer of water vapor from the ocean to the atmosphere, also called evaporation. Then by condensing, often in regions far from which the evaporation occurs in, water vapor releases latent heat in the atmosphere. By doing so, it provides the energy to feed the atmpospheric circulation, partucularly in tropical regions. LHF by transfering water from the ocean to the atmosphere is also part of the hydrological cycle.

These maps present an example of LHF computation exclusively from satellite data. The first three maps represent the parameters available from satellite remote sensing and used to compute the LHF shown in the last map. The water vapor is used to compute the humidity within the atmospheric surface layer. Since the satellite only provide an integrated value, we have to assume an vertical distribution of the water vapor which one of the important assumtion of the method. The Sea surface temperature is used to compute the humidity at the ocean-atmosphere interface. In this case, the air in contact with the water is saturated and a simple relationship applies. These values and the wind speed are input into a model that parameterizes the LHF as a function po the stability of the atmosphere.

These maps are monthly mean values of each parameter and of the LHF for January 1988. The water vapor and Wind Speed have been retrieved from Special Sensor Microwave/Imager (SSM/I) merasurements and the Sea Surface temperature are part of the Advanced Very High Resolution Radiometer (AVHRR) data products. The LHF computation was made by D. Jourdan and the visualization by T. Figel both at ESRG, UCSB

Visualization

Image is displayed using mapping packages in IDL (from RSI)
visualization done by Terry Figel @ ESRG, UCSB

Directory listing of LH

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