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This slideshow gives an overview of the CMEMS Sea Surface Temperature Satellite Products

LEVEL1 – For Beginners- Slides have been prepared in Nov 2016

C M E M S S e a S u r f a c e T e m p e r a t u r e

S a t e l l i t e p r o d u c t s

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O u t l i n e

• What is Satellite Sea Surface Temperature (SST)?

• Which Characteristics and Parameters?

• What is CMEMS added value?

• Who are the CMEMS SST data producers?

• Which Satellite SST products in CMEMS catalogue?

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W H A T I S S A T E L L I T E S E A S U R F A C E T E M P E R A T U R E ? ( 1 / 4 )

• SATELLITE SEA SURFACE TEMPERATURE (SST) is

measured by a sensor called « radiometer » on board of

several satellites.

• CMEMS Satellite SST is obtained by Microwave (MW) and/or

Thermal Infrared radiometers (IR).

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W H A T D O E S S A T E L L I T E M E A S U R E ? ( 2 / 4 )

On the one hand, satellite radiometers retrieve the spectral

radiance signal.

On the other hand, the PLANCK function (Planck, 1918) gives

the relationship between the spectral radiance and the

temperature of the blackbody and its wavelength.

Higher-order computations may be required under unfavorable

atmospheric and surface conditions along with regression

techniques that employ independent in situ measurements.

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W H I C H S A T E L L I T E S A N D S E N S O R S ( 3 / 4 )

• Microwave radiometer SST

Strengths:

• Clouds are mostly transparent

• Relatively insensitive to atmospheric effects

Weaknesses:

• Poorer accuracy and resolution

• Sensitive to surface roughness and precipitation

• Thermal Infrared radiometer SST

Strengths:

• Good resolution and accuracy

• Long heritage (~ 20 years)

Weaknesses:

• Obscured by clouds

• Atmospheric corrections required

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W H I C H S A T E L L I T E S A N D S E N S O R S ( 4 / 4 )

Given the desire to combine the high accuracy and resolution of

the thermal infrared SST with the better temporal and spatial

coverage of passive microwave SST, CMEMS creates blended

products which combines these strengths.

Hence most CMEMS SEA SURFACE TEMPERATURE Satellite

products merge SST originating from :

• Microwave

• and Thermal Infrared radiometers

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O u t l i n e






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WHICH CHARACTERISTICS? (1/3)

SST satellite data provide with Sea Surface Temperature properties:

• In 2 dimensions (at the ocean surface, displayed on a 2D grid)

• Through a period of time:

• A reprocessing of the past (CMEMS provides with ~20 years in

the past)

• An analysis of the current conditions

• No forecast into the future is provided.

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W H I C H P A R A M E T E R S ? ( 2 / 3 )

• CMEMS Satellite SST is obtained by Microwave (MW) and/or

Thermal Infrared radiometers (IR). Those 2 sensors measure

SST at different depths related to the frequency of the satellite

sensor.

• For example, IR sensors measure SST at a depth of about 20

micrometers, while MW sensors measure SST at a depth of a

few millimeters. More info here and here.

Credits: from GHRSST web site

http://ghrsst-pp.metoffice.com/pages/sst_definitions/


http://www2.hawaii.edu/~jmaurer/sst/




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W H I C H P A R A M E T E R S ? ( 3 / 3 )

In order to avoid confusion between various SST at different depth, CMEMS

SEA SURFACE TEMPERATURE Satellite products provide with the following

information:

• SEA SURFACE TEMPERATURE (SST):

• Foundation SST (SST at a depth of about 10 meters,

i.e. not influenced by diurnal cycle) (all SST products except one)

• Skin SST (SST at a depth of about 10 micrometers,

i.e. influenced by diurnal cycle) (only 1 product

SST_GLO_SST_L4_NRT_OBSERVATIONS_010_014)

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O u t l i n e






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W H A T I S C M E M S A D D E D V A L U E ? ( 1 / 3 )

L0 L1 L2 L3 L4

CMEMS PRODUCTS PROCESSING LEVEL

Raw Satellite

Data Raw Satellite

Data with

correction

Derived

geophysical

variables at

same

resolution and

location as L1

Variables

mapped on

space-time

grid, with

calibration,

merging&

validation

Same as L3

but Gap Free

Grid and with

additional

annexed

information

INCREASING ADDED VALUE OF SATELLITE DATA

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Reprocessed products: A new product every 1 to 2 years with optimal

accuracy and homogeneous time series

Real time products: A new product update every day, a few hours after

sensing

REPROCESSING (20years in the past) Real Time

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• Calibration: all satellites are inter-calibrated, i.e. all satellites use

the same reference level.

• Merging and Interpolation: satellite measures from one or several

satellites are condensed as ONE VALUE on a REGULAR GRID :

gridded product with gaps (L3) and gridded product without gaps

(L4).

• Validation: products are scientifically validated following a

thorough methodology.

• Algorithm and Corrections are specific to each European Sea

characteristics.

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O u t l i n e






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C M E M S O c e a n S e a I c e T A C D A T A P R O D U C E R S

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O u t l i n e






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WHICH PRODUCTS IN CMEMS CATALOGUE?

SEA SURFACE TEMPERATURE Satellite products over the GLOBAL

Ocean and all European Seas are sorted into 2 categories:

• Gridded with gaps - Sea Surface Temperature L3 - Real Time and Reprocessed SST_(AREA)_SST_L3_(NRT)or(REP)_OBSERVATIONS_010_XXX

• Gridded gap-free - Sea Surface Temperature

L4 - Real Time and Reprocessed

SST_(AREA)_SST_L4_(NRT )or (REP)_OBSERVATIONS_0010_XXX

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A n y q u e s t i o n , a n y t i m e : s e r v i c e d e s k . c m e m s @ m e r c a t o r - o c e a n . e u

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