[A Satellite Data Primer]{.smallcaps}

Prepared for the NOAA ocean satellite data course at OSU/CIOSS, August
22-24, 2006 to provide a ***very simplified*** summary of the available
satellite data for oceanic uses. The weather and/or atmospheric
applications of different satellites are not covered here. For more
complete information see the Martin textbook "An introduction to Ocean
Remote Sensing", or the powerpoint presentations given during the
course.

Data Websites [1](#data-websites)

Orbital Configurations [2](#orbital-configurations)

Sea-Surface Temperature (SST) [3](#sea-surface-temperature-sst)

Sea-Surface Height (SSH) [4](#sea-surface-height-ssh)

Ocean Color (Chlorophyll) [5](#ocean-color-chlorophyll)

Surface Vector Winds (SVW) [6](#surface-vector-winds-svw)

Sea Ice [7](#sea-ice)

Names & Acronyms [8](#names-acronyms)

# Data Websites

The NOAA Ocean Satellite Course focused on accessing data through the
following websites, or using OpenDap delivery protocol which accessed
the datasets served on these websites. We strive to offer "one-stop
shopping" on these websites, with multiple satellite datasets available,
in a range of different formats. Most of the datasets mentioned in this
document are served on our browsers, however there are some that we do
not yet serve such as microwave SST and sea ice. Other websites serving
satellite datasets are also mentioned in this document on the dataset
pages.

CoastWatch West Coast Regional Node OceanWatch browsers

[http://coastwatch.pfeg.noaa.gov/coastwatch/CWBrowser.jsp](http://coastwatch.pfeg.noaa.gov/coastwatch/CWBrowserWW360.jsp)
(US West Coast only)

<http://coastwatch.pfeg.noaa.gov/coastwatch/CWBrowserWW360.jsp> (global)

<http://coastwatch.pfeg.noaa.gov/coastwatch/CWBrowserWW180.jsp> (global
for ArcGIS)

<http://coastwatch.pfeg.noaa.gov/coastwatch/CWBrowserAK.jsp> (Alaska)

<http://coastwatch.pfeg.noaa.gov/coastwatch/CWBrowserSA.jsp> (South
America)

OceanWatch Live Access Server (LAS) at ERD

<http://oceanwatch.pfel.noaa.gov/>

A list of all the datasets served on the above sites, along with
documentation (temporal coverage, spatial resolutions how to access
directly from your computer using OpenDap, etc.) can be found at:

<http://oceanwatch.pfeg.noaa.gov:8081/thredds/catalog.html>

Dataset documentation is also available via the "Data Set Info" links on
the Coastwatch browsers.

# Orbital Configurations

Satellites orbit the earth in either polar or geostationary orbit (see
Fig. 1). Those in polar orbit continually circle over the poles and
achieve global coverage in roughly a week. Satellites in geostationary
orbit stay in a fixed position relative to the earth. Geostationary
satellites have a much higher sampling frequency for a particular area
than polar orbiting satellites, allowing better sampling of cloudy
areas. However geostationary satellites can't get global coverage, and
they do not sample high latitudes regions very well because of the
oblique angle between the earth's surface and the satellite sensor.
Because of the high orbit of gesostationary data it's more challenging
to obtain the high spatial resolution of data from polar orbiting
satellites. Most environmental satellite data comes from satellites in
polar orbit, however geostationary SST data is available, and there
might be an ocean color sensor on a GOES-R (estimated launch date of
2014).

![](media/image1.pct){width="5.5375in" height="2.2625in"}

# Sea-Surface Temperature (SST)

## Brief Description: SST measurements can be made from both IR and passive microwave, and from both polar-orbiting and geostationary orbit. The highest spatial resolution (\~ 1 km) datasets are from polar-orbiting IR measurements using the AVHRR.

**Caveats:** SST from IR measurements can not measure through clouds.
SST data from passive microwave measurements can see through clouds but
have a lower spatial resolution than IR measurements. Passive microwave
SST measurements are not possible within a \~75 km band next to land, or
in times of heavy rainfall. Geostationary measurements of SST can
alleviate cloud coverage problems because of their frequent sampling.
Geostationary measurements do not sample high latitudes regions very
well because of the oblique angle between the earth's surface and the
satellite sensor.

## Current Platforms/Datasets

**AVHRR Pathfinder** dataset has science-quality data from 1985 onward
from the AVHRRs on NOAA's polar orbiting satellites. The latest version
(version 5) has a spatial resolution of 4 km, an improvement from the
previous version which was 9 km.

**MODIS SST** from Terra (10/00 onward) and Aqua (12/02 onward) is
available at 4km and 9km resolution

**GOES** (geostationary) SST data is available from 5/03 onward at a
resolution of 6 km for the region between 45°S-60°N and 180°-30°W

**TMI** on **TRMM** provides microwave SST between 40°S-40°N, at \~25 km
spatial resolution from 12/97 onward.

**AMSR-E** on **Aqua** provides microwave SST between 40°S-40°N, at 38
km and 56 km spatial resolution from 12/02 onward.

### 

### Derived or related products

Frontal products are derived from SST by measuring the spatial
temperature gradient.

### Additional websites with data or further information

Pathfinder 4km website:

<http://www.nodc.noaa.gov/sog/pathfinder4km>

JPL's PO DAAC (Physical Oceanography Distributed Active Archive Center):

<http://podaac.jpl.nasa.gov/sst>

POET, JPL's PO.DAAC Ocean ESIP Tool (POET) for plotting ands subsetting
data

[http://poet.jpl.nasa.gov](http://poet.jpl.nasa.gov/)

Remote Sensing Systems, specializes in microwave satellite measurements

[http://www.ssmi.com](http://www.ssmi.com/)

GODAE's High Resolution SST Pilot Project

[http://www.ghrsst-pp.org](http://www.ghrsst-pp.org/)

# Sea-Surface Height (SSH)

**Brief Description:** Altimeters use active radar to measure the
surface elevation of the ocean, relative to a reference level (the mean
geoid). Satellite SSH data provides information about the ocean
circulation, integrated surface height content, eddy movement,
geostrophic currents and changes in global sea level. Measurements of
SSH are not affected by cloud coverage. They can not be retrieved within
\~15 km of land.

### Past and Current Platforms

GEOSAT 3/85-1/90

TOPEX/Poseidon 8/92 onward

JASON-1 12/01 onward

ERS-1 7/91-6/95

ERS-2 4/95 onward

Envisat 3/02 onward

### Planned Future Platforms

JASON-2 to be launched in 2008 (NOAA)

**Derived or related products**

**Geostrophic currents** can be derived from the slope of SSH.

**Additional websites with data or further information**

JPL\'s Ocean Surface Topography from Space page

[http://sealevel.jpl.nasa.gov](http://sealevel.jpl.nasa.gov/)

JPL's PO DAAC (Physical Oceanography Distributed Active Archive Center):

<http://podaac-www.jpl.nasa.gov/ost>

POET, JPL's PO.DAAC Ocean ESIP Tool (POET) for plotting and subsetting
data

[http://poet.jpl.nasa.gov](http://poet.jpl.nasa.gov/)

AVISO (France)

[http://www.aviso.oceanobs.com](http://www.aviso.oceanobs.com/)

NOAA's OSCAR (Ocean Surface Current Analyses -- Real time) site

[http://www.oscar.noaa.gov](http://www.oscar.noaa.gov/)

# Ocean Color (Chlorophyll)

### Brief Description

Chlorophyll-a concentration is calculated from the normalized
water-leaving radiances at several different visible wavelengths. The
number of wavelengths varies between different sensors (CZCS had 5,
SeaWiFS 8, and MODIS 9). The algorithm is optimized for open-ocean
(case-I) water, and the presence of sediments and colored dissolved
organic material (CDOM) can affect the accuracy of the measurements in
coastal (case‑II) waters. Cloud coverage prevents the ability to measure
chlorophyll remotely.

### Past and Current Platforms

CZCS: 11/78-6/86 (incomplete global coverage)

SeaWiFS: 9/97 onward\*

MODIS/Terra: 2/00 onward (calibration problems with chlorophyll)

MODIS/Aqua: 6/02 onward

\*SeaWiFS is owned commercially by GeoEye (formerly OrbImage) and they
limit the degree to which this data can be distributed. There is a
two-week embargo on viewing data, and while data older than 2 weeks can
be freely obtained from the NASA DAAC for research purposes, other sites
are not allowed to distribute data until it is 60 months old, although
the distribution of images is allowed.

### Planned Future Platforms

VIIRS on NPP (2010) an NPOESS (2013)

HES-CW on GOES-R (2014)

### Derived or related products

**Primary productivity** can be derived from chlorophyll using PAR, SST
and day length. The most widely-used algorithm is that of Behrenfeld and
Falkowski, 1997. (Limnol. Oceanogr., 42, 1479-1491). This product is
served on the CoastWatch West Coast Regional Node thanks to R&O funding
from NOAA/NESDIS.

**PAR** (Photosynthetically available radiation) measurements from
SeaWiFS provide the amount of incoming radiation from the sun between
400-700 nm.

**Fluorescence Line Height** from MODIS instruments on Aqua and Terra
provides information on the phytoplankton health.

**K490** is diffuse attenuation coefficient data at 490 nm wavelength
available from the MODIS instruments on Aqua and Terra and from SeaWiFS.
It is a good measure of water clarity.

### Additional websites with data or further information

NASA\'s OceanColor Web

[http://oceancolor.gsfc.nasa.gov](http://oceancolor.gsfc.nasa.gov/)

NASA's Ocean Color Time-Series Online Visualization and Analysis System\
<http://reason.gsfc.nasa.gov/Giovanni/>

International Ocean-Colour Coordinating Group\
[http://www.ioccg.org](http://www.ioccg.org/)

# Surface Vector Winds (SVW)

**Brief Description:** A scatterometer is a high frequency microwave
radar designed specifically to measure ocean near-surface wind speed and
direction.

### Past and Current Platforms

**NSCAT** flew 9/96-6/97 on ADEOS

**SeaWinds** on **QuikScat** launched 6/99 and still operating providing
near-surface wind speed and direction at a 25 km resolution.

**SeaWinds** on **ADEOS-II** launched 12/02. ADEOS-II lost power 10/03.

### Planned Future Platforms

**ASCAT** on **METOP-A** to be launched 10/06 by ESA

### Derived or related products

## Wind stress is derived from wind speed and direction and provides an indication of the amount of work done by the wind to the ocean 

**Wind stress curl** provides a measure of the pattern of the wind
field. Areas of strong curl cause divergence in the surface layer and
result in upwelling

**Ekman upwelling** is a measure of the vertical movement of water as a
result of wind-driven horizontal water movement at the ocean surface

### Additional websites with data or further information

JPL\'s Winds Page

[http://winds.jpl.nasa.gov](http://winds.jpl.nasa.gov/)

JPL's PO DAAC (Physical Oceanography Distributed Active Archive Center):

<http://podaac-www.jpl.nasa.gov/ovw>

POET, JPL's PO.DAAC Ocean ESIP Tool (POET) for plotting ands subsetting
data

[http://poet.jpl.nasa.gov](http://poet.jpl.nasa.gov/)

Remote Sensing Systems, specializes in microwave satellite measurements

[http://www.ssmi.com](http://www.ssmi.com/)

NOAA's OSCAR (Ocean Surface Current Analyses -- Real time) site

[http://www.oscar.noaa.gov](http://www.oscar.noaa.gov/)

# Sea Ice

**Brief Description:** Passive microwave instruments such as ESMR, SMMR
and SSM/I, and radar such as ERS-1, ERS-2, and RADARSAT provide the main
data sets used for sea ice studies because of their nighttime and
all-weather capabilities.

Passive microwave data provides measurements of the ice edge, sea ice
concentrations, and classification of different types of sea ice types.
Passive microwave imagery is available from late 1978 through the
present. Earlier but less reliable data from the ESMR are available from
late 1972 to 1976.

### Past and Current Platforms

ESMR Flew 12/72-12/76

SMMR Flew 10/78-8/87

SSM/I 6/87 onward

AMSR-E 4/02 onward

GLAS launched 1/03 on ICESat to discern changes in ice volume (mass
balance) over time

### 

### Additional websites with data or further information

Alaska CoastWatch browser (sea ice data will be available here in 9/06)

<http://coastwatch.pfeg.noaa.gov/coastwatch/CWBrowserAK.jsp>

National Snow and Ice Data Center

[http://nsidc.org](http://nsidc.org/)

# Names & Acronyms

Satellite data products are usually referred to by their sensor name,
when the same instrumentation is on different satellites, they are
distinguished by the name of the satellite (ie MODIS sensors on the
Terra and Aqua satellites).

There is also a longer list of acronyms in the front of the Martin
textbook and there is also a good list at
<http://www.noc.soton.ac.uk/lso/acronyms.php> that has sensors and
satellites listed separately, and has better international coverage than
given here.

ADEOS **AD**vanced **E**arth **O**bserving **S**atellite, ADEOS-1 flew
8/96-6/97, ADEOS‑2 was launched in 12/02 but lost power 10/03 (Japan)

AMSR **A**dvanced **M**icrowave **S**canning **R**adiometer (Japan) on
ADEOS-2

AMSR-E **A**dvanced **M**icrowave **S**canning **R**adiometer-**E**OS
(Japan) on Aqua

Aqua NASA satellite flying multiple sensors (MODIS sensor. Launched
4/02. Part of EOS.

Aquarius Sea-surface salinity satellite to be launched 2012 by NASA

ASCAT **A**dvanced **Scat**terometer to be launched on MetOp in 2006 by
ESA

AVHRR **A**dvanced **V**ery **H**igh **R**esolution **R**adiometer
measures SST. The first AVHRR instrument was launched by NOAA in 1978.

CZCS **C**oastal **Z**one **C**olor **S**canner, measures chlorophyll.
Flew from 1978-1986 (NASA)

GOES **G**eostationary **O**perational **E**nvironmental **S**atellites
(NOAA). Named by letters pre-launch, and numbers post-launch. Collect
primarily weather data, but geostationary SST available from 5/03
onward. GOES-R (2012 launch) might measure ocean color via the HES-CW.

ESMR **E**lectrically **S**canning **M**icrowave **R**adiometer, flew
12/72-12/76

EnviSat **Envi**ronmental **Sat**ellite, follow-on to ERS-1 and ERS-2
(ESA)

EOS **E**[arth **O**bserving
**S**ystem](http://eospso.gsfc.nasa.gov/eos_homepage/description.php)
mission including a series of satellites

ERS **E**uropean **R**emote **S**ensing satellites. ERS-1 7/91-6/95,
ERS-2 launched 4/95

ESA **E**uropean **S**pace **A**gency satellites

GAC **G**lobal **A**rea **C**overage

GCOM **G**lobal **C**hange **O**bservation **M**ission, ADEOS-II follow
on (Japan)

GCOM-C **G**lobal **C**hange **O**bservation **M**ission-**C**arbon,
2011 launch (Japan)

GCOM-W **G**lobal **C**hange **O**bservation **M**ission-**W**ater, 2010
launch (Japan)

HES-CW **H**yper-**E**nvironmental **S**uite-**C**oastal **W**ater
Imager\
Ocean color imager that might be launched on GOES-R in 2014 (NOAA)

IceSat Ice, Cloud, and Land Elevation Satellite, launched 1/03 (NASA)

JASON altimeter for SSH launched 2001 (JASON-1), JASON-2 due to be
launched 2008.

K490 Diffuse attenuation coefficient data at 490 nm wavelength from
MODIS instruments on Aqua and Terra

GLAS **G**eoscience **L**aser **A**ltimeter **S**ystem on ICESat (NASA)

LAC **L**ocal **A**rea **C**overage

MetOp **Met**eorological **Op**erational satellite programme, MetOp-A
due for launch 10/06 (ESA)

MODIS **Mod**erate Resolution **I**maging **S**pectroradiometer (NASA)
measures chlorophyll and SST, instruments on two different satellites:
Aqua and Terra. Chlorophyll from MODIS/Terra has calibration issues.

NESDIS **N**ational **E**nvironmental **S**atellite, **D**ata and
**I**nformation **S**ervice (NOAA)

NPOESS **N**ational **P**olar-orbiting **O**perational **E**nvironmental
**S**atellite **S**ystem\
(a NOAA, NASA, and DOD project)

NPP **N**POESS **P**reparatory **P**roject

OCTS **O**cean **C**olor and **T**emperature **S**canner (Japan). On
ADEOS-1 8/96-6/97.

OCM **O**cean **C**olor **M**onitor (India)

OSCAR **O**cean **S**urface **C**urrent **A**nalyses -- **R**eal time
(NOAA)

PAR **P**hotosynthetically **A**vailable **R**adiation (PAR)

Pathfinder Science-quality 4-km resolution SST product going back to
1985

POES **P**olar **O**perational **E**nvironmental **S**atellites (NOAA)

QuikScat satellite flying the first SeaWinds scatterometer, launched
6/99 (NASA)

SeaWiFS **Sea**-viewing **Wi**de **F**ield-of-view **S**ensor, measures
ocean chlorophyll. Launched in Aug 1997 by NASA, but commercially owned
by GeoEye (formerly OrbImage)

SeaWinds scatterometer on QuikScat and ADEOS-2 satellites

SSH **S**ea-**S**urface **H**eight

SMMR **S**canning **M**ultichannel **M**icrowave Radiometer, 10/78-8/87

SSM/I **S**pecial **S**ensor **M**icrowave/**I**mager

SST **S**ea-**S**urface **T**emperature

Terra NASA satellite flying a MODIS sensor. Launched 2/00. Part of EOS.

TMI **T**RMM **M**icrowave **I**mager, microwave SST sensor on TRMM
satellite

TRMM **T**ropical **R**ainfall **M**easuring **M**ission satellite
(NASA), launched 11/97

TOPEX/Poseidon altimeter for SSH launched 8/92 (NASA, jointly with the
French)

VIIRS **V**isible **I**nfrared **I**mager/**R**adiometer **S**uite to be
flown on NPOESS to measure ocean color and SST