Minimize EARS

EARS (EUMETSAT Advanced Retransmission Service)

Overview     Network of Direct Readout Stations    NOAA data    MetOp data     Suomi-NPP data    FY-3 data    References

 

The aim of EARS is to provide polar satellite data from the EUMETSAT MetOp, the NOAA (National Oceanic and Atmospheric Administration), and the CMA (China Meteorological Administration) satellites with a timeliness suited to the needs of European operational short range regional NWP (Numerical Weather Prediction) models. The geographical coverage of EARS is primarily over data-sparse sea areas around Europe. 1) 2)

The EARS service comprises the following individual polar satellite instrument data services:

• EARS-ATOVS (Advanced TIROS Operational Vertical Sounders) consisting of the AMSU-A and -B (Advanced Microwave Sounding Units) and the HIRS (High Resolution Infrared Radiation Sounder).

• EARS-AVHRR (Advanced Very High Resolution Radiometer)

• EARS-ASCAT (Advanced Scatterometer)

• EARS-IASI (Infrared Atmospheric Sounding Interferometer)

• EARS-NWC (Nowcasting)

• EARS-ATMS (Advanced Technology Microwave Sounder)

• EARS-CrIS (Cross-track Infrared Sounder)

• EARS-VIIRS (Visible Infrared Imaging Radiometer Suite)

• EARS-VASS (Vertical Atmospheric Sounding Service)

Each of these EARS data services retransmits observations from an instrument or an instrument group, while aiming at providing homogeneous services across the NOAA, MetOp and FY3 polar meteorological orbiting satellites. The target timeliness for delivery of data is in the range of 15 to 30 minutes from instrument sensing.

Traditionally polar satellite data has been received via two methods:

1) via the once-per-orbit data download from the spacecraft to the central ground station

2) via the direct transmission from the satellite to a Direct Readout (aka HRPT=High Resolution Picture Transmission) station on ground.

The first mechanism provides global coverage data to end users, but with delays of two to six hours after the time of measurement. The second mechanism provides the data virtually at the time of measurement, but the geographical coverage is limited to the region around the Direct Readout reception station. EARS provides improvements on both of these methods by offering a large geographical coverage combined with timely retransmission. This is achieved by having a network of Direct Readout stations around the Atlantic and Arctic Oceans and using it to rapidly distribute the collected instrument data to end users.

The three methods for receiving data are illustrated in Figure 1 with the EARS-ATOVS service being shown as an example in the center.

EARS_AutoB

Figure 1: Coverage and Timeliness for Global, Regional and Local missions (image credit: EUMETSAT)

EARS service

Satellite Series and Instruments

NOAA KLM:
NOAA-15, -18

NOAA-NN':
NOAA-19

MetOp:
MetOp-A, -B

Suomi-NPP

FY-3:
FY-3C

EARS-ATOVS

HIRS/3
AMSU-A
AMSU-B

HIRS/4
AMSU-A
MHS

HIRS/4
AMSU-A
MHS

-

-

EARS-AVHRR

AVHRR/3

AVHRR/3

AVHRR/3

-

-

EARS-ASCAT

-

-

ASCAT

-

-

EARS-IASI

-

-

IASI

-

-

EARS-NWC

-

AVHRR/3

AVHRR/3

-

-

EARS-ATMS

-

-

-

ATMS

-

EARS-CrIS

-

-

-

CrIS

-

EARS-VIIRS

-

-

-

VIIRS

-

EARS-VASS

-

-

-

-

MWHS-II
IRAS

Table 1: Satellites and instruments supported by EARS

The system elements making up EARS are shown in Figure 2. The NOAA, MetOp and FY-3 spacecraft Direct Readout transmissions are received by a network of Direct Readout stations operated by partner organizations in the EARS project. These stations provide the raw data to a EUMETSAT PPN (Product Processing Node) computer located at the partner organization's site. The PPN handles and processes the data as necessary for the particular EARS service. For example in the EARS-ATOVS service the raw data is processed using the AAPP (ATOVS and AVHRR Processing Package). The resulting products are sent from the PPN to EUMETSAT where these are then forwarded to EUMETCast - EUMETSAT's Broadcast System for Environmental Data. EUMETCast is a multi-service dissemination system based on standard DVB-S2 (Digital Video Broadcast-Second Generation) technology. It uses commercial telecommunication geostationary satellites to multicast files (data and products) to a wide user community.

EARS_AutoA

Figure 2: EARS system elements (image credit: EUMETSAT)

The primary delivery mechanism for EARS is EUMETCast, the EUMETSAT Broadcast Distribution System for Environmental Data. EUMETCast utilizes the satellite services of a satellite operator and telecommunications service provider to distribute data files using DVB-S2 (Digital Video Broadcast) to a wide audience located within a geographical coverage zone which includes most of Europe, Africa and parts of the American continent. All EARS services are available via the Europe Ku-band transmission. EARS-ASCAT is also available via Africa C-band transmission.

 


 

Network of Direct Readout Stations Used to Acquire Data

The aim of EARS has been achieved through the close co-operation of organizations willing to operate the network of Direct Readout stations. A major consideration has been to optimize the area of data coverage and to reduce system costs by making use of existing stations. The following organizations provide the Direct Readout station network:

• CMS (Centre de Météorologie Spatiale) – Météo-France, France

• DMI (Danish Meteorological Institute), Denmark/Greenland

• DGMAN (Directorate General of Meteorology and Air Navigation), Oman

• HNMS (Hellenic National Meteorological Service), Greece

• INTA (Instituto Nacional de Téchnica Aerospacial), Spain

• KSAT (Kongsberg Satellite Services), Norway/Spitsbergen (Svalbard)

• EC (Environment Canada), Canada

• NOAA (National Oceanic and Atmospheric Administration), USA

• ROSHYDROMET (Scientific Research Center of Space Hydrometeorology "Planeta"), SRC Planeta, Russia.

All these organizations currently receive Direct Readout data and are actively making use of it for various purposes. The station's locations contributing to EARS are given in Table 2.

Station Name

Country

Operated by

Location (latitude, longitude)

Edmonton

Canada

EC

53.33ºN, 113.5ºW

Gander

48.95ºN, 54.57ºW

Gilmore Creek


USA


NOAA

64.97ºN, 147.40ºW

Monterey

36.35ºN, 121.55ºW

Miami

25.74ºN, 80.16ºW

Wallops

37.8ºN, 75.3ºW

Maspalomas

Spain

INTA

27.78ºN, 15.63ºW

Kangerlussuaq

Greenland

DMI

66.98ºN, 50.67ºW

Svalbard

Norway

KSAT

78.13ºN, 15.23ºE

Athens

Greece

HNMS

37.815ºN, 23.769ºE

Lannion

France

CMS

48.75ºN, 3.5ºW

Saint-Denis (La Réunion)

20.91ºS, 55.50ºE

Moscow

Russian Federation

SRC Planeta

55.759ºN, 37.569ºE

Muscat

Sultanate of Oman

DGMAN

23.59ºN, 58.29ºE

Table 2: Direct Readout Stations contributing to EARS

Service/
DB Station

EARS
ATOVS

EARS
AVHRR

EARS
ASCAT

EARS
IASI

EARS
NWC

EARS
ATMS

EARS
CrIS

EARS
VIIRS

EARS
VASS

Svalbard
(SVA)

MetB N19
MetA N18

MetB
MetA N19

MetB
MetA

MetB
MetA

MetB
N19

Suomi-NPP

S-NPP

S-NPP

FY-3C

Maspalomas
(MAS)

MetB N19
MetA N18
N15

MetB
MetA N19

MetB
MetA

MetB
MetA

MetB
N19

S-NPP

S-NPP

S-NPP

FY-3C

Kangerlussuagq
(KAN)

MetB N19
N18 N15

MetB
N19

MetB

MetB

MetB
N19

S-NPP

S-NPP

S-NPP

FY-3C

Athens
(ATH)

MetB N19
MetA N18

MetB
MetA N19

MetB
MetA

MetB
MetA

MetB
N19

S-NPP

S-NPP

S-NPP

FY-3C

Lannion
(LAN)

MetB N19
MetA N18
N15

MetB
MetA N19

MetB
MetA

MetB
MetA

MetB
N19

S-NPP

S-NPP

S-NPP

FY-3C

Moscow
(MOS)

MetB N19
MetA N18
N15

MetB
MetA N19

MetB
MetA

MetB

MetB
N19

S-NPP

S-NPP

 

 

Gander
(GAN)

MetB N19
MetA N18
N15

MetB
MetA N19

MetB
MetA

MetB

MetB
N19

S-NPP

S-NPP

 

 

Wallops
(WAL)

MetB N19
MetA N18
N15

MetB
MetA N19

MetB
MetA

MetB
MetA

MetB
N19

 

 

 

 

MIAMI
(MIA)

MetB N19
MetA N18

 

 

 

 

 

 

 

 

Gilmore Creek
(GIL)

MetB N19
N18 N15

 

 

 

 

 

 

 

 

Monterey
(MON)

MetB N19
MetA N18
N15

 

 

 

 

 

 

 

 

Edmonton
(EDM)

MetB N19
N18 N15

 

 

MetB

 

 

 

 

 

Saint-Denis
(STD)

MetB N19
MetA N18

 

MetB
MetA

 

 

 

 

 

 

Muscat
(MUS)

MetB N19
MetA N18

 

MetB
MetA

 

 

 

 

 

 

Table 3: Direct Readout Stations and Support to EARS Services

 

Pass Scheduling Priorities

EUMETSAT will coordinate (as far as possible) the scheduling of pass reception by the Direct Readout stations to achieve an efficient overall utilization of the network in support of the defined EARS services.

To structure the prioritization scheme, a Primary Morning Orbit Satellite and Primary Afternoon Orbit Satellite will be defined. The selection will be based on the status and performance of the operational polar orbiting satellites. The selection will be revised in response to changes of status or performance and when a new satellite enters service. In particular over the European region, the aim is to give first priority to reception from the Primary Morning Orbit Satellite during the local morning and evening periods and to reception from the Primary Afternoon Orbit Satellite during the local afternoon and night periods.

This scheme will aid in the generation of Regional Passes, a sequence of consecutive station passes of a particular satellite.

The generation of Regional Passes will be of importance for an optimal processing of MetOp ASCAT observations due to the particular viewing geometry of the instrument. Since the start of MetOp operations, MetOp is the Primary Morning Orbit Satellite (currently MetOp-B) and a NOAA satellite is the Primary Afternoon Orbit Satellite (currently S-NPP).

 


 

EARS (EUMETSAT Advanced Retransmission Service) Overview

 

NOAA Satellites Providing ATOVS and AVHRR Data

NOAA is responsible for the operation of the polar-orbiting meteorological satellite systems for the United States. NOAA currently has 4 polar orbiting satellites: NOAA 15, 18 and 19 of the KLM series, and S-NPP (Suomi-NPP).

The instrumentation on the operational NOAA KLM series of satellites includes the AVHRR (Advanced Very High Resolution Radiometer ) and the ATOVS (Advanced TIROS Operational Vertical Sounders) consisting of the Advanced Microwave Sounding Units (AMSU-A and -B) and the HIRS (High Resolution Infrared Radiation Sounder). The NOAA N and N' satellites have improved AVHRR and ATOVS instruments. The AMSU-B is replaced by the MHS (Microwave Humidity Sounder).

The AMSU/MHS instruments support a near all-weather capability to generate soundings of the atmosphere on a global scale. They enable the retrieval of sounding information in cloudy and partly cloudy regions as well as the detection of precipitation and the monitoring of ice and snow on the earth's surface.

HIRS measures scene radiance in the infrared spectrum. Data from the instrument is used, in conjunction with the AMSU instruments, to calculate atmospheric vertical temperature profiles. The data is also used to determine ocean surface temperatures, total atmospheric ozone, precipitable water, cloud height and coverage, and surface radiance.

The AVHRR/3 instrument provides image data in the visible and infrared spectral bands. Data from this instrument provides information on cloud coverage within the footprints of the various sounding instruments.

The MHS (Microwave Humidity Sounder) is a self-calibrating microwave radiometer that together with the complementary AMSU-A instruments, provides the operational microwave sounding capability for the NOAA-N, -N' meteorological satellites.

The L-band HRPT (High Resolution Picture Transmission) broadcast carries data from the satellite instruments at a rate of 665,400 bit/s, in real time. The broadcast consists of the digitized unprocessed output of five AVHRR/3 channels, plus the HIRS, AMSU-A and -B, MHS and other data. All information necessary to calibrate the output from the instruments is included in the data stream.

 


 

MetOp Satellites Providing ATOVS, AVHRR, ASCAT and IASI Data

MetOp satellites are part of the EPS (EUMETSAT Polar System), Europe's first polar orbiting operational meteorological satellite system, and the European contribution to the IJPS (Initial Joint Polar-Orbiting Operational Satellite System). In this joint European-US polar satellite system, EUMETSAT has the operational responsibility for the "morning orbit" with their MetOp satellites.

The MetOp satellites carry a wide range of instruments including AVHRR and ATOVS instruments, the ASCAT (Advanced Scatterometer) instrument and the IASI (Infrared Atmospheric Sounding Interferometer) instrument.

The AVHRR and ATOVS instruments are of the same design as those carried on the NOAA N and N' satellites.

The ASCAT mission has been primarily designed to provide global ocean wind vectors operationally. The main application foreseen is the assimilation of those winds into numerical weather prediction models.

The ASCAT system geometry is based on the use of fan-beam antennas. The system covers two 550 km swaths that are separated from the satellite ground track by about 360 km for the minimum orbit height. The ASCAT incidence angle ranges from 25º to 65º. For each swath, three antennae illuminate the sea surface, measuring the backscattered signal. At such incidence angles, the main backscattering mechanism is considered to be Bragg resonance, which describes the interaction of the radar signal with short gravity waves having a wavelength of a few centimeters. The wind speed and direction near the ocean surface with respect to the antenna look angles can be determined using an empirical geophysical model function, which relates these parameters to the observed backscatter normalized radar cross section. ASCAT collects data from three antennae with different look angles to retrieve a wind vector.

EARS_Auto9

Figure 3: ASCAT viewing geometry (image credit: EUMETSAT)

ASCAT being a C-band radar, is unaffected by cloud cover and rain, and provides both a day and night measurement capability. The IASI (Infrared Atmospheric Sounding Interferometer) is composed of a Fourier transform spectrometer and an associated IIS (Integrated Imaging Subsystem). The Fourier transform spectrometer provides infrared spectra with high resolution between 645 and 2760 cm-1 (3.6 µm to 15.5 µm). The IIS consists of a broad band radiometer with a high spatial resolution. However, the IIS information is only used for co-registration with the AVHRR (Advanced Very High Resolution Radiometer).

The main goal of the IASI instrument is to provide atmospheric emission spectra to derive temperature and humidity profiles with high vertical resolution and accuracy. Additionally, it is used for the determination of trace gases such as ozone, nitrous oxide, carbon dioxide and methane, as well as land- and sea surface temperature and emissivity and cloud properties. IASI has 8461 spectral samples, aligned in three bands between 645.0 cm-1 and 2760 cm-1 (15.5µm and 3.63 µm), with a spectral resolution of 0.5 cm-1 (FWMH) after apodization (L1c spectra). The spectral sampling interval is 0.25 cm-1. The IASI sounder is coupled with the IIS, which consists of a broad band radiometer measuring between 833 cm-1 and 1000 cm -1 (12 µm and 10 µm) with a high spectral resolution. Table 4 summarizes the spectral characteristics of IASI.

Band

Wave numbers σ (cm-1)

Wavelength λ (μm)

1

645.0 – 1165.0

8.58 – 15.50

2

1165.0 – 1951.5

5.12 – 8.58

3

1951.5 – 2760.0

3.62 – 5.12

Table 4: Approximate IASI spectral bands

The IIS is used for collocation between IASI and the AVHRR and is only available during Level 1 processing. IASI is an across track scanning system with a scan range of ±48°20', symmetrically with respect to the nadir direction. A nominal scan line covers 30 scan positions towards the Earth and two calibration views. One calibration view is into deep space, the other is observing the internal black body. The scan starts on the left side with respect to the flight direction of the spacecraft.

The EFOV (Effective Field of View) is the useful field of view at each scan position. Each EFOV consists of a 2 x 2 matrix of so-called IFOV (Instantaneous Fields of View). Each IFOV has a diameter of 14.65 mrad (milliradians), which corresponds to a ground resolution of 12 km at nadir and a satellite altitude of 819 km. The 2 x 2 matrix is centered on the viewing direction. The IIS field of view is defined by a square area of 59.63 x 59.63 mrad, consisting of 64 x 64 pixels and covering the same area as the IASI EFOV. The instrument scans in a step and stare modus. Each interferogram is acquired within 151 ms. The 30 Earth interferograms per scan line are taken in equally spaced time intervals every 8/37 seconds so that a synchronization with AMSU is achieved.

The MetOp satellites transmit L-band HRPT (High Resolution Picture Transmission) broadcast of satellite instruments at a rate of 3 Mbit/s, in real time. This is the same transmission band as the NOAA satellites. The transmissions follow the data model recommended by the CCSDS (Consultative Committee for Space Data Systems), which is significantly different from the NOAA satellite transmissions.

EARS provides the MetOp Regional Data service allowing rapid access to MetOp ATOVS, AVHRR, ASCAT and IASI data within the region covered by the EARS network of HRPT stations supporting the particular service. The MetOp Global Data Service is also available to users of EUMETCast providing the complete set of products with global coverage from all of the satellites instruments, but with a slower access time.

The MetOp Regional Data service combines AHRPT and FDES (Fast Dump Extract System) data. The FDES data comprise the most recent part of the X-band global dump for MetOp-A received at Svalbard from the northbound passes, thus providing high-timeliness regional data. FDES data are currently used for EARS-ASCAT, EARS-ATOVS, EARS-AVHRR, and EARS-IASI data streams.

 

ATOVS Data:

Sounder data is produced by a set of the instruments making up the ATOVS (Advanced TIROS Operational Vertical Sounder) and is used to obtain information about the vertical profile of temperature and humidity in the atmosphere. The radiation measurements from the ATOVS instruments can be assimilated directly into numerical models of the atmosphere using advanced techniques that have become operational over the last decade. This vertical profile information has a significant positive impact upon the performance of all meteorological numerical weather prediction models.

EARS_Auto8

Figure 4: Geographical coverage of EARS-ATOVS service (image credit: EUMETSAT)

 

AVHRR Data:

The EARS-AVHRR service collects AVHRR instrument data from the MetOp and NOAA satellites via a network of Direct Readout stations and retransmits it via EUMETCast. The AVHRR is a multi-purpose imaging instrument used for the global monitoring of cloud cover, sea surface temperature, ice, snow and vegetation characteristics.

EARS_Auto7

Figure 5: Geographical coverage of the EARS-AVHRR service (image credit: EUMETSAT)

 

ASCAT Data:

The EARS-ASCAT service collects ASCAT instrument data from MetOp satellite passes via a network of Direct Readout stations and retransmits Level 2 products via EUMETCast. The prime objective of ASCAT is to measure wind speed and direction over the oceans.

The data is disseminated in two products:

• RAS (Regional Assimilation Wind) Product which has a 25 km grid

• ASCAT coastal winds which has a 12.5 km grid.

EARS_Auto6

Figure 6: Geographical coverage of the EARS-ASCAT service (image credit: EUMETSAT)

EARS_Auto5

Figure 7: Geographical coverage of EARS-IASI service (image credit: EUMETSAT)

 

Nowcasting Products:

For the nowcasting and very short range weather forecasting, the near-real time availability of high resolution cloud products is essential. The three cloud products of the EARS-NWC service complement the cloud products from geostationary-satellites like MSG, especially for the high-latitudes where the coverage from the geostationary orbit is limited. The distributed products are: CM (Cloud Mask), CT (Cloud Type). and CTTH (Cloud Top Temperature and Height).

EARS_Auto4

Figure 8: Geographical coverage of the EARS-NWC service (image credit: EUMETSAT)

 


 

Suomi-NPP Satellite Providing ATMS, CrIS and VIIRS Data

The Suomi-NPP satellite (S-NPP) has been developed in a co-operation between NASA, NOAA and the DoD of the USA in the context of the JPSS (Joint Polar Satellite System), as a prototype for the follow-on missions to the NOAA KLM and NN' satellite series. S-NPP carries five key instruments: the ATMS (Advanced Technology Microwave Sounder), the CrIS (Cross-track Infrared Sounder), the OMPS (Ozone Mapping and Profiler Suite), the VIIRS (Visible Infrared Imaging Radiometer Suite), and CERES (Clouds and the Earth's Radiant Energy System).

The ATMS is a cross-track microwave sounder that combines the capabilities of current generation microwave temperature sounders AMSU-A (Advanced Microwave Sounding Unit) and MHS (Microwave Humidity Sounders) that are flying on EUMETSAT's and NOAA's IJPS satellites.

The CrIS provides soundings of the atmosphere with 1305 spectral channels, over 3 wavelength ranges: LWIR (9.14 - 15.38 µm); MWIR (5.71 - 8.26 µm); and SWIR (3.92 - 4.64 µm).

The VIIRS is a scanning radiometer, which collects visible and infrared imagery and radiometric measurements of the land, atmosphere, cryosphere, and oceans. VIIRS data is used to measure cloud and aerosol properties, ocean color, sea and land surface temperature, ice motion and temperature, fires, and the Earth's albedo.

The direct broadcast of S-NPP science data is performed only in the X-band which makes the reception possible only on those reception stations of the EARS network which have already the X-band reception capability. Currently, the Direct Readout stations supporting the S-NPP regional services are the five core European stations: Lannion, Maspalomas, Svalbard, Kangerlussuaq and Athens.

 

ATMS Data:

The ATMS is a cross-track microwave sounder that combines the capabilities of current generation microwave temperature sounders AMSU (Advanced Microwave Sounding Unit) that are flying on EUMETSAT's and NOAA's IJPS satellites. It measures at 22 frequency bands in the range from 23 GHz through 183 GHz. The measurements from the ATMS instrument can be assimilated directly into numerical models of the atmosphere using advanced techniques that have become operational over the last decade.

EARS_Auto3

Figure 9: Geographical coverage of the EARS-ATMS service (image credit: EUMETSAT)

 

EARS-CrIS Data:

The CrIS provides soundings of the atmosphere with 1305 spectral channels, over 3 wavelength ranges: LWIR (9.14-15.38 µm); MWIR (5.71- 8.26 µm); and SWIR (3.92 - 4.64 µm). The CrIS instrument, a Fourier transform spectrometer, scans a 2200 km swath width (±50º) with 30 Earth-scene views. Each field consists of 9 fields of view, arrayed as 3 x 3 array of 14 km diameter spots (nadir spatial resolution). The CrIS instrument is based on the heritage of AIRS.

Data from CrIS are providing the IR sounding component for the afternoon orbit and are therefore complimentary to the IASI data in the morning orbit which have a similar characteristic. IR sounder data play a crucial role for the evaluation of the atmospheric state in NWP models of all scales.

EARS_Auto2

Figure 10: Geographical coverage of the EARS-CrIS service (image credit: EUMETSAT)

 

VIIRS Data:

The EARS-VIIRS service collects data from the VIIRS instrument onboard the Suomi-NPP spacecraft, operated by NASA and NOAA. The VIIRS (Visible Infrared Imaging Radiometer Suite) is a scanning radiometer, which collects visible and infrared imagery and radiometric measurements of the land, atmosphere, cryosphere, and oceans. VIIRS data is used to measure cloud and aerosol properties, ocean color, sea and land surface temperature, ice motion and temperature, fires, and the Earth's albedo.

Climatologists use VIIRS data to improve our understanding of global climate change. The NASA Suomi-NPP webpages (http://npp.gsfc.nasa.gov/viirs.html) have more details. The provision of VIIRS data in the form of an EARS-service is a logical extension of the EARS-AVHRR service, providing operational imager data with high timeliness for nowcasting applications.

EARS_Auto1

Figure 11: Geographical coverage of the EARS-VIIRS service (image credit: EUMETSAT)

 


 

FY-3 Satellites Providing VASS Data

The FY-3 series of CMA/NSMC (China Meteorological Administration/National Satellite Meteorological Center) represents the second generation of Chinese polar-orbiting meteorological satellites (follow-on of the FY-1 series). The FY-3 series represents a cooperative program between CMA and CNSA (China National Space Administration).

The FY-3 satellites carry a wide range of instruments including those that support the EARS -VASS (Vertical Atmospheric Sounding Service): the MWHS-II (Microwave Humidity Sounder –II), the MWTS-II (Microwave Temperature Sounder-II) and the IRAS (Infrared Atmospheric Sounder). The FY-3C MWTS-II service was suspended since 17/02/2015 due to an instrument permanent failure and hence the FY-3C EARS-VASS includes only data from the MWHS-II and the IRAS instruments.

The IRAS instrument is a classical infrared sounder with similar characteristics to the HIRS instrument flown on the MetOp and NOAA satellites. Its 20 bands provide information on the vertical structure of temperature and water vapor in a cloud-free atmosphere and above clouds.

The advantage of microwave sounders like the MWHS-II instrument is their ability to perform vertical atmosphere sounding in cloudy conditions. Like the MHS instrument on the MetOp and NOAA satellites, it focuses on water vapor sounding of the upper troposphere but also provides information on temperature profiles.

The MWTS-II provides temperature sounding in nearly-all-weather conditions. The instrument closely matches the channels of AMSU-A and ATMS. It does not include the AMSU-A2 channels around 23.8 and 31.4 GHz located around the 23.8 GHz oxygen absorption line. However, this is compensated by a new set of channels around the 118.75 GHz oxygen absorption line included in the MWHS-II sounder.

 

VASS Data:

The EARS-VASS service collects data from the Microwave Humidity Sounder –II (MWHS-II) and the IRAS (Infrared Atmospheric Sounder) instruments onboard the FY-3C spacecraft, operated by CMA (Chinese Meteorological Agency). The IRAS instrument is a classical infrared sounder with similar characteristics to the HIRS instrument flown on the MetOp and NOAA satellites. Its 20 bands provide information on the vertical structure of temperature and water vapor in a cloud-free atmosphere and above clouds.

The advantage of microwave sounders like the MWHS-II instrument is their ability to perform vertical atmosphere sounding in cloudy conditions. Like the MHS instrument on the MetOp and NOAA satellites, it focuses on water vapor sounding of the upper troposphere, but also provides information on temperature profiles. The information on the three-dimensional distribution of temperature and water vapor provided by the combination of these two instruments is one of the most valuable inputs for forecast models of all scales.

EARS_Auto0

Figure 12: Geographical coverage of the EARS-VASS service (image credit: EUMETSAT)

 


 

EARS Data via EUMETCast

The primary delivery mechanism for EARS is EUMETCast, the EUMETSAT Broadcast Distribution System for Environmental Data. EUMETCast utilizes the satellite services of a satellite operator and telecommunications service provider to distribute data files using DVB-S2 (Digital Video Broadcast-Second Generation) to a wide audience located within a geographical coverage zone which includes most of Europe, Africa and parts of the American continent. All EARS services are available via the Europe Ku-band transmission. EARS-ASCAT is also available via Africa C-band transmission.

Access to EARS data via EUMETCast is without licence. However, users are required to register in order to receive the service via EUMETCast. New EUMETCast users also need to order EUMETCast Client Software and EKU as part of the registration process.

Users should register via the EO Portal (https://eoportal.eumetsat.int/userMgmt/login.faces) using their login details. If you do not yet have an EO Portal account, you can create one via the link provided above.

Once logged-in, you will be able to register for the EARS service. This will provide you access to METOP, NOAA and FY3 data distributed under the relevant EARS services.

EARS Data via the Global Telecommunications System: In addition to the EUMETCast, EARS-ATOVS, EARS-ASCAT, EARS-IASI, EARS-ATMS, EARS-CrIS and EARS-VASS data are also available via the GTS (Global Telecommunications System) encoded in FM-94 BUFR.

To gain access to these data users should contact their GTS Regional Telecommunication Hub (RTH) to request that the data be forwarded to the user site.

 


 

DBNet (Direct Broadcast Network) — The Future

As of 2015, DBNet is a WMO (World Meteorological Organization) initiative, a "Direct Broadcast Network for Near Real-Time Relay of Low Earth Orbit Satellite Data." As of April 2016, DBNet is under review by all partners and will be submitted to CBS-16 (Commission for Basic Systems 2016) of WMO.

The aim of DBNet is to provide near real-time access to near-global data from LEO (Low Earth Orbit) satellites, in order to meet in a cost-efficient manner the timeliness requirements of regional and global Numerical Weather Prediction (NWP) and other applications. 3)

As a system, DBNet performs the following functions:

• Reception and acquisition of satellite Direct Broadcast signals at local DBNET stations

• Processing of the acquired data into products

• Near-real time delivery of products

• Performance monitoring and quality control

• User information

• Coordination and planning

The substantial improvement in timeliness is crucial for NWP (Numerical Weather Prediction) models with short cut-off, which otherwise cannot take advantage of the most recent satellite passes. This concept was initially promoted by the HIRLAM (HIgh Resolution Limited Area Model) community, a research cooperation of European meteorological institutes, and by EUMETSAT for the collection of ATOVS (Advanced TIROS Operational Vertical Sounders) data to support regional NWP over Europe. It was then extended by WMO to the global scale under the name RARS (Regional ATOVS Retransmission Services) and quickly adopted by the global NWP as the timeliness requirements of global models became more stringent. Impact studies have given evidence of the benefit of RARS for regional and global NWP.

The objective of DBNet is to expand the RARS concept to other data types in support of a wider range of applications. The present Guide thus replaces the former RARS Operators Standards with a wider scope to accommodate new sensor data, to ensure interoperability with the NOAA Direct Broadcast Real Time Network and to take into account the WMO Information System.

DBNet will include the following regional components: 4)

• DBNet-EUMETSAT (EARS)

• DBNet Asia Pacific (with two nodes in Tokyo and Melbourne)

• DBNet South America (with two nodes in INPE/CPTEC and Buenos Aires)

• DBNet-NOAA DBRTN (Direct Broadcast Real-Time Network) and partners

• An extension of DBNet to Africa is under consideration.

Regional network

Regional Network Coordinator

Sub-regional network

Sub-regional Network Coordinator

DBNet-EUMETSAT (EARS European stations and other regional partners)

EUMETSAT

 

 

DBNet-Asia-Pacific

BoM (Bureau of Meteorology), Melbourne, Australia

Asia-Pacific North

JMA (Japan Meteorological Agency)

Asia-Pacific South

BoM

DBNet-South America

 

South America/North

INPE (Brazil)

South America/South

SMN / CONAE (Argentina)

DBNet-NOAA (DBRTN US stations and other regional partners)

NOAA/CIMSS (Cooperative Institute for Meteorological Satellite Studies)

DBNet-NOAA is implemented by NOAA/CIMSS in partnership with EUMETSAT and shares some functions with EARS

Table 5: DBNet regional or sub-regional network components

The WMO Secretariat and all DBNet Network Coordinators strive to ensure smooth operation of the DBNet Services across all regional networks, to plan expansion of DBNet, to review the priorities and to take any appropriate measure to meet evolving user requirements. The regional/sub-regional Network Coordinators identify candidate stations and negotiate agreements with Station Operators with a view to expand the network and fill gaps when necessary.

 


1) EUMETSAT, "TD 14 - EUMETSAT Advanced Retransmission, Service Technical Description," DocumentNo : EUM/OPS/DOC/06/0467, Issue : v4A e-signed, 30 March, 2016, URL: http://www.eumetsat.int/website/wcm/idc
/idcplg?IdcService=GET_FILE&dDocName=PDF_DMT_112370&
;RevisionSelectionMethod=LatestReleased&Rendition=Web

2) "Regional Data Service / EARS," EUMETSAT, URL: http://www.eumetsat.int/website/home/Data/RegionalDataServiceEARS/index.html

3) "Guide to the Direct Broadcast Network (DBNet) For Near Real-Time Relay of Low Earth Orbit Satellite Data," WMO (World Meteorological Organization), 2016, ISBN 978-92-63-1xxxx-x, URL: http://www.wmo.int/pages/prog/sat/documents/DBNet_Guide-to-DBNet.pdf

4) http://www.wmo.int/pages/prog/sat/rars_en.php
 


The information compiled and edited in this article was provided by Herbert J. Kramer from his documentation of: "Observation of the Earth and Its Environment: Survey of Missions and Sensors" (Springer Verlag) as well as many other sources after the publication of the 4th edition in 2002. - Comments and corrections to this article are always welcome for further updates (herb.kramer@gmx.net).

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