Presentazione di PowerPoint

1

• European Perspectives on Geostationary Microwave
  Sounding
•  
• Bizzarro Bizzarri
• CNR Istituto di Scienze dellAtmosfera e del
  Clima, Roma, Italy
• Phone [phone], Fax [phone],
  E-mail bibizzar_at_tin.it
• Content
• European undertaking in the geostationary orbit
• Principle of MW precipitation sounding from
  geostationary orbit
• GOMAS (Geostationary Observatory for MW
  Atmospheric Sounding)
•  
• 2nd GOES Users Conference, Boulder CO, USA, 1-3
  October 2002

2

• European undertaking in the geostationary orbit
• Meteosat 1 was launched on 23 November 1977,
  first of a pre-operational series (Meteosat 1, 2
  and 3).
• Meteosat 4 was launched on 6 March 1989, first of
  an operational series (Meteosat 4, 5, 6 and 7) to
  be used until 2005.
• All these are spinning satellites, equipped with
  a 3-channel VIS/IR imager.
• MSG 1 was launched on 28 August 2002, first of a
  Meteosat Second Generation series (Meteosat 8, 9,
  10 and 11) to be used until 2020.
• These are still spinning satellites, equipped
  with a 12-channel VIS/IR imager (SEVIRI) and an
  Earth Radiation Budget radiometer (GERB).
• Mission definition of post-MSG, or Meteosat Third
  Generation, has started, in view of a first
  launch in 2015. A 1st User Consultation Workshop
  was held on 13-15 November 2001.

3
(No Transcript)
4
WMO and EUMETSAT requirements for precipitation
observation (WMO representative of current or
near-future, EUM of gt 2015)
5

• The problem of measuring precipitation
•  
• The most long-standing practise makes use of
  VIS/IR image sequences from GEO
• The observing frequency is suitable (15 min with
  MSG)
• The measurement is strongly indirect (VIS/IR only
  sees the cloud top)
• The applicability is mostly addressing convective
  precipitation.
•  
• From LEO, MW images are used (from SSM/I, TRMM,
  in the near future GPM)
• The measurement is direct for low frequencies (10
  GHz), less for high frequencies (90 GHz)
• The applicability is better for convective
  precipitation, but extends to all precipitation
  types
• The frequency, with GPM, will be around 3 hours
• Global scale will be served optimally, regional
  scale to a fair extent
• For the mesoscale, fusion between LEO MW images
  and GEO VIS/IR images will be attempted.
•  
• The ideal would be to extend the MW imagery
  technique to the geostationary orbit, but
• The antenna diameter for a 10-km resolution is 15
  m at 90 GHz, 35 m at 37 GHz, 70 m at 19 GHz
• Polarisation diversity is not practical from the
  geostationary orbit (large and variable z-angle).
•  
• GEO requires using higher frequencies and
  exploiting a different physical principle.

6

• The physical principle for measuring
  precipitation from GEO
•  
• MW observation from LEO makes use of atmospheric
  windows
• Most common frequencies 6 GHz, 10 GHz, 19 GHz,
  23 GHz, 37 GHz, 90 GHz, 150 GHz
• Dual polarisation for roughness effects (over the
  sea) and scattering from ice (over land).
•  
• The proposed principle for GEO exploits
  absorption bands
• Profiles of temperature and humidity are measured
  by more bands at different frequencies
• Profiles observed exploiting bands of different
  frequencies are differently sensitive to clouds
• Absorption bands at very high frequencies enable
  using antennas of affordable size
• It is not necessary to differentiate
  polarisations
• In absorption bands the measurement is equally
  effective over sea and land.
• The precipitation measurement passes through the
  sounding one, therefore
• Many more channels are needed, very narrow (lt 1
  ), with SNR gt 100
• In exchange, one simultaneously gets
• - the temperature vertical profile (also
  inside clouds)
• - the humidity vertical profile (also inside
  clouds)
• - the columnar content (or gross profile) of
  liquid water in the cloud

7

• Multi-channel image from an airborne radiometer
  (Gasiewski et al, 1994). Note
• In absorption bands (183 and 325 GHz) increasing
  cloud impact moving from the peak to the window
  (from 183 ? 1 to 183 ? 3 and 183 ? 7 and from
  325 ? 1 to 325 ? 3 and 325 ? 9)
• In windows (89, 150, 183 ? 7, 220 e 325 ? 9)
  increasing cloud impact with increasing frequency.

8
Precipitation images from a cold front on October
7, 1998 NEXRAD precipitation map smoothed to 15
km resolution (left image), and NOAA/AMSU
precipitation map obtained using a neural net
retrieval technique (right image) (Staelin and
Chen, 2000).
9
(No Transcript)
10
(No Transcript)
11
Atmospheric spectrum in the MW/Sub-mm range
(Klein and Gasiewski, 2000). Preferred bands -
for O2 (temperature) 54 GHz, 118 GHz, 425 GHz
for H2O 183 GHz, 380 GHz.
12
(No Transcript)
13
(No Transcript)
14

• Initiatives for MW/Sub-mm sounding from GEO
• Early proposals
• Staelin D.H. and P.W. Rosenkranz, editors, 1978
  "Applications Review Panel High resolution
  passive microwave satellites". A report to NASA.
• Chedin A., D. Pick and R. Rizzi, 1985
  "Definition study and impact analysis of a
  microwave radiometer on a geostationary
  spacecraft". A report to ESA.
• Fresh start
• Staelin D.H., J.P. Kerekes and F.J. Solman III,
  1997 "Final Report of the Geosynchronous
  Microwave Sounder Working Group". A report to
  NOAA/NESDIS.
• Staelin D.H., A.J. Gasiewski, J.P. Kerekes, M.W.
  Shields and F.J. Solman III, 1998 "Concept
  proposal for a Geostationary Microwave (GEM)
  Observatory". A proposal to NASA and NOAA.
• Bizzarri B., 2000 "MW/Sub-mm sounding from
  geostationary orbit". A report to EUMETSAT.
• Current projects
• GEM (Geostationary Microwave observatory).
• GOMAS (Geostationary Observatory for Microwave
  Atmospheric Sounding).

15
Reference user requirements adopted for GOMAS
Resolution v/s frequency and antenna diameter
16
GOMAS (Geostationary Observatory for MW
Atmospheric Sounding) European sector (1/12 of
disk) scanned each 15 minutes. The sector can be
moved everywhere inside the visible Earth
disk. The satellite can be shifted to serve from
USA to India. Simultaneous retrieval of
temperature/humidity profiles, cloud liquid/ice
water and precipitation.
17
Radiometric performance assessment for 15 min
observing cycle
18
The GOMAS instrument with its 3-m antenna
19
 
 
The GOMAS satellite

• Mass 860 kg (dry" 430 kg)
• Electrical power 500 W
• Volume 3.0 x 3.0 x 3.0 m3
• Data rate 128 kbps (S-band, compatible with MSG
  LRIT).

20
List of Proponents of GOMAS (undertaking to
implement the scientific programme) P.I.
Bizzarro BIZZARRI, for the CNR Istituto Scienze
dell'Atmosfera e del Clima, Roma, Italy
21

• Conclusions
•  
• Strong requirements exist for frequent
  precipitation observation.
• From GEO, a new physical principle needs to be
  exploited.
• GOMAS is proposed as a demonstration mission.
• It would be a precursor for future operational
  applications.
• From the technical standpoint, and building on
  the studies conducted in the U.S. on GEM, it is
  believed that no enabling technology is currently
  missing.
• The GOMAS satellite could be developed in time
  for a launch before 2010, in phase with GPM and
  possible overlap with GIFTS.
• It would provide simultaneous retrieval of
• - temperature profile (?x ? 30 km)
• - humidity profile (?x ? 20 km)
• - cloud liquid/ice water total column and
  gross profile (?x ? 20 km)
• - precipitation rate (?x ? 10 km)
• each 15 minutes ! over ? 1 / 12 of the disk
  covering sea and land !