PASSIVE MICROWAVES

PASSIVE MICROWAVES

[email protected]

ATMOSPHERIC OPACITY IN FREQUENCY RANGE 1-275 GHz

1.E-07

1.E-06

1.E-05

1.E-04

1.E-03

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

1 26 51 76 101 126 151 176 201 226 251

Frequency (GHz)

Ver

tica

l op

acit

y (d

B)

Minor constituents

OxygenWater vapour tropical

Water vapour sub-arctic

Figure 5-2 

010 20 30 40

WIND SPEEDSALINITY

LIQUID CLOUDS

WATER VAPOUR

SEA SURFACETEMPERATURE

Frequency (GHz)TbPi

+

_

Sensitivity of brightness temperature to geophysical parameters over ocean surface

Sensitivity of brightness temperature to geophysical parameters over land surfaces

5 10 15 20 25 30 35 40Frequency (GHz)

Soil moisture

Vegetation biomassSurface roughness

Integrated water vapour

Cloud liquid water

Tb Pi

O2 absorption spectrum along a vertical path around 60 GHz

(multiple absorption lines)

55.22 GHz

50 55 60 65 70

Frequency (GHz)

200

100

0

PASSIVE SENSORS REQUIREMENTS IN O2 ABSORPTION SPECTRUM AROUND 60 GHz(U.S. standard atmosphère - Absorption model: Liebe 1993)

Tot

al o

xyg

en a

bso

rptio

n al

ong

a v

ert

ical

pa

th (

dB)

55.78 GHz

RESONANCE FREQUENCIES (GHz)

51.503452.021452.542453.066953.595754.130054.671255.221455.783856.264856.363456.968257.612558.323958.446659.164259.591060.306160.434861.150661.800262.411262.486362.998063.568564.127864.678965.224165.764866.302166.836867.369667.9009

52.6 GHz

50.2-50.4 GHz

Excl.

Excl.

Shared

59.3 GHz

Global composite of radiance temperature (K) measurements from AMSU-A Channel 3

Water vapour absorption spectrum along a vertical path around 183.31 GHz

0

20

40

60

80

100

120

140

160

180

200

174,

81

175,

81

176,

81

177,

81

178,

81

179,

81

180,

81

181,

81

182,

81

183,

81

184,

81

185,

81

186,

81

187,

81

188,

81

189,

81

190,

81

191,

81

Frequency (GHz)

Tota

l abs

orpt

ion

along

a v

ertic

al p

ath

(dB)

Mid-latitude

Tropical

Sub-arctic

Global composite of radiance temperature (K) measurements from AMSU-B Channel 3

ATMOSPHERIC ABSORPTION IN FREQUENCY RANGE 275-1000 GHz

1.E-03

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

1.E+05

1.E+06

275 325 375 425 475 525 575 625 675 725 775 825 875 925 975

Frequency (GHz)

Ver

tica

l op

acit

y (d

B)

Water vapour tropical

Water vapour sub-arctic

Oxygen

Minor constituents

WEB(s) sites fore more infos.

http://cimss.ssec.wisc.edu/itwg/groups/frequency/

http://www.wmo.ch/web/www/TEM/SG-RFC/Handbook.htm

http://www.itu.int/ITU-R/index.html

http://www.eumetnet.eu.org/

( starting next november 2002 )

http://cimss.ssec.wisc.edu/itwg/itsc/itsc12/itsc12agenda.htmlFrequency protection ( Rochard poster near the end)

Spectrum requirements for passive sensing of environmental data

Frequency Band(s)(1) (GHz)

Total BW required (MHz)

Spectral Line(s) or

Centre frequency

(GHz)

MeasurementScan modeN, L(4)

1.37-1.4s,1.4-1.427P

100 1.4Soil moisture, ocean salinity, sea surface temperature, vegetation index

N

2.64-2.655s, 2.655-2.69s,

2.69-2.7P45 2.7

Ocean salinity, soil moisture, vegetation index

N

4.2-4.4s,4.950-4.990s

200 4.3 Sea surface temperature N

6.425-7.25 200 6.85 Sea surface temperature N

10.6-10.68p,10.68-10.7P

100 10.65Rain rate, snow water content, ice morphology, sea state, ocean wind speed

N

Frequency Band(s)(1)

(GHz)Total BW

required (MHz)Required Te

(K)Data availability

(%)(7)

ScanMode (N, L)(4)

1.37-1.4s,1.4-1.427P

100 0.05 99.9 N

2.64-2.655s, 2.655-2.69s,

2.69-2.7P45 0.1 99.9 N

4.2-4.4s,4.950-4.990s

200 0.3/0.05(6) 99.9 N

6.425-7.25 200 0.3/0.05(6) 99.9 N

10.6-10.68p, 10.68-10.7P

100 1.0/0.1(6) 99.9 N

15.2-15.35s, 15.35-15.4P

200 0.1 99.9 N

18.6-18.8p 200 1.0/0.1(6) 95/99.9(6) N

21.2-21.4p 200 0.2/0.05(6) 99/99.9(6) N

22.21-22.5p 300 0.4/0.05(6) 99/99.9(6) N

23.6-24.0P 400 0.05 99.99 N

Some big problems to solve …

1) To conclude what is needed above 275 GHz (central frequencies and bandwidths)

2) To conclude about ‘Delta T ‘ tables betweenWMO and ITU proposal

3) To conclude on % of data availability

4) To archive emissivity pictures of the Earth in microwaves below 50 GHz.