Applications of Remote Sensing: The Cryosphere (Snow

1
Applications of Remote SensingThe Cryosphere
(Snow Ice)

• Menglin Jin, San Jose Stte University
• Outline
• Physical principles
• International satellite sensors enabling remote
  sensing of tropospheric aerosols
• ESMR, SMMR, SSM/I, AVHRR, MODIS, AMSR
• Instrument characteristics
• Spacecraft, spatial resolution, swath width,
  sensor characteristics, and unique
  characteristics
• Sea ice and snow retrieval from existing
  satellite systems
• Future capabilities
• Opportunities for the future

Credit Michael D. King, NASA GSFC
2
Sea Ice of Different Forms and Perspectives

• Sparsely distributed ice floes as viewed from a
  ship in the Bering Sea

Photograph courtesy of Claire Parkinson
3
Sea Ice of Different Forms and Perspectives

• Expansive ice field, as viewed from an aircraft
  in the central Arctic

Photograph courtesy of Claire Parkinson
4
Sea Ice of Different Forms and Perspectives

• Close-up of newly formed ice in the Bering Sea

Photograph courtesy of Claire Parkinson
5
Sea Ice of Different Forms and Perspectives

• Ice floes separated by a lead, as viewed from an
  aircraft over the central Arctic

Photograph courtesy of Claire Parkinson
6
Sea Ice of Different Forms and Perspectives

• Thin sheets of ice, as viewed from an aircraft

Photograph courtesy of Koni Steffen
7
Sea Ice of Different Forms and Perspectives

• Several-months-old ice bearing the weight of a
  helicopter, as viewed from ground level in the
  Bering Sea

Photograph courtesy of Claire Parkinson
8
Remote Sensing of Sea Ice from Passive Microwave
Radiometers

• Nimbus 5
• Electrically Scanning Microwave Radiometer (ESMR)
• December 1972-1976
• single channel (19 GHz 1.55 cm) conically
  scanning microwave radiometer
• Nimbus 7
• Scanning Multichannel Microwave Radiometer (SMMR)
• October 1978-August 1987
• 10 channel (five frequency and dual polarization)
  conically scanning microwave radiometer
• Defense Meteorological Satellite Program (DMSP)
• Special Sensor Microwave Imager (SSM/I)
• June 1987-present
• 7 channel (three frequencies with both vertical
  and horizontal polarization 1 frequency with
  horizontal polarization only)

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Advanced Microwave Scanning Radiometer (AMSR-E)

• NASA, Aqua
• launches July 2001
• 705 km polar orbits, ascending (130 p.m.)
• Sensor Characteristics
• 12 channel microwave radiometer with 6
  frequencies from 6.9 to 89.0 GHz with both
  vertical and horizontal polarization
• conical scan mirror with 55 incident angle at
  Earths surface
• Spatial resolutions
• 6 x 4 km (89.0 GHz)
• 75 x 43 km (6.9 GHz)
• External cold load reflector and a warm load for
  calibration
• 1 K Tb accuracy

10
Microwave Scattering of Snow Cover

• Thicker snow results in lower microwave
  brightness temperatures

From Parkinson, C. L., 1997 Earth from Above
11
Satellite Detection of Sea Ice

• Higher rate of microwave emission from sea ice
  than from open water
• Emissivities indicated are for wavelength of 1.55
  cm (19 GHz)

From Parkinson, C. L., 1997 Earth from Above
12
Spectra of Polar Oceanic Surfaces over the SMMR
Wavelengths
250
FY Ice V
FY Ice H
200
MY Ice V
MY Ice H
Open Ocean V
150
Brightness Temperature (K)
100
Open Ocean H
50
0
0.5
0.0
1.0
2.5
1.5
2.0
3.0
3.5
4.0
4.5
5.0
Wavelength (cm)
13
Brightness Temperature of Polar Regions from
Nimbus 5 ESMR
March 8-10, 1974
September 16-18, 1974
lt132.5 K
281.5 K
200 K
160 K
240 K
140 K
180 K
220 K
260 K
Tb (19 GHz)
Parkinson ( 1997)
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Monthly Average Sea Ice Concentrations from
Nimbus 7 SMMR
100
80
60
40
20
12
March 1986
September 1986
From Parkinson, C. L., 1997 Earth from Above
15
Monthly Average Sea Ice Concentrations from
Nimbus 7 SMMR
March 1986
September 1986
100
80
60
40
20
12
From Parkinson, C. L., 1997 Earth from Above
16
Monthly Average Sea Ice Concentrations from SSM/I
February 1999
September 1999
100
80
60
40
20
12
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Location Maps for North and South Polar Regions
North Polar Region
South Polar Region
From Parkinson, C. L., 1997 Earth from Above
18
Decreases in Arctic Sea Ice Coverage as Observed
from Satellite Observations
November 1978 - December 1996
C. L. Parkinson, D. J. Cavalieri, P. Gloersen, H.
J. Zwally, and J. C. Comiso, 1999 J. Geophys.
Res.
19
Monthly Arctic Sea Ice Extent Deviations
November 1978 - December 1996
34300 3700 km2/year
C. L. Parkinson, D. J. Cavalieri, P. Gloersen, H.
J. Zwally, and J. C. Comiso, 1999 J. Geophys.
Res.
20
Trends in Arctic Sea Ice Coverage
Yearly and Seasonal Ice Extent Trends Yearly 2.8
/decade Winter 2.2/decade Spring 3.1/decade
Summer 4.5/decade Autumn 1.9/decade

• Data Sources
• For November 1978 August 1987, the Scanning
  Multichannel Microwave Radiometer (SMMR) on
  NASAs Nimbus 7 satellite
• Since mid-August 1987, the Special Sensor
  Microwave Imagers (SSM/Is) on satellites of the
  Defense Meteorological Satellite Program

• 37,000 km2/year decrease of sea ice area over a
  19.4 year period observed from satellite
• 19,000 km2/year decrease in sea ice area over a
  46 year period based on Geophysical Fluid
  Dynamics Laboratory (GFDL) model

C. L. Parkinson, D. J. Cavalieri, P. Gloersen, H.
J. Zwally, and J. C. Comiso, 1999 J. Geophys.
Res.
21
Observed Northern Hemisphere Sea Ice Decreases
Placed in a Climate Context
Probability that an observed sea-ice-extent trend
results from natural climate variability, based
on a 5000-year control run of the GFDL General
Circulation Model (GCM)

• Open Circle
• Observed 1953-1998 trend, updated from Chapman
  and Walsh (1993)
• Open Square
• Observed 1978-1998 trend, updated from Parkinson
  et al. (1999)

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Sea Ice Trends

• Probability that observed trends result from
  natural climate variability
• 1953 1998 trend lt 0.1
• 1978 1998 trend lt 2
• Demonstrates how scientists have attempted to
  take the satellite data record and put it into
  context of mans impact on climate

Vinnikov, Robock, Stouffer, Walsh, Parkinson,
Cavalieri, Mitchell, Garrett, and Zakharov,
published in the December 3, 1999 issue of Science
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Brightness Temperature of Polar Regions from SSM/I
March 14, 1997
19 GHz Vertical Polarization
37 GHz Vertical Polarization
lt132.5 K
281.5 K
200 K
160 K
240 K
140 K
180 K
220 K
260 K
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Brightness Temperature of Polar Regions from SSM/I
March 14, 1997
85 GHz Vertical Polarization
lt132.5 K
281.5 K
200 K
160 K
240 K
140 K
180 K
220 K
260 K
25
Brightness Temperature Scatter Diagram for Odden
Region and Greenland Sea
Early Ice
Maximum Extent of Bulge
November 21, 1996
January 18, 1997
260
A
Thick ice (consolidated region)
A
240
D
Brightness Temperature (V19)
D
220
Odden Study Area (pancakes or nilas)
200
180
O
O
240
200
180
220
260
240
200
180
220
260
Brightness Temperature (V37)
Brightness Temperature (V37)
26
Brightness Temperature Scatter Diagram for Odden
Region and Greenland Sea
Maximum Extent of Tongue
Ice Melt Formation of Ice Island
March 14, 1997
April 14, 1997
260
240
Brightness Temperature (V19)
220
200
180
240
200
180
220
260
240
200
180
220
260
Brightness Temperature (V37)
Brightness Temperature (V37)
27
Brightness Temperature of Polar Regions from SSM/I
SSM/I
AVHRR
February 26, 1987
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Brightness Temperature of Polar Regions from SSM/I
SSM/I
AVHRR
March 15, 1987
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Snow Cover in the Northern Andes

• Pucahirca, Peru
• October 1991
• Latitude of 9S
• Foreground altitude is 5325 m

Photograph courtesy of Lonnie Thompson
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Remote Sensing of Snow Cover Thickness from
Passive Microwave Radiometers

• Nimbus 7/SMMR
• Uses two horizontally polarized microwave
  frequencies (18 and 37 GHz)
• snow scatters less at the lower frequency (longer
  wavelength)
• the thicker the snow the greater the difference
  in brightness temperature between 18 and 37 GHz
• Dz 1.59Tb(18 GHz) Tb(37 GHz)
• where
• z snow thickness in cm
• restricted to ice-free land with snow thickness 5
  z 70 cm

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Monthly Average Snow Thickness from Nimbus 7 SMMR
70 cm
55 cm
40 cm
25 cm
10 cm
4 cm
March 1986
February 1986
From Parkinson, C. L., 1997 Earth from Above
32
Monthly Average Snow Thickness from Nimbus 7 SMMR
70 cm
55 cm
40 cm
25 cm
10 cm
4 cm
April 1986
May 1986
From Parkinson, C. L., 1997 Earth from Above
33
Location Map for North Polar Region
From Parkinson, C. L., 1997 Earth from Above
34
Monthly Average Snow Thickness from Nimbus 7 SMMR
70 cm
55 cm
40 cm
25 cm
10 cm
4 cm
February 1979
February 1981
From Parkinson, C. L., 1997 Earth from Above
35
Remote Sensing of Snow Cover from Shortwave
Infrared Radiometers

• NOAA/AVHRR-3
• Uses reflectance at 1.6 µm where snow and ice
  absorb solar radiation much greater than water or
  vegetation
• Advantage
• high spatial resolution (4 km GAC, 1.1 km LAC)
• Disadvantage
• affected by cloud cover
• observations possible only at night
• difficult to detect snow in deep forests
• Terra/MODIS
• Uses reflectance at 1.6 µm
• Higher spatial resolution of AVHRR (global at 1
  km)
• Makes use of better cloud mask for distinguishing
  clouds from snow and land surfaces (and shadows)

36
MODIS Snow Cover Compared to Historical Snow
Record
March 5-12, 2000
(1966-present) March Average February
Average Cloud