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Investigation:

LC-07 (Melack / Novo / Forsberg)

LBA Dataset ID:

LC07_SMMR_INUNDATED_AREA

Originator(s):

1. HAMILTON, S.K.
2. SIPPEL, S.J.
      3. MELACK, J.M.

Point(s) of Contact:

ORNL DAAC User Services Office Oak Ridge National Laboratory Oak Ridge, Tennessee 37 (ornldaac@ornl.gov)

Dataset Abstract:

Passive microwave analysis of inundated area. Multi-scale analysis of inundation and wetland vegetation with microwave and optical remote sensing in the Amazon Basin Collaborative activities conducted at UCSB and INPE focused on analysis of basin-scale optical and microwave data to characterize inundation and wetland vegetation, development of new interferometric and polarimetric synthetic aperture radar (SAR) techniques for examination of floodplains, and coordination and execution of a basin-wide airborne campaign to acquire videographic and laser altimetry data over wetlands and other LBA sites. Using the methods and algorithms that we have developed for determining flooded area with the 37 GHZ polarization difference observed by the Scanning Multichannel Microwave Radiometer, we have completed a monthly time series for seven years of inundation area for the central Amazon and Llanos de Mojos. The high and low water acquisitions of JERS SAR coverage of almost the whole Amazon Basin offers us a rich dataset; we have applied INPE's segmentation algorithms to conduct of polygon-based classification of wetlands using the JERS data. Further, we have developed a method for classifying and mapping floodplain habitats by linking multi-date SAR imagery with river stage records, incorporating information on both vegetation structure and inundation periodicity, and applied the method to sites in the central Amazon. In addition, we have demonstrated that interferometric SAR is capable of measuring subtle changes in water level in regions with inundated vegetation. Using SIR-C data from the central Amazon, we were able to determine 2 to 9 cm/day changes in water level in hundreds of floodplain lakes. Recent analyses of the mainstem Amazon floodplain based on Landsat Thematic Mapper images indicate considerable landscape heterogeneity. Upstream reaches are dominated by forests, which transition through the middle reaches to lower reaches dominated by macrophytes. By combining field measurements of methane emissions with our analyses of inundation and vegetation, we calculate a regional estimate of methane emission from the central Amazon of about 1.8 Tg C per year. Satellite observations of passive microwave emission have been analyzed to determine inundation patterns in the major floodplains of South America, including the fringing floodplain of the Amazon River and the savanna floodplains of the upper Madeira River (Llanos de Moxos, Bolivia). Passive microwave remote sensing can reveal the presence of surface water despite cloud and vegetative cover. We have developed methods to determine flooded area from the 37 GHz polarization difference observed by the Scanning Multichannel Microwave Radiometer (SMMR) and the Special Sensor Microwave Imager (SSMI). These systems offer coarse spatial resolution (ca. 25 km pixels) but frequent temporal coverage (ca. weekly). Typically, we estimate inundation separately for subregions using mixing models to account for major landscape units with distinctive microwave emission characteristics. Our methods require auxiliary information on river stage and open water area in lakes, obtained from synthetic aperture radar or optical imagery.

Beginning Date:

1978-12-01

Ending Date:

1987-08-31

Metadata Last Updated on:

2011-12-20

Data Status:

Archived

Access Constraints:

PUBLIC

Data Center URL:

http://daac.ornl.gov/

Distribution Contact(s):

ORNL DAAC User Services Office Oak Ridge National Laboratory Oak Ridge, Tennessee 37 (ornldaac@ornl.gov)

Access Instructions:

PUBLIC

Data Access:

IMPORTANT: The LBA-ECO Project website is no longer being supported. Links to external websites may be inactive. Final data products from the LBA project can be found at the ORNL DAAC. Please follow the fair use guidelines found in the dataset documentation when using or citing LBA data.
Datafile(s):

LBA-ECO LC-07 Monthly Inundated Areas, Amazon, Orinoco and Pantanal Basins: 1978-1987:  http://daac.ornl.gov/cgi-bin/dsviewer.pl?ds_id=1051

Documentation/Other Supporting Documents:

LBA-ECO LC-07 Monthly Inundated Areas, Amazon, Orinoco and Pantanal Basins: 1978-1987:  http://daac.ornl.gov/LBA/guides/LC07_SMMR_Inundated_Area.html

Citation Information - Other Details:

Hamilton, S.K., S.J. Sippel, and J.M. Melack. 2011. LBA-ECO LC-07 Monthly Inundated Areas, Amazon, Orinoco and Pantanal Basins: 1978-1987. Data set. Available on-line [http://daac.ornl.gov] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A. doi:10.3334/ORNLDAAC/1051

Keywords - Theme:

Parameter Topic Term Source Sensor
LAND COVER LAND SURFACE LAND USE/LAND COVER NIMBUS-7 SMMR (SCANNING MULTICHANNEL MICROWAVE RADIOMETER)

Uncontrolled Theme Keyword(s):  AMAZON, BANANAL, FLOODING, FLOODPLAIN, INUNDATION, JURUA, MADEIRA, OPEN WATER, ORINOCO, PANTANAL, PURUS, WETLAND, WETLANDS

Keywords - Place (with associated coordinates):

Region
(click to view profile)
Site
(click to view profile)
North South East West
  AMAZON BASIN 10.00000 -21.00000 -35.00000 -80.00000

Related Publication(s):

Hamilton, S.K., S.J. Sippel, and J.M. Melack. 2002. Comparison of inundation patterns among major South American floodplains. Journal of Geophysical Research-Atmospheres, 107(D20):Article-8038.

Hamilton, S.K., Sippel, S.J. and Melack, J.M. 2004. Seasonal inundation patterns in two large savanna floodplains of South America: the Llanos de Moxos (Bolivia) and the Llanos del Orinoco (Venezuela and Colombia), Hydrological Processes, 18(11):2103-2116.

Hamilton, S.K., Sippel, S.J., and Melack, J.M. 1996. Inundation patterns in the Pantanal wetland of South America determined from passive microwave remote sensing. Archiv für Hydrobiologie, 137(1):1-23.

Sippel, S.J., Hamilton, S.K., Melack, J.M. and Choudhury, B.J. 1994. Determination of inundation area in the Amazon River floodplain using the SMMR 37 GHz polarization difference. Remote Sensing of Environment 48:70-76.

Sippel, S.J., Hamilton, S.K., Melack, J.M. and Novo, E.M.M. 1998. Passive microwave observations of inundation area and the area/stage relation in the Amazon River floodplain. International Journal of Remote Sensing, 19(16):3055-3074.

Sippel, S.J., S.K. Hamilton and J.M. Melack. 1991. Inundation area and morphometry of lakes on the Amazon River floodplain, Brazil. Archiv fur Hydrobiologie 123(4):385-400.

Data Characteristics (Entity and Attribute Overview):

Data Characteristics:

Data are provided in several formats and are organized in subdirectories according to format:


/data/csv contains comma-delimited files formatted per ORNL DAAC archive specifications


/data/xls contains the data as Microsoft Excel spreadsheets -- some added value and formatting would be lost in the conversion to ASCII so the Excel spreadsheets are provided for the user's convenience


/data/evf contains vector files for the region bounds


/comp/ contains images/pictures in jpeg (.jpg) format that the user may find helpful





Acronyms:


ow = open water


fp = floodplain


SMMR = Scanning Multichannel Microwave Radiometer


AT = Delta Temperature


Data Application and Derivation:

Data Application:


This data set may be applied to modeling the monthly inundation to spread the two-season wetland habitat classification over 12 months. This spatial time series of flooding may be used to compare river-gauge based measures of flooding or to model the relationship between river stage and area inundated.





Data Derivation:


This data set was derived from SMMR image data. [Excerpt from p.71, Sippel, 1994] The SMMR data presented here are drawn from the global data set of 37 GHz AT observations that was originally studied by Choudhury (1989).

Quality Assessment (Data Quality Attribute Accuracy Report):

Quality Assessment:

Grid cells are 0.25 degrees x 0.25 degrees. One value is reported for each grid cell. An area this size can contain multiple habitats.





[Excerpts from Sippel, 1994, p.74]





No seasonal pattern is evident in individual grid cells composed entirely of

upland forest, which usually ranged in AT from 4 K to

6 K. The lack of a strong effect of local rainfall may be

explained partly by the screening procedure, which

eliminated extreme AT values within a particular month

and thus resulted in monthly AT values that reflect

gradual seasonal changes, rather than ephemeral effects

such as saturation of soils by rainfall.





It is more likely that local rainfall explains the

fluctuations in AT on the rising limb of the river hydrograph.

The differences in timing between the fluctuations

at our study area and at Manaus may reflect the

high spatial and temporal variability of rainfall in the

area (Ribeiro and Adis, 1984). Local rainfall could increase

AT by saturating soils and forming pools of water

on the land surface, although the effect of wet soils on

AT decreases exponentially with increasing vegetation

density (Choudhury, 1989). Increased atmospheric water

associated with heavy rainfall is known to have the

opposite effect, decreasing AT by 2-3 K because of

scattering and absorption of microwave radiation (Choudhury,

1989). These two phenomena may counteract

each other to some extent, and at this time it is difficult

to identify which one causes the fluctuations in AT.

We tested the performance of the low-water mixing

model [Eq. (1)] by using it to calculate the fractional

area of open water at bankfull stage (12.5 m). The AT obs

for months in which the river stage was close to bankfull

(between 10 m and 12.5 m) is 7.4 + 0.3 K (mean + a,

N= 10), This mean AT obs yields a fractional open-water

area of 6.1% using Eq. (1). The open-water area determined

from SLAR images is 6.6%. This good agreement

between the low-water mixing model and the SLAR

data indicates that our use of 60 K for the AT of open

water and 4 K for the AT of nonflooded land (upland

forest and vegetated floodplain) is reasonable. During

the dry season, as exposed mud and sand banks that

lack vegetation become more extensive, the validity of

the low-water mixing model is difficult to evaluate. Mud

banks tend to be colonized quickly by herbaceous plants

upon emergence, which would bring their AT closer to

that of the vegetated floodplain (4 K).

Process Description:

Data Acquisition Materials and Methods:

Flooding extent was measured from SMMR image data.


[Excerpt from p.71, Sippel, 1994]


For the study of land surface features, the effects of atmospheric variability

can be minimized by calculating the difference

between vertically and horizontally polarized brightness

temperatures at the 37 GHz frequency. We will hereafter

use AT to refer to the 37 GHz polarization difference

observed by a passive microwave radiometer at satellite

altitude.





These data were collected from December 1978 to August 1987.





The polarization difference at the 37 GHz frequency

provides a sensitive indicator of the presence of surface

water (Choudhury, 1991). The lowest AT (ca. 4 K or

less for SMMR) is observed for nonflooded land covered

with dense vegetation. Perennial tropical savannas lacking

surface flooding show SMMR AT around 5-7 K

throughout the year (Justice et al., 1989). Higher SMMR

AT values are observed for more sparsely vegetated

land; the most barren deserts show AT as high as 30 K.

The SMMR AT for calm standing water is ca. 60 K.

Water-saturated, exposed soils would show a similar AT

if the soil surface were very smooth, but lower values

are typically observed because of the roughness of soil

surfaces. Increasing surface roughness, whether as topographic

variation on land or as waves on water surfaces,

decreases AT. The observed seasonal variation in AT for South

American floodplains reflects seasonal changes in inundation

area rather than vegetation water content.





The SMMR data presented here are drawn from the global

data set of 37 GHz AT observations that was originally

studied by Choudhury (1989). This data set uses the

daytime SMMR 37 GHz brightness temperatures, which

have been calibrated and remapped into 0.25 degree x 0.25 degree

grid cells on a linear latitude / longitude projection. After

calculation of AT for each grid cell, the AT observations

were ranked within each month and the second lowest

value (usually out of four) was selected. The purpose of

this screening was to eliminate outlying values that

might have resulted from particularly dense cloud cover

or temporary saturation of soils after heavy rainfall.





References:

Choudhary, B.J. 1989. Monitoring global land surface using Nimbus-7 37 GHz data: theory and examples. International Journal of Remote Sensing 10: 1579-1605.





Choudhary, B.J. 1991. Passive microwave remote sensing contribution to hydrological variables. Surveys in Geophysics. 13: 63-84.





Hamilton, S.K., S.J. Sippel, and J.M. Melack. 1996. Inundation patterns in the Pantanal wetland of South America determined from passive microwave remote sensing. Archiv fur Hydrobiologie, 137 (1):1-23.




Hamilton, S.K., Sippel, S.J. and Melack, J.M. 2002. Comparison of Inundation Patterns among major South American Floodplains. Journal of Geophysical Research.





Hamilton, S.K., S.J. Sippel, and J.M. Melack. 2004. Seasonal inundation patterns in two large savanna floodplains of South America: the Llanos de Moxos (Bolivia) and the Llanos del Orinoco (Venezuela and Colombia). Hydrological Processes.





Justice, C.O., J.R.G. Townsend and B.J. Choudhary. 1989. Comparison of AVHRR and SMMR data for monitoring vegetation phenology on a continental scale. International Journal of Remote Sensing 10: 1607-1632.





Ribeiro, M.N.G. and J. Adis. 1984. Local rainfall variability-a potential bias for bioecological studies in the central Amazon. Acta Amazonica 14: 159-174.





Sippel, S.J., Hamilton,S.K. and Melack, J.M. 1991. Inundation area and morphometry of lakes on the Amazon River floodplain, Brazil. Arch. Hydrobiol. 123: 385-400.





Sippel, S.J., S.K. Hamilton, J.M. Melack, and B.J. Choudhary. 1994. Determination of inundation area in the Amazon River floodplain using the SMMR 37 GHz polarization difference. Remote Sensing of Environment 48:70-76.





Sippel, S.J., S.K. Hamilton, J.M. Melack, and E.M.M. Novo. 1998. Passive microwave observations of inundation area and the area/stage relation in the Amazon River floodplain. International Journal of Remote Sensing, 19(16):3055-3074.






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