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Investigation:

CD-04 (Goulden / Rocha)

LBA Dataset ID:

CD04_SOILMOISTURE

Originator(s):

1. GOULDEN, M.L.
2. MILLER, S.D.
      3. DA ROCHA, H.R.

Point(s) of Contact:

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

Dataset Abstract:

This data set reports continuous high-resolution frequency-domain reflectometry measurements of soil moisture to 10 m depth and precipitation data near each of the two towers located at the km 83 tower site (logged forest site) in the Tapajos National Forest in the state of Para, Brazil. Measurements were made during 2002 and 2003. Soil moisture and precipitation data are provided in two comma-delimited ASCII files. The first tower was installed in an intact forest area at this site in June 2000 (the \'intact\' tower) and instrumented for eddy flux and micrometerological measurements and operated 15 months prior to any logging in the area (Goulden et al., 2004; Miller et al., 2004; Rocha et al., 2004). In September 2001, the area adjacent to the tower was selectively logged (Bruno et al., 2006). The second tower (the �gap� tower) was installed and operating in June 2002, 400 m east of the intact tower. The gap tower was installed in the middle of a 50 m x 50 m log landing. Soil moisture measurements were made in 10 m deep vertical pits (1 x 1 m2) approximately 20 m from the micrometerological tower sites in undisturbed forest patches. Reflectometers were inserted horizontally into shaft walls at 0.15, 0.30, 0.60, 1, 2, 3, 4, 6, 8, and 10 meters beneath the surface. These data were used to determine how soil moisture varies on diel, seasonal and multi-year timescales and to better understand the quantitative and mechanistic relationships between soil moisture and forest evapotranspiration.

Beginning Date:

2001-12-31

Ending Date:

2003-12-17

Metadata Last Updated on:

2010-07-22

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 CD-04 Soil Moisture Data, km 83 Tower Site, Tapajos National Forest, Brazil:  http://daac.ornl.gov/cgi-bin/dsviewer.pl?ds_id=979

Documentation/Other Supporting Documents:

LBA-ECO CD-04 Soil Moisture Data, km 83 Tower Site, Tapajos National Forest, Brazil:  http://daac.ornl.gov/LBA/guides/CD04_Soil_Moisture_Km83.html

Citation Information - Other Details:

Goulden, M.L. S.D. Miller and H.R. da Rocha. 2010. LBA-ECO CD-04 Soil Moisture Data, km 83 Tower Site, Tapajos National Forest, Brazil. 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/979

Keywords - Theme:

Parameter Topic Term Source Sensor
PRECIPITATION AMOUNT ATMOSPHERE PRECIPITATION TOWER RAIN GAUGE
SOIL MOISTURE/WATER CONTENT LAND SURFACE SOILS FIELD INVESTIGATION TDR (TIME DOMAIN REFLECTOMETRY PROBE)

Uncontrolled Theme Keyword(s):  GAP TOWER, INTACT TOWER, KILOMETER 83, LOGGED SITE, PRECIPITATION, SOIL MOISTURE, TAPAJOS FOREST

Keywords - Place (with associated coordinates):

Region
(click to view profile)
Site
(click to view profile)
North South East West
Pará Western (Santarém) km 83 Logged Forest Tower Site -3.01700 -3.01700 -54.97070 -54.97070

Related Publication(s):

Bruno, R.D., H.R. da Rocha, H.C. de Freitas, M.L. Goulden, and S.D. Miller. 2006. Soil moisture dynamics in an eastern Amazonian tropical forest. Hydrological Processes 20(12):2477-2489.

da Rocha, H.R., M.L. Goulden, S.D. Miller, M.C. Menton, L.D.V.O. Pinto, H.C. de Freitas, and A.M.E.S. Figueira. 2004. Seasonality of water and heat fluxes over a tropical forest in eastern Amazonia. Ecological Applications 14(4):S22.

Data Characteristics (Entity and Attribute Overview):

Data Characteristics:

Data are provided in two comma-delimited ASCII files.

CD04_TNF_KM83_Soil_Moisture.csv contains soil moisture data (March 2002 - December 2003) and rainfall (January 2002 through December 2003) measurements from the km 83 site intact tower location.



CD04_TNF_KM83_Gap_Soil_Moisture.csv contains soil moisture data and rainfall measurements (February 2002 - December 2003) from the km 83 site gap tower location.



File name: CD04_TNF_KM83_Soil_Moisture.csv



Column number Column heading Units/format Description

1 Date yyyy/mm/dd Sample date

2 Hour HH:MM Time at the start of the sampling period 24 hour clock: time in local time which is GMT -4 hours

3 Exp_Day Decimal day since Jan 1 2000

( 1= midnight January 1 2000)

4 Rainfall mm Total rainfall in millimeters (mm) recorded over the 30-minute sampling period

5 VWC_15cm m3/m3 Volumetric water content at 15 cm depth

6 VWC_30cm m3/m3 Volumetric water content at 30 cm depth

7 VWC_60cm m3/m3 Volumetric water content at 60 cm depth

8 VWC_100cm m3/m3 Volumetric water content at 100 cm depth

9 VWC_200cm m3/m3 Volumetric water content at 200 cm depth

10 VWC_300cm m3/m3 Volumetric water content at 300 cm depth

11 VWC_400cm m3/m3 Volumetric water content at 400 cm depth

12 VWC_600cm m3/m3 Volumetric water content at 600 cm depth

13 VWC_800cm m3/m3 Volumetric water content at 800 cm depth

14 VWC_1000cm m3/m3 Volumetric water content at 1000 cm depth

missing data are represented by -999





Example data records:





Date,Hour,Exp_Day,Rainfall,VWC_15cm,VWC_30cm,VWC_60cm,VWC_100cm,VWC_200cm,VWC_300cm,

VWC_400cm,VWC_600cm,VWC_800cm,VWC_1000cm,



2001/12/31, 00:00,731,0.0000,-999,-999,-999,-999,-999,-999,-999,-999,-999,-999,

2001/12/31, 00:30,731.020813,-999,-999,-999,-999,-999,-999,-999,-999,-999,-999,-999,

...

2003/05/25, 03:00,1241.125,0.0000,0.5039,0.4986,0.4895,0.4890,0.4882,0.4789,0.4867,0.5118,0.5070,0.5301,

2003/05/25, 03:30,1241.145874,0.0000,0.5040,0.4987,0.4894,0.4890,0.4881,0.4789,0.4867,0.5118,0.5071,0.5300,

2003/05/25, 04:00,1241.166626,0.0000,0.5040,0.4986,0.4894,0.4890,0.4881,0.4789,0.4867,0.5118,0.5071,0.5299,

...

2003/12/17, 23:00,1447.958374,0.0000,0.4855,0.4771,0.4609,0.4548,0.4604,0.4666,0.4572,0.4692,-999,0.5014,

2003/12/17, 23:30,1447.979126,0.0000,0.4855,0.4771,0.4608,0.4549,0.4604,0.4667,0.4567,0.4692,-999,0.5015,









CD04_TNF_KM83_Gap_Soil_Moisture.csv



Column number Column heading Units/format Description

1 Exp_Day Decimal day since Jan 1 2000 ( 1= midnight January 1 2000)

2 Date yyyy/mm/dd Sample date

3 Hour HH:MM Time at the start of the sampling period 24 hour clock: time in local time which is GMT -4 hours

4 Rainfall mm Total rainfall in millimeters (mm) recorded over the 60-minute sampling period

5 VWC_15cm m3/m3 Volumetric water content at 15 cm depth

6 VWC_30cm m3/m3 Volumetric water content at 30 cm depth

7 VWC_60cm m3/m3 Volumetric water content at 60 cm depth

8 VWC_100cm m3/m3 Volumetric water content at 100 cm depth

9 VWC_200cm m3/m3 Volumetric water content at 200 cm depth

10 VWC_300cm m3/m3 Volumetric water content at 300 cm depth

11 VWC_400cm m3/m3 Volumetric water content at 400 cm depth

12 VWC_600cm m3/m3 Volumetric water content at 600 cm depth

13 VWC_800cm m3/m3 Volumetric water content at 800 cm depth

14 VWC_1000cm m3/m3 Volumetric water content at 1000 cm depth



missing data are represented by -999



Example data records:



Date,Hour,Exp_Day,Rainfall,VWC_15cm,VWC_30cm,VWC_60cm,VWC_100cm,VWC_200cm,VWC_300cm,

VWC_400cm,VWC_600cm,VWC_800cm,VWC_1000cm,



2002/02/28,17:00,790.708374,0.0000,0.5613,0.5376,0.5006,0.5340,0.5436,0.4864,0.5276,0.5595,0.5672,0.5559,

2002/02/28,18:00,790.75,0.0000,0.5606,0.5369,0.5004,0.5345,0.5426,0.4856,0.5259,0.5602,0.5674,0.5558,

...

2002/11/12,10:00,1047.416626,0.0000,0.5500,0.5406,0.5029,0.5268,0.5406,0.4895,0.4833,0.5583,0.5699,0.5636,

2002/11/12,11:00,1047.458252,0.0000,0.5499,0.5404,0.5027,0.5266,0.5406,0.4894,0.4833,0.5583,0.5699,0.5635,

2002/11/12,12:00,1047.5,0.0000,0.5497,0.5403,0.5025,0.5265,0.5405,0.4894,0.4834,0.5583,0.5699,0.5636,

...

2003/12/16,19:00,1446.791626,-999,-999,-999,-999,-999,-999,-999,-999,-999,-999,-999,

2003/12/16,20:00,1446.833252,-999,-999,-999,-999,-999,-999,-999,-999,-999,-999,-999,







Data Application and Derivation:

Effects of predicted climate changes in tropical regions are poorly understood. Scenarios for alterations of the Amazonian vegetation in the coming decades point to a possible shift to a new equilibrium with \'savanaisation\' in some regions (Oyama and Nobre 2003), or in more extreme cases the possible collapse of forest faced with a drier climate (Cox et al. 2000). These scenarios are based on mechanistic models of ecosystem function and land-atmosphere exchange that contain many assumptions about the relationships between drought, soil water, plant uptake and plant physiology (e.g. Sellers et al. 1996). These scenarios of the future of the Amazon region can be improved by accurate measures of the forest response to drought. The data we report can be used to test, validate and calibrate models of the Amazonian land-atmosphere exchange.

Quality Assessment (Data Quality Attribute Accuracy Report):

Quality Assessment:

These data have been carefully reviewed and there are no known problems. We caution the data user that we sampled single profiles at each location and that spatial heterogeneity may confound the quantitative relationships between soil measurements and the entire forest\'s hydrological budget.



Site specific calibrations for the CS615-G probes were developed using 10 cm x 10 cm x 40 cm soil blocks collected at 6 cm (2 samples) and 76 cm (1 sample) depth (Bruno et al. 2006). Calibration data were collected continuously comparing the sensor signal with the soil water content determined by gravimetry throughout a drying cycle. Calibration curves were fit using a sigmoidal function that constrained the asymptotic lower (dry soil) and upper (saturation) limits. The use of a site specific calibration resulted in calculated water contents that were as much as 40 percent greater than those that would have been calculated from a generic cubic polynomial for clayey soil (Campbell Scientific 1996).

Process Description:

Data Acquisition Materials and Methods:

This study was conducted at the LBA km 83 research site (logged forest site) in the Tapajos National Forest in the state of Para (Bruno et al., 2006). The site was located on flat, upland terrain. The soil at the site was a yellow distrophic latosol (a clay Oxisol). The vegetation was dense, tropical, humid forest with a canopy height of 35-40 m.



The first tower was installed in an intact forest area at this site in June 2000 (the \'intact\' tower) and instrumented for eddy flux and micrometerological measurements and operating 15 months prior to any logging in the area In September 2001 the area along the tower fetch was selectively logged with 2-3 trees per hectare removed. Soil moisture measurements were made in a soil pit approximately 20 m southeast of the micrometerological tower site in an undisturbed patch within the selectively logged area. The second tower (the \'gap\' tower) was installed and operating in June 2002, 400 m east of the intact tower. The gap tower was installed in the middle of a 50 m x 50 m log landing. Soil moisture measurements were made in a 10 m deep vertical pits (1 x 1 m2) approximately 20 m from the micrometerological tower sites in undisturbed forest patches. Reflectometers were inserted horizontally into shaft walls at 0.15, 0.30, 0.60, 1, 2, 3, 4, 6, 8, and 10 meters beneath the surface.





Soil water content

Soil water content was estimated using transit time (Tau) measured with water content reflectometers (CS615-G, Campbell Scientific, Logan , Utah USA) installed in a 10 m deep vertical pit (1 x 1 m2). Reflectometers were inserted horizontally into shaft walls at 0.15, 0.30, 0.60, 1, 2, 3, 4, 6, 8, and 10 meters beneath the surface. Two sensors were installed at each depth and the volumetric water content at each depth was averaged, except at the 8 meter depth where only one sensor was installed. The CS615-G is a bistable mutlivibrator connected to two stainless steel rods (30 cm long, 3.2 mm diameter and 32 mm spaced). The output signal (period tau) ranges from 0.7 to 1.6 ms and varies with the medium dielectric constant and therefore the soil moisture. The soil moisture data were recorded at 0.5 Hz throughout the study. The intact tower data are reported on a 30-minute basis and the gap tower data are reported on a 60-minute basis.



Rainfall

Rainfall (mm) was measured at 64 meters on the towers and totaled over the 30 or 60-minute sampling period (TE525 Texas Electronics, Dallas, Texas, USA). During the 3 year sampling period on the intact forest tower, between January 2001 and December 2003, gaps in rain data occurred in May 2002, November 2002, and May 2003. The intact tower data are reported on a 30-minute basis and the gap tower data are reported on a 60-minute basis.

References:

Brun, RD 2004. Variabilidade observada da umidade do solo em Floresta Tropical e Cerrado. Master\'s Thesis. Institute of Astronomy, Geophysics and Atmospheric Sciences (IAG), University of Sao Paulo, Sao Paulo Brazil.



Bruno, R.D., H.R. da Rocha, H.C. de Freitas, M.L. Goulden, and S.D. Miller. 2006. Soil moisture dynamics in an eastern Amazonian tropical forest. Hydrological Processes 20(12):2477-2489. doi:10.1002/hyp.6211



da Rocha, H.R., M.L. Goulden, S.D. Miller, M.C. Menton, L.D.V.O. Pinto, H.C. de Freitas, and A.M.E.S. Figueira. 2004. Seasonality of water and heat fluxes over a tropical forest in eastern Amazonia. Ecological Applications 14(4):S22. doi:10.1890/02-6001



Campbell Scientific 1996. CS615 Water Content Reflectometer- Instruction Manual. Version 8221-07, Revised 10/1996. Campbell Scientific Inc. Utah USA.



Cox PM, Betts RA, Jones CD, Spall SA, and Totterdell IJ. 2000. Acceleration of global warming due to carbon-cycle feedbacks in a coupled climate model. Nature 408: 184-187. doi:10.1038/35041539



Oyama MD and Nobre CA. 2003. A new climate-vegetation equilibrium state for tropical South America. Geophysical Research Letters doi:10.1029/2003GL018600



Sellers PJ, Randall DA, Collatz GJ, et al. 1996. A revised land surface parameterization (SiB2) for atmospheric GCMs. Part I: Model formulation. Journal of Climate 9: 676-705. doi:10.1175/1520-0442(1996)009<0676:ARLSPF>2.0.CO;2







Related Publications



�Bruno, R.D., H.R. da Rocha, H.C. de Freitas, M.L. Goulden, and S.D. Miller. 2006. Soil moisture dynamics in an eastern Amazonian tropical forest. Hydrological Processes 20(12):2477-2489. doi:10.1002/hyp.6211

�da Rocha, H.R., M.L. Goulden, S.D. Miller, M.C. Menton, L.D.V.O. Pinto, H.C. de Freitas, and A.M.E.S. Figueira. 2004. Seasonality of water and heat fluxes over a tropical forest in eastern Amazonia. Ecological Applications 14(4):S22. doi:10.1890/02-6001

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