Growing Season Energy and CO2 Fluxes over a Larch Forest Tundra Ecosystem in Siberia

Summary

Eddy covariance measurements of carbon and energy fluxes over a larch forest tundra ecosystem near the latitudinal treeline were collected near Cherskii, Siberia, in summer 2001. A series of basic micrometeorological variables were also measured, including vertical profiles of air temperature and relative humidity, wind speed, net radiation, albedo, incoming and outgoing long-wave radiation, wind direction, and precipitation. At each, site four soil micro sites were also selected to measure soil temperature at five depths, soil heat flux, and soil moisture.

This research was conducted as part of the Russian-American Initiative on Shelf-Land Environments in the Arctic (RAISE) and was funded by the Arctic System Sciences (ARCSS) Program, grant number OPP-0097439.

Data are available for ordering through NCAR.

Citing These Data:

Randerson, J. 2003. Growing season energy and CO2 fluxes over a larch forest tundra ecosystem in Siberia. Boulder, CO: National Center for Atmospheric Reasearch ARCSS Data Archive.

Overview Table

Table of Contents

1. Contacts:

Investigator(s) Name and Title:

Technical Contact:

2. Detailed Data Description:

Format:

The data are available as a tab-delimited ASCII text file.

File Size:

The file is 403 KB.

Spatial Coverage:

Data were collected near Cherskii, Siberia, at 69.0 N, 161.0 E. The sites are representative of the coastal plain of Northeast Siberia, a one million square kilometer area of carbon-rich loess sediments that accumulated carbon during the Pleistocene and have gradually been releasing this carbon to the atmosphere and ocean through melting of previously frozen soils during the Holocene.

Temporal Coverage:

Data were collected every 30 minutes from 2001-07-14 to 2001-08-10.

Parameters or Variables:

Parameter Description:

Parameters included eddy covariance measurements of carbon and energy fluxes over a larch forest-tundra ecosystem. A series of basic micrometeorological variables were also measured, including vertical profiles of air temperature and relative humidity, wind speed, net radiation, albedo, incoming and outgoing long wave radiation, wind direction, and precipitation. At each site, four soil micro sites were also selected to measure soil temperature (at five depths: 1, 2, 5, 10 and 20 cm), soil heat flux (one probe at 7 cm) and soil moisture (one probe at 7 cm).

The column headings are in two rows. The first row contains the abbreviation of the measured parameter. The second row indicates the description and units of the parameter in the first row.

Unit of Measurement:

Sensible heat flux: W/m²
Latent heat flux: W/m²
CO2 flux: Umol/m²/s
Net radiation: W/m²
CO2 concentration: ppm
Soil temperature: ºCelsius
Soil heat flux: W/m²
Air temperature: ºCelsius
Downward shortwave radiation: W/m2
Upward shortwave radiation: W/m2
Downward longwave radiation: W/m2
Upward longwave radiation: W/m2
Photosynthetically Active Radiation (PAR): Umol/m²/s
Wind speed: m/s
Atmospheric pressure: mb

Sample Data Record:

Date	H (3.1m)	LE (3.1m)	Fc (3.1)	Rn (7.9m)	u* (3.1m)	PCO2 (3.1m)	Soil11 (1cm)	Soil12 (2cm)	soil13 (5cm)	Soil14(10cm)	Soil15(20cm)	Soil21 (1cm)	Soil22 (2cm)	soil23 (5cm)	Soil24(10cm)	Soil25(20cm)	Soil31 (1cm)	Soil32 (2cm)	soil33 (5cm)	Soil34(10cm)	Soil35(20cm)	Soil41 (1cm)	Soil42 (2cm)	soil43 (5cm)	Soil44(10cm)	Soil45(20cm)	Soil51 (1cm)	Soil52 (2cm)	soil53 (5cm)	Soil54(10cm)	Soil55(20cm)	SHFP1 (7cm)	SHFP2 (7cm)	SHFP3(7cm)	SHFP4(7cm)	SHFP5(7cm)(W/m2)	TD1(9.1m)	RH1(9.1m)	TD2(5.3m)	RH2(5.3m)	TD3(2.1m)	RH3(2.1m)	Downk(8m)	Upk(8m)	Downl(8.3)	upl(8.3m)	Pyr(9.3m)	PAR(9.3m)	WS(10m)	WD(10m)	WS(2.4m)	P 
	Sensible heat flux(W/m2)	Latent heat flux(W/m2)	CO2 flux (umol/m2/s)	Net Radiation(W/m2)	ustar(m/s)	CO2 concentration (ppm)	Soil temperature at site 1	Soil temperature at site 1	Soil temperature at site 1	Soil temperature at site 1	Soil temperature at site 1	Soil temperature at site 2	Soil temperature at site 2	Soil temperature at site 2	Soil temperature at site 2	Soil temperature at site 2	Soil temperature at site 3	Soil temperature at site 3	Soil temperature at site 3	Soil temperature at site 3	Soil temperature at site 3	Soil temperature at site 4	Soil temperature at site 4	Soil temperature at site 4	Soil temperature at site 4	Soil temperature at site 4	Soil temperature at site 5	Soil temperature at site 5	Soil temperature at site 5	Soil temperature at site 5	Soil temperature at site 5	Soil heat flux at Site 1(W/m2)	Soil heat flux at Site 2(W/m2)	Soil heat flux at Site 3(W/m2)	Soil heat flux at Site 4(W/m2)	Soil heat flux at Site 5	Air temperature	Relative humidity	Air temperature	Relative humidity	Air temperature	Relative humidity	Downward shortwave radiation (W/m2)	Upward shortwave radiation (W/m2)	Downward longwave radiation (W/m2)	Upward longwave radiation (W/m2)	Downward solar radiation (W/m2)	PAR(umol/m2/s)	Wind speed(m/s)	Wind direction(degree)	Wind speed (m/s)	Atmospheric pressure (mb)
7/14/2001 0:00	-70.536	15.661	1.899	-56.477	0.374	374.095	12.023	11.403	9.84	6.911	5.887	10.803	10.763	9.82	9.43	7.84	9.123	8.413	7.527	6.281	4.913	11.123	10.357	8.707	7.383	6.082	12.77	12.103	11.793	-6999	-6999	-8.617	-12.233	-16.507	-14.813	-14.66	19.243	45.373	18.997	45.34	18.35	48.443	-40.05	0	299	379.4	13.98	27	5.133	70.067	2.798	999
7/14/2001 0:30	-72.503	8.302	2.156	-55.33	0.357	374.085	11.63	11.04	9.537	6.827	5.868	10.503	10.463	9.643	9.29	7.797	8.81	8.14	7.323	6.182	4.889	10.75	10.06	8.5	7.3	6.065	12.477	11.81	11.56	-6999	-6999	-7.893	-10.793	-15.437	-13.603	-12.753	18.9	45.81	18.64	45.94	17.973	49.16	-45.507	0	299.067	379.5	10.603	22.25	4.952	69.41	2.702	999
7/14/2001 1:00	-73.331	15.96	2.263	-54.45	0.334	375.02	11.127	10.583	9.257	6.748	5.852	10.173	10.167	9.48	9.163	7.763	8.507	7.893	7.143	6.088	4.865	10.257	9.687	8.297	7.217	6.048	11.807	11.54	11.34	-6999	-6999	-7.3	-9.59	-14.47	-12.563	-11.183	18.597	44.91	18.313	45.15	17.59	48.677	-47.037	0	298.8	372.2	9.423	20.19	4.564	73.933	2.379	998.667

3. Data Access and Tools:

Data Access:

Data are available for ordering through NCAR.

4. Data Acquisition and Processing:

Sensor or Instrument Description:

Fluxes of sensible heat, water vapor, and carbon dioxide between the land surface and the atmosphere were measured using the eddy covariance technique. The eddy covariance system consisted of a 3D sonic anemometer (Solent RH, Gill Instruments, Lymington, UK) to measure vertical and horizontal wind speed and temperature fluctuation, and a CO2/H2O infrared gas analyzer (IRGA) (model 6262, LiCor Inc., Lincoln, NE, USA) to measure water vapor and carbon dioxide fluctuations at each site. The sampled air was pumped from the outlet side of the LiCor 6262 at approximately 6-7 L min^-1 within Bevaline tubing from an inlet immediately adjacent to the sonic anemometer. Raw data from the sonic anemometer and IRGA were collected continuously at 10 Hz and stored on a laptop computer.

A series of basic micrometeorological variables were also measured, including vertical profiles of air temperature and relative humidity, wind speed, net radiation, albedo, incoming and outgoing long-wave radiation, wind direction, and precipitation. At each site, four soil micro sites were also selected to measure soil temperature (at five depths: 1, 2, 5, 10 and 20 cm), soil heat flux (one probe at 7 cm) and soil moisture (one probe at 7 cm). The sensor configuration on the two towers is described in Table 1 of Isolating Vegetation and Soil Contributions to Energy and Carbon fluxes in Siberian Forest Tundra by Liu et al. Heat storage in the 7 cm layer above the soil heat flux was calculated using the combination method (Oke, 1987) using volume fractions of mineral, organic, and water content of the surface soil for calculating surface heat capacity (Chambers and Chapin, 2002).

Processing Algorithm:

Fluxes of sensible heat, latent heat, and CO2 were calculated using the 30-minute covariance of vertical wind velocity and temperature, water vapor density, and CO2 concentration. The wind vector was rotated to the plane where the mean vertical wind and the latitudinal wind were zero. The data series was detrended by subtracting a best-fit line from the data segment (Stull 1988). The time lags between the wind speed measurements and the measurements of the concentrations of CO2 and H2O were determined by maximizing the correlation between vertical wind speed and the two gases, CO2 and H2O (Goulden et al., 1996). Because the temperature obtained from the sonic anemometer is the buoyancy temperature, and because crosswind effects need to be considered (Kaimal and Finnigan, 1994; Kaimal and Gaynor, 1991; Schotanus et al., 1983), investigators converted the buoyancy flux derived directly from the sonic temperature to sensible heat flux, according to the formula proposed by Liu et al. (2001).

5. References and Related Publications:

Chambers, S.D. and F.S. Chapin. 2002. Fire effects on surface-atmosphere energy exchange in Alaskan black spruce ecosystems: Implications for feedbacks to regional climate. Journal of Geophysical Research 107: 8145 doi:10.1029/2001JD000530.

Goulden, M.L., J.W. Munger, S.M. Fan, D.C. Daube, and S.C. Wofsy. 1996. Measurements of carbon sequestration by long-term eddy covariance: methods and a critical evaluation of accuracy. Global Change Biology 2: 101.114.

Kaimal, J.C. and J.J. Finnigan. 1994. Atmospheric Boundary Layer Flow: Their Structure and Measurement. New York: Oxford University Press. 289p.

Kaimal, J.C. and J.E. Gaynor. 1991. Another look at sonic thermometry. Boundary-Layer Meteorology 56: 401-410.

Liu, H.P., G. Peters, and T. Foken. 2001. New equations for omnidirectional sonic temperature variance and buoyancy heat flux with a sonic anemometer. Boundary-Layer Meteorology 100: 459-468.

Liu, H.P., J. Henkelman, I. McHugh, J.T. Randerson, S. Davydov, F.S. Chapin III, and S.A. Zimov. 2003. Isolating vegetation and soil contributions to energy and carbon fluxes in Siberian forest tundra. Submitted to Ecosystems.

Oke, T.R. 1987. Boundary Layer Climates. Methuen.

Schotanus, P., F.T.M. Nieuwstadt, and H.A.R. De Bruin. 1983. Temperature measurement with a sonic anemometer and its application to heat and moisture fluctuations. Boundary-Layer Meteorology 26: 81-93.

Stull, R.B. 1988. An Introduction to Boundary Layer Meteorology. Dordreche: Kluwer Academic Publishers. 666 p.

6. Document Information:

Document Creation Date:

2003-08-05

Document URL:

http://data.eol.ucar.edu/codiac/dss/id=106.ARCSS114