2. Data Sources¶

In this course, we focus on the AmeriFlux datasets for analysis. The URAO dataset might also be used, so some knowledge of both will be helpful.

2.1. Period selection¶

Note

Raw observational data undergoing a large amount of processing prior to be used (e.g. calculation of fluxes using Eddy Covariance techniques). They are usually collected with preliminary, or even without, “cleaning”.

It is thus crucial to consider different aspects for different parameters:

cloud cover (e.g. this is important for the first plot)
vegetation state (e.g. are leaves on the trees?) (LAI (Leaf Area Index))
wind direction (e.g. does land cover type vary with wind direction?)
Check that most of the data are available.
Look carefully at the turbulent heat fluxes, i.e. small numbers of 30 min periods can be missing – that is ok

2.2. AmeriFlux¶

Tip

Become familiar with AmeriFlux website and data.

2.2.1. Sites for analysis¶

Group	Site Id	Name	Principal Investigator	Vegetation Abbreviation (IGBP)	Vegetation Description (IGBP)	Climate Class Abbreviation (Koeppen)	Climate Class Description (Koeppen)	Mean Average Precipitation (mm)	Mean Average Tempurature (degrees C)	Country	Latitude (degrees)	Longitude (degrees)	Elevation (m)	Years of Data
1	CA-Obs	Saskatchewan - Western Boreal, Mature Black Spruce	Andrew Black (andrew.black@ubc.ca)	ENF	Evergreen Needleleaf Forests	Dfc	Subarctic: severe winter, no dry season, cool summer	406	0.79	Canada	53.99	-105.12	628.94	1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
1	US-Blk	Black Hills	Tilden Meyers (Tilden.Meyers@noaa.gov)	ENF	Evergreen Needleleaf Forests	Dfb	Warm Summer Continental: significant precipitation in all seasons	574	6.23	USA	44.16	-103.65	1718	2004, 2005, 2006, 2007, 2008
2	US-MMS	Morgan Monroe State Forest	Kim Novick (knovick@indiana.edu)	DBF	Deciduous Broadleaf Forests	Cfa	Humid Subtropical: mild with no dry season, hot summer	1032	10.85	USA	39.32	-86.41	275	1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018
2	US-MOz	Missouri Ozark Site	Jeffrey Wood (woodjd@missouri.edu)	DBF	Deciduous Broadleaf Forests	Cfa	Humid Subtropical: mild with no dry season, hot summer	986	12.11	USA	38.74	-92.2	219.4	2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015
3	US-Dia	Diablo	Sonia Wharton (wharton4@llnl.gov)	GRA	Grasslands	Csa	Mediterranean: mild with dry, hot summer	265	15.6	USA	37.68	-121.53	323	2010, 2011, 2012
3	US-KUT	KUOM Turfgrass Field	Joe McFadden (mcfadden@ucsb.edu)	GRA	Grasslands	Dfa	Humid Continental: humid with severe winter, no dry season, hot summer	777	7.9	USA	44.99	-93.19	301	2005, 2006, 2007, 2008, 2009
4	CA-Qcu	Quebec - Eastern Boreal, Black Spruce/Jack Pine Cutover	Hank A. Margolis (Hank.Margolis@sbf.ulaval.ca)	ENF	Evergreen Needleleaf Forests	Dfc	Subarctic: severe winter, no dry season, cool summer	950	0.13	Canada	49.27	-74.04	392.3	2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
4	CA-Qfo	Quebec - Eastern Boreal, Mature Black Spruce	Hank A. Margolis (Hank.Margolis@sbf.ulaval.ca)	ENF	Evergreen Needleleaf Forests	Dfc	Subarctic: severe winter, no dry season, cool summer	962	-0.36	Canada	49.69	-74.34	382	2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
5	US-Slt	Silas Little- New Jersey	Ken Clark (kennethclark@fs.fed.us)	DBF	Deciduous Broadleaf Forests	Dfa	Humid Continental: humid with severe winter, no dry season, hot summer	1138	11.04	USA	39.91	-74.6	30	2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014
5	US-UMB	Univ. of Mich. Biological Station	Christopher Gough (cmgough@vcu.edu)	DBF	Deciduous Broadleaf Forests	Dfb	Warm Summer Continental: significant precipitation in all seasons	803	5.83	USA	45.56	-84.71	234	2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018
6	US-Br3	Brooks Field Site 11- Ames	Tim Parkin (parkin@nstl.gov)	CRO	Croplands	Dfa	Humid Continental: humid with severe winter, no dry season, hot summer	847	8.9	USA	41.97	-93.69	313	2005, 2006, 2007, 2008, 2009, 2010, 2011
6	US-Bo1	Bondville	Tilden Meyers (Tilden.Meyers@noaa.gov)	CRO	Croplands	Dfa	Humid Continental: humid with severe winter, no dry season, hot summer	991	11.02	USA	40.01	-88.29	219	1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008
7	US-NC1	NC_Clearcut	Asko Noormets (noormets@tamu.edu)	OSH	Open Shrublands	Cfa	Humid Subtropical: mild with no dry season, hot summer	1320	16.6	USA	35.81	-76.71	5	2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012
7	US-Whs	Walnut Gulch Lucky Hills Shrub	Russ Scott (russ.scott@ars.usda.gov)	OSH	Open Shrublands	Bsk	Steppe: warm winter	320	17.6	USA	31.74	-110.05	1370	2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018
8	US-SRG	Santa Rita Grassland	Russell Scott (russ.scott@ars.usda.gov)	GRA	Grasslands	Bsk	Steppe: warm winter	420	17	USA	31.79	-110.83	1291	2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018
8	US-Var	Vaira Ranch- Ione	Dennis Baldocchi (Baldocchi@berkeley.edu)	GRA	Grasslands	Csa	Mediterranean: mild with dry, hot summer	559	15.8	USA	38.41	-120.95	129	2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018
9	US-Bo2	Bondville (companion site)	Carl Bernacchi (bernacch@uiuc.edu)	CRO	Croplands	Dfa	Humid Continental: humid with severe winter, no dry season, hot summer	991	11.02	USA	40.01	-88.29	219	2004, 2005, 2006, 2007, 2008
9	US-Br1	Brooks Field Site 10- Ames	Tim Parkin (parkin@nstl.gov)	CRO	Croplands	Dfa	Humid Continental: humid with severe winter, no dry season, hot summer	842	8.95	USA	41.97	-93.69	313	2005, 2006, 2007, 2008, 2009, 2010, 2011
10	CA-TPD	Ontario - Turkey Point Mature Deciduous	Altaf Arain (arainm@mcmaster.ca)	DBF	Deciduous Broadleaf Forests	Dfb	Warm Summer Continental: significant precipitation in all seasons	1036	8	Canada	42.64	-80.56	260	2012, 2013, 2014, 2015, 2016, 2017
10	US-Oho	Oak Openings	Jiquan Chen (jqchen@msu.edu)	DBF	Deciduous Broadleaf Forests	Dfa	Humid Continental: humid with severe winter, no dry season, hot summer	849	10.1	USA	41.55	-83.84	230	2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013

Tip

Refer to AmeriFlux Site Search page for full details of all sites used here.

2.2.2. Key variables for analysis¶

Tip

Refer to AmeriFlux Data Variables for full details of all measured variables.

Surface Radiation Balance

Variable	Description	Unit
`SW_IN`	Shortwave radiation, incoming	\(\text{W m}^{-2}\)
`SW_OUT`	Shortwave radiation, outgoing	\(\text{W m}^{-2}\)
`LW_IN`	Longwave radiation, incoming	\(\text{W m}^{-2}\)
`LW_OUT`	Longwave radiation, outgoing	\(\text{W m}^{-2}\)

Surface Energy Balance

Variable	Description	Unit
`NETRAD`	Net radiation	\(\text{W m}^{-2}\)
`H`	Sensible heat turbulent flux (no storage correction)	\(\text{W m}^{-2}\)
`LE`	Latent heat turbulent flux (no storage correction)	\(\text{W m}^{-2}\)
`G`	Soil heat flux	\(\text{W m}^{-2}\)

Standard Meteorological Conditions

Variable	Description	Unit
`TA`	Air temperature	\(^{\circ} \text{C}\)
`RH`	Relative humidity, range 0-100	\(\text{%}\)
`PA`	Air pressure	\(\text{kPa}\)
`P`	Precipitation	\(\text{mm}\)
`WS`	Wind speed	\(\text{m s}^{-1}\)
`WD`	Wind direction	\({\circ}\)

Others

Variable	Description	Unit
`SWC`	Soil water content (volumetric), range 0-100	\(\text{%}\)
`LAI`	Leaf area index by MODIS	\(\text{m}^{2} \text{ m}^{-2}\)

2.2.3. MODIS data associated with AmeriFlux sites¶

MODIS land products provides summaries of selected datasets for validation of models and remote-sensing products and to characterise field sites. Specifically, we use the LAI product in the class to help understand the relationships between surface parameters (e.g., albedo, surface resistance, etc.) and vegetation phenology.

2.2.4. Useful papers for understanding AmeriFlux datasets¶

Bergeron, Onil, Margolis, Hank A., Black, T. Andrew, Coursolle, Carole, Dunn, Allison L., Barr, Alan G., and Wofsy, Steven C. Comparison of carbon dioxide fluxes over three boreal black spruce forests in Canada. Global Change Biol, 13(1):89–107, January 2007. doi:10.1111/j.1365-2486.2006.01281.x.
Curtis, Peter S, Hanson, Paul J, Bolstad, Paul, Barford, Carol, Randolph, J.C, Schmid, H.P, and Wilson, Kell B. Biometric and eddy-covariance based estimates of annual carbon storage in five eastern north American deciduous forests. Agric. For. Meteorol., 113(1-4):3–19, December 2002. FLUXNET 2000 Synthesis. doi:10.1016/s0168-1923(02)00099-0.
Hollinger, D. Y., Ollinger, S. V., Richardson, A. D., Meyers, T. P., Dail, D. B., Martin, M. E., Scott, N. A., Arkebauer, T. J., Baldocchi, D. D., Clark, K. L., Curtis, P. S., Davis, K. J., Desai, A. R., Dragoni, D., Goulden, M. L., Gu, L., Katul, G. G., Pallardy, S. G., Paw U, K. T., Schmid, H. P., Stoy, P. C., Suyker, A. E., and Verma, S. B. Albedo estimates for land surface models and support for a new paradigm based on foliage nitrogen concentration. Global Change Biol., 16(2):696–710, February 2010. doi:10.1111/j.1365-2486.2009.02028.x.
Noormets, Asko, McNulty, Steve G., DeForest, Jared L., Sun, Ge, Li, Qinglin, and Chen, Jiquan. Drought during canopy development has lasting effect on annual carbon balance in a deciduous temperate forest. New Phytol., 179(3):818–828, August 2008. doi:10.1111/j.1469-8137.2008.02501.x.

2.3. URAO¶

Please visit URAO documentation site for information about observations at URAO.