Transcript Document
Lake Superior Region Carbon Cycle Viewed from the air Ankur R Desai Atmospheric & Oceanic Sciences University of Wisconsin-Madison (and the CyCLeS team) Lake Superior Biogeochemistry Workshop Ankur R Desai, UW-Madison August 5, 2008 [email protected] What’s in the airwaves? • Lakes, lands, & carbon • The atmospheric tracer view • An eddy flux view • Lake Superior & micrometerology Ankur R Desai, UW-Madison [email protected] Lakes, Land, & Carbon Ankur R Desai, UW-Madison [email protected] The big picture • Sarmiento and Gruber, 2002, Physics Today Ankur R Desai, UW-Madison [email protected] Slightly smaller picture • Cardille et al. (2007) QuickTime™ and a decompressor are needed to see this picture. Ankur R Desai, UW-Madison [email protected] Real Numbers Are Complicated • Atmos. flux: ~3-12 Tg yr-1 - 35-140 gC m-2 yr-1 QuickTime™ and a decompressor are needed to see this picture. Ankur R Desai, UW-Madison [email protected] An Oceanic Lake • CyCLeS: Cycling of Carbon in Lake Superior • Adapt the MIT-GCM ocean model to simulate physical and biogeochemical environment of Lake Superior • Physical model of temperature, circulation – Mostly implemented • Biogeochemical model of trace nutrients and air-sea exchange – In progress Ankur R Desai, UW-Madison [email protected] Interesting Questions • How do magnitudes of lake and land flux compare and what does it imply for regional carbon budgets? (NACP, SOCCR) • Are interannual variations in lake and land CO2 surface-atmosphere flux related and if so, due to what environmental forcing? • Can we “see” and constrain lake (and land) flux from regional atmospheric CO2 observations? • What are impacts on atmospheric forcing (temperature, stable layer depth, CO2) on lake biogeochemistry? Ankur R Desai, UW-Madison [email protected] The Atmospheric Tracer View Ankur R Desai, UW-Madison [email protected] Global CO2 • NOAA/ESRL/GMD/CCGG 390 380 370 360 350 340 330 1980 Ankur R Desai, UW-Madison 1985 1990 1995 2000 2005 2010 [email protected] Global Experiment • Marland et al., DOE/CDIAC 8000 7000 6000 5000 4000 3000 2000 1000 0 1750 1800 T otal S olid Ankur R Desai, UW-Madison 1850 1900 G as C ement 1950 2000 L iquid G as Flare [email protected] The Inverse Idea QuickTime™ and a decompressor are needed to see this picture. Ankur R Desai, UW-Madison [email protected] The Inverse Idea • Courtesy S. Denning, CSU QuickTime™ and a decompressor are needed to see this picture. Ankur R Desai, UW-Madison [email protected] The Inverse Idea QuickTime™ and a decompressor are needed to see this picture. Ankur R Desai, UW-Madison QuickTime™ and a decompressor are needed to see this picture. • Peters et al (2007) PNAS [email protected] Inversion and a Very Big Tower • • • • WLEF-TV (PBS) Park Falls, WI 447-m tall 6 levels [CO2] – 11 to 396 m • 3 levels CO2 flux – 30,122,396 m • Mixed landscape – Representative? • Running 1995- Ankur R Desai, UW-Madison [email protected] A 1-point Inversion • [CO2] Air flowing over lake > [CO2] over land QuickTime™ and a decompressor are needed to see this picture. Ankur R Desai, UW-Madison [email protected] Air and Lake CO2 Comparison • Simple boundary layer budget tracer study suggests summer 2007 efflux: 4-14 gC m-2 d-1 – extrapolated to ~30-140 gC m-2 yr-1 – Analysis requires modeling of stable marine boundary layer – Larger than traditional air-sea pCO2 exchange calculation – Requires significant respiration in water column – Urban et al. (in press) Ankur R Desai, UW-Madison [email protected] The Boundary Layer Problem • Courtesy of S. Spak, UW QuickTime™ and a decompressor are needed to see this picture. Ankur R Desai, UW-Madison [email protected] Getting More Sophisticated • Courtesy M. Uliasz, CSU – Tracer transport modeled influence function August 2003 at WLEF entire domain 1100 1000 land 900 water 1 1100 0.5 1000 0.1 1 900 0.05 0.5 800 0.01 0.1 700 0.005 0.05 600 0.001 0.01 500 0 0.005 1100 900 1 700 0.5 600 Y [km] 800 0.1 500 700 0.05 400 600 Y [km] Y [km] 800 1000 0.01 300 500 0.005 200 200 400 300 400 500 600 0.001 700 X [km] 300 400 800 900 0.001 1000 1100 300 0 0 200 200 300 400 500 600 700 800 900 1000 1100 200 200 300 400 500 600 700 800 900 1000 1100 X [km] X [km] Ankur R Desai, UW-Madison [email protected] Great Lakes Influence at WLEF 1 • Land: 85.4% 0.8 0.6 0.4 • Lake Superior: 9.5% 0.2 LA N D 0 • Lake Michigan: 1.8% 1 LA K E S U P E R IO R 0.8 0.6 • Other water: 3.1% 0.4 0.2 0 Ankur R Desai, UW-Madison [email protected] The Potential 6 6 4 4 2 2 C O 2 [p p m ] C O 2 [p p m ] • Potential exists for constraining flux and interannual var. with local observations of CO2 0 -2 -4 0 -2 -4 1996 -6 2003 -6 -8 -8 5 6 7 8 m on th s Ankur R Desai, UW-Madison 9 10 11 5 6 7 8 9 10 11 m on th s [email protected] An Eddy Flux View Ankur R Desai, UW-Madison [email protected] Eddies? • Tracers in boundary layer primarily transported by turbulence • Ensemble average turbulent equations of motion and tracer concentration provide information about the effect of random, chaotic turbulence on the evolution of mean tracer profiles with time • In a quasi-steady, homogenous surface layer, we can simplify this equation to infer the surface flux of a tracer Ankur R Desai, UW-Madison [email protected] Eddies! Ankur R Desai, UW-Madison [email protected] The Maths • *Some simplifications made… Fc a wc c t dz 0 Turbulent flux h Storage Equipment: • 3D sonic anemometer • Open or closed path gas analyzer • 5--20 Hz temporal resolution • Multiple level CO2 profiler Ankur R Desai, UW-Madison [email protected] The Data Ankur R Desai, UW-Madison [email protected] The Data Pt. 2 Ankur R Desai, UW-Madison [email protected] The Data Pt. 3 Ankur R Desai, UW-Madison [email protected] Much Data… QuickTime™ and a decompressor are needed to see this picture. Ankur R Desai, UW-Madison [email protected] A CHEAS-y Lake QuickTime™ and a decompressor are needed to see this picture. Ankur R Desai, UW-Madison [email protected] Scale This! Ankur R Desai, UW-Madison [email protected] Some Observations Desai et al, 2008, Ag For Met Ankur R Desai, UW-Madison [email protected] The 6x6 km View QuickTime™ and a decompressor are needed to see this picture. Ankur R Desai, UW-Madison QuickTime™ and a decompressor are needed to see this picture. [email protected] More Observations Ankur R Desai, UW-Madison [email protected] Land History Ankur R Desai, UW-Madison [email protected] Land History • Have to account for age structure too QuickTime™ and a decompressor are needed to see this picture. Ankur R Desai, UW-Madison [email protected] All The ChEAS Flux Data Quic kTime™ and a dec ompr es sor are needed to s ee this pic ture. Ankur R Desai, UW-Madison [email protected] Magically Scaled Quic kTime™ and a dec ompr es sor are needed to s ee this pic ture. Ankur R Desai, UW-Madison [email protected] The “Bottom-Up” Flux 50 30 NEE gC m-2 mo-1 10 -10 -30 -50 -70 -90 -110 -130 -150 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 Year Ankur R Desai, UW-Madison [email protected] Evaluation • “Top-down” vs “Bottom-up” Regional Flux 40 20 NEE gC m-2 mo-1 0 -20 -40 -60 -80 -100 -120 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year Flux towers Ankur R Desai, UW-Madison FIA Model ABL Budget [email protected] Evaluation Annual flux (NEE) 1997 1998 1999 2000 2001 2002 2003 2004 0 gC m-2 yr-1 -50 -100 Flux towers FIA model ABL Budget -150 -200 -250 Year Ankur R Desai, UW-Madison [email protected] Land • 1989-2006 average Mean NEE 40 20 gC m-2 mo-1 0 -20 -40 -60 -80 -100 1 2 3 4 5 6 7 8 9 10 11 12 Month Ankur R Desai, UW-Madison [email protected] Lake? Ankur R Desai, UW-Madison [email protected] Lake and Land Cumulative NEE 150 100 gC m -2 m o-1 50 0 -50 -100 -150 -200 1 2 3 4 5 6 7 8 9 10 11 12 Month Ankur R Desai, UW-Madison [email protected] Lake Superior & Micrometeorology Ankur R Desai, UW-Madison [email protected] Better Forcing? • Many observations are sparse Ankur R Desai, UW-Madison [email protected] Better [CO2] 390 385 380 375 370 365 360 355 350 345 340 1996 1997 Ankur R Desai, UW-Madison 1998 1999 2000 2001 2002 2003 2004 2005 2006 [email protected] Coherent Interannual Variability Quic kTime™ and a dec ompres sor are needed to s ee this pic tur e. Ankur R Desai, UW-Madison [email protected] Lake Interannual Variability Annual avg. dissolved organic carbon (DOC) 3.5 3 DOC (mgL-1) 2.5 2 1.5 1 0.5 0 1973 Ankur R Desai, UW-Madison 1983 1986 1987 1996 1997 2001 2005 [email protected] More measurements • [CO2] over Lake Superior • Continuous CO2 eddy covariance on the lake • Better models of stability over lakes • Spatial atmospheric met data – Temp, wind, precip?, shortwave radiation Ankur R Desai, UW-Madison [email protected] Conclusions • On annual and decadal timescales, Lake Superior is possibly a source of CO2 to the atmosphere • This source could be on the same order of magnitude as the terrestrial regional sink • Regional carbon budgets have to take lakes into account • We can estimate this flux from a number of techniques • Lake models may need to worry about spatiotemporal variability in atmospheric forcing • Models to tie land carbon flows into lake carbon can be useful for Lake Superior • Model-data fusion/optimization/assimilation techniques should be explored Ankur R Desai, UW-Madison [email protected] Thanks • Desai lab and friends: Ben Sulman, Jonathan Thom, Shelley Knuth, Scott Spak • ChEAS collaborators, esp. Bruce Cook, Paul Bolstad, Ken Davis, D. Scott Mackay, Nic Saliendra, Sudeep Samanta • CyCLeS team: Galen McKinley, Noel Urban, Chin Wu, Nazan Atilla, Val Bennington • Funding: DOE NICCR, NSF, USDA, NSF/NCAR, NASA, NOAA, under auspices of the North American Carbon Program (NACP) • Come visit us: – AOSS 1549, [email protected], 265-9201 • More info: – http://flux.aos.wisc.edu Ankur R Desai, UW-Madison [email protected]