Constructing a Seasonal and Sub-seasonal Variance Budget for OCO-2 XCO2 for North America and Adjacent Ocean Basins

Kayla Alexis Mitchell,  University of Virginia,  kam9rc@virginia.edu (Presenter)
Scott Doney,  University of Virginia,  scd5c@virginia.edu
Gretchen Keppel-Aleks,  University of Michigan,  gkeppela@umich.edu

We characterize seasonal and sub-seasonal variance in OCO-2 XCO₂ over North America from 2014-2019. Hemispheric and regional-scale patterns emerge in XCO₂ seasonal amplitudes, reflecting a combination of seasonality in underlying surface ecosystem CO₂ fluxes and transported ecosystem signals. The terrestrial Pacific Northwest exhibits lower seasonal amplitudes compared to the adjacent northeast Pacific Ocean, demonstrating that seasonal variance XCO₂ is not totally shaped by local surface fluxes. We find significant regional variations and land-ocean contrasts in sub-seasonal XCO₂ variance (synoptic plus mesoscale XCO₂ anomalies), with the greatest sub-seasonal variance of 1.2 - 1.8 ppm² over the northern continental U.S. and Canada. Along the west coast, sub-seasonal variance over land was nearly double that over the ocean (1.9 ppm² versus 1.0 ppm²). Along the east coast, sub-seasonal variance over land was also greater than that over the ocean (1.6 ppm² versus 1.1 ppm²), with possible advection of the continental signal offshore. Sub-seasonal XCO₂ variance across the domain primarily peaks during the summer months, likely reflecting synoptic-scale advection across the hemispheric summertime XCO₂ concentration gradient and a more sensitive biosphere. Further research efforts will partition the sub-seasonal XCO₂ variance across the domain into noise, mesoscale, and synoptic-scale variations. We will assess these patterns in terms of pointing mode, retrieval covariates (surface type, albedo, topography), atmosphere dynamics (wind direction/speed, large-scale gradients, synoptic storm patterns), and surface CO₂ flux variability. We will quantify the contributions of these different sources of variance in OCO-2 observations for use in formal inverse modeling and flux inference.

Poster: Poster_Mitchell_0_85_25.pdf 

Presentation Type: Poster

Session: 3.5c Flux estimates and atmospheric inversions from space-based GHG measurements

Session Date: Wednesday (6/16) 12:00 PM