A stochastic model for daily subsurface CO2 concentration and related soil respiration

Edoardo Daly, A. Christopher Oishi, Amilcare Porporato, Gabriel G. Katul

Research output: Contribution to journalArticlepeer-review

56 Scopus citations


Near-surface soil CO2 gas-phase concentration (C) and concomitant incident rainfall (Pi) and through-fall (Pt) depths were collected at different locations in a temperate pine forest every 30 min during the 2005 and 2006 growing seasons (and then averaged to the daily timescale). At the daily scale, C temporal variations were well described by a sequence of monotonically decreasing functions interrupted by large positive jumps induced by rainfall events. A stochastic model was developed to link rainfall statistics responsible for these jumps to near-surface C dynamics. The model accounted for the effect of daily rainfall variability, both in terms of timing and amount of water, and permitted an analytical derivation of the C probability density function (pdf) using the parameters of the rainfall pdf. Given the observed positive correlation between daily C and soil CO2 fluxes to the atmosphere (Fs), the effects of various rainfall regimes on the statistics of Fs can be deduced from the behavior of C under different climatic conditions. The predictions from this analytical model are consistent with flux measurements reported in manipulative experiments that varied rainfall amount and frequency.

Original languageEnglish (US)
Pages (from-to)987-994
Number of pages8
JournalAdvances in Water Resources
Issue number7
StatePublished - Jul 2008
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Water Science and Technology


  • CO pulses
  • Rainfall
  • Soil CO
  • Soil respiration


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