TY - JOUR

T1 - Modeling Isoprene Emission Response to Drought and Heatwaves Within MEGAN Using Evapotranspiration Data and by Coupling With the Community Land Model

AU - Wang, Hui

AU - Lu, Xinchen

AU - Seco, Roger

AU - Stavrakou, Trissevgeni

AU - Karl, Thomas

AU - Jiang, Xiaoyan

AU - Gu, Lianhong

AU - Guenther, Alex B.

N1 - Funding Information: H. Wang, X. Jiang and A. Guenther were supported by the U.S. National Science Foundation (NSF) Atmospheric Chemistry program award AGS‐1643042, the National Aeronautics and Space Administration (NASA) and the Atmospheric Composition Modeling and Analysis Program (ACMAP) program award 80NSSC19K0986. R. Seco acknowledges Grants RYC2020‐029216‐I and CEX2018‐000794‐S funded by MCIN/AEI/10.13039/501100011033 and by “ESF Investing in your future.” T. Stavrakou and A. Guenther were partly supported by the ALBERI project, funded by the Belgian Science Policy Office via the STEREO II programme (SR/00/373). T. Karl received support from projects FWF P30600‐NBL and FWF P33701. The authors would like to acknowledge high‐performance computing support from Cheyenne ( https://doi.org/10.5065/D6RX99HX ) provided by NCAR's Computational and Information Systems Laboratory, sponsored by the National Science Foundation. Funding Information: H. Wang, X. Jiang and A. Guenther were supported by the U.S. National Science Foundation (NSF) Atmospheric Chemistry program award AGS-1643042, the National Aeronautics and Space Administration (NASA) and the Atmospheric Composition Modeling and Analysis Program (ACMAP) program award 80NSSC19K0986. R. Seco acknowledges Grants RYC2020-029216-I and CEX2018-000794-S funded by MCIN/AEI/10.13039/501100011033 and by “ESF Investing in your future.” T. Stavrakou and A. Guenther were partly supported by the ALBERI project, funded by the Belgian Science Policy Office via the STEREO II programme (SR/00/373). T. Karl received support from projects FWF P30600-NBL and FWF P33701. The authors would like to acknowledge high-performance computing support from Cheyenne (https://doi.org/10.5065/D6RX99HX) provided by NCAR's Computational and Information Systems Laboratory, sponsored by the National Science Foundation. Publisher Copyright: © 2022 The Authors. Journal of Advances in Modeling Earth Systems published by Wiley Periodicals LLC on behalf of American Geophysical Union.

PY - 2022

Y1 - 2022

N2 - We introduce two new drought stress algorithms designed to simulate isoprene emission with the Model of Emissions of Gases and Aerosols from Nature (MEGAN) model. The two approaches include the representation of the impact of drought on isoprene emission with a simple empirical approach for offline MEGAN applications and a more process-based approach for online MEGAN in Community Land Model (CLM) simulations. The two versions differ in their implementation of leaf-temperature impacts of mild drought. For the online version of MEGAN that is coupled to CLM, the impact of drought on leaf temperature is simulated directly and the calculated leaf temperature is considered for the estimation of isoprene emission. For the offline version, we apply an empirical algorithm derived from whole-canopy flux measurements for simulating the impact of drought ranging from mild to severe stage. In addition, the offline approach adopts the ratio (fPET) of actual evapotranspiration to potential evapotranspiration to quantify the severity of drought instead of using soil moisture. We applied the two algorithms in the CLM-CAM-chem (the Community Atmosphere Model with Chemistry) model to simulate the impact of drought on isoprene emission and found that drought can decrease isoprene emission globally by 11% in 2012. We further compared the formaldehyde (HCHO) vertical column density simulated by CAM-chem to satellite HCHO observations. We found that the proposed drought algorithm can improve the match with the HCHO observations during droughts, but the performance of the drought algorithm is limited by the capacity of the model to capture the severity of drought.

AB - We introduce two new drought stress algorithms designed to simulate isoprene emission with the Model of Emissions of Gases and Aerosols from Nature (MEGAN) model. The two approaches include the representation of the impact of drought on isoprene emission with a simple empirical approach for offline MEGAN applications and a more process-based approach for online MEGAN in Community Land Model (CLM) simulations. The two versions differ in their implementation of leaf-temperature impacts of mild drought. For the online version of MEGAN that is coupled to CLM, the impact of drought on leaf temperature is simulated directly and the calculated leaf temperature is considered for the estimation of isoprene emission. For the offline version, we apply an empirical algorithm derived from whole-canopy flux measurements for simulating the impact of drought ranging from mild to severe stage. In addition, the offline approach adopts the ratio (fPET) of actual evapotranspiration to potential evapotranspiration to quantify the severity of drought instead of using soil moisture. We applied the two algorithms in the CLM-CAM-chem (the Community Atmosphere Model with Chemistry) model to simulate the impact of drought on isoprene emission and found that drought can decrease isoprene emission globally by 11% in 2012. We further compared the formaldehyde (HCHO) vertical column density simulated by CAM-chem to satellite HCHO observations. We found that the proposed drought algorithm can improve the match with the HCHO observations during droughts, but the performance of the drought algorithm is limited by the capacity of the model to capture the severity of drought.

KW - drought

KW - evapotranspiration

KW - isoprene

KW - MEGAN

U2 - 10.1029/2022MS003174

DO - 10.1029/2022MS003174

M3 - Journal article

C2 - 37035629

AN - SCOPUS:85145228227

VL - 14

JO - Journal of Advances in Modeling Earth Systems

JF - Journal of Advances in Modeling Earth Systems

SN - 1942-2466

IS - 12

M1 - e2022MS003174

ER -