Global terrestrial stilling: Does Earth's greening play a role?

Zhenzhong Zeng, Shilong Piao, Laurent Z.X. Li, Philippe Ciais, Yue Li, Xitian Cai, Long Yang, Maofeng Liu, Eric F. Wood

Research output: Contribution to journalReview articlepeer-review

38 Scopus citations

Abstract

Previous studies have documented that surface wind speed (u) has been increasing over the ocean but decreasing over land for the past several decades. The decreasing u at the surface over land has been referred to as terrestrial stilling. A plausible hypothesis for terrestrial stilling is an increase in surface roughness associated with changes in land surface (e.g. enhanced vegetation growth, landscape fragmentation or urbanization). One of the most widespread land surface changes is enhanced vegetation leaf area index (LAI) known as greening, particularly over the middle to high latitudes of the Northern Hemisphere where strong stilling is observed from weather station data. In this study, we examine the hypothesis that enhanced vegetation LAI is a key driver of global terrestrial stilling. We first characterized the trend in u over the ocean using long-term satellite altimeter measurements, and the trend in u over land using continuous wind records from 4305 in situ meteorological stations. We then performed initial condition ensemble Atmospheric Model Intercomparison Project-type simulations using two state-of-the-art Earth system models (IPSL-CM and CESM) to isolate the response of u to the historical increase in LAI (representing the greening) for the period 1982-2011. Both models, forced with observed sea surface temperature and sea ice and with LAI from satellite observation, captured the observed strengthening of Pacific trade winds and Southern Ocean westerly winds. However, these simulations did not reproduce the weakening of surface winds over land as significantly as it appears in the observations (-0.006 m s -1 versus -0.198 m s -1 during 1982-2011), indicating that enhanced LAI (greening) is not a dominant driver for terrestrial stilling.

Original languageEnglish (US)
Article number124013
JournalEnvironmental Research Letters
Volume13
Issue number12
DOIs
StatePublished - Dec 2018

All Science Journal Classification (ASJC) codes

  • Renewable Energy, Sustainability and the Environment
  • General Environmental Science
  • Public Health, Environmental and Occupational Health

Keywords

  • Earth's greening
  • leaf area index
  • surface roughness
  • surface wind speed
  • terrestrial stilling
  • weather station

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