Impact of Mountains on Tropical Circulation in Two Earth System Models

Naiman, Zachary; Goodman, Paul J.; Krasting, John P.; Malyshev, Sergey L.; Russell, Joellen L.; Stouffer, Ronald J.; Wittenberg, Andrew T.

doi:10.1175/jcli-d-16-0512.1

i

Impact of Mountains on Tropical Circulation in Two Earth System Models

2017
By Naiman, Zachary ; Goodman, Paul J. ; Krasting, John P. ; ...

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Journal Title:

Journal of Climate
Personal Author:

Naiman, Zachary ; Goodman, Paul J. ; Krasting, John P. ; Malyshev, Sergey L. ; Russell, Joellen L. ; Stouffer, Ronald J. ; Wittenberg, Andrew T.
NOAA Program & Office:

OAR (Oceanic and Atmospheric Research) ; CICSP (Cooperative Institute for Climate Science) ; GFDL (Geophysical Fluid Dynamics Laboratory)
Description:

Two state-of-the-art Earth systemmodels (ESMs) were used in an idealized experiment to explore the role of mountains in shaping Earth's climate system. Similar to previous studies, removing mountains from both ESMs results in the winds becoming more zonal and weaker Indian and Asian monsoon circulations. However, there are also broad changes to the Walker circulation and El Nino-Southern Oscillation (ENSO). Without orography, convection moves across the entire equatorial Indo-Pacific basin on interannual time scales. ENSO has a stronger amplitude, lower frequency, and increased regularity. A wider equatorial wind zone and changes to equatorial wind stress curl result in a colder cold tongue and a steeper equatorial thermocline across the Pacific basin during La Nina years. Anomalies associated with ENSO warm events are larger without mountains and have greater impact on the mean tropical climate than when mountains are present. Without mountains, the centennial-mean PacificWalker circulation weakens in both models by approximately 45%, but the strength of the mean Hadley circulation changes by less than 2%. Changes in the Walker circulation in these experiments can be explained by the large spatial excursions of atmospheric deep convection on interannual time scales. These results suggest that mountains are an important control on the large-scale tropical circulation, impacting ENSO dynamics and the Walker circulation, but have little impact on the strength of the Hadley circulation.
Source:

Journal of Climate, 30(11), 4149-4163.
DOI:

https://doi.org/10.1175/jcli-d-16-0512.1
Document Type:

Journal Article
Funding:

Grant no. NA14OAR4320106
Rights Information:

Other
Compliance:

Submitted
Main Document Checksum:

urn:sha256:bdc274e39606f555d0da07a34b7fb0577c73705c6ff8c5172d2384e8f091957c
Download URL:

https://repository.library.noaa.gov/view/noaa/20825/noaa_20825_DS1.pdf
File Type:

[PDF - 4.32 MB ]

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