Abstract
Large changes in tropical circulation from the mid-to-late 1990s to the present, in particular changes related to the summer monsoon and cooling of the sea surface in the equatorial eastern Pacific, are noted. The cause of such recent decadal variations in the tropics was studied using a meteorological reanalysis dataset. Cooling of the equatorial southeastern Pacific Ocean occurred in association with enhanced cross-equatorial southerlies that were associated with a strengthening of the deep ascending branch of the boreal summer Hadley circulation over the continental sector connected to stratospheric circulation. From boreal summer to winter, the anomalous convective activity center moves southward following the seasonal march to the equatorial Indian Ocean-Maritime Continent region, which strengthens the surface easterlies over the equatorial central Pacific. Accordingly, ocean surface cooling extends over the equatorial central Pacific. We suggest that the fundamental cause of the recent decadal change in the tropical troposphere and the ocean is a poleward shift of convective activity that resulted from a strengthening of extreme deep convection penetrating into the tropical tropopause layer, particularly over the African and Asian continents and adjacent oceans. We conjecture that the increase in extreme deep convection is produced by a combination of land surface warming due to increased <span classCombining double low line"inline-formula">CO2</span> and a reduction of static stability in the tropical tropopause layer due to tropical stratospheric cooling.
| Original language | English |
|---|---|
| Pages (from-to) | 2655-2669 |
| Number of pages | 15 |
| Journal | Atmospheric Chemistry and Physics |
| Volume | 19 |
| Issue number | 4 |
| DOIs | |
| Publication status | Published - Feb 28 2019 |
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All Science Journal Classification (ASJC) codes
- Atmospheric Science
Cite this
Implication of tropical lower stratospheric cooling in recent trends in tropical circulation and deep convective activity. / Kodera, Kunihiko; Eguchi, Nawo; Ueyama, Rei; Kuroda, Yuhji; Kobayashi, Chiaki; Funatsu, Beatriz; Claud, Chantal.
In: Atmospheric Chemistry and Physics, Vol. 19, No. 4, 28.02.2019, p. 2655-2669.Research output: Contribution to journal › Article
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TY - JOUR
T1 - Implication of tropical lower stratospheric cooling in recent trends in tropical circulation and deep convective activity
AU - Kodera, Kunihiko
AU - Eguchi, Nawo
AU - Ueyama, Rei
AU - Kuroda, Yuhji
AU - Kobayashi, Chiaki
AU - Funatsu, Beatriz
AU - Claud, Chantal
PY - 2019/2/28
Y1 - 2019/2/28
N2 - Large changes in tropical circulation from the mid-to-late 1990s to the present, in particular changes related to the summer monsoon and cooling of the sea surface in the equatorial eastern Pacific, are noted. The cause of such recent decadal variations in the tropics was studied using a meteorological reanalysis dataset. Cooling of the equatorial southeastern Pacific Ocean occurred in association with enhanced cross-equatorial southerlies that were associated with a strengthening of the deep ascending branch of the boreal summer Hadley circulation over the continental sector connected to stratospheric circulation. From boreal summer to winter, the anomalous convective activity center moves southward following the seasonal march to the equatorial Indian Ocean-Maritime Continent region, which strengthens the surface easterlies over the equatorial central Pacific. Accordingly, ocean surface cooling extends over the equatorial central Pacific. We suggest that the fundamental cause of the recent decadal change in the tropical troposphere and the ocean is a poleward shift of convective activity that resulted from a strengthening of extreme deep convection penetrating into the tropical tropopause layer, particularly over the African and Asian continents and adjacent oceans. We conjecture that the increase in extreme deep convection is produced by a combination of land surface warming due to increased CO2 and a reduction of static stability in the tropical tropopause layer due to tropical stratospheric cooling.
AB - Large changes in tropical circulation from the mid-to-late 1990s to the present, in particular changes related to the summer monsoon and cooling of the sea surface in the equatorial eastern Pacific, are noted. The cause of such recent decadal variations in the tropics was studied using a meteorological reanalysis dataset. Cooling of the equatorial southeastern Pacific Ocean occurred in association with enhanced cross-equatorial southerlies that were associated with a strengthening of the deep ascending branch of the boreal summer Hadley circulation over the continental sector connected to stratospheric circulation. From boreal summer to winter, the anomalous convective activity center moves southward following the seasonal march to the equatorial Indian Ocean-Maritime Continent region, which strengthens the surface easterlies over the equatorial central Pacific. Accordingly, ocean surface cooling extends over the equatorial central Pacific. We suggest that the fundamental cause of the recent decadal change in the tropical troposphere and the ocean is a poleward shift of convective activity that resulted from a strengthening of extreme deep convection penetrating into the tropical tropopause layer, particularly over the African and Asian continents and adjacent oceans. We conjecture that the increase in extreme deep convection is produced by a combination of land surface warming due to increased CO2 and a reduction of static stability in the tropical tropopause layer due to tropical stratospheric cooling.
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UR - http://www.scopus.com/inward/citedby.url?scp=85062355427&partnerID=8YFLogxK
U2 - 10.5194/acp-19-2655-2019
DO - 10.5194/acp-19-2655-2019
M3 - Article
AN - SCOPUS:85062355427
VL - 19
SP - 2655
EP - 2669
JO - Atmospheric Chemistry and Physics
JF - Atmospheric Chemistry and Physics
SN - 1680-7316
IS - 4
ER -