The Response of Local Precipitation and Sea Level Pressure to Hadley Cell Expansion

Schmidt, Daniel F.; Grise, Kevin M.

doi:10.1002/2017gl075380

Cited by 46 publications

(43 citation statements)

References 53 publications

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“…There are two dominant hypotheses regarding the physical mechanisms causing the subtropic precipitation decline. The amplification of moisture export at the descending branches of the Hadley cells ("dry-get-drier") (Held & Soden, 2006) and the poleward expansion of the Hadley cells (Boos & Korty, 2016;Schmidt & Grise, 2017). As discussed in section 1, it has been noted that the precipitation changes over land do not follow the mechanism of atmospheric divergence (Byrne & O'Gorman, 2015;Greve et al, 2014;Markonis et al, 2018;Roderick et al, 2014), even though that arid regions appear to increase globally in model projections (Koutroulis, 2019).…”

Section: Synthesismentioning

confidence: 99%

Assessment of Water Cycle Intensification Over Land using a Multisource Global Gridded Precipitation DataSet

et al. 2019

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The change in the empirical distribution of future global precipitation is one of the major implications regarding the intensification of global water cycle. Heavier events are expected to occur more often, compensated by decline of light precipitation and/or number of wet days. Here, we scrutinize a new global, high‐resolution precipitation data set, namely, the Multi‐Source Weighted‐Ensemble Precipitation v2.0, to determine changes in the precipitation distribution over land during 1979–2016. To this end, the fluctuations of wet days precipitation quantiles on an annual basis and their interplay with annual totals and number of wet days were investigated. The results show increase in total precipitation, number of wet days, and heavy events over land, as suggested by the intensification hypothesis. However, the decline in light/medium precipitation or wet days was weaker than expected, debating the “compensation” mechanism.

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Section: Synthesismentioning

confidence: 99%

Assessment of Water Cycle Intensification Over Land using a Multisource Global Gridded Precipitation DataSet

et al. 2019

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“…This expansion is often implicated in observed drying trends over subtropical to midlatitude regions (e.g., Prein et al, 2016) but to date remains difficult to actually detect and attribute in observations (Davis & Rosenlof, 2012). Also, the expansion is not necessarily expected to manifest itself over land in the form of circulation-driven precipitation declines, especially over the U.S. SW (Greve et al, 2014;He & Soden, 2016a;Schmidt & Grise, 2017). Rather, a thermodynamically driven decrease in mean moisture convergence during the warm season seems to dominate the projected drying there (Ting et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Attributing the U.S. Southwest's Recent Shift Into Drier Conditions

Lehner

Deser

Simpson

et al. 2018

Geophysical Research Letters

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The U.S. Southwest experienced a strong hydroclimate trend from the 1980s to the 2010s, from cool and wet to warm and dry conditions. Attribution of this trend is challenging due to the influence of internal variability but desired by water managers eager to plan for robust signals of climate change in this water‐scarce region. Here we use an empirical method based on constructed circulation analogues to assess the contribution of atmospheric circulation variability to the recent observed hydroclimate trend. Consistent with other studies, we find the observed precipitation trend from 1983 to 2012 to be mainly due to internal atmospheric circulation variability that is driven in part by decadal‐scale tropical Pacific sea surface temperature changes. Removing this internal dynamical component brings the observed precipitation trend into closer agreement with the anthropogenically forced response in climate models, demonstrating progress toward an integrated perspective on climate change attribution.

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“…But outgoing longwave radiation is affected not only by changes in the tropical circulation but also by thermodynamic changes and is thus a poor measure of variability and change in the tropical overturning circulation, at least in the zonal mean (Waugh et al, ). The SLP changes associated with the HC are strongest over oceans (Schmidt & Grise, ), even though the tropical overturning circulation has clear impacts over both land and ocean (Chen et al, ; Freitas et al, ; Huang et al, ; Lucas & Nguyen, ; Zhao & Moore, ). For example, all of the world's hot deserts occur in or near subtropics.…”

Section: Introductionmentioning

confidence: 99%

Regional Widening of Tropical Overturning: Forced Change, Natural Variability, and Recent Trends

et al. 2019

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The width of the tropical Hadley circulation (HC) has garnered intense interest in recent decades, owing to the emerging evidence for its expansion in observations and models and to the anticipated impacts on surface climate in its descending branches. To better clarify the causes and impacts of tropical widening, this work generalizes the zonal mean HC to the regional level by defining meridional overturning cells (RC) using the horizontally divergent wind. The edges of the RC are more closely connected to surface hydroclimate than more traditional metrics of regional tropical width (such as the sea level pressure ridge) or even than the zonal mean HC. Simulations reveal a robust weakening of the RC in response to greenhouse gas increases, along with a widening of the RC in some regions. For example, simulated widening of the zonal mean HC in the Southern Hemisphere appears to arise in large part from regional overturning anomalies over the Eastern Pacific, where there is no clear RC. Unforced interannual variability in the position of the zonal mean HC edge is associated with a more general regional widening. These distinct regional signatures suggest that the RCs may be well suited for the attribution of observed circulation trends. The spatial pattern of regional meridional overturning trends in reanalyses corresponds more closely to the pattern associated with unforced interannual variability than to the pattern associated with CO2 forcing, suggesting a large contribution of natural variability to the recent observed tropical widening trends.

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The Response of Local Precipitation and Sea Level Pressure to Hadley Cell Expansion

Cited by 46 publications

References 53 publications

Assessment of Water Cycle Intensification Over Land using a Multisource Global Gridded Precipitation DataSet

Assessment of Water Cycle Intensification Over Land using a Multisource Global Gridded Precipitation DataSet

Attributing the U.S. Southwest's Recent Shift Into Drier Conditions

Regional Widening of Tropical Overturning: Forced Change, Natural Variability, and Recent Trends

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