Upper‐Tropospheric Troughs and North American Monsoon Rainfall in a Long‐Term Track Dataset

Igel, Matthew R.; Ullrich, P. A.; Boos, William R.

doi:10.1029/2021jd034541

Cited by 3 publications

(4 citation statements)

References 34 publications

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“…In contrast, the positive PV200 anomalies are relatively smaller for westward-moving UTTs, and they are located in the tropical easterlies. This follows Igel et al (2021), where it is argued that TUTTs are advected by the background easterlies. Moreover, the boundary of westerly and easterly flow moves further north during westward-UTT events.…”

Section: Upper Troposphere Troughsmentioning

confidence: 88%

“…For the NAM region, tropical upper-troposphere troughs (TUTTs) are the most common IT type. TUTTs, unlike RWBs, are more common in subtropical easterlies, albeit they are also connected to mid-latitude wave breaking events (Igel et al, 2021). To assess their impact on precipitation, Finch and Johnson (2010b) utilized quasigeostrophic (QG) theory to study a TUTT event over the NAM region in July 2004.…”

Section: Upper Troposphere Troughsmentioning

confidence: 99%

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Meteorological Drivers of North American Monsoon Extreme Precipitation Events

Duan

Ullrich

Boos

2022

Preprint

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In this paper the meteorological drivers of North American Monsoon (NAM) extreme precipitation events (EPEs) are identified and analyzed. First, the NAM area and its subregions are distinguished using self-organizing maps (SOM) applied to the Climate Prediction Center (CPC) global precipitation dataset. This delineation emphasizes the distinct extreme precipitation character and drivers in each subregion, and we subsequently argue these subregions are more suitable for regional analysis given the inhomogeneous geographical features in the NAM area. For each EPE, defined as daily precipitation exceeding the 95th precipitation percentile, five synoptic features and one mesoscale feature are investigated and assigned as potential drivers. Essentially all EPEs can be associated with at least one selected driver, with only one event remaining as unclassified. The attribution result demonstrates the dominant role of Gulf of California moisture surges, followed by mesoscale convective systems. Finally, a frequency and probability analysis is conducted to contrast precipitation distributions conditioned on the associated meteorological drivers. Interactions and influences among candidate features are revealed by the precipitation probability density functions.

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Section: Upper Troposphere Troughsmentioning

confidence: 88%

Section: Upper Troposphere Troughsmentioning

confidence: 99%

Meteorological Drivers of North American Monsoon Extreme Precipitation Events

Duan

Ullrich

Boos

2022

Preprint

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“…In addition to near‐surface features, upper‐level disturbances were identified as influential controls on precipitation by Igel et al. (2021), who examined the impact of tropical upper troposphere troughs (TUTTs) on NAM precipitation, and Sierks et al. (2020), who highlighted the role of Rossby wave breaking (RWBs) and inverted troughs (ITs) over Lake Mead.…”

Section: Introductionmentioning

confidence: 99%

“…Frontal systems were found to be another significant driver associated with 44% of EPEs in the southwestern US summertime, as shown in Kunkel et al (2012). In addition to near-surface features, upper-level disturbances were identified as influential controls on precipitation by Igel et al (2021), who examined the impact of tropical upper troposphere troughs (TUTTs) on NAM precipitation, and Sierks et al (2020), who highlighted the role of Rossby wave breaking (RWBs) and inverted troughs (ITs) over Lake Mead. Beyond these synoptic features, Finch and Johnson (2010) and Mejia et al (2016) revealed the significance of mesoscale convection system (MCS) activities in the NAM region.…”

Section: Introductionmentioning

confidence: 99%

Meteorological Drivers of North American Monsoon Extreme Precipitation Events

Duan,

Ullrich,

Boos

2024

JGR Atmospheres

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In this paper the meteorological drivers of North American Monsoon (NAM) extreme precipitation events (EPEs) are identified and analyzed. First, the NAM area and its subregions are distinguished using self‐organizing maps applied to the Climate Prediction Center global precipitation data set. This reveals distinct subregions, shaped by the inhomogeneous geographic features of the NAM area, with distinct extreme precipitation character and drivers. Next, defining EPEs as days when subregion‐mean precipitation exceeds the 95th percentile of rainy days, five synoptic features and one mesoscale feature are investigated as potential drivers of EPEs. Essentially all EPEs can be associated with at least one selected driver, with only one event remaining unclassified. This analysis shows the dominant role of Gulf of California moisture surges, mesoscale convective systems and frontal systems in generating NAM extreme precipitation. Finally, a frequency and probability analysis is conducted to contrast precipitation distributions conditioned on the associated meteorological drivers. The findings demonstrate that the co‐occurrence of multiple features does not necessarily enhance the EPE probability.

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