The Convective Instability Pathway to Warm Season Drought in Texas. Part I: The Role of Convective Inhibition and Its Modulation by Soil Moisture

Myoung, Boksoon; Nielsen‐Gammon, John W.

doi:10.1175/2010jcli2946.1

Cited by 60 publications

(46 citation statements)

References 52 publications

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“…CIN is also found to be significantly correlated with rain days (daily precipitation ≥ 1 mm day −1 ) in summer in Texas (Myoung and Nielsen-Gammon, 2010b). Here a similar positive correlation between CIN and rain days in the CGP is also found from 1990 to 2015 (r = 0.79, p < 0.001), suggesting that CIN could influence fine dust concentration via its connection with rain days.…”

Section: Trends Of Surface Fine Dust Concentration Duringsupporting

confidence: 62%

Climatic factors contributing to long-term variations in surface fine dust concentration in the United States

Ginoux

2018

Atmos. Chem. Phys.

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Abstract. High concentrations of dust particles can cause respiratory problems and increase non-accidental mortality. Studies found fine dust (with an aerodynamic diameter of less than 2.5 µm) is an important component of the total PM 2.5 mass in the western and central US in spring and summer and has positive trends. This work examines climatic factors influencing long-term variations in surface fine dust concentration in the US using station data from the Interagency Monitoring Protected Visual Environments (IM-PROVE) network during 1990-2015. The variations in the fine dust concentration can be largely explained by the variations in precipitation, surface bareness, and 10 m wind speed. Moreover, including convective parameters such as convective inhibition (CIN) and convective available potential energy (CAPE) that reveal the stability of the atmosphere better explains the variations and trends over the Great Plains from spring to fall.While the positive trend of fine dust concentration in the southwestern US in spring is associated with precipitation deficit, the increase in fine dust over the central Great Plains in summer is largely associated with enhanced CIN and weakened CAPE, which are caused by increased atmospheric stability due to surface drying and lower-troposphere warming. The strengthening of the Great Plains low-level jet also contributes to the increase in fine dust concentration in the central Great Plains in summer via its positive correlation with surface winds and negative correlation with CIN.Summer dusty days in the central Great Plains are usually associated with a westward extension of the North Atlantic subtropical high that intensifies the Great Plains low-level jet and also results in a stable atmosphere with subsidence and reduced precipitation.

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Section: Trends Of Surface Fine Dust Concentration Duringsupporting

confidence: 62%

Climatic factors contributing to long-term variations in surface fine dust concentration in the United States

Ginoux

2018

Atmos. Chem. Phys.

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“…Our findings are, however, not consistent with those of Myoung and NielsenGammon (Myoung and Nielsen-Gammon 2010a), who used NCEP-NCAR reanalysis data to investigate mechanisms controlling the variability of convective precipitation. They found that the convective inhibition (CIN) is negatively correlated with precipitation over the continents in July, including over the Canadian Prairies (see their Figure 6c).…”

Section: Comparison With Other Conceptual Modelscontrasting

confidence: 99%

Impacts of Land–Atmosphere Feedbacks on Deep, Moist Convection on the Canadian Prairies

2011

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The purpose of this study was to focus on how anomalies in the normalized difference vegetation index (NDVI; a proxy for soil moisture) over the Canadian Prairies can condition the convective boundary layer (CBL) so as to inhibit or facilitate thunderstorm activity while also considering the role of synoptic-scale forcing. This study focused on a census agricultural region (CAR) over central Alberta for which we had observed lightning data (proxy for thunderstorms), remotely sensed NDVI data, and in situ rawinsonde data (to quantify impacts of vegetation vigor on the CBL characteristics) for 11 summers from 1999 to 2009. The authors' data suggest that the occurrence of lightning over the study area is more likely (and is of longer duration) when storms develop in an environment in which the surface and upper-air synoptic-scale forcing are synchronized. On days when surface forcing and midtropospheric ascent are present, storms are more likely to be triggered when NDVI is much above average, compared to when NDVI is much below average. Additionally, the authors found the response of thunderstorm duration to NDVI anomalies to be asymmetric. That is, the response of lightning duration to anomalies in NDVI is marked when NDVI is below average but is not necessarily discernible when NDVI is above average. The authors propose a conceptual model, based largely on observations, that integrates all of the above findings to describe how a reduction in vegetation vigor-in response to soil moisture deficits-modulates the partitioning of available energy into sensible and latent heat fluxes at the surface, thereby modulating lifting condensation level heights, which in turn affect lightning activity.

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“…Myoung and NielsenGammon (2010) showed that on monthly timescales, CIN was a better determinant to the occurrence of precipitation during the warm season in Texas. However, their results also showed a strong, negative relationship between soil moisture and CIN such that drier than normal soils resulted in stronger CIN values and therefore stronger atmospheric stability (Myoung and Nielsen-Gammon, 2010). The results from our analysis are not necessarily in disagreement because we evaluated the relationship between soil moisture and the 06:00 to 12:00 LST change in CIN.…”

Section: Discussionmentioning

confidence: 64%

Soil moisture–precipitation coupling: observations from the Oklahoma Mesonet and underlying physical mechanisms

Ford

Rapp

Quiring

et al. 2015

Hydrol. Earth Syst. Sci.

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Abstract.Interactions between soil moisture and the atmosphere are driven by the partitioning of sensible and latent heating, through which soil moisture has been connected to atmospheric modifications that could potentially lead to the initiation of convective precipitation. The majority of previous studies linking the land surface to subsequent precipitation have used atmospheric reanalysis or model data sets. In this study, we link in situ observations of soil moisture from more than 100 stations in Oklahoma to subsequent unorganized afternoon convective precipitation. We use hourly next generation (NEXRAD) radar-derived precipitation to identify convective events, and then compare the location of precipitation initiation to underlying soil moisture anomalies in the morning. Overall we find a statistically significant preference for convective precipitation initiation over drier than normal soils, with over 70 % of events initiating over soil moisture below the long-term median. The significant preference for precipitation initiation over drier than normal soils is in contrast with previous studies using satellite-based precipitation to identify the region of maximum precipitation accumulation. We evaluated 19 convective events occurring near Lamont, Oklahoma, where soundings of the atmospheric profile at 06:00 and 12:00 LST are also available. For these events, soil moisture has strong negative correlations with the level of free convection (LFC), planetary boundary layer (PBL) height, and surface temperature changes between 06:00 and 12:00 LST. We also find strong positive correlations between morning soil moisture and morning-toafternoon changes in convective available potential energy and convective inhibition. In general, the results of this study demonstrate that both positive and negative soil moisture feedbacks are important in this region of the USA.

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The Convective Instability Pathway to Warm Season Drought in Texas. Part I: The Role of Convective Inhibition and Its Modulation by Soil Moisture

Cited by 60 publications

References 52 publications

Climatic factors contributing to long-term variations in surface fine dust concentration in the United States

Climatic factors contributing to long-term variations in surface fine dust concentration in the United States

Impacts of Land–Atmosphere Feedbacks on Deep, Moist Convection on the Canadian Prairies

Soil moisture–precipitation coupling: observations from the Oklahoma Mesonet and underlying physical mechanisms

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