Sensitivity of Extreme Rainfall to Atmospheric Moisture Content in the Arid/Semiarid Southwestern United States: Implications for Probable Maximum Precipitation Estimates

2018 ◽  
Vol 123 (3) ◽  
pp. 1638-1656 ◽  
Author(s):  
Long Yang ◽  
James Smith
Keyword(s):  
United States ◽  
Moisture Content ◽  
Extreme Rainfall ◽  
Atmospheric Moisture ◽  
Southwestern United States ◽  
Probable Maximum Precipitation ◽  
Maximum Precipitation ◽  
Precipitation Estimates ◽  
Atmospheric Moisture Content

scholarly journals Causes and Implications of Extreme Atmospheric Moisture Demand during the Record-Breaking 2011 Wildfire Season in the Southwestern United States

2014 ◽  
Vol 53 (12) ◽  
pp. 2671-2684 ◽  
Author(s):  
A. Park Williams ◽  
Richard Seager ◽  
Max Berkelhammer ◽  
Alison K. Macalady ◽  
Michael A. Crimmins ◽  
...  
Keyword(s):  
United States ◽  
Moisture Content ◽  
Vapor Pressure ◽  
Coupled Model ◽  
Warm Season ◽  
Cold Season ◽  
Atmospheric Moisture ◽  
Southwestern United States ◽  
Dewpoint Temperature ◽  
Atmospheric Moisture Content

AbstractIn 2011, exceptionally low atmospheric moisture content combined with moderately high temperatures to produce a record-high vapor pressure deficit (VPD) in the southwestern United States (SW). These conditions combined with record-low cold-season precipitation to cause widespread drought and extreme wildfires. Although interannual VPD variability is generally dominated by temperature, high VPD in 2011 was also driven by a lack of atmospheric moisture. The May–July 2011 dewpoint in the SW was 4.5 standard deviations below the long-term mean. Lack of atmospheric moisture was promoted by already very dry soils and amplified by a strong ocean-to-continent sea level pressure gradient and upper-level convergence that drove dry northerly winds and subsidence upwind of and over the SW. Subsidence drove divergence of rapid and dry surface winds over the SW, suppressing southerly moisture imports and removing moisture from already dry soils. Model projections developed for the fifth phase of the Coupled Model Intercomparison Project (CMIP5) suggest that by the 2050s warming trends will cause mean warm-season VPD to be comparable to the record-high VPD observed in 2011. CMIP5 projections also suggest increased interannual variability of VPD, independent of trends in background mean levels, as a result of increased variability of dewpoint, temperature, vapor pressure, and saturation vapor pressure. Increased variability in VPD translates to increased probability of 2011-type VPD anomalies, which would be superimposed on ever-greater background VPD levels. Although temperature will continue to be the primary driver of interannual VPD variability, 2011 served as an important reminder that atmospheric moisture content can also drive impactful VPD anomalies.

scholarly journals Blowing snow in coastal Adélie Land, Antarctica: three atmospheric-moisture issues

2014 ◽  
Vol 8 (5) ◽  
pp. 1905-1919 ◽  
Author(s):  
H. Barral ◽  
C. Genthon ◽  
A. Trouvilliez ◽  
C. Brun ◽  
C. Amory
Keyword(s):  
Moisture Content ◽  
Snow Accumulation ◽  
Blowing Snow ◽  
Atmospheric Moisture ◽  
Atmospheric Models ◽  
Moisture Fluxes ◽  
Measurement Uncertainties ◽  
Strong Winds ◽  
The Impact ◽  
Atmospheric Moisture Content

Abstract. A total of 3 years of blowing-snow observations and associated meteorology along a 7 m mast at site D17 in coastal Adélie Land are presented. The observations are used to address three atmospheric-moisture issues related to the occurrence of blowing snow, a feature which largely affects many regions of Antarctica: (1) blowing-snow sublimation raises the moisture content of the surface atmosphere close to saturation, and atmospheric models and meteorological analyses that do not carry blowing-snow parameterizations are affected by a systematic dry bias; (2) while snowpack modelling with a parameterization of surface-snow erosion by wind can reproduce the variability of snow accumulation and ablation, ignoring the high levels of atmospheric-moisture content associated with blowing snow results in overestimating surface sublimation, affecting the energy budget of the snowpack; (3) the well-known profile method of calculating turbulent moisture fluxes is not applicable when blowing snow occurs, because moisture gradients are weak due to blowing-snow sublimation, and the impact of measurement uncertainties are strongly amplified in the case of strong winds.

scholarly journals Why Does Air Passage over Forest Yield More Rain? Examining the Coupling between Rainfall, Pressure, and Atmospheric Moisture Content*

2014 ◽  
Vol 15 (1) ◽  
pp. 411-426 ◽  
Author(s):  
A. M. Makarieva ◽  
V. G. Gorshkov ◽  
D. Sheil ◽  
A. D. Nobre ◽  
P. Bunyard ◽  
...  
Keyword(s):  
Moisture Content ◽  
Forest Cover ◽  
Meteorological Data ◽  
Circulation Pattern ◽  
Forest Loss ◽  
Amazon Forest ◽  
Atmospheric Moisture ◽  
Wet Season ◽  
Atmospheric Moisture Content ◽  
Rainy Days

Abstract The influence of forest loss on rainfall remains poorly understood. Addressing this challenge, Spracklen et al. recently presented a pantropical study of rainfall and land cover that showed that satellite-derived rainfall measures were positively correlated with the degree to which model-derived air trajectories had been exposed to forest cover. This result confirms the influence of vegetation on regional rainfall patterns suggested in previous studies. However, the conclusion of Spracklen et al.—that differences in rainfall reflect air moisture content resulting from evapotranspiration while the circulation pattern remains unchanged—appears undermined by methodological inconsistencies. Here methodological problems are identified with the underlying analyses and the quantitative estimates for rainfall change predicted if forest cover is lost in the Amazon. Alternative explanations are presented that include the distinct role of forest evapotranspiration in creating low-pressure systems that draw moisture from the oceans to the continental hinterland. A wholly new analysis of meteorological data from three regions in Brazil, including the central Amazon forest, reveals a tendency for rainy days during the wet season with column water vapor (CWV) exceeding 50 mm to have higher pressure than rainless days, while at lower CWV, rainy days tend to have lower pressure than rainless days. The coupling between atmospheric moisture content and circulation dynamics underlines that the danger posed by forest loss is greater than suggested by consideration of moisture recycling alone.

scholarly journals Increase in Near-Surface Atmospheric Moisture Content due to Land Use Changes: Evidence from the Observed Dewpoint Temperature Data

2008 ◽  
Vol 136 (4) ◽  
pp. 1554-1561 ◽  
Author(s):  
Rezaul Mahmood ◽  
Kenneth G. Hubbard ◽  
Ronnie D. Leeper ◽  
Stuart A. Foster
Keyword(s):  
Land Use ◽  
Land Use Change ◽  
Moisture Content ◽  
Great Plains ◽  
Growing Season ◽  
Atmospheric Moisture ◽  
Near Surface ◽  
Dewpoint Temperature ◽  
Atmospheric Moisture Content

Abstract Land use change can significantly affect root zone soil moisture, surface energy balance, and near-surface atmospheric temperature and moisture content. During the second half of the twentieth century, portions of the North American Great Plains have experienced extensive introduction of irrigated agriculture. It is expected that land use change from natural grass to irrigated land use would significantly increase near-surface atmospheric moisture content. Modeling studies have already shown an enhanced rate of evapotranspiration from the irrigated areas. The present study analyzes observed dewpoint temperature (Td) to assess the affect of irrigated land use on near-surface atmospheric moisture content. This investigation provides a unique opportunity to use long-term (1982–2003) mesoscale Td data from the Automated Weather Data Network of the high plains. Long-term daily Td data from 6 nonirrigated and 11 irrigated locations have been analyzed. Daily time series were developed from the hourly data. The length of time series was the primary factor in selection of these stations. Results suggest increase in growing-season Td over irrigated areas. For example, average growing-season Td due to irrigation can be up to 1.56°C higher relative to nonirrigated land uses. It is also found that Td for individual growing-season month at irrigated locations can be increased up to 2.17°C by irrigation. Based on the results, it is concluded that the land use change in the Great Plains has modified near-surface moistness.

scholarly journals Future humidity trends over the western United States in the CMIP5 global climate models and variable infiltration capacity hydrological modeling system

2012 ◽  
Vol 9 (12) ◽  
pp. 13651-13691 ◽  
Author(s):  
D. W. Pierce ◽  
A. L. Westerling ◽  
J. Oyler
Keyword(s):  
Moisture Content ◽  
Climate Models ◽  
Global Climate ◽  
Global Climate Models ◽  
Positive Trend ◽  
Atmospheric Moisture ◽  
Variable Infiltration Capacity ◽  
Infiltration Capacity ◽  
Western Us ◽  
Atmospheric Moisture Content

Abstract. Global climate models predict relative humidity (RH) in the western US will decrease at a rate of about 0.1–0.6% per decade, although with seasonal differences (most drying in spring and summer), geographical variability (greater declines in the interior), stronger reductions for greater anthropogenic radiative forcing, and notable spread among the models. Although atmospheric moisture content increases, this is more than compensated for by higher air temperatures, leading to declining RH. Fine-scale hydrological simulations driven by the global model results should reproduce these trends. It is shown that the meteorological algorithms used by the Variable Infiltration Capacity (VIC) hydrological model, when driven by daily Tmin, Tmax, and precipitation (a configuration used in numerous published studies), do not preserve the original global model's humidity trends. Trends are biased positive in the interior western US, so that strong RH decreases are changed to weak decreases, and weak decreases are changed to increases. This happens because the meteorlogical algorithms VIC incorporates infer an overly large positive trend in atmospheric moisture content in this region. The result could downplay the effects of decreasing RH on plants and wildfire. RH trends along the coast have a weak negative bias due to neglect of the ocean's moderating influence. A numerical experiment where VIC's values of Tdew are altered to compensate for the RH error suggests that eliminating the atmospheric moisture bias could, in and of itself, decrease runoff up to 14% in high-altitude regions east of the Sierra Nevada and Cascades, and reduce estimated Colorado River runoff at Lees Ferry up to 4 % by the end of the century.

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