scholarly journals Variations of U.S. Regional Precipitation and Simulations by the NCEP CFS: Focus on the Southwest

2009 ◽  
Vol 22 (12) ◽  
pp. 3211-3231 ◽  
Author(s):  
Song Yang ◽  
Yundi Jiang ◽  
Dawei Zheng ◽  
R. Wayne Higgins ◽  
Qin Zhang ◽  
...  
Keyword(s):  
United States ◽  
Atmospheric Circulation ◽  
Annual Cycle ◽  
West Coast ◽  
Time Scale ◽  
Gulf Coast ◽  
The United States ◽  
The West ◽  
Western Atlantic ◽  
Precipitation Seasonality

Abstract Variations of U.S. regional precipitation in both observations and free-run experiments with the NCEP Climate Forecast System (CFS) are investigated. The seasonality of precipitation over the continental United States and the time–frequency characteristics of precipitation over the Southwest (SW) are the focus. The differences in precipitation variation among different model resolutions are also analyzed. The spatial distribution of U.S. precipitation is characterized by high values over the East and the West Coasts, especially over the Gulf Coast and southeast states, and low values elsewhere except over the SW in summer. A large annual cycle of precipitation occurs over the SW, northern plains, and the West Coast. Overall, the CFS captures the above features reasonably well, except for the SW. However, it overestimates the precipitation over the western United States, except the SW in summer, and underestimates the precipitation over the central South, except in springtime. It also overestimates (underestimates) the precipitation seasonality over the intermountain area and Gulf Coast states (SW, West Coast, and northern Midwest). The model using T126 resolution captures the observed features more realistically than at the lower T62 resolution over a large part of the United States. The variability of observed SW precipitation is characterized by a large annual cycle, followed by a semiannual cycle, and the oscillating signals on annual, semiannual, and interannual time scales account for 41% of the total precipitation variability. However, the CFS, at both T62 and T126 resolution, fails in capturing the above feature. The variability of SW precipitation in the CFS is much less periodic. The annual oscillation of model precipitation is much weaker than that observed and it is even much weaker than the simulated semiannual oscillation. The weakly simulated annual cycle is attributed by the unrealistic precipitation simulations of all seasons, especially spring and summer. On the annual time scale, the CFS fails in simulating the relationship between the SW precipitation and the basinwide sea surface temperature (SST) and the overlying atmospheric circulation. On the semiannual time scale, the model exaggerates the response of the regional precipitation to the variations of SST and atmospheric circulation over the tropics and western Atlantic, including the Gulf of Mexico. This study also demonstrates a challenge for the next-generation CFS, at T126 resolution, to predict the variability of North American monsoon climate.

Characterizing Predictability of Precipitation Means and Extremes over the Conterminous United States, 1949–2010*

2016 ◽  
Vol 29 (7) ◽  
pp. 2621-2633 ◽  
Author(s):  
Mingkai Jiang ◽  
Benjamin S. Felzer ◽  
Dork Sahagian
Keyword(s):  
United States ◽  
Pacific Northwest ◽  
West Coast ◽  
Climate Models ◽  
Regional Climate ◽  
Regional Climate Models ◽  
The United States ◽  
Monthly Precipitation ◽  
The West ◽  
Precipitation Seasonality

Abstract The proper understanding of precipitation variability, seasonality, and predictability are important for effective environmental management. Precipitation and its associated extremes vary in magnitude and duration both spatially and temporally, making it one of the most challenging climate parameters to predict on the basis of global and regional climate models. Using information theory, an improved understanding of precipitation predictability in the conterminous United States over the period of 1949–2010 is sought based on a gridded monthly precipitation dataset. Predictability is defined as the recurrent likelihood of patterns described by the metrics of magnitude variability and seasonality. It is shown that monthly mean precipitation and duration-based dry and wet extremes are generally highly variable in the east compared to those in the west, while the reversed spatial pattern is observed for intensity-based wetness indices except along the Pacific Northwest coast. It is thus inferred that, over much of the U.S. landscape, variations of monthly mean precipitation are driven by the variations in precipitation occurrences rather than the intensity of infrequent heavy rainfall. It is further demonstrated that precipitation seasonality for means and extremes is homogeneously invariant within the United States, with the exceptions of the West Coast, Florida, and parts of the Midwest, where stronger seasonality is identified. A proportionally higher role of variability in regulating precipitation predictability is demonstrated. Seasonality surpasses variability only in parts of the West Coast. The quantified patterns of predictability for precipitation means and extremes have direct applications to those phenomena influenced by climate periodicity, such as biodiversity and ecosystem management.

scholarly journals A Climatology of 500-hPa Closed Lows in the Northeastern Pacific Ocean, 1948–2011

2014 ◽  
Vol 53 (6) ◽  
pp. 1578-1592 ◽  
Author(s):  
Nina S. Oakley ◽  
Kelly T. Redmond
Keyword(s):  
United States ◽  
Pacific Ocean ◽  
Interannual Variability ◽  
West Coast ◽  
The United States ◽  
Western United States ◽  
The West ◽  
Reanalysis Dataset ◽  
The Pacific ◽  
Northeastern Pacific

AbstractThe northeastern Pacific Ocean is a preferential location for the formation of closed low pressure systems. These slow-moving, quasi-barotropic systems influence vertical stability and sustain a moist environment, giving them the potential to produce or affect sustained precipitation episodes along the west coast of the United States. They can remain motionless or change direction and speed more than once and thus often pose difficult forecast challenges. This study creates an objective climatological description of 500-hPa closed lows to assess their impacts on precipitation in the western United States and to explore interannual variability and preferred tracks. Geopotential height at 500 hPa from the NCEP–NCAR global reanalysis dataset was used at 6-h and 2.5° × 2.5° resolution for the period 1948–2011. Closed lows displayed seasonality and preferential durations. Time series for seasonal and annual event counts were found to exhibit strong interannual variability. Composites of the tracks of landfalling closed lows revealed preferential tracks as the features move inland over the western United States. Correlations of seasonal event totals for closed lows with ENSO indices, the Pacific decadal oscillation (PDO), and the Pacific–North American (PNA) pattern suggested an above-average number of events during the warm phase of ENSO and positive PDO and PNA phases. Precipitation at 30 U.S. Cooperative Observer stations was attributed to closed-low events, suggesting 20%–60% of annual precipitation along the West Coast may be associated with closed lows.

Last Years

2018 ◽  
pp. 376-386
Author(s):  
Robert E. Lerner
Keyword(s):  
United States ◽  
West Coast ◽  
The United States ◽  
Virgin Islands ◽  
Ruptured Aneurysm ◽  
Nuclear War ◽  
The West ◽  
Richard Nixon ◽  
The 1950S

This chapter details Ernst Kantorowicz's final years. Kantorowicz died of a ruptured aneurysm in September 1963. Before this, he worked on a succession of recondite articles, attended the annual meetings of the Medieval Academy and the Byzantine Institute at “Oakbarton Dumps,” vacationed on the West Coast and the Virgin Islands, and carried on earnestly with his dining and imbibing. His politics also became more leftward from the postwar years until the time of his death. For a decade and a half he was deeply worried about the possibility of nuclear war, and he held the United States responsible. During the 1950s, he was bitterly hostile to Dwight Eisenhower and Richard Nixon. On the day after Kennedy's inauguration, Kantorowicz wrote the he “couldn't be worse than Eisenhower, ” although he did change his mind.

From the Gulf to the Courts

2017 ◽  
Author(s):  
Stephanie Hinnershitz
Keyword(s):  
United States ◽  
Civil Rights ◽  
Gulf Of Mexico ◽  
Great Lakes ◽  
Vietnam War ◽  
West Coast ◽  
The United States ◽  
District Court ◽  
The West ◽  
Family Connections

The wreckage of the Vietnam War and new American polices geared toward resettling refugees brought thousands of Vietnamese to the United States. Although many Vietnamese settled on the West Coast and in the Great Lakes region, thousands more came to the Gulf of Mexico through sponsors or established family connections seeking work in the shrimping or oil industries of Alabama, Louisiana, Mississippi, and Texas. But, as the Vietnamese soon discovered, they were not welcomed by the largely white population who feared competition and distrusted racial outsiders. The Vietnamese fought back in the Houston District Court, filing a civil rights suit against the Klan with the assistance of the Southern Poverty Law Center.

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