USGS Science⌕ Search
Home/Archive/USGS

USGS · 70016863

General circulation model simulations of winter and summer sea-level pressures over North America

G. J. McCabe·D.R. Legates
View original source ↗Export metadata ↓

Abstract

Temporal variability of synoptic-scale circulation is a dominant factor in regional temporal climate variations. In the midlatitudes, temporal variability of synoptic-scale circulation has been found to be related to temporal variations in regional air temperature and precipitation. General circulation model (GCM) simulations of long-term changes in synoptic-scale circulation may be useful in assessing the effects of climate change on regional air temperature and precipitation. Atmospheric pressure is an important component of synoptic-scale circulation. In this paper, observed sea-level pressures were used to evaluate winter and summer sea-level pressures over North America simulated by the Goddard Institute for Space Studies (GISS) and the Geophysical Fluid Dynamics Laboratory (GFDL) general circulation models. The objective of the study is to determine how similar the spatial and temporal distributions of GCM-simulated daily sea-level pressures over North America are to observed distributions. Overall, both models are better at reproducing observed within-season variance of winter and summer sea-level pressures than they are at simulating the magnitude of mean winter and summer sea-level pressures. Results indicate that winter sea-level pressures are better simulated by the GISS model than by the GFDL model. The GFDL model simulates anomalously high winter sea-level pressures over north-eastern North America. In summer, the GISS model underestimates sea-level pressures, whereas the GFDL model overestimates sea-level pressures over most of North America. Kolmogorov-Smirnov tests indicate that much of the error in model simulations can be attributed to differences between simulated and observed means. Comparisons of spatial correlation matrices of observed and simulated sea-level pressures indicate that GCMs simulate spatial variability of sea-level pressures that is similar to observed. These results suggest that GCMs are able to simulate major components of synoptic-scale circulation over North America, especially for winter.

Explore related subjects

International Journal of ClimatologyArticle

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

G. J. McCabe, D.R. Legates. 2006-11-29. General circulation model simulations of winter and summer sea-level pressures over North America. https://doi.org/10.1002/joc.3370120805

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related USGS reports

USGS2026

Tropicalization of the temperate zone: Spatiotemporal variability of winter warming and declining freeze days across the United States

We investigate changes in cool-season and winter daily minimum (T min ) and maximum (T max ) temperatures, and the occurrence of freeze days, from 1952 to 2024 across the conterminous United States (CONUS). Emphasis is placed on the tropical-temperate transition zone (TTTz) in the southeastern CONUS. During winter, ~70% of the land area exhibited T min warming rates exceeding those of T max . The countywide coldest T min became milder across 57% of the CONUS, while the coldest T max showed little change and even cooled east of the Rocky Mountains in the central CONUS. Across the TTTz, 75% of freeze days occur within a ~25–100-day window, often fewer than 75 days in the southernmost areas. Approximately 80% of counties exhibited significant contractions in freeze-day concentration, with the largest and most spatially consistent changes occurring in the Southeast, primarily driven by later start dates. Roughly 85% of the CONUS experienced a significant decline in freeze days, with the largest relative declines in regions where average winter T min is above freezing, while parts of the Pacific Northwest showed no significant change. An analysis of freeze day isopleths (30, 45, 60 and 75 days) across 20-year periods showed that the mean latitude of freeze days has migrated poleward substantially. Between 101° W and 79° W in the TTTz, the 30 freeze-day isopleth for the late period (2005–2024) was, on average, 122 km (~1.1° latitude) farther north than in the early period (1952–1971). Generally, the largest latitudinal shifts and percentage losses in freeze days occurred across low-elevation, low-relief regions at lower latitudes (e.g., the Mississippi River Valley), with abrupt shifts occurring near topographic gradients. Regions with sharp elevational gradients (e.g., Balcones Escarpment, Ouachita Mountains and Tennessee Valley) exhibited smaller temporal changes, likely reflecting the barrier-like influence of higher terrain on the poleward retreat of freeze days.

conterminous United States↗
USGS2022

A hydrologic perspective of major U.S. droughts

Drought is a recurring natural hazard that has substantial human and environmental impacts. Given continued global warming and associated climate change, there is concern that droughts could become more severe and longer lasting. To better monitor and understand drought development and persistence, it is helpful to understand the development and climatic drivers of past droughts. In this study we use monthly runoff percentiles to identify five major drought events in the conterminous United States (CONUS) from 1901 through 2020. For each drought event we examined spatial patterns of departures of mean monthly precipitation, temperature, soil moisture storage, and runoff for 2,107 hydrologic units (HUs) across the CONUS. Results indicated that precipitation deficits have been the primary driver of past major-drought events and temperature a secondary driver, even of the most recent drought event (September 1999 through September 2015) when positive temperature anomalies occurred over most of the CONUS. Additionally, negative soil moisture storage departures were more negative than runoff departures during the five drought events we examined, which emphasizes the importance of measuring both runoff and soil moisture to monitor drought conditions. We also examined the use of statistical persistence to develop short-term (i.e., 1 month) forecasts of runoff drought conditions in the CONUS by developing autoregressive integrated moving average (ARIMA) models for each HU. Results indicated that persistence can be used to predict short-term changes in the spatial pattern of drought and the areal extent of drought, but that predictions of runoff magnitude for any particular site are often poor.

International Journal of Climatology↗
USGS2021

Multi-year hydroclimatic droughts and pluvials across the conterminous United States

Time series of water‐year runoff for 2,109 hydrologic units (HUs) across the conterminous United States (CONUS) for the 1900 through 2014 period were used to identify drought and pluvial (i.e., wet) periods. Characteristics of the drought and pluvial events including frequency, duration, and severity were examined and compared. Additionally, a similar analysis was performed using gridded tree‐ring reconstructions of the Palmer Drought Severity Index (PDSI) for the period 1475 through 2005 to place the drought and pluvial characteristics determined using water‐year runoff for 1900 through 2014 in the context of multi‐century climate variability. The temporal and spatial variability of droughts and pluvials determined using runoff for the 1900 through 2014 period indicated that most drought events in the CONUS occurred before about 1970, whereas most pluvial periods occurred after about 1970. This change in the frequencies of drought and pluvial events around 1970 was largely related to an increase in fall (October through December) precipitation across much of the central United States. Also, the duration and severity of droughts and pluvials identified using runoff for the 1900 through 2014 period generally were not significantly different from the drought and pluvial characteristics identified using the PDSI for the 1475 through 2005 period.

International Journal of Climatology↗