Evaluation of SMAP Freeze/Thaw Retrieval Accuracy at Core Validation Sites in the Contiguous United States

Seasonal freeze-thaw (FT) impacts much of the northern hemisphere and is an important control on its water, energy, and carbon cycle. Although FT in natural environments extends south of 45°N, FT studies using the L-band have so far been restricted to boreal or greater latitudes. This study addresses this gap by applying a seasonal threshold algorithm to Soil Moisture Active Passive (SMAP) data (L3_SM_P) to obtain a FT product south of 45°N (‘SMAP FT’), which is then evaluated at SMAP core validation sites (CVS) located in the contiguous United States (CONUS). SMAP landscape FT retrievals are usually in good agreement with 0–5 cm soil temperature at SMAP grids containing CVS stations (>70%). The accuracy could be further improved by taking into account specific overpass time (PM), the grid-specific seasonal scaling factor, the data aggregation method, and the sampling error. Annual SMAP FT extent maps compared to modeled soil temperatures derived from the Goddard Earth Observing System Model Version 5 (GEOS-5) show that seasonal FT in CONUS extends to latitudes of about 35–40°N, and that FT varies substantially in space and by year. In general, spatial and temporal trends between SMAP and modeled FT were similar.

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Spatial Disparities of COVID-19 Cases and Fatalities in United States Counties

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18168259 ◽

2021 ◽

Vol 18 (16) ◽

pp. 8259

Author(s):

Sarah L. Jackson ◽

Sahar Derakhshan ◽

Leah Blackwood ◽

Logan Lee ◽

Qian Huang ◽

...

Keyword(s):

United States ◽

Great Plains ◽

Explanatory Power ◽

Temporal Trends ◽

The United States ◽

First Year ◽

Significant Case ◽

Urban Rural ◽

Spatial And Temporal Trends ◽

Mitigation Policies

This paper examines the spatial and temporal trends in county-level COVID-19 cases and fatalities in the United States during the first year of the pandemic (January 2020–January 2021). Statistical and geospatial analyses highlight greater impacts in the Great Plains, Southwestern and Southern regions based on cases and fatalities per 100,000 population. Significant case and fatality spatial clusters were most prevalent between November 2020 and January 2021. Distinct urban–rural differences in COVID-19 experiences uncovered higher rural cases and fatalities per 100,000 population and fewer government mitigation actions enacted in rural counties. High levels of social vulnerability and the absence of mitigation policies were significantly associated with higher fatalities, while existing community resilience had more influential spatial explanatory power. Using differences in percentage unemployment changes between 2019 and 2020 as a proxy for pre-emergent recovery revealed urban counties were hit harder in the early months of the pandemic, corresponding with imposed government mitigation policies. This longitudinal, place-based study confirms some early urban–rural patterns initially observed in the pandemic, as well as the disparate COVID-19 experiences among socially vulnerable populations. The results are critical in identifying geographic disparities in COVID-19 exposures and outcomes and providing the evidentiary basis for targeting pandemic recovery.

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Spatial and temporal trends of precipitation chemistry in the United States, 1985–2002

Environmental Pollution ◽

10.1016/j.envpol.2004.11.016 ◽

2005 ◽

Vol 135 (3) ◽

pp. 347-361 ◽

Cited By ~ 102

Author(s):

Christopher M.B. Lehmann ◽

Van C. Bowersox ◽

Susan M. Larson

Keyword(s):

United States ◽

Temporal Trends ◽

The United States ◽

Precipitation Chemistry ◽

Spatial And Temporal Trends

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Temporal and spatial variations in freeze warnings in the conterminous United States: 2005–2018

Theoretical and Applied Climatology ◽

10.1007/s00704-019-03056-8 ◽

2019 ◽

Vol 139 (3-4) ◽

pp. 1379-1384

Author(s):

Brandon Lawhorn ◽

Robert C. Balling

Keyword(s):

United States ◽

Temporal Trends ◽

The United States ◽

Temporal Variations ◽

Atmospheric Composition ◽

Southeastern Us ◽

The Us ◽

Temporal And Spatial ◽

Frost Free Period ◽

Spatial And Temporal Trends

AbstractIt is well-documented that the United States (US), along with other mid-latitude land locations, has experienced warming in recent decades in response to changes in atmospheric composition. Among other changes, Easterling (2002) reported that the frost-free period is now longer across much of the US with the first frost in fall occurring later and the last freeze in spring occurring earlier. In this investigation, we explore spatial and temporal variations in all freeze warnings issued by the US National Weather Service. Freeze warning counts are highest in the southeastern US peaking overall in the spring and fall months. Freeze warnings tend to occur more toward summer moving northward and westward into more northerly states. Consistent with the warming in recent decades, we find statistically significant northward movements in freeze warning centroids in some months (December, February) across the study period (2005–2018). Detection of spatial and temporal trends in freeze warnings may be of interest to any number of scientists with applied climatological interests.

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Spatial and Temporal Trends in PM2.5Organic and Elemental Carbon across the United States

Advances in Meteorology ◽

10.1155/2013/367674 ◽

2013 ◽

Vol 2013 ◽

pp. 1-13 ◽

Cited By ~ 51

Author(s):

J. L. Hand ◽

B. A. Schichtel ◽

W. C. Malm ◽

N. H. Frank

Keyword(s):

United States ◽

Elemental Carbon ◽

Temporal Trends ◽

The United States ◽

Carbonaceous Aerosols ◽

Eastern United States ◽

The West ◽

Urban Impacts ◽

Rural And Urban ◽

Spatial And Temporal Trends

The rural/remote IMPROVE network (Interagency Monitoring of Protected Visual Environments) and the Environmental Protection Agency's urban Chemical Speciation Network have measured PM2.5organic (OC) and elemental carbon (EC) since 1989 and 2000, respectively. We aggregated OC and EC data from 2007 to 2010 at over 300 sites from both networks in order to characterize the spatial and seasonal patterns in rural and urban carbonaceous aerosols. The spatial extent of OC and EC was more regional in the eastern United States relative to more localized concentrations in the West. The highest urban impacts of OC and EC relative to background concentrations occurred in the West during fall and winter. Urban and rural carbonaceous aerosols experienced a large (although opposite) range in seasonality in the West compared to a much lower seasonal variability in the East. Long-term (1990–2010) trend analyses indicated a widespread decrease in rural TC (TC = OC + EC) across the country, with positive, though insignificant, trends in the summer and fall in the West. Short-term trends indicated that urban and rural TC concentrations have both decreased since 2000, with the strongest and more spatially homogeneous urban and rural trends in the West relative to the East.

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Spatial and Temporal Trends in Sunshine Duration over Western Europe (1938–2004)

Journal of Climate ◽

10.1175/2008jcli2442.1 ◽

2008 ◽

Vol 21 (22) ◽

pp. 6089-6098 ◽

Cited By ~ 88

Author(s):

Arturo Sanchez-Lorenzo ◽

Josep Calbó ◽

Javier Martin-Vide

Keyword(s):

Western Europe ◽

Sunshine Duration ◽

Linear Trend ◽

Temporal Trends ◽

Principal Component ◽

Annual Series ◽

Remarkable Result ◽

Seasonal Analysis ◽

Spatial And Temporal Trends ◽

Good Agreement

Abstract This work analyzes sunshine duration variability in the western part of Europe (WEU) over the 1938–2004 period. A principal component analysis is applied to cluster the original series from 79 sites into 6 regions, and then annual and seasonal mean series are constructed on regional and also for the whole WEU scales. Over the entire period studied here, the linear trend of annual sunshine duration is found to be nonsignificant. However, annual sunshine duration shows an overall decrease since the 1950s until the early 1980s, followed by a subsequent recovery during the last two decades. This behavior is in good agreement with the dimming and brightening phenomena described in previous literature. From the seasonal analysis, the most remarkable result is the similarity between spring and annual series, although the spring series has a negative trend; and the clear significant increase found for the whole WEU winter series, being especially large since the 1970s. The behavior of the major synoptic patterns for two seasons is investigated, resulting in some indications that sunshine duration evolution may be partially explained by changes in the frequency of some of them.

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Impacts of Historic Climate Variability on Seasonal Soil Frost in the Midwestern United States

Journal of Hydrometeorology ◽

10.1175/2009jhm1141.1 ◽

2010 ◽

Vol 11 (2) ◽

pp. 229-252 ◽

Cited By ~ 23

Author(s):

Tushar Sinha ◽

Keith A. Cherkauer ◽

Vimal Mishra

Keyword(s):

United States ◽

Climate Variability ◽

Soil Temperature ◽

Cold Season ◽

Soil Frost ◽

Midwestern United States ◽

Model Simulations ◽

Freeze Thaw ◽

Soil Temperatures ◽

Frost Depth

Abstract The present study examines the effects of historic climate variability on cold-season processes, including soil temperature, frost depth, and the number of frost days and freeze–thaw cycles. Considering the importance of spatial and temporal variability in cold-season processes, the study was conducted in the midwestern United States using both observations and model simulations. Model simulations used the Variable Infiltration Capacity (VIC) land surface model (LSM) to reconstruct and to analyze changes in the long-term (i.e., 1917–2006) means of soil frost variables. The VIC model was calibrated using observed streamflow records and near-surface soil temperatures and then evaluated for streamflow, soil temperature, frost depth, and soil moisture before its application at the regional scale. Soil frost indicators—such as the number of frost days and freeze–thaw cycles—were determined from observed records and were tested for the presence of significant trends. Overall trends in extreme and mean seasonal soil temperature from 1967 onward indicated a warming of soil temperatures at a depth of 10 cm—specifically in northwest Indiana, north-central Illinois, and southeast Minnesota—leading to a reduction in the number of soil frost days. Model simulations indicated that by the late-century period (1977–2006), soil frost duration decreased by as much as 36 days compared to the midcentury period (1947–76). Spatial averages for the study area in warm years indicated shallower frost penetration by 15 cm and greater soil temperatures by about 3°C at 10-cm soil depth than in the cold years.

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