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Title: Observed and Projected Precipitation Changes over the Nine US Climate Regions

Abstract

Here, we analyze the past (1900–2015) temperature and precipitation changes in nine separate US climate regions. We find that the temperature increased in a statistically significant (95% confidence level equivalent to alpha level of 0.05) manner in all of these regions. However, the variability in the observed precipitation was much more complex. In the eastern US (east of Rocky Mountains), the precipitation increased in all five climate regions and the increase was statistically significant in three of them. In contract, in the western US, the precipitation increased in two regions and decreased in two with no statistical significance in any region. The CMIP5 climate models (an ensemble mean) were not able to capture properly either the large precipitation differences between the eastern and the western US, or the changes of precipitation between 1900 and 2015 in eastern US. The statistical regression model explains the differences between the eastern and western US precipitation as results of different significant predictors. The anthropogenic greenhouse gases and aerosol (GHGA) are the major forcing of the precipitation in the eastern part of US, while the Pacific Decadal Oscillation (PDO) has the major influence on precipitation in the western part of the US. This analysis suggestsmore » that the precipitation over the eastern US increased at an approximate rate of 6.7%/K, in agreement with the Clausius-Clapeyron equation, while the precipitation of the western US was approximately constant, independent of the temperature. Future precipitation over the western part of the US will depend on the behavior of the PDO, and how it (PDO) may be affected by future warming. Low hydrological sensitivity (percent increase of precipitation per one K of warming) projected by the CMIP5 models for the eastern US suggests either an underestimate of future precipitation or an overestimate of future warming.« less

Authors:
 [1];  [2];  [3];  [4]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Earth and Environmental Sciences; New Mexico State Univ., Las Cruces, NM (United States). Dept. of Physics
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Earth and Environmental Sciences
  3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Biology and Biophysics
  4. New Mexico State Univ., Las Cruces, NM (United States). Dept. of Physics
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1406227
Report Number(s):
LA-UR-17-25198
Journal ID: ISSN 2073-4433; ATMOCZ
Grant/Contract Number:
AC52-06NA25396
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Atmosphere (Basel)
Additional Journal Information:
Journal Name: Atmosphere (Basel); Journal Volume: 8; Journal Issue: 11; Journal ID: ISSN 2073-4433
Publisher:
MDPI
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; Planetary Sciences

Citation Formats

Chylek, Petr, Dubey, Manvendra, Hengartner, Nicholas, and Klett, James. Observed and Projected Precipitation Changes over the Nine US Climate Regions. United States: N. p., 2017. Web. doi:10.3390/atmos8110207.
Chylek, Petr, Dubey, Manvendra, Hengartner, Nicholas, & Klett, James. Observed and Projected Precipitation Changes over the Nine US Climate Regions. United States. doi:10.3390/atmos8110207.
Chylek, Petr, Dubey, Manvendra, Hengartner, Nicholas, and Klett, James. 2017. "Observed and Projected Precipitation Changes over the Nine US Climate Regions". United States. doi:10.3390/atmos8110207. https://www.osti.gov/servlets/purl/1406227.
@article{osti_1406227,
title = {Observed and Projected Precipitation Changes over the Nine US Climate Regions},
author = {Chylek, Petr and Dubey, Manvendra and Hengartner, Nicholas and Klett, James},
abstractNote = {Here, we analyze the past (1900–2015) temperature and precipitation changes in nine separate US climate regions. We find that the temperature increased in a statistically significant (95% confidence level equivalent to alpha level of 0.05) manner in all of these regions. However, the variability in the observed precipitation was much more complex. In the eastern US (east of Rocky Mountains), the precipitation increased in all five climate regions and the increase was statistically significant in three of them. In contract, in the western US, the precipitation increased in two regions and decreased in two with no statistical significance in any region. The CMIP5 climate models (an ensemble mean) were not able to capture properly either the large precipitation differences between the eastern and the western US, or the changes of precipitation between 1900 and 2015 in eastern US. The statistical regression model explains the differences between the eastern and western US precipitation as results of different significant predictors. The anthropogenic greenhouse gases and aerosol (GHGA) are the major forcing of the precipitation in the eastern part of US, while the Pacific Decadal Oscillation (PDO) has the major influence on precipitation in the western part of the US. This analysis suggests that the precipitation over the eastern US increased at an approximate rate of 6.7%/K, in agreement with the Clausius-Clapeyron equation, while the precipitation of the western US was approximately constant, independent of the temperature. Future precipitation over the western part of the US will depend on the behavior of the PDO, and how it (PDO) may be affected by future warming. Low hydrological sensitivity (percent increase of precipitation per one K of warming) projected by the CMIP5 models for the eastern US suggests either an underestimate of future precipitation or an overestimate of future warming.},
doi = {10.3390/atmos8110207},
journal = {Atmosphere (Basel)},
number = 11,
volume = 8,
place = {United States},
year = 2017,
month =
}

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