Changes in the convective population and thermodynamic environments in convection-permitting regional climate simulations over the United States

Abstract Numerical models have long predicted that the deforestation of the Amazon would lead to large regional changes in precipitation and temperature, but the extratropical effects of deforestation have been a matter of controversy. This paper investigates the simulated impacts of deforestation on the northwest United States December–February climate. Integrations are carried out using the Ocean–Land–Atmosphere Model (OLAM), here run as a variable-resolution atmospheric GCM, configured with three alternative horizontal grid meshes: 1) 25-km characteristic length scale (CLS) over the United States, 50-km CLS over the Andes and Amazon, and 200-km CLS in the far-field; 2) 50-km CLS over the United States, 50-km CLS over the Andes and Amazon, and 200-km CLS in the far-field; and 3) 200-km CLS globally. In the high-resolution simulations, deforestation causes a redistribution of precipitation within the Amazon, accompanied by vorticity and thermal anomalies. These anomalies set up Rossby waves that propagate into the extratropics and impact western North America. Ultimately, Amazon deforestation results in 10%–20% precipitation reductions for the coastal northwest United States and the Sierra Nevada. Snowpack in the Sierra Nevada experiences declines of up to 50%. However, in the coarse-resolution simulations, this mechanism is not resolved and precipitation is not reduced in the northwest United States. These results highlight the need for adequate model resolution in modeling the impacts of Amazon deforestation. It is concluded that the deforestation of the Amazon can act as a driver of regional climate change in the extratropics, including areas of the western United States that are agriculturally important.

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On the Potential Change in Surface Water Vapor Deposition over the Continental United States due to Increases in Atmospheric Greenhouse Gases

Journal of Climate ◽

10.1175/jcli3693.1 ◽

2006 ◽

Vol 19 (8) ◽

pp. 1576-1585

Author(s):

Zaitao Pan ◽

Moti Segal ◽

Charles Graves

Keyword(s):

United States ◽

Water Vapor ◽

Surface Water ◽

Vapor Deposition ◽

Climate Model ◽

Regional Climate ◽

Climate Scenario ◽

The United States ◽

Eastern United States ◽

Present Climate

Abstract Characteristics of surface water vapor deposition (WVD) over the continental United States under the present climate and a future climate scenario reflecting the mid-twenty-first-century increased greenhouse gas concentrations were evaluated by using a regional climate model forced by initial and lateral boundary conditions generated by a GCM. Simulated seasonal WVD frequency and daily amounts are presented and elaboration on their relation to potential surface dew/frost is also provided. The climate scenario showed in winter a noticeable decline in WVD frequency over snow-covered areas in the Midwest and over most of the elevated terrain in the western United States, contrasted by an overall increase in the eastern United States. In summer, a decline in frequency was simulated for most of the United States, particularly over the mountains in the west. A spatially mixed trend of change in the frequency was indicated in spring and fall. The trend of change in WVD amount resembled that of the frequency in summer, whereas a largely reversed relation was shown in winter. Quantitatively, changes in frequency and amount of WVD in the range of −30% to +30% generally were indicated for all locations and seasons, except for the western half of the United States, where the change was larger in summer. While areas passing a local statistical test on WVD changes ranged from 11% to 36% of land domain, the WVD differences as a whole field between present climate and future scenarios are significant.

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A sensitivity study of high-resolution regional climate simulations to three land surface models over the western United States

Journal of Geophysical Research Atmospheres ◽

10.1002/2014jd021827 ◽

2014 ◽

Vol 119 (12) ◽

pp. 7271-7291 ◽

Cited By ~ 31

Author(s):

Feng Chen ◽

Changhai Liu ◽

Jimy Dudhia ◽

Ming Chen

Keyword(s):

United States ◽

High Resolution ◽

Land Surface ◽

Regional Climate ◽

Sensitivity Study ◽

Western United States ◽

Land Surface Models ◽

Climate Simulations ◽

Surface Models

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Baseline Conditions and Projected Future Hydro-Climatic Change in National Parks in the Conterminous United States

Water ◽

10.3390/w12061704 ◽

2020 ◽

Vol 12 (6) ◽

pp. 1704

Author(s):

William Battaglin ◽

Lauren Hay ◽

David Lawrence ◽

Greg McCabe ◽

Parker Norton

Keyword(s):

United States ◽

Climatic Change ◽

National Park ◽

General Circulation ◽

Circulation Model ◽

The United States ◽

Climatic Conditions ◽

Balance Model ◽

Climate Simulations ◽

Baseline Conditions

The National Park Service (NPS) manages hundreds of parks in the United States, and many contain important aquatic ecosystems and/or threatened and endangered aquatic species vulnerable to hydro-climatic change. More effective management of park resources under future hydro-climatic uncertainty requires information on both baseline conditions and the range of projected future conditions. A monthly water balance model was used to assess baseline (1981–1999) conditions and a range of projected future hydro-climatic conditions in 374 NPS parks. General circulation model outputs representing 214 future climate simulations were used to drive the model. Projected future changes in air temperature (T), precipitation (p), and runoff (R) are expressed as departures from historical baselines. Climate simulations indicate increasing T by 2030 for all parks with 50th percentile simulations projecting increases of 1.67 °C or more in 50% of parks. Departures in 2030 p indicate a mix of mostly increases and some decreases, with 50th percentile simulations projecting increases in p in more than 70% of parks. Departures in R for 2030 are mostly decreases, with the 50th percentile simulations projecting decreases in R in more than 50% of parks in all seasons except winter. Hence, in many NPS parks, R is projected to decrease even when p is projected to increase because of increasing T in all parks. Projected changes in future hydro-climatic conditions can also be assessed for individual parks, and Rocky Mountain National Park and Congaree National Park are used as examples.

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Regional climate simulations over the continental United States during the summer of 1988 driven by a GCM and the ECMWF analyses

Global and Planetary Change ◽

10.1016/s0921-8181(00)00019-9 ◽

2000 ◽

Vol 25 (1-2) ◽

pp. 19-38 ◽

Cited By ~ 4

Author(s):

Gregory S Jenkins ◽

Eric J Barron

Keyword(s):

United States ◽

Regional Climate ◽

Climate Simulations

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A Maieutic Exploration of Nudging Strategies for Regional Climate Applications Using the WRF Model

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-17-0360.1 ◽

2018 ◽

Vol 57 (8) ◽

pp. 1883-1906 ◽

Cited By ~ 6

Author(s):

Tanya L. Spero ◽

Christopher G. Nolte ◽

Megan S. Mallard ◽

Jared H. Bowden

Keyword(s):

United States ◽

Climate Models ◽

Weather Prediction ◽

Regional Climate ◽

Wrf Model ◽

Regional Climate Models ◽

The United States ◽

Spectral Nudging ◽

Temperature And Precipitation ◽

Quality Health

AbstractThe use of nudging in the Weather Research and Forecasting (WRF) Model to constrain regional climate downscaling simulations is gaining in popularity because it can reduce error and improve consistency with the driving data. While some attention has been paid to whether nudging is beneficial for downscaling, very little research has been performed to determine best practices. In fact, many published papers use the default nudging configuration (which was designed for numerical weather prediction), follow practices used by colleagues, or adapt methods developed for other regional climate models. Here, a suite of 45 three-year simulations is conducted with WRF over the continental United States to systematically and comprehensively examine a variety of nudging strategies. The simulations here use a longer test period than did previously published works to better evaluate the robustness of each strategy through all four seasons, through multiple years, and across nine regions of the United States. The analysis focuses on the evaluation of 2-m temperature and precipitation, which are two of the most commonly required downscaled output fields for air quality, health, and ecosystems applications. Several specific recommendations are provided to effectively use nudging in WRF for regional climate applications. In particular, spectral nudging is preferred over analysis nudging. Spectral nudging performs best in WRF when it is used toward wind above the planetary boundary layer (through the stratosphere) and temperature and moisture only within the free troposphere. Furthermore, the nudging toward moisture is very sensitive to the nudging coefficient, and the default nudging coefficient in WRF is too high to be used effectively for moisture.

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