New Paper “Impacts Of Wind Farms On Land Surface Temperature” By Zhou Et Al 2012 Documents An Effect Of Local And Regional Landscape Change On Long Term Surface Air Temperature Trends

Update April 30 2012  The authors have prepared

Q&A on “Impacts of Wind Farms on Land Surface Temperature” Published by Nature Climate Change on April 29, 2012

**********ORIGINAL POST**********************

In the papers

Walters, J. T., R. T. McNider, X. Shi, W. B Norris, and J. R. Christy (2007): Positive surface temperature feedback in the stable nocturnal boundary layer, Geophys. Res. Lett., 34, L12709, doi:10.1029/2007GL029505

Pielke Sr., R.A., C. Davey, D. Niyogi, S. Fall, J. Steinweg-Woods, K. Hubbard, X. Lin, M. Cai, Y.-K. Lim, H. Li, J. Nielsen-Gammon, K. Gallo, R. Hale, R. Mahmood, S. Foster, R.T. McNider, and P. Blanken, 2007: Unresolved issues with   the assessment of multi-decadal global land surface temperature trends. J. Geophys. Res., 112, D24S08, doi:10.1029/2006JD008229.

Klotzbach, P.J., R.A. Pielke Sr., R.A. Pielke Jr.,  J.R. Christy, and R.T. McNider, 2009: An alternative explanation for differential temperature trends at the  surface and in the lower troposphere. J. Geophys. Res., 114, D21102, doi:10.1029/2009JD011841.

Steeneveld, G.J., A.A.M. Holtslag, R.T. McNider,  and R.A Pielke Sr, 2011: Screen  level temperature increase due to higher atmospheric carbon dioxide in calm and  windy nights revisited. J. Geophys. Res., 116, D02122,   doi:10.1029/2010JD014612.

and in Professor Dick McNider’s powerpoint talk

Response and Sensitivity of the Stable Boundary Layer to Added Downward Long-wave Radiation

and guest weblog

In the Dark of the Night – the Problem with the Diurnal Temperature Range and Climate Change by Richard T. McNider

we present evidence as to why the use of the minimum land surface air temperature should not be used as part of the construction of a global average multi-decadal surface  temperature trend.

As Dick writes in his post

Because of the redistribution phenomena and the shallow layer affected, observed minimum temperatures are a very poor measure of the accumulation of heat in the atmosphere.

In the Pielke et al 2007 paper, we wrote [highlight added]

In a series of papers exploring the nonlinear dynamics of the stable boundary layer [McNider et al., 1995a, 1995b; Shi et al., 2005; Walters et al., 2007] it was shown that in certain parameter spaces the nocturnal boundary layer can rapidly transition from a cold light wind solution to a warm windy solution. In these parameter spaces, even slight changes in longwave radiative forcing or changes in surface heat capacity can cause large changes in surface temperatures as the boundary mixing changes. However, these temperature changes reflect changes in the vertical distribution of heat, not in the heat content of the deep atmosphere.

There is a new paper which confirms this finding that changes in time in the vertical redistribution of heat makes a significant difference to long term trends in minimum temperatures. This paper is

Zhou, Liming, Yuhong Tian, Somnath Baidya Roy, Chris Thorncroft, Lance F. Bosart and Yuanlong Hu 2012: Impacts of wind farms on land surface temperature. Nature Climate Chnage. doi:10.1038/nclimate1505

The abstract reads

The wind industry in the United States has experienced a remarkably rapid expansion of capacity in recent years and this fast growth is expected to continue in the future. While converting wind’s kinetic energy into electricity, wind turbines modify surface–atmosphere exchanges and the transfer of energy, momentum, mass and moisture within the atmosphere. These changes, if spatially large enough, may have noticeable impacts on local to regional weather and climate. Here we present observational evidence for such impacts based on analyses of satellite data for the period of 2003–2011 over a region in west-central Texas, where four of the world’s largest wind farms are located. Our results show a significant warming trend of up to 0.72 °C per decade, particularly at night-time, over wind farms relative to nearby non-wind-farm regions. We attribute this warming primarily to wind farms as its spatial pattern and magnitude couples very well with the geographic distribution of wind turbines.

An excerpt from the conclusions reads

Very probably the diurnal and seasonal variations in wind speed and the changes in near-surface ABL conditions owing to wind-farm operations are primarily responsible for the LST changes described above.

While the Zhou et al 2012 applies to wind farms, such changes in the vertical distribution of mixing of heat will occur whenever land use change, such as urbanization, deforestation, irrigation, etc occurs.

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