Land-Use Change and Microclimate Exposure Effects on Near-Surface Air Temperature Assessments: Unresolved Issues

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1 Land-Use Change and Microclimate Exposure Effects on Near-Surface Air Temperature Assessments: Unresolved Issues Prof. Roger A. Pielke Sr. University of Colorado, CIRES, Boulder, Detecting the Atmospheric Response to the Changing Face of the Earth: A Focus on Human-Caused Regional Climate Forcings, Land-Cover/Land-Use Change, and Data Monitoring August 27-29, 2007 Boulder CO

2 The CCSP Report "Temperature Trends in the Lower Atmosphere: Steps for Understanding and Reconciling Differences" inadequately reported on these issues Pielke Sr., Roger A., 2005: Public Comment on CCSP Report "Temperature Trends in the Lower Atmosphere: Steps for Understanding and Reconciling Differences". 88 pp including appendices.

3 Specific Questions Not Investigated in the CCSP Report What is the bias in degrees Celsius introduced as a result of aggregating temperature data from different measurement heights, aerodynamic roughnesses, and thermodynamic stability? What is the quantitative uncertainty in degrees Celsius that are associated with each of the steps in the homogenization of the surface temperature data? What is the overlap in the raw data that utilized by the three groups? What is the value-added of using annually-averaged surface temperatures to assess global climate system heat changes ("global warming") over the last several decades in lieu of assessing the regional, zonally-average and global trends in ocean, and other climate component heat storage in units of Joules?

4 Examples Of Overview Papers On The Robustness of Land-Surface Temperature Network Mahmood, Rezaul, Stuart A. Foster and David Logan, 2006: The Geoprofile metadata, exposure of instruments, and measurement bias in climatic record revisited International Journal of Climatology Pielke Sr., R.A. J. Nielsen-Gammon, C. Davey, J. Angel, O. Bliss, N. Doesken, M. Cai., S. Fall, D. Niyogi, K. Gallo, R. Hale, K.G. Hubbard, X. Lin, H. Li, and S. Raman, 2007: Documentation of uncertainties and biases associated with surface temperature measurement sites for climate change assessment. Bull. Amer. Meteor. Soc., 88:6, 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. in press.

5 How spatially representative is each surface observing site?

6 Fort Morgan site showing images of the cardinal directions from the sensor (from Hanamean et al. 2003).

7 Photographs of the temperature sensor exposure characteristics of the NWS COOP station at Las Animas, CO. Panel a) shows the temperature sensor, while panels b)-e) illustrate the exposures viewed from the sensor looking N, E, S, and W, respectively. From Davey, C.A., and R.A. Pielke Sr., 2005: Microclimate exposures of surface-based weather stations - implications for the assessment of long-term temperature trends. Bull. Amer. Meteor. Soc., 4,

11 We need to extend this assessment worldwide!

12 Jamiyansharav, K., D. Ojima, and R.A. Pielke Sr., 2006: Exposure characteristics of the Mongolian weather stations. Atmospheric Science Paper No. 779, Colorado State University, Fort Collins, CO 80523, 75 pp.

15 Do surface sites adequately measure heat? Pielke Sr., R.A., C. Davey, and J. Morgan, 2004: Assessing "global warming" with surface heat content. Eos, 85, No. 21, Pielke, R.A. Sr., K. Wolter, O. Bliss, N. Doesken, and B. McNoldy, 2006: The July 2005 Denver heat wave: How unusual was it? Nat. Wea. Dig., accepted. Davey, C.A., R.A. Pielke Sr., and K.P. Gallo, 2006: Differences between near-surface equivalent temperature and temperature trends for the eastern United States - Equivalent temperature as an alternative measure of heat content. Global and Planetary Change, 54,

16 Moist enthalpy provides a proper measure of surface air heat content, which is not provided by air temperature alone. T E =H/C p H = C p T + L q

Hourly data from automated weather stations at Fort Collins and DIA are used to pick and calculate the highest air temperature and effective temperature for each day in July 2005.

17 Hourly data from automated weather stations at Fort Collins and DIA are used to pick and calculate the highest air temperature and effective temperature for each day in July The average high air temperature is higher at DIA, while the average high effective temperature is higher at Fort Collins. From Pielke, R.A. Sr., K. Wolter, O. Bliss, N. Doesken, and B. McNoldy, 2005: July 2005 heat wave: How unusual was it. National Weather Digest, submitted.

19 Davey, C.A., R.A. Pielke Sr., and K.P. Gallo, 2006: Differences between near-surface equivalent temperature and temperature trends for the eastern United States - Equivalent temperature as an alternative measure of heat content. Global & Planetary Change, 54,

20 Does a temperature sample at a single level accurately monitor temperature trends? Pielke Sr., R.A., and T. Matsui, 2005: Should light wind and windy nights have the same temperature trends at individual levels even if the boundary layer averaged heat content change is the same? Geophys. Res. Letts., 32, No. 21, L21813, /2005GL 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: /2007gl Lin, X., R.A. Pielke Sr., K.G. Hubbard, K.C. Crawford, M. A. Shafer, and T. Matsui, 2007: An examination of surface layer temperature trends at two heights in Oklahoma. Geophys. Res. Letts., submitted.

21 From: Pielke Sr., R.A., and T. Matsui, 2005: Should light wind and windy nights have the same temperature trends at individual levels even if the boundary layer averaged heat content change is the same? Geophys. Res. Letts., 32, No. 21, L21813, /2005GL

22 From: Pielke Sr., R.A., and T. Matsui, 2005: Should light wind and windy nights have the same temperature trends at individual levels even if the boundary layer averaged heat content change is the same? Geophys. Res. Letts., 32, No. 21, L21813, /2005GL

23 Does Reanalyses provide more spatially representative surface temperature trends? Cai, M, and E. Kalnay, 2005: Can reanalysis have anthropogenic climate trends without model forcing? J. Climate, 18, Fall, S., D. Niyogi, R.A. Pielke Sr., A. Gluhovsky, and E. Kalnay, 2007: Impacts of land surface properties on temperature trends using North American regional reanalysis over the USA. Int. J. Climatol., submitted. Frauenfeld, O.W., T. Zhang, and M.C. Serreze, 2005: Climate change and variability using European Center for Medium-Range Weather Forecast analysis (ERA-40) temperatures on the Tibetan Plateau. J. Geophys. Res., 110, D02101, doi: /2004jd Kalnay, E., and M. Cai, 2003: Impact of urbanization and land-use change on climate, Nature, 423,

24 From: Pielke Sr., R.A. J. Nielsen-Gammon, C. Davey, J. Angel, O. Bliss, N. Doesken, M. Cai., S. Fall, D. Niyogi, K. Gallo, R. Hale, K.G. Hubbard, X. Lin, H. Li, and S. Raman, 2007: Documentation of uncertainties and biases associated with surface temperature measurement sites for climate change assessment. Bull. Amer. Meteor. Soc., 88:6,

25 How many sites are used to monitor each grid point within the global land surface analyses from NCDC, CRU, and GISS? Do they use the same raw data? Davey, C.A., and R.A. Pielke Sr., 2007: Comparing station density and reported temperature trends for land-surface sites. Climatic Change, in revision

26 Does land-use change and vegetation/soil dynamics alter the trends in surface temperatures? [A small sample of papers that address this issue are listed below ] Carleton, A.M., J. Adegoke, J. Allard, D.L. Arnold, and D.J. Travis, 2001: Summer season land coverconvective cloud associations for the Midwest U.S. "Corn Belt", Geophys. Res. Lett., 28(9), Hale, R.C., K.P. Gallo, T.W. Owen, and T.R. Loveland, 2006: Land use/land cover change effects on temperature trends at U.S. Climate Geophys. Res. Lett. Lawrence, P.J., and T.N. Chase, 2007: Representing a new MODIS consistent land surface in the Community Land Model (CLM 3.0), J. Geophys. Res., 112, G01023, doi: /2006jg Lim, Y.-K., M. Cai, E. Kalnay, and L. Zhou, 2005: Observational evidence of sensitivity of surface climate changes to land types and urbanization. Geophys. Res. Lett., 32, Niyogi, D., H. Chang, F. Chen, L. Gu, A. Kumar, S. Menon, R. Pielke Sr., 2007: Potential impacts of aerosolland-atmosphere interaction on the Indian monsoonal rainfall characteristics, Nat. Haz.- Monsoon Spe. Iss,, DOI /s y Pielke Sr., R.A., J.O. Adegoke, T.N. Chase, C.H. Marshall, T. Matsui, and D. Niyogi, 2007: A new paradigm for assessing the role of agriculture in the climate system and in climate change. Agric. Forest Meteor., Special Issue, 132, Pielke, R.A. Sr., J. Adegoke, A. Beltran-Przekurat, C.A. Hiemstra, J. Lin, U.S. Nair, D. Niyogi, and T.E. Nobis, 2007: An overview of regional land use and land cover impacts on rainfall. Tellus B, 59, Roy, S.S., R. Mahmood, D. Niyogi, M. Lei, S.A. Foster, K.G. Hubbard, E. Douglas, and R.A. Pielke Sr., 2007: Impacts of the agricultural green revolution induced land use changes on air temperatures in India. J. Geophys. Res., accepted. Rozoff, C.M., W.R. Cotton, and J.O. Adegoke, 2003: Simulation of St. Louis, Missouri, Land Use Impacts on Thunderstorms DOI: / (2003)042<0716:SOSLML>2.0.CO;2

27 U.S. Geological Survey land-cover classes for pre-1900 s natural conditions (left) and 1993 land-use patterns (right). From Marshall, C.H. Jr., R.A. Pielke Sr., L.T. Steyaert, and D.A. Willard, 2004: The impact of anthropogenic land-cover change on the Florida peninsula sea breezes and warm season sensible weather. Mon. Wea. Rev., 132,

28 Max and Min Temp Trends

Two-month average of the daily maximum shelter-level temperature (

land cover, (middle) current land cover. From Marshall et al.

peninsula sea breezes and warm season sensible weather. Mon. Wea.

29 Two-month average of the daily maximum shelter-level temperature ( C) from the model simulations of Jul-Aug 1989 with (top) natural land cover, (middle) current land cover. From Marshall et al. 2004: The impact of anthropogenic land-cover change on the Florida peninsula sea breezes and warm season sensible weather. Mon. Wea. Rev., 132,

30 Conclusions Many surface temperature observing sites are poorly located and cannot be corrected for multi-decadal trends in tenths of a degree C. Surface temperature only measures part of the heat content of the air; water vapor content also needs to be measured and its multi-decadal trend also assessed. Measuring the temperature at night at one level in the surface introduces a bias that is on the order of tenths of a degree C.

31 Conclusions Regional reanalyses which have dense observed atmospheric input data provide an effective tool to assess long-term near-surface temperature trends as well as identify surface observing sites that are not spatially representative. Land-use change and/or vegetation-soil dynamics can significantly alter multi-decadal surface temperature trends. Many grid points in the NCDC, CRU, and GISS data sets base their anomalies on none or just 1 site. The degree of correspondence between the raw data used in the three analyses needs to be quantified. Also, how many of these sites in urban areas need to be determined. The use of ocean heat content changes in Joules is a more robust method to assess global warming and cooling than the surface temperature data; an example follows...

32 Figure 4 from Ellis, J. S., T. H. Vonder Haar, S. Levitus, and A. H. Oort, 1978: The annual variation in the global heat balance of the Earth. J. Geophys. Res., 83, See also Pielke Sr., R.A., 2003: Heat storage within the Earth system. Bull. Amer. Meteor. Soc., 84,

33 From Lyman, J.M., J. Willis, and G. Johnson, 2006: Recent cooling of the upper ocean. Geophys Res. Lett., 33, L18604, doi: /2006gl Correction completed April 2007 which eliminates cooling but finds no warming in recent years.

34 2007 IPCC SPM View

35 2007 IPCC Total Radiative Forcing = 1.72 (0.66 to 2.7) Watts per meter squared Best Estimate of Total Radiative Imbalance ( ) = 0.33 (0.10 to 0.56) Watts per meter squared If the IPCC Forcing is accepted as the current forcing, than the net global radiative feedbacks are negative!

36 Background Photograph Courtesy of Mike Hollingshead

37 Roger A. Pielke Sr. Research Group Weblog Roger A. Pielke Sr. Website

38 PowerPoint Presentation Prepared by Dallas Jean Staley Research Assistant and Webmaster University of Colorado Boulder, Colorado

An Overview On the Complexity of the Climate System and the Role of Humans Within It

An Overview On the Complexity of the Climate System and the Role of Humans Within It Roger A. Pielke Sr. University of Colorado, CIRES, Boulder, CO Lecture Presented to University of Colorado Class ATOC4800/5000