THE ENERGY BALANCE CLIMATOLOGY OF A CITY-MAN SYSTEM

ABSTRACT

The urban energy balance climatology of the city and man in the Los Angeles basin was examined during a cloudy day (“Catalina eddy”) in September, 1968, from about sunrise to sunset, by measuring or estimating solar radiation, net radiation, ground heat flux, actual surface temperature, terrain radiant temperature, radiant sky temperature, and dry and wet-bulb temperature for the physical urban interface. An analogous theoretical model attempted to define the input of energy to the human interface via the solar heat load, and the disposal of human net radiation was shown via the channels of latent, sensible, and body heat flux. In spite of an apparent uniform cloud cover, the energy parameters had considerable areal variation in intensity and trend. During the daylight hours seventy percent of the solar radiation was absorbed. An additional thirty-two percent was removed by longwave radiation. Of the net radiation received on the dry surface (forty-seven percent of solar radiation), about eighty percent was disposed via sensible heat flux, and the remainder entered the pavement as storage. Air temperatures taken at shelter height were out of phase with the ongoing energy regime and were deemed of dubious value in urban climatic studies. Urban man received only thirty-seven percent and seventy percent of the values available at the horizontal pavement for solar radiation and net radiation, respectively. A series of empirical and theoretical models show high correlations with the observations. It appeared that solar radiation and net radiation (physical and human) could have been estimated via the solar constant and appropriate transmissivities.

Notes

1 Arthur W. Dakan, Robert N. Hawkins, Richard D. Hickey, Robert B. Howard, Ronald N. Kickert, Jack P. Mrowka, Simon O. Ojo, Gerald L. Potter, Stanley W. Swarts, and Stanton E. Tuller. This study was supported, in part, by a grant from the University of California. The use of the computer facilities of the Campus Computing Network, University of California, Los Angeles, is acknowledged. Grateful acknowledgment is given to Jane E. Terjung, who helped in the data collection phase.

2 C. W. Thornthwaite, “The Task Ahead,”Annals, Association of American Geographers, Vol. 51 (1961), pp. 345 56; M. I. Budyko and I. P. Gerasimov“The Heat and Water Balance of the Earth's Surface, the General Theory of Physical Geography and the Problem of the Transformation of Nature,”Soviet Geography: Review and Translation, Vol. 2 (1961), pp. 3 12; H. E. Landsberg, “Goals for Climatology,”Journal of the Washington Academy of Science, Vol. 52 (1962), pp. 85 90; D. H. Miller, “The Heat and Water Budget of the Earth's Surface,”Advances in Geophysics, Vol. 11 (1965), pp. 175 302; A. D. Tweedie, “Challenges in Climatology,”Australian Journal of Science, Vol. 29 (1967), pp. 273 78.

3 D. H. Miller, A Survey Course: The Energy and Mass Budget of the Earth (Washington, D. C.: Association of American Geographers, 1968); C. C. Nikiforoff, “Reappraisal of the Soil,”Science, Vol. 129 (1959), pp. 186 96; E. S. Roth, “Temperature and Water Content as Factors in Desert Weathering,”Journal of Geology, Vol. 73 (1965), pp. 454 68; G. E. Hutchinson, A Treatise on Limnology (New York: Wiley, 1957); W. D. Sellers, “The Energy Balance of the Atmosphere and Climatic Change,”Journal of Applied Meteorology, Vol. 3 (1964), pp. 337 39; D. M. Gates, “Toward Understanding Ecosystems,”Advances in Ecological Research, Vol. 5 (1968), pp. 1 35; D. M. Gates, Energy Exchange in the Biosphere (New York: Harper & Row, 1962); J. H. Linford, An Introduction to Energetics (London: Butterworths, 1966); W. E. Billings, Plants and the Ecosystem (Belmont, California: Wadsworth, 1964); W. E. Reifsnyder and H. W. Lull, Radiant Energy in Relation to Forests (Washington: Government Printing Office, 1965); J. H. Chang, Climate and Agriculture: An Ecological Survey (Chicago: Aldine, 1968).

4 L. D. Stamp, “The Measurement of Land Resources,”Geographical Review, Vol. 48 (1958), pp. 1 15; D. L. Linton, “The Geography of Energy,”Geography, Vol. 50 (1965), pp. 197 228; H. V. Warren, “Some Pertinent Facts in Energy Studies,”Canadian Geographer, Vol. 5 (1961), pp. 16 23; A. Garnett, “Insolation, Topography and Settlement in the Alps,”Geographical Review, Vol. 25 (1935), pp. 601 17.

5 A. Sundborg, “Local Climatological Studies of the Temperature Conditions in an Urban Area,”Tellus, Vol. 2 (1950), pp. 222 32; F. S. Duckworth and J. S. Sandberg“The Effect of Cities Upon Horizontal and Vertical Temperature Gradients,”Bulletin of the American Meteorological Society, Vol. 35 (1954), pp. 198 207; J. M. Mitchell, “The Temperature of Cities,”Weatherwise, Vol. 14 (1961), pp. 224 29; T. J. Chandler, “London's Urban Climate,”Geographical Journal, Vol. 128 (1962), pp. 279 302; C. A. Woollum, “Notes from a Study of the Microclimatology of the Washington, D. C., Area for the Winter and Spring Season,”Weatherwise, Vol. 17 (1964), pp. 263 71; W. Eriksen, “Das Stadtklima: seine Stellung in der Klimatologie und Beiträge zu einer witterungsklimatologischen Betrachtungsweise,”Erdkunde, Vol. 18 (1964), pp. 257 66; T. Sekiguti, “Local Climate and City Climate,”Tokyo Journal of Climatology, Vol. 1 (1964), pp. 1 5; T. Sekiguti et al., “Geographical Distribution of Lower Upper Air Temperature Above City Area,”Tokyo Journal of Climatology, Vol. 1 (1964), pp. 29 34; K. Sasakura, “On the Distribution of Relative Humidity in Tokyo and Its Secular Change in the Heart of Tokyo,”Tokyo Journal of Climatology, Vol. 2 (1965), pp. 45 46; R. J. Hutcheon et al., “Observations of the Urban Heat Island in a Small City,”Bulletin of the American Meteorological Society, Vol. 48 (1967), pp. 7 9; A. Garnett, “Some Climatological Problems in Urban Geography with Reference to Air Pollution,”Transactions, Institute of British Geographers, No. 42 (1967), pp. 21 43; S. Lindqvist, “Studies on the Local Climate in Lund and Its Environs,”Geografiska Annaler, Vol. 50A (1968), pp. 79 93.

6 R. E. Munn, Descriptive Micrometeorology (New York: Academic Press, 1966), p. 196; Miller, op. cit., footnote 3, p. 14.

7 P. A. Kratzer, Das Stadtklima (Braunschweig: Verlag Vieweg, 1956); A. Garnett and W. Bach“An Estimate of the Ratio of Artificial Heat Generation to Natural Radiation Heat in Sheffield,”Monthly Weather Review, Vol. 93 (1965), pp. 383 85; I. F. Hand, “Transmission of the Total and the Infrared Component of Solar Radiation Through a Smoky Atmosphere,”Bulletin of the American Meteorological Society, Vol. 24 (1943), pp. 201 04; P. A. Sheppard, “The Effect of Pollution on Radiation in the Atmosphere,”International Journal of Air and Water Pollution, Vol. 1 (1958), pp. 31 43.

8 R. F. Fuggle, “Preliminary Thoughts on Long-Wave Radiative Flux Divergence and the Urban Heat Island,”Climatological Bulletin, No. 4 (1968), pp. 31 39; T. Sekiguti and Collaborators, “The Geographical Distribution of Solar Radiation in the Tokyo Metropolitan Area,”Tokyo Journal of Climatology, Vol. 1 (1964), pp. 35 44; T. Fujita, G. Baralt, and K. Tsuchiya, “Aerial Measurement of Radiation Temperatures Over Mt. Fuji and Tokyo Areas and Their Application to the Determination of Ground- and Water-Surface Temperatures,”Journal of Applied Meteorology, Vol. 7 (1968), pp. 801 16; M. Neiburger, “Weather Modification and Smog,”Science, Vol. 126 (1957), pp. 637 45; W. Bach and W. Patterson, “Heat Budget Studies in Greater Cincinnati,”Proceedings, Association of American Geographers, Vol. 1 (1969), pp. 7 11.

9 I. M. Osokin, “The Study of the Climate of Cities as an Urgent Present-Day Task for University Geographers,”Soviet Geography: Review and Translation, Vol. 3 (1962), pp. 55 58.

10 G. A. DeMarrais, G. C. Holzworth, and C. R. Hosler, Meteorological Summaries Pertinent to Atmospheric Transport and Dispersion Over Southern California (Washington, D. C.: Government Printing Office, 1965), p. 64.

11 For excellent satellite pictures of the development of a Catalina eddy see J. Rosenthal, “Picture of the Month—A Catalina Eddy,”Monthly Weather Review, Vol. 96 (1968), pp. 472 73.

12 W. H. Terjung, “Urban Energy Balance Climatology: A Preliminary Investigation of the City-Man System in Downtown Los Angeles,”Geographical Review, Vol. 60 (1970), pp. 31 53.

13 Langley (ly) = one gram-calorie per square centimeter (cal cm-2) = 3.655 British thermal units per square foot (BTU ft-2) = 4.1855 joules per square centimeter (J cm-2).

 14Certain very small and local components which were neglected include energy dissipation by wind, waves, current; energy used seasonally for melting snow and ice; energy used for photosynthesis; and energy additions from combustion and volcanic eruptions. All these could easily be incorporated into the equations.

15 Gates, op. cit., footnote 3, pp. 86–89, has a more complete description of the instrument.

16 The Stefan-Boltzmann law states that the amount of energy radiated by a black body is proportional to the fourth power of the absolute temperature of the object. The conversions were accomplished by using tables given in K. Ya. Kondrat'yev, Radiative Heat Exchange in the Atmosphere (Oxford: Pergamon Press, 1965), p. 407.

17 W. D. Sellers, Physical Climatology (Chicago: University of Chicago Press, 1965), pp. 144–46; C. B. Tanner, “Comparison of Energy Balance and Mass Transport Methods for Measuring Evaporation,” in Conference Proceedings: Evapotranspiration and Its Role in Water Resources Management (St. Joseph, Michigan: American Society of Agricultural Engineers, 1966), pp. 45–53; E. K. Webb, “Aerial Micro-climate,”Meteorological Monographs, Vol. 6 (1965), pp. 27 58; I. C. McIlroy and D. E. Angus“Grass, Water and Soil Evaporation at Aspendale,”Agricultural Meteorology, Vol. 1 (1964), pp. 201 24; E. I. Mukammal, K. M. King, and H. F. Cork, “Comparison of Aerodynamic and Energy Budget Techniques in Estimating Evapotranspiration from a Cornfield,”Archiv für Meteorologie, Geophysik und Bioklimatologie, Series B, Vol. 14 (1966), pp. 384 95; W. O. Pruitt and F. J. Lourence, “Tests of Aerodynamic, Energy Balance and Other Evaporation Equations Over a Grass Surface,” in F. A. Brooks and W. O. Pruitt, eds., Investigation of Energy, Momentum and Mass Transfers Near the Ground (Davis: University of California, Department of Agricultural Engineering and Department of Water Science, 1966), pp. 37–63.

18 An attempt has been made to determine evaporation and other components of the energy balance equation at the urban surface during a cyclonic storm.

19 Sellers, op. cit., footnote 17, p. 114; Munn, op. cit., footnote 6, p. 39; Chang, op. cit., footnote 3, p. 47, 54; W. Mahringer, “Das Temperatureregime einer Betonoberfläche,”Archiv für Meteorologie, Geophysik und Bioklimatologie, Series B, Vol. II (1962), pp. 533 59.

20 M. Neiburger, “Reflection, Absorption, and Transmission of Insolation by Stratus Cloud,”Journal of Meteorology, Vol. 6 (1949), pp. 98 104.

21 Terjung, op. cit., footnote 12.

22 A. M. Stoll and J. D. Hardy, “Thermal Radiation Measurements in Summer and Winter Alaskan Climates,”Transactions, American Geophysical Union, Vol. 36 (1955), pp. 213 26.

23 W. H. Terjung et al., “Energy and Moisture Balances of an Alpine Tundra in Mid-July,”Arctic and Alpine Research, Vol. 1 (1969), pp. 247 66.

24 Data courtesy of the Los Angeles Air Pollution Control District.

25 r= correlation coefficient; SE = standard error of estimate.

26 W. H. Terjung et al., “Terrestrial, Atmospheric and Solar Radiation Fluxes on a High Desert Mountain in Mid-July: White Mountain Peak, California,”Solar Energy, Vol. 12 (1969), pp. 363 75; Terjung et al., op. cit., footnote 23; W. H. Terjung, “The Energy Budget of Man at High Altitudes,”International Journal of Biometeorology, Vol. 14 (1970), in press.

27 As quoted in Chang, op. cit., footnote 3, p. 19.

28 F. A. Brooks and W. O. Pruitt, eds., op. cit., footnote 17.

29 C. A. Federer, “Spatial Variation of Net Radiation, Albedo and Surface Temperature of Forests,”Journal of Applied Meteorology, Vol. 7 (1968), pp. 789 95.

30 W. H. Terjung, “Some maps of Isanomalies in Energy Balance Climatology,”Archiv für Meteorologie, Geophysik und Bioklimatologie, Series B, Vol. 16 (1968), pp. 279 315.

31 It was assumed that -0.05 ly min-1 was the lowest value at about 0400 hrs.

32 W. H. Terjunget al., “The Annual March of the Topoclimatic Spatial Patterns of Net Radiation in Southern California,”Archiv für Meteorologie, Geophysik und Bioklimatologie, Series B, Vol. 16 (1968), pp. 21 50.

33 Gates, op. cit., footnote 3 (1968), p. 6.

34 Terjung, op. cit., footnote 12; Terjung, op. cit., footnote 26.

35 K. J. Kondratyev and M. P. Manolova“The Radiation Balance of Slopes,”Solar Energy, Vol. 4 (1960), pp. 14 19.

36 Kcal = 1000 cal. To change ly min-1 to Kcal hr-1 multiply the former by 600.

37 This is about 0.99 for human skin. Most other interfaces in urban climatology also radiate as near-black bodies in the range of wavelengths in which they radiate.

38 J. D. Hardy, “Heat Transfer,” in L. H. Newburgh, ed., Physiology of Heat Regulation and the Science of Clothing (Philadelphia: W. B. Saunders, 1949), pp. 78–108, esp. p. 81.

39 A. Guibert and C. L. Taylor, “Radiation Area of the Human Body,”Journal of Applied Physiology, Vol.5 (1952), pp. 24 37.

40 Terjung, op. cit., footnote 12.

41 D. H. K. Lee, Heat and Cold Effects and their Control (Washington, D. C.: Government Printing Office, 1964).

42 L. Fourt and M. Harris, “Physical Properties of Clothing Fabrics,” in L. H. Newburgh, ed., Physiology of Heat Regulation and the Science of Clothing (Philadelphia: W. B. Saunders, 1949), pp. 291–319.

43 Hardy, op. cit., footnote 38, p. 105; S. Robinson, “Physiological Adjustments to Heat,” in L. H. Newburgh, ed., op. cit., footnote 42, pp. 193–231.

44 W. H. Terjung, “World Patterns of the Distribution of the Monthly Comfort Index,”International Journal of Biometeorology, Vol. 12 (1968), pp. 119 51.

45 Sellers, op. cit., footnote 17, p. 240; Terjung et al., op. cit., footnote 32.

46 Sellers, op. cit., footnote 17, p. 55.

47 S. E. Tuller, “World Distribution of Mean Monthly and Annual Precipitable Water,”Monthly Weather Review, Vol. 96 (1968), pp. 785 97.

48 Sellers, op. cit., footnote 17.

49 G. J. Haltiner and F. L. Martin, Dynamical and Physical Meteorology (New York: McGraw-Hill, 1957), p. 90; Sellers, op. cit., footnote 17, p. 14.

50 N. Robinson, ed., Solar Radiation (Amsterdam: Elsevier, 1966), p. 31.

51 F. Kasten, “A New Table and Approximation Formula for the Relative Optical Air Mass,”Archiv für Meteorology, Geophysik und Bioklimatologie, Series B, Vol. 14 (1966), pp. 206 23.

52 P. Bener, “Der Einfluss der Bewölkung auf die Himmelsstrahlung,”Archiv für Meteorologie, Geophysik und Bioklimatologie, Series B, Vol. 12 (1963), pp. 442 57.

53 Gates, op. cit., footnote 3 (1968), p. 6.