Articles Tagged "Roy Clark"

The analysis of minimum temperature data using the PDO as a reference baseline has been demonstrated as a powerful technique for climate trend evaluation.

This technique may be extended to other regions using the appropriate local ocean surface temperature reference. The analysis found no evidence for CO2 induced warming trends in the California data. This confirms prior ‘Null Hypothesis’ work that it is impossible for a 100 ppm increase in atmospheric CO2 concentration to cause any climate change.

INTRODUCTION

The weather is always changing on a daily basis and climate is often evaluated using long term averages of daily maximum and minimum temperatures and precipitation. This is the weather station record that is available from about 1880 onwards. However, the meteorological surface air temperatures (MSAT) are recorded by a thermometer located in an enclosure placed at eye level, 1.5 to 2 m above the ground.[1] The surface or ‘skin’ temperature is the temperature of the ground itself below the thermometer. This is set by the dynamic energy balance at the surface between the short wave (solar) flux, the long wave infra red (LWIR) flux, surface evaporation and convection. It also includes subsurface heating and cooling. The incoming solar flux can reach 1000 W.m-2 and the night time LWIR cooling flux can easily vary between 0 and 100 W.m-2, depending on cloud cover and humidity.

The increase in downward atmospheric LWIR flux from the observed 100 ppm increase in CO2 concentration over the last 200 years is 1.7 W.m-2 under ideal ‘clear sky’ conditions. When this CO2 flux is added to the daily flux balance with fluctuations that can exceed 1100 W.m-2, it becomes clear that there can be no CO2 ‘signature’ in the MSAT record.[2]

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The Air-Land Interface

The ground is heated by the sun during the day and the increase in LWIR flux from the warm surface heats the air. It is important to distinguish clearly between the actual ground surface temperature and meteorological surface air temperature. The surface temperature needed for energy transfer analysis is the ground surface temperature. The meteorological surface air temperature is the air temperature measured in an enclosure placed 1.5 to 2 m above the ground.21 There is no obvious or simple relationship between these two temperatures. Solar radiation is absorbed and reflected by the ground.

The resulting surface temperature depends on the absorption coefficient, the thermal conductivity and heat capacity of the ground, the surface area and angles of incidence, the balance of the upward and downward LWIR flux and the direct air convection. If the ground is moist, latent heat effects also have to be included. The meteorological surface air temperature depends on the origin of the bulk air mass of the local weather system, surface LWIR flux heating, air convection and wind speed. As for the air-ocean interface, the First Law of Thermodynamics imposes energy conservation, but there is no requirement that the flux be conserved on any time scale.

The Second Law of Thermodynamics requires that the heat transfer follow the thermal gradient. Surface heating may be analyzed using a simple thermal conduction model analogous to the ocean heating model. This is illustrated in Figure 5. The results for summer and winter illumination of a concrete surface are shown in Figure 6. The calculated daily temperature excursions for summer and winter solar heating are 40 and 20 C at 35° latitude. A 1% increase in solar flux produces peak summer and winter temperature increases of 0.34 and 0.17 C.