Regional changes in California surface temperatures over the last 80 years are analyzed using station data from the US Historical Climate Network and the National Weather Service Cooperative Network. Statistical analyses using annual and seasonal temperature data over the last 80 years show distinctly different spatial and temporal patterns in trends of maximum temperature (Tmax) compared to trends of minimum temperature (Tmin). For trends computed between 1918 and 2006, the rate of warming in Tmin is greater than that of Tmax. Trends computed since 1970 show an amplified warming rate compared to trends computed from 1918, and the rate of warming is comparable between Tmin and Tmax. This is especially true in the southern deserts, where warming trends during spring (March-May) are exceptionally large. While observations show coherent statewide positive trends in Tmin, trends in Tmax vary on finer spatial and temporal scales. Accompanying the observed statewide warming from 1970 to 2006, regional cooling trends in Tmax are observed during winter and summer. These signatures of regional temperature change suggest that a collection of different forcing mechanisms or feedback processes must be present to produce these responses.

Urbanization reflects how human-activities affect natural climate system. Accurately assessing the urban system by comparing it with the nearby rural regions helps to identify the impacts of urbanization. This work uses the recent satellite observed aerosol, skin temperature, land cover, albedo, cloud fraction and water vapor measurements to reveal how the city of Shanghai, one of the biggest, dense urban areas in East Asia, affects land surface and atmosphere conditions. In addition, the National Aeronautics and Space Administration (NASA) ground observations from AErosol RObotic NETwork (AERONET) is also used to reveal diurnal, seasonal, and interannual variations of the heavy aerosol load over Shanghai region. Furthermore, Shanghai reduces surface albedo, total column water vapor, cloud fraction and increases land skin temperature than rural region. These observations prove that Shanghai significantly modifies local and regional land surface physical properties as well as physical processes, which lead to the urban heat island effect (UHI).

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ANALYSIS OF CALIFORNIA SURFACE TEMPERATURE TRENDS BASED ON OBSERVATIONS by Wittaya Kessomkiat Analysis of California surface temperature based on observations has been conducted using United States Historical Climatology Network (USHCN) stations and Cooperative Weather (COOP) stations throughout California to understand spatial and temporal changes in temperature. Monthly maximum and minimum temperatures (Tmax and Tmin) were used to calculate and analyze annual and seasonal trends over the last 86 years via statistical analyses. For annual trends, Tmin is warming faster than Tmax for both 1918-2006 and 1950-2006 time periods. Since 1970, both Tmax and Tmin, however, have increased at the same rate. For seasonal trends, interestingly, by far the largest warming trends are found during spring (March-May) in both Tmax and Tmin, particularly in Southern California since 1970. While Tmin reveals a strong coherent temperature variation statewide in both annual and seasonal temperatures, Tmax shows spatial and temporal variations in finer scales. Particularly in Southern California during winter and summer, cooling and warming trends are leveled in Tmax. These regional temperature changes must be caused by different forcing mechanisms.