Reconciling Observations of Global Temperature Change (2000) / Chapter Skim
Currently Skimming:
9 Trend Comparisons
9 Trend Comparisons
Pages 58-71
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 58... ...
The red curve represents full global coverage, while the pink curve is based on just a limited sampling of grid points designed to mimic the existing distribution of radiosonde stations. The least squares trend of the global coverage time series is 0.06 +0.11 °C/decade, compared with 0.14 +0.10 °C/decade for the sub-sampled time series.
|
From page 59... ...
There is no unique set of confidence intervals for the relatively short atmospheric temperature time series considered here. The estimated confidence intervals depend on the underlying statistical mode]
|
From page 60... ...
Both data sets were supplied by the UKMO. Some of the discrepancies between the MSU- and radiosonde-based time series are a consequence of changes in radiosonde instrumentation that have not been corrected.
|
From page 61... ...
represents the difference between the MSU and radiosonde data sets shown in this figure. The axes are the same as in Figure 9.
|
From page 62... ...
Efforts to produce such data sets are already under way. EVIDENCE CONCERNING SURFACE VERSUS TROPOSPHERIC TEMPERATURE TRENDS Figure 2.3 shows time series of surface and tropospheric globalmean temperature anomalies.
|
From page 63... ...
Nino. Spatial averages of surface and tropospheric temperature trends over the tropics/extratropics, Northern Hemisphere/Southern Hemisphere, and land/ocean exhibit qualitatively similar differences.
|
From page 64... ...
it, 1950 1960 1970 1980 1990 2000 Yeas o.s o.o -o.s FIGURE 9.4. Time series of average daily maximum (gray curve)
|
From page 65... ...
. However, on decadal time scales, the trends of sea surface temperature and water vapor continue to exhibit the same close coupling, whereas the MSU and radiosonde temperature trends are less correlated.
|
From page 66... ...
SST ~N ~ (~..~ NOAA-9 1 1 1 1 1 1 1 1 1 1 ' ' ' ' - - , , I , 1 , 1980 1985 1990 1995 2000 Year FIGURE 9.5. Lower to mid-tropospheric temperature time series from MSU version C with orbital decay corrections (C+O.D.)
|
From page 67... ...
The emissions from volcanic eruptions are believed to produce stronger cooling of the troposphere than at the earth's surface (Bengtsson et al., 1999; Hansen et al., 19971. Within a given sampling interval like the past 20-years, any changes in the temperature structure of the atmosphere that might be occurring in response to a long-term increase in atmospheric concentrations of greenhouse gases and aerosols may be masked by internal variability of
|
From page 68... ...
Climate models are capable of simulating many of the processes that contribute to the observed differences between variations in surface temperature and tropospheric temperature, and they realistically represent the vertical structure of E! Nino-related temperature fluctuations and the thermal signature of time-varying circulation patterns over higher latitudes.
|
From page 69... ...
Bengtsson et al. note that the natural variability in globally averaged temperature time series which typically have a standard deviation of 0.2 to 0.3 °C for a 20-year interval makes it difficult to establish longterm temperature trends using a 20-year period.
|
From page 70... ...
and aerosols play a significant role in defining the vertical structure of the observed atmospheric temperature changes, model~bservation discrepancies indicate that the definitive mode} experiments have not yet been done. To reduce model-based discrepancies, we need better information on the changes in radiative forcings as a function of height, especially tropospheric aerosols and ozone, as well as water vapor changes and cloud changes caused by aerosols.
|
From page 71... ...
the subtle variations in the vertical temperature profile of the lower atmosphere that occur in association with the internal variability of the climate system in response to volcanic eruptions and solar forcing, and in connection with changes in atmospheric composition due to human activities. It will also require more precise and extensive satellite- and ground-based observations for monitoring climate change, and changes in the way these observations are implemented and processed.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.