Atmospheric science: The effect of diurnal correction on satellite-derived lower tropospheric temperature

Science

Volumn 309, Issue 5740, 2005, Pages 1548-1551

  Mears, Cart A ^a   Wentz, Frank J ^a  

^a REMOTE SENSING SYSTEMS   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

ATMOSPHERIC TEMPERATURE; EARTH (PLANET); GLOBAL WARMING; MICROWAVE MEASUREMENT; SATELLITES; TEMPERATURE MEASUREMENT; TROPICS;

ATMOSPHERIC SCIENCE; DIURNAL CORRECTION; EARTH'S SURFACE; TROPOSPHERIC TEMPERATURE;

TROPOSPHERE;

AIR TEMPERATURE; DIURNAL VARIATION; ERROR CORRECTION; REMOTE SENSING; SATELLITE DATA; TROPOSPHERE;

ARTICLE; CLIMATE CHANGE; COOLING; ENVIRONMENTAL TEMPERATURE; GLOBAL CLIMATE; GREENHOUSE EFFECT; PRIORITY JOURNAL; TELECOMMUNICATION; TEMPERATURE MEASUREMENT; TROPICS; TROPOSPHERE;

EID: 24644467695     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.1114772     Document Type: Article

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21. The decay of orbital height also has an important effect on measurements of long-term temperature trends (34). This adjustment is done in the same way in the work reported here and in (15). Because it is not a cause of the current discrepancy, we do not discuss it further.
22. Both at Earth's surface and in the troposphere, the diurnal cycle in temperature is dominated by the first harmonic. At a given point on Earth, the ascending and descending passes of the NOAA satellites make measurements separated by approximately 12 hours, so that averaging together the data from ascending and descending orbits has the effect of removing most of the first harmonic of the diurnal cycle. This cancellation becomes less effective as one moves toward the polar regions, where the local measurement times become closer together. We define diurnal correction to be the removal of any residual effects remaining after averaging the ascending and descending parts of the orbit together.
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26. We chose these values of the target factors to produce our final results because we have concluded that they are the most likely to be free of errors. They are calculated from oceanic observations to reduce errors from uncorrected diurnal variations, and we use unweighted MSU channel 2 data (T2 in SOM) to avoid additional noise due to the differencing procedure used to calculate TLT. The values of the intersatellite offsets needed to be recalculated to remove obvious intersatellite differences. In the supporting online material, we discuss the impact of using different data subsets to determine the target factors. This information is used to help determine the structural uncertainty.
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35. This work was supported by the NOAA Climate and Global Change Program. We thank J. Christy and R. Spencer for providing numerical values for their diurnal adjustment.