Surface Temperature Errors Research Articles

Surface temperature measurement of semi-transparent material by thermocouple in real site experimental approach and simulation

This study's aim is to appreciate real site surface temperature error values obtained using a thermocouple on semi-transparent materials and to determine a method of correction. Using an efficient measurement system, an experimental study was carried out under a number of climatic conditions. The results show that high values for solar radiation and wind speed have a significant influence on thermocouple measurement. The authors, therefore, decided to validate and develop a corrective model for the measurement errors of these two parameters. The conclusion also provides data on the model's relative drawbacks and current limitations.

Climatology and variability in the ECHO coupled GCM

ECHO is a new global coupled ocean-atmosphere general circulation model (GCM), consisting of the Hamburg version of the European Centre atmospheric GCM (ECHAM) and the Hamburg Primitive Equation ocean GCM (HOPE). We performed a 20-year integration with ECHO. Climate drift is significant, but typical annual mean errors in sea surface temperature (SST) do not exceed 2° in the open oceans. Near the boundaries, however, SST errors are considerably larger. The coupled model simulates an irregular ENSO cycle in the tropical Pacific, with spatial patterns similar to those observed. The variability, however, is somewhat weaker relative to observations. ECHO also simulates significant interannual variability in mid-latitudes. Consistent with observations, variability over the North Pacific can be partly attributed to remote forcing from the tropics. In contrast, the interannual variability over the North Atlantic appears to be generated locally.

Climatology and variability in the ECHO coupled GCM

ECHO is a new global coupled ocean-atmosphere general circulation model (GCM), consisting of the Hamburg version of the European Centre atmospheric GCM (ECHAM) and the Hamburg Primitive Equation ocean GCM (HOPE). We performed a 20-year integration with ECHO. Climate drift is significant, but typical annual mean errors in sea surface temperature (SST) do not exceed 2° in the open oceans. Near the boundaries, however, SST errors are considerably larger. The coupled model simulates an irregular ENSO cycle in the tropical Pacific, with spatial patterns similar to those observed. The variability, however, is somewhat weaker relative to observations. ECHO also simulates significant interannual variability in mid-latitudes. Consistent with observations, variability over the North Pacific can be partly attributed to remote forcing from the tropics. In contrast, the interannual variability over the North Atlantic appears to be generated locally.

Longwave surface radiation over the globe from satellite data: An error analysis

Errors have been analyzed for monthly-average downward and net longwave surface fluxes derived on a 5-deg equal-area grid over the globe, using a satellite technique. Meteorological data used in this technique are available from the TIROS Operational Vertical Sounder (TOVS) system flown aboard NOAA's operational sun-synchronous satellites. The data used are for February 1982 from NOAA-6 and NOAA-7 satellites. The errors in the parametrized equations were estimated by comparing their results with those from a detailed radiative transfer model. The errors in the TOVS-derived surface temperature, water vapor burden, and cloud cover were estimated by comparing these meteorological parameters with independent measurements obtained from other satellite sources. Analysis of the overall errors shows that the present technique could lead to underestimation of downward fluxes by 5 to 15 W/sq m and net fluxes by 4 to 12 W/sq m.

Surface temperature and slope errors on plane mirrors exposed to high power synchrotron radiation

The temperature at the surface and the distortion of plane mirrors made from various materials have been investigated with incident surface power densities of the order of 0.4 W/mm 2 and total powers of up to 170 W. Although the surface temperature could be significantly lowered by increasing the cooling water flow rate, the temperature gradients and the deformation of the surface were found to be independent of the cooling. Si and SiC were found to be much superior to all other samples. Contrary to the theoretical expectations the surface distortion was found to depend not just on the figure of merit for thermal distortions. This is interpreted by taking into account the penetration depth of the radiation emitted by the hard-X-ray wiggler (HARWI) in the 5.3 GeV storage ring DORIS.

Correction of thermal imagery for atmospheric effects using aircraft measurement and atmospheric modeling techniques

Airborne measurements of atmospheric-path transmission and atmospheric-path (upwelled) radiance in the 8–14-μm band were obtained by applying a multiple altitude and a dual-view angle calibration technique to thermal IR line scanner data. A spectrally corrected lowtran code was used to generate path transmission and upwelled radiance values corresponding to the empirical measurements. Using lowtran and the multiple-altitude method, calibration of thermograms to account for atmospheric effects yields computed surface temperatures within 0.7°C of concurrent kinetic temperature readings. The angular calibration method results in similar computed surface temperature errors for 304.8-m (1000-ft) altitude data and increasing by 1.2°C/304.8-m up to a 1828.8-m (6000-ft) altitude. This paper contains results of a comparative analysis of these approaches for atmospheric calibration.

An analysis of errors in sea surface temperature in a series of infrared images from NOAA 6

As part of the Coastal Ocean Dynamics Experiment, 58 infrared satellite images were analyzed for the magnitude and source of their errors in predicting sea surface temperature. Comparisons with near‐surface thermistors on moorings and differences between images from consecutive days showed that a two‐channel atmospheric correction using the 3.7‐μ m and the 11‐μ m channels was ineffective in reducing errors. Large systematic errors, which have the form of a constant over an image, were found in both channels. A simple viewing angle correction reduced fluctuations in the area‐mean 11‐μ m channel temperature from 0.74° to 0.45°C; a satisfactory correction could not be found for the larger fluctuations in the 3.7‐μ m channel, which appears to be degraded by reflected or scattered solar radiation. By taking account of the known dependence of atmospheric effects on viewing angle geometry, it was possible to isolate the primary causes of error, to estimate typical magnitudes, and to correct for them. The 11‐μ m channel temperature error from the northern California atmosphere was found to be nearly constant in time over a 100‐day period, but to vary slowly with distance from the coast.

An inverse problem technique for detecting irregular cavities in circular cylinders by infrared scanning

An inverse problem technique has been developed for detecting irregular cavities in circular cylinders. In this method, the cavity is considered a part of the unknown geometry of the investigated system, and the evaluated temperature is used to locate this geometry. An auxiliary problem is introduced in the solution of this problem; and in the solution, the cavity wall is located by forcing the temperature to satisfy the condition imposed at the cavity. The new methodology is validated by an experiment presented in this paper, and the test results indicate that this method is highly successful in locating cavities. The accuracy of the method is closely related to the accuracy of the temperature that can be measured at the surface. A small error in the surface temperature results in a slight cavity error for deep cavities, while a shallow cavity is not severely affected by a surface temperature error. This method is particularly attractive in detecting shallow cavities in nondestructive evaluation.

Errors in radiometric remote sensing of sea-surface temperature and salinity

Techniques for remote measurement of sea-surface physical temperature and salinity using radiometric measurements from aircraft or satellite are reviewed. Studies have been conducted to determine the sensitivity of the errors in surface temperature and salinity to errors in the measured brightness temperatures using combinations of UHF, L, S, and C-band measurements. These investigations were made using values of conductivity, static dielectric constant, and relaxation time derived from the regression equations of Klein and Swift [1]. Results of the error sensitivity study are presented in the form of error contour plots which permit the calculation of errors in the estimation of the physical parameters for given errors in the raw radiometric measurements.

The Short-Term Influence of the Mount St. Helens Volcanic Eruption on Surface Temperature in the Northwest United States

Abstract The surface temperature effects of the 18 May 1980 eruption of the Mount St. Helens volcano were examined for the two days immediately following the eruption. The volcanic signal was investigated by examining regional maps of surface temperature, 24 h surface temperature differences and Model Output Statistics (MOS) errors, as well as the detailed temporal evolution of surface temperature and MOS errors at selected stations. The analysis was simplified by the presence of a large anticyclone which dominated the synoptic situation both before and after the eruption. During the daytime hours immediately after the eruption; temperatures in eastern Washington State were up to 8°C colder because of the volcanic plume. That night, because of low-level volcanic dust, temperatures were up to 8°C warmer in Idaho and Montana. These effects, caused by large aerosols in the troposphere, quickly diminished the following day as the volcanic dust cloud dissipated and moved toward the east. This is believed to be...

The evaporation and condensation coefficient of water, ice and carbon tetrachloride

The evaporation and condensation coefficients of water, ice and carbon tetrachloride were determined in the same experimental apparatus. Both low and high values were obtained for all three materials. An unsteady-state experimental method was used and the high values resulted when the evaporating or condensing times were very short. Surface temperature errors of two different types are shown to be the major factor in contributing to low values. The condensation coefficient of water is at least 0·7 and could easily be 1·0. Condensation coefficients of 0·55 were measured for ice and 0·94 for carbon tetrachloride.

Application of Error Analysis to Surface Temperature Determination by Radiation Budget Techniques

Error analysis based on the definition of the total differential is used to evaluate uncertainties in indirect determination of surface temperature from radiation budget data. The analysis indicates that the uncertainty in temperature estimates can be large, but that the range of error can be reduced if a net pyrradiometer equipped with a blackbody cavity is used. Radiometer calibration accuracy is more important than recording system resolution in determining surface temperature errors under sampling conditions tested.

Temperature Error Associated with Imbedded Thermocouples

The error in surface temperature of a thin plate in a vacuum as measured by an imbedded thermocouple is investigated experimentally and theoretically. It is found that the error is proportional to the 52 power of the absolute temperature provided the surrounding temperature is much lower than the plate temperature.