Estimation of Total Precipitable Water from Observed Values of Infrared Bamds of VTIR of MOS-1
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概要
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An expression which estimates the total precipitable water from the infrared observed data of VTIR of MOS-1 is developed :<BR>W= α [1-I<SUB>2</SUB>/B<SUB>2</SUB> (T<SUB>s</SUB>)] +β [1-I<SUB>4</SUB>/B<SUB>4</SUB> (T<SUB>s</SUB>)]<BR>where I<SUB>2</SUB> and I<SUB>4</SUB> are respectively observed radiation value of the second band (67 μm band) and that of the fourth band (11.512.5 μm band) of VTIR, B<SUB>2</SUB> (T<SUB>s</SUB>) and B<SUB>4</SUB> (T<SUB>s</SUB>) are respectively the black body radiation values for a surface temperature T<SUB>s</SUB> of the second and the fourth bands<BR>I<SUB>2</SUB>, I<SUB>4</SUB> B<SUB>2</SUB> (T<SUB>s</SUB>) and B<SUB>4</SUB> (T<SUB>s</SUB>) are expressed by the observed brightness temperatures T<SUB>2</SUB> and T<SUB>4</SUB> of the second and the fourth bands of VTIR and surface temperatures T<SUB>s</SUB>. And the surface temperature T<SUB>s</SUB> can be also estimated from observed values of brightness temperature T<SUB>3</SUB> of the third band and T<SUB>4</SUB> of the fourth band of VTIR.<BR>The coefficients α and β in the above expression are given by the function of surface water vapor pressure P<SUB>v</SUB> (0) :<BR>For P<SUB>v</SUB> (0)≤2.91 mb<BR>α =0.3671, β = 26.95<BR>For P<SUB>v</SUB> (0)≥26.66 mb<BR>α =1.288, β= 32.38<BR>For 2.91 < P<SUB>v</SUB> (0) <26.66 mb<BR>α =0.3671+0.9209 [ (P<SUB>v</SUB>(0) - 2.91)/19.75]<SUP>4</SUP><BR>β= 26.95 + 5.430 [ (P<SUB>v</SUB> (0) - 2.91)/19.75]<SUP>4</SUP><BR>and for the case in which the proper surface vapor pressure is not available, the following expressions of α and β in terms of surface temperature T<SUB>s</SUB> are given :<BR>For T<SUB>s</SUB> ≤257.1°K<BR>α =0.3671, β= 26.95<BR>For T<SUB>s</SUB> ≥300.0°K<BR>α =1.288, β = 32.38<BR>For 257.1 <T<SUB>s</SUB> <300.0°K<BR>α =0.3671+0.9207 [(T<SUB>s</SUB>-257.1)/42.9]<SUP>6</SUP><BR>β = 26.95+5.430 [(T<SUB>s</SUB>-257.1)/42.9]<SUP>6</SUP><BR>The root mean square residuals between the precipitable waters from VTIR data and those from radiosonde data are 0.39 g/cm<SUP>2</SUP>/ (for α and β of functions of P<SUP>v</SUP> (0)) and 0.51 g/cm<SUP>2</SUP> (for α and β of functions of T<SUP>s</SUP>)
- 社団法人 日本リモートセンシング学会の論文