• water vapor;
  • polar stratosphere;
  • validation;
  • satellite sensor;
  • Improved Limb Atmospheric Spectrometer (ILAS)

[1] In the paper “Validation and data characteristics of water vapor profiles observed by the Improved Limb Atmospheric Spectrometer (ILAS) and processed with the version 5.20 algorithm” by H. Kanzawa et al. (Journal of Geophysical Research, 108(D24), 8217, doi:10.1029/2001JD000881, 2002), the caption for Figure 3 was incorrect. The correct caption appears below.

[2] Figure 3. Comparison of vertical profiles of water vapor volume mixing ratio of ILAS version 5.20 measurement and balloon validation measurement, and relative percentage difference D (see section 4 for the definition), for the seven ILAS validation flights detailed in Table 3. The error bar of ILAS shows the total error defined in the text. The meanings of the error bars in the validation measurements are given in parentheses: (a) FISH (the error bars are not shown; 0.15 ppmv precision; 0.35 ppmv or 6% accuracy); (b) LPMA (one-sigma precision); (c) ELHYSA (the error bars are not shown; 3% precision: 6% accuracy); (d) LPMA (one-sigma precision); (e) MIPAS (one-sigma precision); (f) FIRS-2 (one-sigma precision); (g) MkIV (one-sigma precision). The vertical range of (a)–(e) is 10–35 km while that of (f)–(g) is 10–40 km. Comparison of Ertel's potential vorticity (PV) profiles at the locations of ILAS and validation measurements by percentage are added to the right-hand side of each panel (see section 5 for the definitions): Note that the lines of “ILAS-Edge” and “Val-Edge” are not drawn for the altitudes where the polar vortex edge cannot be defined as in the case of (f) and (g).

[3] Also, Tables 1 and 6 were incorrect. The correct tables appear below.

Table 1. Summary of Error Analysis for the ILAS Version 5.20 Water Vapor Data: Total Errors and Repeatability
Altitude, kmAverage vmr,a ppmvInternal Error,b ppmvExternal Error,c ppmvTotal Error,d ppmvTotal Error,d %RSD,e %RSD,e ppmv
  • a

    Average volume mixing ratios (vmr) of all water vapor retrievals.

  • b

    Average of internal errors for all water vapor retrievals.

  • c

    External error, which is given in common for all water vapor data.

  • d

    Total error: RSS (root-sum-square) of internal and external errors (in ppmv) and its relative value (%). The latter is given by dividing the RSS by the average mixing ratio in the second column.

  • e

    Relative standard deviation (RSD in %), which is a measure of repeatability of the measurement, i.e., empirically determined precision (see text). For reference, the corresponding mixing ratio of RSD (in ppmv) is given by multiplying RSD (%) by the average volume mixing ratio in the second column.

Table 6. Summary of Percentage Difference of ILAS Water Vapor Measurements Against Various Coincident Validation Measurementsa
Altitude Experiment19961997
  • a

    The table is arranged by altitude range, validation experiment, month, and hemisphere. NH and SH represent Northern Hemisphere and Southern Hemisphere, respectively. HALOE and SAGE II are satellite measurements. POLARIS consists of aircraft measurements. Balloon measurements include FISH (designated by FI), LPMA (LP), ELHYSA (EL), MIPAS (MI), FIRS-2 (FS), and MkIV (Mk). The percent figures are estimated with an interval of 5%. The positive values mean that ILAS is larger than validation. The notation “+–10” means that the values change within the altitude region with plus (+10) in lower altitudes and minus (−10) in higher altitudes, and vice versa. The notation “−0” means that the values are zero but slightly less than zero, and vice versa.

  • b

    The asterisk denotes no satellite measurements in the month and the hemisphere.

  • c

    The percent figures are not suitable for evaluation of ILAS (see text).

50–60 km
45–50 km
  SAGE II*−10***−10*−10**−25*−10***
40–45 km
  SAGE II*−5***−0*+0**+10*−10***
35–40 km
  SAGE II*−0***+5*+10**+10*+5***
  BALLOON          −5FS −0Mk   
30–35 km
  SAGE II*+0***+5*+5**0*−0***
  BALLOON          −5FS −0Mk   
25–30 km
  SAGE II*+0***+10*+10**0*−5***
  BALLOON      −5LP +5MI −5FS −5Mk   
20–25 km
  SAGE II*+5c***+20c*+20c**+20c*+15c***
  BALLOON      +15FI +5MI −5FS −10Mk   
15–20 km
  SAGE II*+15c***+35c*+30c**+35c*+35c***
  POLARIS            −25   
BALLOON      −+10FI −5MI −5FS −10Mk   
10–15 km
  POLARIS            −30   
  BALLOON        −20MI −10FS −10Mk   

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