| CPC G01N 21/84 (2013.01) [G01N 21/3103 (2013.01); G16C 60/00 (2019.02)] | 18 Claims |
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1. A method for measuring and analyzing an internal structure of a semi-transparent transitory source (STTS) by remote sensing, said method comprising
i. bore-sighting at least one spectrometer and at least one optic device selected from a group consisting of one or more spectrometers; one or more imagers; and at least one spectrometer and at least one imager, wherein bore-sighting is configured to align and synchronize multiple sensing instruments;
ii. mounting at least one bore-sighted pair on at least one platform;
iii. pointing simultaneously all of said at least one platform towards at least one field of view;
iv. acquiring spectral data in a manner selected from the group consisting of:
a. simultaneously by said at least one spectrometer and said at least one optic device, from at least one platform of semi-transparent transient source; or
b. simultaneously or alternately by said at least one spectrometer and by said at least one optic device from at least one platform of semi-transparent transient source; and a reference field of view for semi-transparent transient source; or
c. simultaneously or alternately by said at least one spectrometer and by said at least one optic device from at least one platform of at least two complementary fields of view of the source; and
d. any combination thereof
v. repeating at least one of step (a) to (c), from at least one platform, for a total timescale which is shorter than a source timescale;
vi. adjusting data measured for different solid angles of different platforms;
vii. relating spectral data from a first spectrometer with data from said at least one optic device as a reference point for spatial resolution in observed properties of the semi-transparent transient source, by corresponding the overlapping fields of view;
viii. using a window to extract absorption coefficients from database without losing spectral data information, thereby enabling calculation of exact spectral line profiles from data measured from STTS by said spectrometer; said exact spectral line profiles are tool to study STTS and its environment; and
ix. evaluating vertical chemical profile within the STTS, by building a curve of growth (COG) from weakly absorbing chemical species characterized by an optical depth of about 1, thereby measuring and analyzing STTS;
wherein said extracting absorption coefficients comprising
a. providing absorption coefficients of at least one molecular species from an up-to-date database list of all molecular absorption parameters of said species, as a function of wavelength;
b. creating a user defined list of distinct equally-spaced or arbitrarily chosen wavelengths to provide for which the absorption coefficients are used for the radiative transfer analysis so that their periodicity is chosen as a function:
I. of the total wavelength range for which the RT is done, including range of 103 to 106 Å for Earth;
II. of the required resolution of the calculation vis-a-vis the wavelength range of the window; and
III. of the density of the spectral lines with that wavelength range;
c. defining a chosen window wavelength range symmetrically, or non-symmetrically, about the defined wavelengths of the list, chosen so as to include the contribution of adjacent lines to the calculation wavelengths, such that widening the window additionally, does not change significantly the absorption at the chosen calculation points;
d. reading the molecular absorption parameters of said at least one molecular substance at a first data wavelength in the database list;
e. if first database wavelength does not fall within the chosen wavelength range of at least one distinct user-defined wavelength, reading the next database wavelength until it overlaps with the chosen wavelength window range of the first user defined distinct wavelength;
f. calculating from said molecular absorption data a line profile for said database wavelength, given the pressure, temperature, concentration (P,T,C) conditions for the chemical species and atmospheric layer such that the contribution of each line of every species is a function of the species' concentration in the atmosphere, its statistical weight and its calculated profile at high or at low pressure by steps of:
I. preparing the partition function;
II. calculating the Voigt function;
III. choosing, according to the pressure shift, the function for the line shape; at low pressures, pressure shift <200 cm−1, use Van-Vleck Weisskopf line shape; at higher pressures, taper the wing effect by reducing the distant effect; and,
IV. calculating the statistical weight of the lower level times the transition probability;
g. extracting the contribution from said line profile to the absorption coefficients at each wavelength in the wavelength window range about the user-defined distinct wavelength, as the line profile extends throughout many wavelengths, their contribution to the different calculation points is collected throughout the window range;
h. repeating steps (d) to (g) for each database wavelength until it exceeds the wavelength window range about the last user-defined distinct wavelength; for each calculation point, the window is moved one calculation unit further, thus the initial window wavelength is adjusted accordingly; and
i. obtaining a list of the user defined distinct wavelengths and the respective absorption coefficients which may be stored in the computer for further use for radiative transfer or other calculations or any other use,
further comprising a step for enhancing signal to noise ratio (SNR), selected from the group consisting of:
a. tilting said platform towards said source and said reference field of view (FOV); said reference field of view comprises a field of view other than the measured field of view;
b. observing through the source via a longer path, resulting in a larger optical depth of a weakly absorbing chemical species; said method comprising step(s) of tilting said either platform or said bore sighted pair towards an optical path being longer than the vertical line;
c. observing through an STTS within a planetary atmosphere via a longer path than the vertical; comprising step(s) of tilting said either platform or said bore sighted pair towards the limb off the Nadir;
d. observing through an STTS illuminated from the background by an external radiation source in the visible and/or other spectral domain, resulting in direct spectroscopy of a weakly absorbing species; said method comprising step(s) of tilting said either platform or said bore sighted pair towards an external radiation source occulted by the STTS;
e. observing the STTS through a planetary atmosphere illuminated from the background by an external radiation source in the visible and/or other spectral domain, resulting in direct spectroscopy of the weakly absorbing species in the STTS; said method comprising step(s) of tilting said either platform or said bore sighted pair towards the limb of the planetary surface in angle to the Nadir
f. providing a background reference measurement with no source from bore-sighted pair;
g. providing a reference measurement of said external radiation source from bore-sighted pair, providing for isolating the STTS's spectrum from that of the external source;
h. providing a reference point for spatial resolution of the spectral measurement with the other optic device;
i. acquiring many repeated measurements within a timescale of the measurement shorter than source timescale;
j. tilting at least one platform to any solid angle for measuring from said bore-sighted pair;
k. correcting for measuring solid angle;
l. Correcting for solar angle; or
m. any combination thereof.
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