# US 2018/0024036 A1 · Method of estimating cloud particle sizes using lidar ratio > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0024036 A1 - Document ID: US20180024036A1 - Status: Published application - Kind: A1 - Application number: 15/216,340 - Filed: 2016-07-21 - Published: 2018-01-25 - Earliest claimed: 2016-07-21 - Assignees: Rosemount Aerospace Inc. - Applicants: Rosemount Aerospace Inc. - Inventors: Mark Ray; Kaare Josef Anderson - Web page: https://patentgrep.com/patent/US20180024036A1 ## CPC - G01N 15/0211: {Investigating a scatter or diffraction pattern} - G01S 7/4812: {transmitted and received beams following a coaxial path} - G01S 7/499: using polarisation effects - G01S 17/95: for meteorological use - G01W 1/00: Meteorology - G01N 2015/0046: {in gas, e.g. smoke} - Y02A 90/10: Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) - G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES - G01W: METEOROLOGY (radar, sonar, lidar or analogous systems, designed for meteorological use G01S13/95, G01S15/88, G01S17/95) - Y02A: TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE ## Abstract Apparatus and associated methods relate to determining sizes of water particles in a cloud atmosphere based on a detected portion of signals generated from a single monochromatic source and backscattered by water particles in a cloud atmosphere. A backscatter coefficient and an optical extinction coefficient are calculated, based on the detected portion of signals generated from the monochromatic source and backscattered by water particles in the cloud atmosphere. A LIDAR ratio—a ratio of the optical extinction coefficient to the backscatter coefficient, is calculated. Sizes of water particles in the cloud atmosphere are estimated based on the LIDAR ratio. An output signal indicative of the estimated sizes of water particles in the cloud atmosphere is generated. Estimating sizes of water particles using signals from a single monochromatic source advantageously can alert a pilot of an aircraft of cloud conditions, without requiring multi-chromatic sources. ## Claims ### Claim 1 A system for measuring an effective size of water particles in a cloud atmosphere, the system comprising: a laser configured to generate a pulse of light of a wavelength and to direct the pulse of light into the cloud atmosphere; an optical detector configured to detect a portion of the pulse of light backscattered by the water particles in the cloud atmosphere; and a cloud metric calculator configured to determine, based on the detected portion of the pulse of light backscattered by the water particles in the cloud atmosphere, an optical extinction coefficient and a backscatter coefficient, wherein the cloud metric calculator is further configured to estimate, based on a ratio of the determined optical extinction coefficient to the determined backscatter coefficient, the effective size of the water particles in the cloud atmosphere. ### Claim 2 (depends on 1) The system of claim 1, wherein the cloud metric calculator is configured to estimate the effective size of the water particles in the cloud atmosphere using a look-up table. ### Claim 3 (depends on 1) The system of claim 1, wherein the cloud metric calculator is further configured to calculate, based on the detected portion of the pulse of light backscattered by the water particles in the cloud atmosphere, a concentration of the water particles of the cloud atmosphere. ### Claim 4 (depends on 1) The system of claim 1, wherein the wavelength of the generated pulse of light is between 700 nano-meters and 2.0 micro-meters. ### Claim 5 (depends on 1) The system of claim 1, further comprising a polarizer configured to circularly polarize the pulse of light. ### Claim 6 (depends on 5) The system of claim 5, wherein the portion of the pulse of light is a first portion of the circularly polarized pulse of light, the first portion having a first polarization, wherein the signal detector is further configured to detect a second portion of the circularly polarized pulse of light backscattered by the cloud atmosphere, the second portion having a second polarization oppositely oriented to the first polarization. ### Claim 7 (depends on 6) The system of claim 6, wherein the cloud metric calculator is further configured to calculate, based on the detected first signal and the detected second signal, an ice/liquid phase ratio of the droplets in the cloud atmosphere. ### Claim 8 A method for measuring an effective size of water particles in a cloud atmosphere, the method comprising: generating a pulse of light of a wavelength; directing the generated pulse of light into the cloud atmosphere; detecting a portion of the pulse of light backscattered by the water particles in the cloud atmosphere; determining, based on the detected portion of the pulse of light backscattered by the water particles in the cloud atmosphere, an optical extinction coefficient and a backscatter coefficient; and estimating, based on a ratio of the determined optical extinction coefficient to the determined backscatter coefficient, the effective size of the water particles in the cloud atmosphere; generating an output signal indicative of the estimated effective size of the water particles in the cloud atmosphere. ### Claim 9 (depends on 8) The method of claim 8, wherein estimating, based on a ratio of the determined optical extinction coefficient to the determined backscatter coefficient, the effective size of the water particles in the cloud atmosphere comprises: using a look-up table in which the ratio of the determined optical extinction coefficient to the determined backscatter coefficient is correlated to the effective size of water particles in the cloud atmosphere. ### Claim 10 (depends on 8) The method of claim 8, further comprising: calculating, based on the detected portion of the pulse of light backscattered by the water particles in the cloud atmosphere, a concentration of the water particles in the cloud atmosphere. ### Claim 11 (depends on 8) The method of claim 8, wherein the wavelength of the generated pulse of light is between 700 nano-meters and 2.0 micro-meters. ### Claim 12 (depends on 8) The method of claim 8, further comprising: polarizing the generated pulse of light, such that the pulse of light directed into the cloud atmosphere is polarized. ### Claim 13 (depends on 12) The method of claim 12, wherein the portion of the pulse of light backscattered by the water particles in the cloud atmosphere is a first portion of the pulse of the circularly polarized light backscattered by the water particles in the cloud atmosphere, the first portion having a first polarization, the method further comprising: detecting a second portion of the circularly polarized pulse of light backscattered by the water particles in the cloud atmosphere, the second portion having a second polarization oppositely oriented to the first polarization. ### Claim 14 (depends on 13) The method of claim 13, further comprising: calculating, based on the detected first portion and the detected second portion, an ice/liquid phase ratio of the droplets in the cloud atmosphere. ### Claim 15 A system for measuring an effective size of water particles in a cloud atmosphere, the system comprising: a laser; a signal detector; one or more processors; and computer-readable memory encoded with instructions that, when executed by the one or more processors, cause the system to: emit a pulse of light from the laser; receive, from the signal detector, a signal indicative of a detected portion of the emitted pulse of light backscattered by the water particles in the cloud atmosphere; determine, based on the received signal indicative of the detected portion of the emitted pulse of light backscattered by the water particles in the cloud atmosphere, an optical extinction coefficient and a backscatter coefficient; estimate, based on a ratio of the determined optical extinction coefficient to the determined backscatter coefficient, the effective size of the water particles in the cloud atmosphere; and generate an output signal indicative of the estimated effective size of the water particles in the cloud atmosphere. ### Claim 16 (depends on 15) The system of claim 15, wherein estimating, based on a ratio of the determined optical extinction coefficient to the determined backscatter coefficient, sizes of the water particles in the cloud atmosphere comprises: using a look-up table in which the ratio of the determined optical extinction coefficient to the determined backscatter coefficient is correlated to the effective size of water particles. ### Claim 17 (depends on 15) The system of claim 15, wherein the computer-readable memory is further encoded with instructions that, when executed by the one or more processors, cause the system to: calculate, based on the detected portion of the pulse of light backscattered by the water particles in the cloud atmosphere, a concentration of the water particles in the cloud atmosphere. ### Claim 18 (depends on 15) The system of claim 15, wherein the emitted pulse of light has a wavelength between 700 nano-meters and 2.0 micrometers. ### Claim 19 (depends on 15) The system of claim 15, further comprising a polarizer configured to circularly polarize the pulse of light emitted from the laser. ### Claim 20 (depends on 19) The system of claim 19, wherein the portion of the pulse of light backscattered by the water particles in the cloud atmosphere is a first portion of the circularly polarized pulse of light backscattered by the water particles in the cloud atmosphere, the computer-readable memory is further encoded with instructions that, when executed by the one or more processors, cause the system to: detect a second portion of the circularly polarized pulse of light backscattered by the water particles in the cloud atmosphere, the second portion having a second polarization oppositely oriented to the first polarization; and calculate, based on the detected first portion and the detected second portion, an ice/liquid phase ratio of the droplets in the cloud atmosphere.