VIIRS Cloud Phase Validation VIIRS Cloud Phase Validation
- Slides: 12
VIIRS Cloud Phase Validation
VIIRS Cloud Phase Validation • The VIIRS cloud phase algorithm was validated using a 24 -hour period on November 10, 2012. • Validation was performed using collocated CALIPSO data for pixels detected as cloud from both the VIIRS and CALIPSO cloud masks. • Validation was performed for the entire dataset but was also separated by day/night, land/water and high latitude/low latitude (60 deg) pixels • The validation was also filtered by the optical depth calculated by CALIPSO • The initial thresholds for the VIIRS cloud phase algorithm tests were calculated using modeled single layer water and ice clouds • These results show that updated thresholds improved the performance of the VIIRS cloud phase algorithm
VIIRS Cloud Phase Validation Using the CALIPSO Cloud Phase filtered by Optical Depth November 10, 2012 Optical Depth Filter > 0. 0 >0. 1 >0. 2 >0. 3 >0. 4 >0. 5 >2. 0 All data 0. 742 0. 803 0. 823 0. 831 0. 834 0. 835 0. 809 daytime 0. 737 0. 793 0. 813 0. 822 0. 826 0. 807 nighttime 0. 747 0. 812 0. 833 0. 840 0. 843 0. 808 Over land 0. 726 0. 767 0. 790 0. 802 0. 804 0. 751 Over water 0. 746 0. 813 0. 833 0. 840 0. 843 0. 844 0. 822 Lat > 60 deg 0. 740 0. 778 0. 789 0. 797 0. 798 0. 767 Lat <60 deg 0. 742 0. 808 0. 831 0. 843 0. 844 0. 819 CIMSS version of the VIIRS cloud type algorithm with the original threshold function This chart shows the fraction of the VIIRS cloud phase pixels (filtered by the CALIPSO optical depth) that report a water or ice cloud when the collocated CALIPSO cloud phase agreed
VIIRS Cloud Phase Validation • After looking at individual scenes, it appeared that some opaque ice clouds were being misclassified as supercooled water • Looking at the circled area below, the clouds that appear pink in the RGB on the left image are ice clouds • The VIIRS cloud type algorithm on the right falsely identifies those clouds as supercooled (green)
VIIRS Cloud Phase Validation • Further investigation of the infrared cloud phase discrimination test revealed that the original threshold function was not properly differentiating water and ice clouds • The scatter plot was created using the 8. 5 -11 micron BTD from VIIRS and the cloud phase classification from CALIPSO • The green line represents the original threshold function calculated using modeled single layer water and ice clouds • The red line represents the new threshold function calculated using data from this plot
VIIRS Cloud Phase Validation • Previous research has shown that the sensitivity of the 8. 5 -11 micron BTD changes as a function of the satellite viewing angle • For this reason offsets to the threshold function were calculated to account for different viewing angles in 10 degree increments • The top red line represents the threshold function for viewing angles < 10 degrees • The bottom red line represents the threshold function for viewing angles > 70 degrees
VIIRS Cloud Phase Validation • After the new threshold functions were applied the VIIRS cloud phase accurately classified the opaque ice clouds shown in the circled area
VIIRS Cloud Phase Validation • The updated threshold function improved the performance of the cloud phase algorithm, however, some discontinuity developed at the edge of the pre-defined viewing angle ranges chosen for the threshold function • A linear interpolation of the threshold function as a function of the satellite viewing angle was applied to remove the areas of discontinuity shown in the left image below
VIIRS Cloud Phase Validation • The next 3 slides show the 24 -hour validation results for the following VIIRS cloud phase algorithms: – CIMSS version of the VIIRS cloud phase algorithm with the original infrared cloud phase discrimination threshold function – CIMSS version of the VIIRS cloud phase algorithm with the updated infrared cloud phase discrimination threshold function and viewing angle interpolation – Official VIIRS cloud phase algorithm (version ADL 4. 2+Mx 8. 0 - provided by Weizhong Chen) with the updated infrared cloud phase discrimination threshold function and viewing angle interpolation
VIIRS Cloud Phase Validation Using the CALIPSO Cloud Phase filtered by Optical Depth November 10, 2012 Optical Depth Filter > 0. 0 >0. 1 >0. 2 >0. 3 >0. 4 >0. 5 >2. 0 All data 0. 742 0. 803 0. 823 0. 831 0. 834 0. 835 0. 809 daytime 0. 737 0. 793 0. 813 0. 822 0. 826 0. 807 nighttime 0. 747 0. 812 0. 833 0. 840 0. 843 0. 808 Over land 0. 726 0. 767 0. 790 0. 802 0. 804 0. 751 Over water 0. 746 0. 813 0. 833 0. 840 0. 843 0. 844 0. 822 Lat > 60 deg 0. 740 0. 778 0. 789 0. 797 0. 798 0. 767 Lat <60 deg 0. 742 0. 808 0. 831 0. 843 0. 844 0. 819 CIMSS version of the VIIRS cloud type algorithm with the original threshold function This chart shows the fraction of the VIIRS cloud phase pixels (filtered by the CALIPSO optical depth) that report a water or ice cloud when the collocated CALIPSO cloud phase agreed
VIIRS Cloud Phase Validation Using the CALIPSO Cloud Phase filtered by Optical Depth November 10, 2012 Optical Depth Filter > 0. 0 >0. 1 >0. 2 >0. 3 >0. 4 >0. 5 >2. 0 All data 0. 771 0. 830 0. 848 0. 855 0. 857 0. 858 0. 822 daytime 0. 763 0. 817 0. 835 0. 841 0. 844 0. 807 nighttime 0. 779 0. 842 0. 869 0. 871 0. 834 Over land 0. 785 0. 826 0. 846 0. 855 0. 856 0. 797 Over water 0. 766 0. 830 0. 848 0. 854 0. 856 0. 857 0. 826 Lat > 60 deg 0. 805 0. 834 0. 838 0. 839 0. 837 0. 835 0. 784 Lat <60 deg 0. 763 0. 828 0. 850 0. 851 0. 862 0. 863 0. 831 CIMSS version of the VIIRS cloud type algorithm with updated threshold function and viewing angle interpolation This chart shows the fraction of the VIIRS cloud phase pixels (filtered by the CALIPSO optical depth) that report a water or ice cloud when the collocated CALIPSO cloud phase agreed
VIIRS Cloud Phase Validation Using the CALIPSO Cloud Phase filtered by Optical Depth November 10, 2012 Optical Depth Filter > 0. 0 >0. 1 >0. 2 >0. 3 >0. 4 >0. 5 >2. 0 All data 0. 778 0. 833 0. 849 0. 855 0. 858 0. 821 daytime 0. 770 0. 819 0. 834 0. 840 0. 842 0. 800 nighttime 0. 785 0. 847 0. 865 0. 872 0. 874 0. 875 0. 839 Over land 0. 790 0. 827 0. 847 0. 856 0. 858 0. 797 Over water 0. 772 0. 833 0. 849 0. 854 0. 856 0. 857 0. 824 Lat > 60 deg 0. 817 0. 846 0. 850 0. 851 0. 849 0. 847 0. 797 Lat <60 deg 0. 769 0. 829 0. 849 0. 856 0. 859 0. 860 0. 825 VIIRS cloud type algorithm version ADL 4. 2+Mx 8. 0 with updated threshold function and viewing angle interpolation This chart shows the fraction of the VIIRS cloud phase pixels (filtered by the CALIPSO optical depth) that report a water or ice cloud when the collocated CALIPSO cloud phase agreed
- Phase to phase voltage
- Normal phase vs reverse phase chromatography
- Normal phase vs reverse phase chromatography
- Csce 441
- Hplc reverse phase vs normal phase
- Power formula three phase
- Mobile phase and stationary phase
- Chromatography mobile phase and stationary phase
- Stationary phase and mobile phase in hplc
- Public cloud vs private cloud cost analysis
- Cloud disaster recovery cloud snap
- Seven step model of migration into cloud
- Cloud integration patterns