DoD Center for Geosciences/Atmospheric Research at Colorado State University Annual Review Nov 15-17, Meteosat Second Generation Algorithms for Use at AFWA Objectives: u Develop algorithms using Meteosat Second Generation data for installation at AFWA u When appropriate, utilize channels which are not available on other satellites, thereby extending and improving AFWA capabilities Stanley Q. Kidder, J. Adam Kankiewicz, and Kenneth E. Eis

DoD Center for Geosciences/Atmospheric Research at Colorado State University Annual Review Nov 15-17, DoD Relevance Clouds have a significant impact on DoD operations u CI clouds impact reconnaissance, air-to-air refueling operations, and add error to infrared MASINT. u Mid-level clouds to fog impact air operations and flight safety as well as air-to-ground operations.

DoD Center for Geosciences/Atmospheric Research at Colorado State University Annual Review Nov 15-17, Algorithms Developed u Cloud Mask u Nocturnal Thin Cirrus u Daytime Cirrus u Nocturnal Cloud Mask u Precipitating Clouds u Multi-Channel Skin Temperature u Snow/Ice Mask, and u Contrail Detection Imagery (Phase I)

DoD Center for Geosciences/Atmospheric Research at Colorado State University Annual Review Nov 15-17, MSG Channels Band Center (µm) 99% Energy Band (µm) Resolution (km) Band Center (µm) 99% Energy Band (µm) Resolution (km) HRV0.751IR VIS IR VIS WV IR WV – IR IR – IR IR –

DoD Center for Geosciences/Atmospheric Research at Colorado State University Annual Review Nov 15-17, Cloud Mask u Uses 8.7 µm channel u The warmest pixel in the previous 10 days is used as a background u Pixels colder than the background are cloudy t Over land, radiance difference = 30 W m -2 sr -1 µm -1 t Over water, radiance difference = 7.5 W m -2 sr -1 µm -1 Background T 8.7 Cloud Mask

DoD Center for Geosciences/Atmospheric Research at Colorado State University Annual Review Nov 15-17, Cloud Mask Improvements u 8.7 um more sensitive than current 10.7 um method u Dynamic background u Uses only satellite data, no model data are used Background T 8.7 Cloud Mask

DoD Center for Geosciences/Atmospheric Research at Colorado State University Annual Review Nov 15-17, Nocturnal Thin Cirrus u At night, A 3.9 = 1 − L 3.9 /B 3.9 (T 10.8 ), where A is albedo, L is observed radiance, B is the Planck function, and T is brightness temperature. u Radiation leaks through thin cirrus from below resulting in a negative albedo. u Algorithm: cirrus (black) are indicated if T 10.8 < -30ºC or A 3.9 <

DoD Center for Geosciences/Atmospheric Research at Colorado State University Annual Review Nov 15-17, Daytime Cirrus u Define A i ≡ πL i /(S i cosζ), where L i = observed radiance in channel i S i = solar irradiance in channel i ζ = solar zenith angle u (Red, Green, Blue) = 255*(A 1.6, A 0.8, A 0.6 ) u Ice clouds are highly reflective at 0.8 and 0.6 µm, but poorly reflective at 1.6 µm. They therefore appear cyan in the resulting image. u Through color analysis, pick out the cyan points in the image and identify them as daytime cirrus. (Must filter snow.) 255*( A 1.6, A 0.8, A 0.6 ) Cirrus

DoD Center for Geosciences/Atmospheric Research at Colorado State University Annual Review Nov 15-17, Nocturnal Cloud Mask u Liquid water clouds, as well as cirrus clouds, can be detected at night with the 3.9 µm albedo. u At night, A 3.9 = 1 − L 3.9 /B 3.9 (T 10.8 ), where A is albedo, L is observed radiance, B is the Planck function, and T is brightness temperature. u Define A 8.7 ≡ 1 − L 8.7 /B 8.7 (T 10.8 ) u Form background A 3.9 as the A 3.9 value which corresponds to the warmest T 10.8 in the past 10 days. T 10.8 A 3.9 White = Liquid Water CloudBlack = Ice Cloud

DoD Center for Geosciences/Atmospheric Research at Colorado State University Annual Review Nov 15-17, Note: the A3.9 Background test was not applied in these examples Nocturnal Cloud Mask (cont.) u Cloud classification t Ice cloud: T 10.8 < −30ºC or A 3.9 < t Liquid Water Cloud: s Over Water A 3.9 > 0.18 and A 3.9 > background A 3.9 s Over Land A 3.9 > 0.21 and A 3.9 > background A 3.9 and A 8.7 < t Otherwise, clear T 10.8 A 3.9 White = Liquid Water CloudBlack = Ice Cloud

DoD Center for Geosciences/Atmospheric Research at Colorado State University Annual Review Nov 15-17, Precipitating Clouds u Identifies deep, cold clouds which are likely to be precipitating. u Water vapor is used to screen out low clouds u Precipitation clouds are those for which T 10.8 – T 6.2 < 11 K (an empirically determined threshold). T 10.8 T 6.2 Precipitating Clouds

DoD Center for Geosciences/Atmospheric Research at Colorado State University Annual Review Nov 15-17, Multi-Channel Skin Temperature u Uses the algorithm of Price (1984), modified for MSG channels u T skin = T (T 10.4 – T 12.0 ) T 10.8 T skin

DoD Center for Geosciences/Atmospheric Research at Colorado State University Annual Review Nov 15-17, Snow/Ice Mask u Relies on the facts that t Snow/Ice are below the freezing point t The diurnal temperature change of snow/ice- covered surfaces is small u Uses 10 days of hourly 10.8 µm brightness temperatures, i.e., at each pixel there is a 10  24 matrix T 10.8

DoD Center for Geosciences/Atmospheric Research at Colorado State University Annual Review Nov 15-17, Snow/Ice Mask u The algorithm: t IF MAX(T 10.8 ) > 0ºC, no snow t Form 24-element array T max (hour) = MAX day [T 10.8 (day, hour)] t Calculate average hourly change:

DoD Center for Geosciences/Atmospheric Research at Colorado State University Annual Review Nov 15-17, Snow/Ice Mask t Snow/Ice covered if u u The test fails if t t Cloudiness persists for 10 days t t Snow/ice does not persist for 10 days Note: We don’t have a current example of snow/ice cover because it’s the wrong season.

DoD Center for Geosciences/Atmospheric Research at Colorado State University Annual Review Nov 15-17, Contrail Detection u Contrails can be identified as near-linear cirrus clouds. They tend to be visible in areas which have naturally occurring thin cirrus. u We offer enhanced imagery which can help an analyst locate areas in which cirrus might occur. u We do not offer a cirrus detection algorithm because MSG imagery, at 3 km resolution, is not sufficient to do this accurately. u During the daytime, the enhanced imagery can be “checked” using the 1-km-resolution HRV (broadband visible) data.

DoD Center for Geosciences/Atmospheric Research at Colorado State University Annual Review Nov 15-17, Contrail Detection (cont.) u Two products are suggested to aid the analyst in locating cirrus. u T 10.8 – T 12.0, scaled between –1 and +6 K (black to white) u T 6.2 – T 7.3, scaled between –30 and 0 K

DoD Center for Geosciences/Atmospheric Research at Colorado State University Annual Review Nov 15-17, Contrail Detection (cont.) T 10.8 – T 12.0

DoD Center for Geosciences/Atmospheric Research at Colorado State University Annual Review Nov 15-17, Contrail Detection (cont.) T 6.2 – T 7.3

DoD Center for Geosciences/Atmospheric Research at Colorado State University Annual Review Nov 15-17, Contrail Detection (cont.) 1-km Resolution Visible (HRV) Data

DoD Center for Geosciences/Atmospheric Research at Colorado State University Annual Review Nov 15-17, Project Status u These eight products have been documented and delivered to Lockheed Martin. Lockheed Martin coded and installed the products at AFWA. We are awaiting AFWA implementation.

DoD Center for Geosciences/Atmospheric Research at Colorado State University Annual Review Nov 15-17, Future Plans Validate the algorithms: u Compare with t CDFS II data t MODIS cloud products t CloudSat and CALIPSO data u Develop improved algorithms for more specific DoD needs (e.g., cloud heights and icing)