Presentation is loading. Please wait.

Presentation is loading. Please wait.

DoD Center for Geosciences/Atmospheric Research at Colorado State University Annual Review Nov 15-17, 2005 1 Meteosat Second Generation Algorithms for.

Similar presentations


Presentation on theme: "DoD Center for Geosciences/Atmospheric Research at Colorado State University Annual Review Nov 15-17, 2005 1 Meteosat Second Generation Algorithms for."— Presentation transcript:

1 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

2 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.

3 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)

4 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 –

5 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

6 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

7 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 <

8 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

9 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

10 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

11 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

12 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

13 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

14 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:

15 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.

16 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.

17 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

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

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

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

21 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.

22 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)


Download ppt "DoD Center for Geosciences/Atmospheric Research at Colorado State University Annual Review Nov 15-17, 2005 1 Meteosat Second Generation Algorithms for."

Similar presentations


Ads by Google