Data acquisition From satellites with the MODIS instrument

Terra/Aqua ASTER MODIS CERES MISR MOPITT

Moderate-resolution Imaging Spectroradiometer NASA, Terra & AquaNASA, Terra & Aqua –launches 1999, 2002 –705 km polar orbits, descending (10:30 a.m.) & ascending (1:30 p.m.) Sensor CharacteristicsSensor Characteristics –36 spectral bands ranging from 0.41 to µ m –cross-track scan mirror with 2330 km swath width –Spatial resolutions: 250 m (bands 1 - 2)250 m (bands 1 - 2) 500 m (bands 3 - 7)500 m (bands 3 - 7) 1000 m (bands )1000 m (bands ) –2% reflectance calibration accuracy –onboard solar diffuser & solar diffuser stability monitor

Swath and orbit track Scan description (at 1km resolution)Scan description (at 1km resolution) 2330km scanline (203 across track)2330km scanline (203 across track) 1354km scans (135 along track)1354km scans (135 along track) Pixel size at nadir: 1 X 1kmPixel size at nadir: 1 X 1km GeneralGeneral Scan mirror scans 55° from nadir to both sidesScan mirror scans 55° from nadir to both sides Pixel arrays: 10 (1km) 20 (Hkm) and 40 (Qkm)Pixel arrays: 10 (1km) 20 (Hkm) and 40 (Qkm)

MODIS Level 1B products MODIS Level 1B Calibrated, Geolocated Products MOD021KM MOD021KM MODIS Level-1B Calibrated, Geolocated Radiance (1000 m( MODIS Level-1B Calibrated, Geolocated Radiance (1000 m( MOD02HKM MOD02HKM MODIS Level-1B Calibrated, Geolocated Radiance (500 m) MODIS Level-1B Calibrated, Geolocated Radiance (500 m) MOD02QKM MOD02QKM MODIS Level-1B Calibrated, Geolocated Radiance (250 m) MODIS Level-1B Calibrated, Geolocated Radiance (250 m)

Principal Channels MODIS Channels

The Bowtie effect

Aqua over Brazil (Oct. 4 th )

MODIS Cloud Mask (W. P. Menzel, S. A. Ackerman, R. A. Frey) MODIS cloud mask uses multispectral imagery to indicate whether the scene is clear, cloudy, or affected by shadows MODIS cloud mask uses multispectral imagery to indicate whether the scene is clear, cloudy, or affected by shadows Cloud mask is input to rest of atmosphere, land, and ocean algorithms Cloud mask is input to rest of atmosphere, land, and ocean algorithms Mask is generated at 250 m and 1 km resolutions Mask is generated at 250 m and 1 km resolutions Mask uses 17 spectral bands ranging from µm (including new 1.38 µm band) Mask uses 17 spectral bands ranging from µm (including new 1.38 µm band) – 11 different spectral tests are performed, with different tests being conducted over each of 5 different domains (land, ocean, coast, snow, and desert) – temporal consistency test is run over the ocean and at night over the desert – spatial variability is run over the oceans Algorithm based on radiance thresholds in the infrared, and reflectance and reflectance ratio thresholds in the visible and near-infrared Algorithm based on radiance thresholds in the infrared, and reflectance and reflectance ratio thresholds in the visible and near-infrared Cloud mask consists of 48 bits of information for each pixel, including results of individual tests and the processing path used Cloud mask consists of 48 bits of information for each pixel, including results of individual tests and the processing path used – bits 1 & 2 give combined results (confident clear, probably clear, probably cloudy, cloudy)

Terra over Brazil (Oct. 4 th )

MODIS aerosol product (MOD04_L2)

MODIS cloud product (MOD06_L2)

Gridded Level-3 Joint Atmosphere Products (M. D. King, S. Platnick, P. A. Hubanks, et al. – NASA GSFC, UMBC) – Daily, 8-day, and monthly products (474.8, 883.2, MB) – 1° ´1° equal angle grid – Mean, standard deviation, marginal probability density function, joint probability density functions – Quicklook imagery available at MODIS atmosphere web site: modis-atmos.gsfc.nasa.gov