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One of the most important ecological issues concerning our planet is climate change. It is generally agreed that the Earth's climate will modify in response to radiative forcing induced by changes in atmospheric trace gases, cloud cover, cloud type, solar radiation, and tropospheric aerosols (liquid or solid particles suspended in the air). In order to develop conceptual and predictive global climate models, it is vital to monitor these properties. Two MODIS (Moderate Resolution Imaging Spectroradiometer) instruments, the first launched on 18 December 1999 onboard the Terra Platform and the second on 4 May 2002 onboard the Aqua platform, are uniquely designed (wide spectral range, high spatial resolution, and near daily global coverage) to observe and monitor these and other Earth changes. (MORE)


Feature L1B Granule Image

Record Breaking California Wildfires On October 23rd 2007, the Terra-MODIS instrument captured this image of multiple wildfires and smoke driven by powerful Santa Ana winds in southern California. The fires flared up over the previous weekend, when temperatures surged past 110 degrees in some parts of the state, creating tinder-like conditions in areas already starved of water by an unusually dry winter. The wildfires have forced nearly 1/2 a million people to evacuate their homes from San Diego to just north of Los Angeles. Image by Ridgway & Hubanks, NASA GSFC. More RGB images of MODIS granules can be found in the L1B Granules section.

L1B & L2 Granule Case Study:   Kamchatka Cloud Properties

		L1B RGB Composite The RGB (MODIS bands 1:4:3) true-color composite for a single daytime granule of Terra-MODIS data over the Western Pacific Ocean near the Kamchatka Peninsula (0025 UTC on 10 August 2001) shows extensive cloud cover over the Sea of Okhotsk, including mid-level and upper-level ice clouds, whereas the Bering Sea to the east of the Peninsula contains extensive marine stratocumulus clouds with numerous ship tracks in the southeastern portion of the image.
		Cloud Optical Thickness Cloud optical thickness (at 0.66 µm) derived for this granule shows optically thick (values up to 25) marine stratocumulus to the east of the Peninsula and identifies them as liquid water clouds. The optically thick ice clouds over the Sea of Okhotsk and around the southern portion of the Kamchatka Peninsula have cloud optical thicknesses approaching 40. Note that two separate color bars were implemented to help visually differentiate clouds identified as ice (violet-green) vs. liquid water (yellow-red), both scales cover the range 1-75.
		Cloud Top Pressure Cloud top pressures derived for all cloud-filled pixels in the scene clearly show that liquid water clouds lie predominantly between 700 and 850-hPa, whereas the optically thick ice clouds over the Sea of Okhotsk lie at altitudes above the 500-hPa level. Note that the scale used in the image ranges from 300-hPa (violet) to 1000-hPa (red).
		Cloud Effective Radius This image shows cloud effective particle radius derived for cloudy pixels in the scene. Separate color bars were used again here to differentiate cloud phase; ice (violet-green, which covers the range 6-50) vs. liquid water (yellow-red, which covers the range 2-30). It is noteworthy that the ship tracks are not easily identified in the cloud optical thickness image, above, but are visible in the cloud effective radius image from the reduced effective radii in the microphysical retrievals. For this scene, the thermal infrared and decision tree algorithms for deriving cloud thermodynamic phase, discussed by Platnick et al., are in quite good agreement. [For more detail, see King et. al]. Images by Mark Gray, Dr. Steven Platnick, & Dr. Michael King. More images of MODIS Atmosphere Level 2 products can be found in the L2 Granules section.

L3 Global Imagery:   Monthly Average Timeseries

		Clear-sky Preciptable Water (IR) This animation shows clear-sky total-column atmospheric water vapor (precipitable water) from November 2002 through June 2003. The monthly average data, ranging from 0 (violet) to 7.5 cm (red), were derived using infrared (IR) retrieval techniques. The seasonal migration of high vapor content in the inter-tropical convergence zone (ITCZ) is clearly visible.
		Cloud Fraction (Daytime) Monthly average daytime-only cloud fraction data from November 2002 through June 2003, computed at 1-degree resolution using 5x5 1-km cloud mask data as input, range from 0% (violet) to 100% (red). Large scale Hadley cell circulations in the equatorial regions as well as the stormy latitude bands between 40 and 60 degrees, driven by dynamic global-scale thermal gradients, are clearly visible.
		Aerosol Optical Depth This animation depicts monthly average aerosol optical depth from November 2002 through June 2003. The unit-less data, computed in daytime scenes only, range from 0.0 (violet) to 3.0 (red). High-concentration aerosol plumes being transported over the Atlantic Ocean west of the Sahara and over the Pacific Ocean northeast of the dust-producing deserts of China are clearly visible.
		Cloud Optical Thickness (Water) Monthly average cloud optical thickness for liquid water clouds from November 2002 through June 2003 are displayed on a log scale to help bring out detail. The unit-less data values range from 1.0 (violet) to 10.0 (green) to 76.0 (red). Optical thickness is a measure of the quanity of solar radiation allowed to travel through a column of atmosphere and is an important new tool for helping scientists understand the role clouds play in the global climate system. Red and yellow regions indicate very cloudy skies (on average), which reduces the solar radiation reaching the Earth's surface. Green and light blue areas show moderately cloudy skies. Dark blue to violet colors show regions where there is little or no cloud cover (on average), and low attenuation of solar radiation from clouds. Animations by Paul Hubanks. A complete set of monthly global atmosphere images can be found in the L3 Low-Res Monthly section.

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Webmaster: Paul Hubanks Responsible NASA Official: Dr. Steven Platnick Last Updated: Friday, 6-June-2008   1:00 PM EDT