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Data Sources
NOAA Satellite  The National Oceanic and Atmospheric Administration (NOAA) is a scientific agency of the United States Department of Commerce focused on the conditions of the oceans and the atmosphere. NOAA warns of dangerous weather, charts seas and skies, guides the use and protection of ocean and coastal resources, and conducts research to improve understanding and stewardship of the environment. In addition to its civilian employees, NOAA research and operations are supported by 300 uniformed service members who make up the NOAA Corps. NOAA Data holdings:
Platform/Instrument | Parameters | Period | NOAA AVHRR | AVHRR Raw Data | 1986 onwards |
MODIS (Terra/Aqua) Satellite MODIS (or Moderate Resolution Imaging Spectroradiometer) is a key instrument aboard the Terra (EOS AM) and Aqua (EOS PM) satellites. Terra's orbit around the Earth is timed so that it passes from north to south across the equator in the morning, while Aqua passes south to north over the equator in the afternoon. Terra MODIS and Aqua MODIS are viewing the entire Earth's surface every 1 to 2 days, acquiring data in 36 spectral bands, or groups of wavelengths (see MODIS Technical Specifications). These data will improve our understanding of global dynamics and processes occurring on the land, in the oceans, and in the lower atmosphere. MODIS is playing a vital role in the development of validated, global, interactive Earth system models able to predict global change accurately enough to assist policy makers in making sound decisions concerning the protection of our environment. NOAA Data holdings:
Platform/Instrument | Parameters | Period | MODIS – Tera/Aqua | Raw Pass Data & Processed Data on Ocean & Atmosphere parameters | 2005 onwards |
QuickSCAT NASA's Quick Scatterometer (QuikSCAT) was lofted into space at 7:15 p.m. Pacific Daylight Time on Saturday (6/19/99) atop a U.S. Air Force Titan II launch vehicle from Space Launch Complex 4 West at California's Vandenberg Air Force Base. The satellite was launched in a south-southwesterly direction, soaring over the Pacific Ocean at sunset as it ascended into space to achieve an initial elliptical orbit with a maximum altitude of about 800 kilometers (500 miles) above Earth's surface. The SeaWinds on QuikSCAT mission is a "quick recovery" mission to fill the gap created by the loss of data from the NASA Scatterometer (NSCAT), when the satellite it was flying on lost power in June 1997. The SeaWinds instrument on the QuikSCAT satellite is a specialized microwave radar that measures near-surface wind speed and direction under all weather and cloud conditions over Earth's oceans. SeaWinds uses a rotating dish antenna with two spot beams that sweep in a circular pattern. The antenna radiates microwave pulses at a frequency of 13.4 gigahertz across broad regions on Earth's surface. The instrument will collect data over ocean, land, and ice in a continuous, 1,800-kilometer-wide band, making approximately 400,000 measurements and covering 90% of Earth's surface in one day. Science Objectives - Acquire all-weather, high-resolution measurements of near-surface winds over global oceans.
- Determine atmospheric forcing, ocean response, and air-sea interaction mechanisms on various spatial and temporal scales.
- Combine wind data with measurements from scientific instruments in other disciplines to help us better understand the mechanisms of global climate change and weather patterns.
- Study both annual and semi-annual rain forest vegetation changes.
- Study daily/seasonal sea ice edge movement and Arctic/Antarctic ice pack changes.
Operational Objectives - Improve weather forecasts near coastlines by using wind data in numerical weather- and wave-prediction models.
- Improve storm warning and monitoring.
Mission Description - Launch Vehicle: Titan II
- Mission Life: 2 years (3 years consumables)
- Orbit: Sun-synchronous, 803 km, 98.6° inclination orbit
Spacecraft - ADCS approach: 3-axis stabilized, Star Tracker/IRU/Reaction Wheels, C/A Code GPS
- Pointing Acc.: < 0.1° absolute per axis
- Pointing Knowl.: < 0.05° per axis
- Telecom: (Science) 2 Mbps S-band P/L
(Hskp) 5, 16, 256 Kbps S-Band, 2 Kbps S-Band uplink - Propulsion: N2H4 Blowdown
- Mass: 970 Kg
- Orbital Avg Power: 874 W
- Data Capacity: 8 Gbits
Instrument Description - Radar: 13.4 gigahertz; 110-watt pulse at 189-hertz pulse repetition frequency (PRF)
- Antenna: 1-meter-diameter rotating dish that produces two spot beams, sweeping in a circular pattern
- Mass: 200 kilograms
- Power: 220 watts
- Average Data Rate: 40 kilobits per second
Data holdings:
Platform/Instrument | Parameters | Period | Quickscat | Wind Vector | 1998 – 2005 |
OCM Satellite While the earlier IRS series of satellites carried cameras (LISS-I, II, III, WiFS & PAN) designed predominantly to meet the needs of land-based applications, IRS-P4 is the first Indian satellite envisaged to meet the data requirements of the oceanographic community. IRS-P4 is planned to be launched by PSLV (Polar Satellite Launch Vehicle) in March 1999. The payload to be flown on-board IRS-P4 are: (a) OCM (Ocean Colour Monitor) operating in eight narrow spectral bands in the visible / near-infrared region of the electromagnetic spectrum and with high revisit time (2 days), and (b) MSMR ( Multi-frequency Scanning Microwave Radiometer) operating in microwave bands 6.6, 10.65, 18 and 21 GHz in dual polarisation mode. The multifrequency scanning microwave radiometer is envisaged to provide information on physical oceanographic parameters such as sea surface temperature, wind speed and atmospheric water vapour. The IRS-P4 spacecraft will be a polar orbiting satellite in sun synchronous orbit with nominal altitude of 720 km, providing revisit time of 2 days for OCM. Table 1 : Major specifications and features of IRS-P4 : OCM |
Parameter | |
Specification | 1. IGFOV at nominal altitude (m) | | 360 x 250 | 2. Swath (km) | | >1420 | 3. No. of spectral bands | | 8 | 4. Spectral range (nm) | | 402-885 | 5. Spectral band |
Central wavelength
(bandwidth) in nm |
Saturation radiance
(mw cm-2 sr-1 µm-1) |
C1 |
414 (20) |
35.5 |
C2 |
442 (20) |
28.5 |
C3 |
489 (20) |
22.8 |
C4 |
512 (20) |
25.7 |
C5 |
557 (20) |
22.4 |
C6 |
670 (20) |
18.1 |
C7 |
768 (40) |
9.0 |
C8 |
867 (40) |
17.2 | 6. Quantisation bits | | 12 | 7. Camera MTF
(at Nyquist frequency) | | >0.2 | 8. Data rate
(Mbits s-1) | | 20.8 | Along Track Steering | | +20, 0, 20 | Table 2 : Types of data products from IRS-P4 OCM |
Level |
Type of Products |
Remarks | Level 1 | Browse product | Raw product | Level 2 | Standard product | | Level 2.1 | Raw + Gain & bias | This product is geometrically and radiometrically corrected. Gain and bias values for each CCD element will be provided with data. | Level 2.2 | Radiometrically corrected | Product is geometrically raw. Top of the atmosphere (TOA) data will be provided. | Level 2.3 | Atmospherically corrected | Product is corrected for atmospheric path radiances and panoramic corrections for across track direction. | Level 3 | Special products | The derived products such as chlorophyll, suspended sediment maps. |
NOAA Data holdings:
Platform/Instrument | Parameters | Period | IRS - P4 OCM | Raw Data | 2000 onwards | IRS - P4 OCM | Processed Data (Chl) | 2002 onwards |
TRMM Satellite The Tropical Rainfall Measuring Mission (TRMM), is the first mission dedicated to measuring tropical and subtropical rainfall. Measurements from TRMM are used to find out where it's raining, and how hard it's raining. Not all clouds cause rain, and when rain does fall, it falls through various heights in the atmosphere, sometimes not reaching the ground at all!
Because rain is so variable, we have never known before just how much rain actually falls across the earth, but it is something we need to know if we are going to be able to predict wind patterns and ocean currents, floods and droughts.
TRMM won't be used for the daily rainfall measurements in your city, but it will be used by atmospheric scientists and weather forecasters to understand better how rainfall happens and why, so they can improve their forecasts in the future.
Payload - Precipitation Radar (PR)
- TRMM Microwave Imager (TMI)
- Visible Infrared Scanner (VIRS)
- Clouds and the Earths Radiant Energy System (CERES)
- Lightning Imaging Sensor (LIS)
Orbit
 The TRMM orbit is circular and is at an altitude of 218 nautical miles (350 km) and an inclination of 35 degrees to the Equator. The spacecraft takes about 91 minutes to complete one orbit around the Earth. This orbit allows for as much coverage of the tropics and extraction of rainfall data over the 24-hour day (16 orbits) as possible. SeaWifs The purpose of the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) Project is to provide quantitative data on global ocean bio-optical properties to the Earth science community. Subtle changes in ocean color signify various types and quantities of marine phytoplankton (microscopic marine plants), the knowledge of which has both scientific and practical applications. The SeaWiFS Project will develop and operate a research data system that will process, calibrate, validate, archive and distribute data received from an Earth-orbiting ocean color sensor. A detailed description of the objectives, organization and operations as well as the current status of the SeaWiFS Project is available. The SeaWiFS Mission is a part of NASA's Earth Science Enterprise, which is designed to look at our planet from space to better understand it as a system in both behavior and evolution.
The concentration of microscopic marine plants, called phytoplankton, can be derived from satellite observation and quantification of ocean color. This is due to the fact that the color in most of the world's oceans in the visible light region, (wavelengths of 400-700 nm) varies with the concentration of chlorophyll and other plant pigments present in the water, i.e., the more phytoplankton present, the greater the concentration of plant pigments and the greener the water.
Ocean color data have been deemed critical by the oceanographic community for the study of ocean primary production and global biogeochemistry. "Primary production" refers to the organic material in the sea that is produced by "primary producers." These "primary producers," i.e. algae and some bacteria, exist at the lowest levels of the food chain and use sunlight or chemical energy, rather than other organic material, as sources of energy. It is thought that marine plants remove carbon from the atmosphere at a rate equivalent to terrestrial plants, but knowledge of interannual variability is very poor. Data holdings:
Platform/Instrument | Parameters | Period | SeaWifs | Chlorophyll | 2000 – 2005 |
Altimeters Altimeter
Any device which measures the height of an aircraft. The two chief types are: - the pressure altimeter, which measures the aircraft's distance above sea level, and
- the radar altimeter, which measures distance above the ground.
Pressure altimeter: A pressure altimeter precisely measures the pressure of the air at the level an aircraft is flying and converts the pressure measurement to an indication of height above sea level according to a standard pressure-altitude relationship. In essence, a pressure altimeter is a highly refined aneroid barometer since it utilizes an evacuated capsule whose movement or force is directly related to the pressure on the outside of the capsule. Various methods are used to sense the capsule function and cause a display to respond such that the pilot sees the altitude level much as one looks at a watch. Because altitude measured in this manner is also subject to changes in local barometric pressure, altimeters are provided with a barosetting that allows the pilot to compensate for these weather changes, the sea-level air pressure to which the altimeter is adjusted appearing in a window of the dial. Flights below 18,000 ft (5486 m) must constantly contact the nearest traffic center to keep the altimeters so updated. Flights above 18,000 ft and over international waters utilize a constant altimeter setting of 29.92 in. Hg, or 1013.2 millibars (101.32 kilopascals), so that all high-flying aircraft have the same reference and will be interrelated, providing an extra margin of safety. See also Air navigation. Radar altimeter: A radar altimeter is a low-power radar that measures the distance of an aircraft (or other aerospace vehicle) above the ground. Radar altimeters are often used in aircraft during bad-weather landings. They are an essential part of many blind-landing and automatic navigation systems and are used over mountains to indicate terrain clearance. Special types are used in surveying for quick determination of profiles. Radar altimeters are used in bombs, missiles, and shells as proximity fuses to cause detonation or to initiate other functions at set altitudes. Radar altimeters have been used on various spacecraft, starting with Skylab in 1973, to measure the shape of the geoid and heights of waves and tides over the oceans. Other spacecraft altimeters provide topographic information on other planets, particularly Venus. See also Automatic landing system; Ground proximity warning system. Like other radar devices, the altimeter measures distance by determining the time required for a radio wave to travel to and from a target, in this case the Earth's surface. If the Earth were a perfectly flat horizontal plane or smooth sphere, the signal would come only from the closest point, and would be a true measure of altitude. Actually, the Earth is not smooth, and energy is scattered back to the radar from all parts of the surface illuminated by the transmitter. For the radar to measure distance to the ground accurately, it must distinguish between the energy from points near the vertical and that from more distant points. Click here for Satellite Real Time Images
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