Applications: Atmosphere Artists impression of Spot 5 The MODIS sensor, aboard NASA’s Terra satellite, measures cloud optical thickness over the entire globe every day. Basically, cloud optical thickness is a measure of how much sunlight is prevented from traveling down through a column of atmosphere by clouds. This image shows a composite for April 2001. Reds indicate high values while blues and purples show where the air is relatively clear; no data are available for the region colored black. The MODIS instrument, aboard NASA’s Terra satellite Source: NASAArtists impression of Spot 5 ! Definition ! Radiation budget ! Aerosols ! Clouds ! Data and satellites Applications: Atmosphere (Outline)Applications: Atmosphere Earth's atmosphere is the layer of gases surrounding the planet Earth and retained by the Earth's gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation and reducing temperature extremes between day and night.Anthropogenic and natural forcing of the Climate for the year 2000Anthropogenic and natural forcing of the Climate for the year 2005What is weather and what is climate? ! Weather: is the instantaneous state(s) of the atmosphere as time passes. It can be described by different parameters that characterize the physical state of air such as temperature, pressure,… ! Climate: is the long term average of weather  14 day weather prediction limit, but no limit to climate prediction  Weather data accuracy is 1 degree, climate accuracy 0.1 degreeNASA/Goddard Institute for Space StudiesWe are entering new territory; old relationships may not apply. NASAMilankovitch Cycles (100,000 yrs) (41,000 yrs) (23,000 yrs)Anthropogenic and natural forcing of the Climate for the year 2000Radiation budget Measurements of radiant energy within the Earth’s atmosphere are very important for climate change studies. How climate changes is directly related to how our planet balances the amount of incoming sunlight with outgoing radiant energyPlatforms and sensors for radiation budget ! 1978 Nimbus-7 carrying Earth Radiation Budget (ERB) experiment sensor. The sensor designed to measure direct solar irradiance, reflected shortwave radiation, and emitted longwave radiation every day. ! Launch of the Clouds and the Earth’s Radiant Energy System (CERES) sensor aboard:  1997 Tropical Rainfall Measuring Mission (TRMM) satellite.  1999 Twin CERES instruments aboard NASA’s Terra  2002 Twin CERES instruments aboard NASA’s AquaSource: NOAASource: NOAASource: NOAASource: NOAASource: NOAAThese global scale composite images show where more or less shortwave radiant energy is reflected back into space (left), and where more or less longwave radiant energy is emitted to space (right). These measurements were acquired by CERES, flying aboard NASA’s Terra satellite, on May 25, 2001. Source: NASACERES LW and SW of the globe for the period 03/2000 to 05/2001CERES LW for the period 03/2000 to 05/2001Aerosols ! Aerosols are tiny particles suspended in the air. Aerosols come from natural sources or human produced. ! The effect of aerosols is to cool the surface by absorbing and reflecting incoming solar radiation. They also serve as cloud condensation nuclei for cloud formation, which again helps to cool the surfaceOptical Depth ! The optical depth (τ) expresses the quantity of light removed from a beam by scattering or absorption during its path through a medium. I/Io = e-τ (Eq. 1) Where:  Io = intensity of a source  I = Intensity observed after a given path ! When a surface is viewed at an angle, Eq 1 becomes: I/Io = e-τ/cos(θ) (Eq. 2) Where θ = the viewing angle ! Optical depth also determines how visible a surface isOptical DepthPlatforms and sensors for aerosols ! 1980s and most of the 1990s the NOAA AVHRR was the most used sensor for measuring aerosol optical thickness ! 1991 Along Track Scanning Radiometer (ATSR), aboard the first European Remote Sensing Satellite (ERS-1). ! 1995 Advanced Along Track Scanning Radiometer (AATSR), aboard ERS-2Platforms and sensors for aerosols ! 1996, Japan launched the first in their series of Advanced Earth Observation Satellites (ADEOS) satellites, which carried two sensors: (1) the Polarization and Directionality of the Earth’s Reflectances (POLDER), and (2) the Ocean Color and Temperature Scanner (OCTS). ! 1999 Terra satellite, three of its sensors are suitable for studying the effect of aerosols on climate (CERES, MISR, and MODIS).The MISR instrument, aboard NASA’s Terra satellite, is sensitive to four different wavelengths—red, green, blue, and one channel in the near-infrared. MISR “sees” the Earth simultaneously at nine different angles, so it is particularly well designed for measuring how much sunlight aerosols reflect back to space.Giant smoke plume from Canadian forest fires was generated from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument aboard NASA's Terra SatelliteClouds ! Clouds are plentiful and widespread throughout Earth’s atmosphere—covering up to 75 percent of our planet at any given time ! Clouds play a dominant role in determining how much sunlight reaches the surface, how much sunlight is reflected back into space, how and where warmth is spread around the globe, and how much heat escapes from the surface and atmosphere back into space! SAGE-III Limb soundingPlatforms and sensors for clouds ! 1980’s AVHRR and ERBE satellite data coupled with aircraft and surface-based measurements ! 1999 two sensors of Terra satellite:  The Moderate-resolution Imaging Spectroradiometer (MODIS) and  The Multi-angle Imaging Spectroradiometer (MISR) ! 2002 Aqua and 2006 Cloudsat and Calipso! The paper described the AVHRR Pathfinder Atmosphere (PATMOS) processing system and some of its atmospheric parameters for the period 1981-1999. ! The parameters are: total cloud amount, aerosol optical thickness over oceans, outgoing long-wave radiation, and absorbed or reflected radiation at the top of the atmosphere. ! To determine the accuracy, results were compared to ground data or to result of other satellite data ! Comparison indicated that the data are of sufficient of accuracy for studies of climate phenomena with large signals, such as ENSO, major volcanic eruptions, and monsoons.Time