Atmospheric Applications of Multi- and Hyperspectral Remote Sensing Climate, Meteorology and Atmospheric Chemistry

Learning Objectives Understand the advantages of different orbital patterns for meteorology. What are the primary uses for visible vs. thermal RS in meteorology? In general terms, how do we estimate atmospheric constituents with RS data? What is the difference between tropospheric and stratospheric ozone?

Applications of satellites for atmospheric studies Weather monitoring and forecasting Cloud type identification Active RS (e.g., radar) Atmospheric Composition Atmospheric chemistry Pollution monitoring Aerosols Volcanic ash Climate studies Atmospheric role in climate Land-atmosphere interactions Ocean-atmosphere interactions

Von Karman Vortices Named after Theodore von Karman. Caused by unsteady fluid flow around blunt objects (like islands in this image).

Hurricane Fran, 1996

MODIS Image Saharan dust moving across Mediterranean to Turkey

Sulfur Dioxide Plume – Kahlua

Meteorological RS: Early History (Review) Earliest man-made satellites were designed for weather observations Vanguard 2 (1959) – designed to measure cloud cover but didn’t work well TIROS 1 (1960) – crude weather observations allowed scientists to view earth’s weather as a system Application Technology Satellites (1966) – full disk view of earth Nimbus satellites (1964 – 78) – atmospheric temperature and ozone profiles and other atmospheric properties

Types of weather satellites Defined by orbital characteristics Polar orbiting – travel roughly over poles on each orbit Typically two views/day of each place on earth Relatively high spatial resolution due to lower altitude than geostationary Geostationary – orbit parallel to the equator at an altitude of 22,300 miles; always over one place. Full hemisphere or large area viewing but usually at lower resolution due to altitude

Modern weather satellites GOES – Geostationary Operational Environmental Satellites GOES 13 also called GOES East – over Brazil but captures imagery for our entire hemisphere GOES 15 also called GOES West – over eastern Pacific Ocean GOES 16 launched in November 2016 NOAA operates several polar orbiting weather satellites (NPOES) Many other countries have their own weather satellites that are either polar orbiting and geostationary

GOES 16 As of early March, still undergoing testing before being declared operational. Improvements over previous GOES include: Higher spatial and spectral resolution Lightning monitoring in real time Better water vapor sensing Geomagnetic storm forecasts Solar flare monitoring

GOES 16 1-hour cumulative lightning optical emission GOES 16 1-hour cumulative lightning optical emission. GOES can monitor lightning continuously. (NOAA image)

Spring snowstorm in Wyoming (April 15, 2016) GOES Composite Image of US Warm (low) clouds bluish, Cold (high) clouds yellow and red. Spring snowstorm in Wyoming (April 15, 2016)

GOES West Image Thermal IR Full Disk April 6, 2015

GOES East full disk Visible April 6, 2015

How are weather satellites used? Interpretation of visible (panchromatic) images Cloud and aerosol thicknesses Interpretation of infrared images Cloud temperatures and heights Prognostication (prediction) Time-lapse views that show movement of systems Hurricane tracking and monitoring Data inputs for weather models

Visible wavelength satellite imagery Can see clouds (bright) and relative cloud thickness (brighter = thicker until saturation) Can see haze and aerosol (relatively bright) Cannot distinguish cloud heights (low, middle and high altitude clouds all look the same) Visible can only be used in the daytime Image from April 15, 2016

IR satellite imagery Long-wave IR (thermal) allows sensing of the temperature of the cloud tops--related to height Higher cloud tops colder than low cloud tops IR Weather images are processed so that coldest places appear BRIGHT and warmest appear DARK Opposite of normal thermal imagery!! Can be used day or night.

Water vapor images IR Satellite imagery can also be used to create images of the amount of water vapor in the atmosphere

Remote sensing for monitoring atmospheric constituents Several satellites have bands that are used for atmospheric chemistry (e.g., MODIS) or are completely dedicated to the atmosphere (e.g., AURA) Aura flies “in formation” about 15 minutes behind MODIS Aura carries several instruments that measure the concentration of atmospheric constituents Other satellites TOMS – Total Ozone Mapping Spectrometer UARS – Upper Atmosphere Research Satellite AURA: NO2, ozone, sulfur dioxide, etc.

Human activities have changed the composition of the atmosphere since the pre- industrial era Some sulfate is natural (e.g., volcanoes), but some is anthropogenic (e.g. from burning coal).

Photo by Mark Gocke, Casper Star Tribune.

Ground based sensors Note: Ground based sensors are used more than satellite sensors for atmospheric chemistry (and pollution) Can look outwards just as a satellite looks downwards and measure amount of light in various wavelengths Atmospheric absorption of particular wavelengths indicative of particular chemicals Strength of absorption relates to concentration of chemical Value of space based sensors is more in getting whole- atmosphere view; Ground based sensors limited spatially

Air pollution monitoring with satellites Satellites can measure and track plumes of air pollution E.g., MOPITT – Measurements Of Pollution In The Troposphere Measures amount of carbon monoxide and methane in the atmosphere On same satellite as MODIS Many satellites for atmospheric chemistry can also measure some pollutants

Global carbon monoxide during MOPITT’s first year of operation CO produced by burning of fossil fuels, biomass, volcanoes, wildfire, etc.

Summary Satellites are critical for weather forecasting and climate studies Optical data primarily used for cloud studies Thermal IR data also extremely useful (will discuss thermal later in semester) Atmospheric scientists use satellites for global and local monitoring Atmospheric pollution is a subset of atmospheric chemistry Satellites allow mapping of general pattern of pollutant concentration and tracking of plumes, etc.