Mekelle UniversityInstitute of Geo-information and Earth Observation Sciences(I-

GEOS)Department of GEOS – NRM

Course: RS and GIS Applications for Water ResourcesTitle: Remote Sensing of Aerosols Parameters, Water Vapor Parameters

and Cloud Parameters

Prepared by: Esayas Meresa Id-Pr-001/08

Submitted to Dr. Govindu V. Academic year – 2008e.c. Mekelle, Tigray, Ethiopia

Presentation Outline

Applications of GIS and RS for Water resources Remote Sensing of Aerosols Parameters Water Vapor Parameters Cloud Parameters

Applications of GIS and RS for Water resources

Our water supply is finite. From areas of abundance to places struck with drought, ensuring access to a clean, reliable source of water is critical. With Esri technology, you can protect water supplies and their integrity by understanding how human behaviors impact the natural system.

Document water sources and quantify their capacity based on current and historic data. Then share the story of the water system through engaging maps so everyone can see how today’s actions affect tomorrow’s water system.

Accurate, adequate and contemporary information on the state of water resources is must for planning & water resources management strategy . Increasing public awareness elevates the importance of water information & enlighten public involvement in water management / decisions.

Satellite Remote Sensing & GPS for temporal, multi - scale information generation at country level Geographic information system (GIS) is an effective tool for storing, managing, analyzing , displaying and dissemination of spatial data. Some RS and GIS applications in H2O resources:

Basin – wise water resources assessment • Groundwater Budgeting • Development of Decision support systems for WR Management • Flood forecasting and flood inundation modeling • Real time Irrigation management.

To address challenges in water sector the ultimate requirement is an information system having four elements:

(1) data input / collection system

(2) data storage, analysis, and transformation into "user-friendly“ information

(3) interactive system to geo - visualization & for decision making

(4) information dissemination system in public domain RS and GIS is a good tool for planning and management of water resources. Remote sensing and GIS specifically in monitoring water quality parameter

such as suspended matter, phytoplankton, turbidity, and dissolved organic matter.

Potential application and management is identified in promoting concept of sustainable water resource management.

The integration of remote sensing and GIS techniques has enabled assessments of NPS pollution, aquatic vegetation growth, salt marsh quality and floodplain disturbances over time.

Modeling water resources amount for the future…..etc.

Remote Sensing of Aerosols Parameters

What are Aerosols: Aerosols are bright particles that reflect Sunlight back to space reducing the amount of

solar radiation that can be absorbed by the surface below (Kahn, 1999). The magnitude of this effect depends on the size and composition of the aerosols, and in the reflecting properties of the underlying surface.

Aerosol particles may be solid or liquid and range in size from 0.01 micrometers to several tens of micrometers. Cigarette smoke particles are in the middle of this size range ; typical cloud drops are 10 or more micrometers in diameter.

Aerosol particles scatter and absorb radiation, and thus modify the radiation in the atmosphere. Satellite sensors measure the TOA radiance, which is areflected by the aerosol optical properties. Passive satellite remote sensing analyzes the TOA radiance to extract the aerosol optical properties. Clouds will have a very large impact on the TOA radiance. Aerosol retrieval is not possible when clouds are present.

To model and understand the forces modifying the Earth’s global climate system (Kahn, 1999)= NASA Earth Science Enterprise scientists:

The amount and type of atmospheric particles (aerosols), including those formed by nature and by human activities.

The amount, type, and height of clouds; and The distribution of land-surface cover, including vegetation canopy structure.

Remote Sensing for Aerosols Parameters The aerosol particles are characterized by their shape, size, chemical

composition, and total concentration, which in turn determine the aerosol optical properties. The typical range for the aerosol optical depth, the single scattering albedo, and the scattering coefficient, direction of the scattered light.

Remote sensing aerosols, clouds, and aerosol–cloud interactions is a hot topic of modern atmospheric remote sensing studies. Both aerosols and clouds influence climate and weather.

Optical and thermal infrared remote sensing of aerosols and clouds is a mature research field with a long history. Great progress has been achieved (especially in the last 40 years) using both ground-based and satellite instrumentation. The main parameters of interest are aerosol/cloud optical and microphysical properties, concentration, and aerosol/cloud geometrical characteristics (e.g., the altitudes, thickness and spatial extent).

Sate llite senso rs fo r Aer osol retri eval

Water Vapor Parameters

It is well established that water vapor from the environment can be absorbed into the bulk structure of amorphous solids of pharmaceutical interest, such as drugs, sugars, polymers, and proteins, in addition to being adsorbed on the surface. The amount of water taken up depends on environmental conditions, such as relative humidity and temperature, as well as the relative polarity of the solid A fundamental understanding of the mechanisms giving rise to various types of isotherms can therefore be helpful in understanding the effects sorbed water might have on the physical and chemical properties of such solids.

Water vapor is essential for precipitation. It is possible to detect and map water vapor by sensing in water vapor absorption bands. Several wavelengths can be used, but the most common is centered around 6.7µm.

METEOSAT 1, lunched in 1978 by the European Space Agency, was the first geostationary satellite to obtain images of mid to upper troposphere water vapor in the 6.7µm region in addition to visible and 10 – 12 µm infrared images (Kidder and Vander Haar, 1995).

Geostationary Operational Environmental Satellite (GOES) sensor routinely provide water vapor images obtained in the 6.7µm region. At this wavelength, most of the radiation sensed by the satellite comes from the atmospheric layer between 300 and 600 km, i.e., from the middle layers of the troposphere.

MODIS has several bands that are sensitive to atmospheric water vapor, including band 17(890-920 nm), 18 (931-941 nm), and 19 (915-965 nm).

Cloud Parameters

Clouds play an important role in terrestrial atmospheric dynamics, thermodynamics, chemistry, and radiative transfer and are key elements of the water and energy cycles. Cloud properties can be modified by anthropogenic and natural gaseous and aerosol emissions (i.e. aerosol indirect effect) and are important for understanding climate change. Therefore, it is of a great importance to understand cloud characteristics and their distributions on a global scale. This can only be achieved usingsatellite observations.

On average, about 70% of the Earth’s surface is covered by clouds. cloudfraction is a very important parameter, e.g. for the climate studies and also for the retrievals of the vertical columns of trace gases using space-borne instrumentation.

A cloud may warm or cool the Earth, depending upon its thickness and height above the surface. Low, thick clouds reflect incoming solar radiation back to space, which cause cooling.

High clouds trap outgoing infrared radiation and produce greenhouse warming. Because cloud type, height, moisture content, and location are so variable, their effect on global climate is very difficult to measure.

Clouds in Visible Imagery: The first meteorological satellite only measured visible energy reflected

clouds (0.4-0.7µm). New GOES sensors provide data in both the visible and thermal infrared

portion of the spectrum. In the daylight hours, visible imagery provides detailed views of the cloud

patterns that closely match our visual sense, i.e., clouds usually appear bright while land and water appear darker on the images.

GOES was first lunched on October 16,1975. Since that time many new GOES satellites have been parked at 35,790km in geostationary orbit to obtain visible and infrared imagery.

Visible imagery can only be obtained during the daytime. However, a light – sensitive instrument onboard the Defense Meteorological Satellite Program (DMSP) can obtain visible images at night. This is done by recording the features illuminated at night by moonlight.

The EOS Terra MISR collects stereoscopic cloud information by viewing each cloud from nine angles previously discussed. The stereoscopic data can be analyzed to yield three dimensional quantitative information about cloud height, structure, thickness, shape, and roughness of cloud tops. Accurate albedo information can also be computed.

In general, clouds do not reflect solar radiation equally well in all directions. Therefore, a single measurement of reflectivity from a single direction (e.g. at nadir) makes it difficult to determine the total amount of light reflected by the cloud (its albedo) relative to the incident energy.

The main cloud products derived from passive optical satellite observations are: Cloud cover, Cloud thermodynamic phase, Cloud optical thickness, Cloud droplet/crystal effective radius, Cloud liquid/ice water path, and Cloud top properties (temperature, pressure/height).

Clouds in thermal Infrared: The most common thermal infrared band used in meteorological investigations is

10–12.5µm. The atmosphere is relatively transparent to this wavelength energy upwelling from the Earth surface and clouds. Also, thermal infrared images can be obtained at night, so we can have a continuous 24-hour record events taking place at night.

Cloud-height information extracted from thermal infrared data can be used to generate pseudo three dimensional oblique images of major storm events.

It has been known for some time that is possible to extract information on the type of clouds and their height using multispectral remote sensing. Visible and infrared data can be used to differentiate between the sea, land, cumuliform clouds, semitransparent high clouds, and convective clouds (like thunderstorms). Tall convective cumulonimbus clouds are clod and bright. The sea and land surface are warm and dark. The analyst extracts the pixel value in the visible and thermal infrared bands, locates it in the diagram, and identifies the nature of the cloud under investigation.

The TRMM Visible Infrared Scanner (VIRS) lunched in 1997 provides high resolution information on cloud cover age, type, and cloud top temperature using a five channel cross track scanning radiometer.

The Terra MISR (Multi-angle Imaging Spector Radiometer) sensor collects information in only the visible and near-infrared portions of the spectrum, while the terra Clouds and Earth’s Radiant Energy System (CERES) sensor collects data from just one look angle, but across the entire solar spectrum.

CERES measures both solar reflected and Earth emitted radiation from the top of the atmosphere to the surface. It also determine cloud properties including amount, height, thickness, and particle size.

Thus, the VIRS, MISR, and CERES instruments complement one another in the collection of cloud information. Moderate Resolution Imaging Spector radiometer (MODIS) obtain cloud top information from bands 33-36 in the thermal infrared region from 13.185-14.385µm.

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PATIENCE!!!