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1<!doctype html public "-//w3c//dtd html 4.0 transitional//en">
2<html>
3<head>
4   <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
5   <meta name="Author" content="Alexey Chursin">
6   <meta name="GENERATOR" content="Mozilla/4.72 [en] (Windows NT 5.0; I) [Netscape]">
7   <title>Global Aerosol Data Set (GADS)</title>
8</head>
9<body background="/icons-geisa/alexei_backgr.gif">
10&nbsp;
11<center><table BORDER=8 COLS=1 WIDTH="80%" BGCOLOR="#FFFF00" >
12<tr>
13<td>
14<center><b><font color="#FF0000">Global Aerosol Data Set (GADS)</font></b></center>
15</td>
16</tr>
17</table></center>
18
19<p><b>What is on this page?</b>
20<p><a href="#globdistr">Global distribution of basic aerosol microphysical
21properties and online access to data files</a>
22<br><a href="#hess_art">Integral text of paper by Hess et al., 1998</a>
23<br><a href="#microphys">Computations of aerosol microphysical properties
24in each grid point</a>
25<br><a href="#opt">Computations of aerosol optical properties in each grid
26point</a>
27<br><a href="#opt">Download the complete version of GADS</a>
28<br><a href="#prog_online">GADS programs online</a>
29<br><a href="alexei_aer_ref.html">References</a>
30<p>&nbsp;&nbsp;&nbsp; Aerosol data globally existing from different measurements
31and extensive models have been compiled by <a href="http://www.lrz-muenchen.de/~uh234an/www/mitarb/mhess.html">Hess</a>
32and Koepke (Meteorolgisches Institut der Universitat Munchen, Germany),
33Schult (Max-Plank-Institut fur Meteorologie, Hamburg, Germany), and Shetle
34(Remote Sensing Division, Naval Research Lab. Washington, USA)&nbsp; into
35<a href="http://www.lrz-muenchen.de/~uh234an/www/radaer/gads.html">Global
36Aerosol Data Set (GADS) </a>(Koepke et al., 1997). The copy of the GADS
37web page is available also <a href="alexei_gads_des.html">here</a>.
38<br>&nbsp;&nbsp;&nbsp; The GADS is a completely revised version of the
39aerosol climatology by d'Almeida et al., 1991. The data now are consistent
40in number distribution, mass per volume and optical properties. Aerosols
41are modeled as 10 components which are described with size distribution
42and spectral refractive index (on the basis of (WMO, 1983), (d'Almeida
43et al., 1991)). From these data the optical properties are calculated with
44the Mie theory at wavelengths between 0.25 micrometers and 40 micrometers
45and for 8 values of relative humidity, if necessary. The properties of
46the aerosol components themselves are available in the software package
47<a href="alexei_opac.html">OPAC
48(Optical Properties of Aerosols and Clouds)</a>. In GADS, for the entire
49globe, on a grid of 5 degrees longitude and latitude, with 7 differentiating
50height profiles, and both for summer and winter, the aerosol at the gridpoints
51is composed from the aerosol components.
52<br>&nbsp;&nbsp;&nbsp; This data set consists of aerosol properties averaged
53in space and time and therefore is mainly determined for use in climate
54<br>modelling.
55<center><a NAME="globdistr"></a><b>The following basic averaged aerosol
56microphysical properties at each grid point have been archived in the GADS
57for two seasons of the Northen Hemisphere&nbsp; </b>(into the winter.dat&nbsp;
58and summer.dat files below)<i>:</i></center>
59
60<ul>
61<li>
62Aerosol height profile (7 different profiles are used in GADS. <a href="http://ara.lmd.polytechnique.fr/ftpgeisa?geisa/iasi/aerosol/glodat/profiles.dat">Click
63here to view them</a>.)</li>
64
65<li>
66Total particle number density at surface in particles cm<sup>-3</sup></li>
67
68<li>
69Number and list of aerosol components which compose the aerosol at a given
70grid point (up to 4 aerosol components are used at each grid point). The
71full list of possible aerosol components is given in column 2 of <a href="alexei_gads_comp.html">Table
721</a>.</li>
73
74<li>
75Mixing ratio of each of these aerosol components</li>
76</ul>
77Click with the mouse left button to view or with the mouse right button
78to download the following files:
79<ul>
80<li>
81<b><a href="http://ara.lmd.polytechnique.fr/ftpgeisa?geisa/iasi/aerosol/glodat/winter.dat">winter.dat</a></b>: valid
82for the period September to February.</li>
83
84<li>
85<b><a href="http://ara.lmd.polytechnique.fr/ftpgeisa?geisa/iasi/aerosol/glodat/summer.dat">summer.dat</a></b>: valid
86for the period March to August.</li>
87</ul>
88&nbsp;The detailed description of the file contents is given in the header
89of each file.
90<center>
91<p><a NAME="opt"></a><b>The following averaged&nbsp; aerosol optical propertiesat
92each grid point, at wavelengths between 0.25 micrometers and 40 micrometers
93and for 8 values of relative humidity (for some components) can be computed
94using <a href="http://ara.lmd.polytechnique.fr/ftpgeisa?geisa/iasi/aerosol/prog/gads.f">the GADS FORTRAN code</a></b>:</center>
95
96<ul>
97<li>
98Extinction coefficient [km<sup>-1</sup>]</li>
99
100<li>
101Scattering coefficient [km<sup>-1</sup>]</li>
102
103<li>
104Absorption coefficient [km<sup>-1</sup>]</li>
105
106<li>
107Single scattering albedo</li>
108
109<li>
110Asymmetry parameter</li>
111
112<li>
113Optical depth</li>
114
115<li>
116Lidar ratio [sr]</li>
117</ul>
118<a href="http://ara.lmd.polytechnique.fr/ftpgeisa?geisa/iasi/aerosol/example/aererg">Click here</a> to view an example
119of output file with computed aerosol optical properties. File format is
120given in headers of each file.
121<p><a NAME="hess_art"></a>All formulas and definitions are given in the
122basic paper by Hess et al., 1998: Click with the mouse right button and
123select "Save link as" item of the pop-up menu to download :
124<ul>
125<li>
126<a href="http://ara.lmd.polytechnique.fr/ftpgeisa?geisa/iasi/aerosol/doc/hess-etal.pdf">Pdf-version of paper by Hess
127et al., 1998</a></li>
128
129<li>
130<a href="http://ara.lmd.polytechnique.fr/ftpgeisa?geisa/iasi/aerosol/doc/hess-etal.ps">PostScript version of paper
131by Hess et al., 1998</a></li>
132</ul>
133
134<center><a NAME="microphys"></a><b>The following averaged aerosol microphysical
135properties at each grid point can be computed using <a href="http://ara.lmd.polytechnique.fr/ftpgeisa?geisa/iasi/aerosol/prog/gads.f">the
136GADS FORTRAN code</a>:</b></center>
137
138<p><br>
139<br>&nbsp;
140<br>&nbsp;
141<br>&nbsp;
142<center><table BORDER COLS=2 WIDTH="90%" >
143<tr>
144<td>
145<center><b>Aerosol microphysical property</b></center>
146</td>
147
148<td>
149<center><b>Example of an output file of such a type<sup>(*)</sup></b></center>
150</td>
151</tr>
152
153<tr>
154<td>Total number density of aerosol particles in particles cm<sup>-3 </sup>or
155in microgram m<sup>-3</sup>.</td>
156
157<td>
158<center><a href="http://ara.lmd.polytechnique.fr/ftpgeisa?geisa/iasi/aerosol/example/tonde.out">Click here</a></center>
159</td>
160</tr>
161
162<tr>
163<td>Number densities of aerosol components listed in column 2 of <a href="alexei_gads_comp.html">Table
1641</a>.&nbsp;</td>
165
166<td>
167<center><a href="http://ara.lmd.polytechnique.fr/ftpgeisa?geisa/iasi/aerosol/example/inson.out">Click here</a></center>
168</td>
169</tr>
170
171<tr>
172<td>Aerosol types<sup>(**)</sup>, listed in column 1 of <a href="alexei_opac.html#TB6">Table
1736</a>, typical for each grid point at sea level</td>
174
175<td>
176<center><a href="http://ara.lmd.polytechnique.fr/ftpgeisa?geisa/iasi/aerosol/example/aetyp.out">Click here</a></center>
177</td>
178</tr>
179
180<tr>
181<td>Aerosol profile types listed in <a href="http://ara.lmd.polytechnique.fr/ftpgeisa?geisa/iasi/aerosol/glodat/profiles.dat">profiles.dat</a>
182file, typical for each grid point.</td>
183
184<td>
185<center><a href="http://ara.lmd.polytechnique.fr/ftpgeisa?geisa/iasi/aerosol/example/prtyp.out">Click here</a></center>
186</td>
187</tr>
188</table></center>
189
190<p><sup>(*)</sup> All output files with microphysical properties have the
191same format: a file header, and rows with 3 values: latitude of a grid
192point (in degree) in column 1, longitude of a grid point (in degree) in
193column 2, a computed parameter (number density in particles cm<sup>-3 </sup>or
194in microgram m<sup>-3</sup>, aerosol type or aerosol profile type for this
195grid point) in column 3.
196<br><sup>(**)</sup> Aerosol types are coded as integers in the GADS output
197files: the fist aerosol listed column 1 of <a href="alexei_opac.html#TB6">Table
1986</a> (continental clean) is refered as 1, the second one (continental
199average) is refered as 2, etc.
200<center>
201<p><a NAME="avail"></a><b>Availability and use of GADS</b></center>
202
203<p><i>How to get GADS?</i>
204<p>&nbsp;&nbsp;&nbsp; The complete version of the GADS as well as the detailed
205description of its content can be gotten:
206<ol>
207<li>
208directly from the <a href="http://www.lrz-muenchen.de/~uh234an/www/radaer/gads_des.html">GADS
209web site</a></li>
210
211<li>
212from this web site: click <a href="http://ara.lmd.polytechnique.fr/ftpgeisa?geisa/iasi/aerosol/prog/gads22a_tar.gz">here</a>
213with the mouse right button and select the "Save link as" item of the pop-up
214menu. The detailed instructions on installation of the GADS are given <a href="alexei_instgads.html">here</a>.The
215FORTRAN source of the gads.f program is given <a href="http://ara.lmd.polytechnique.fr/ftpgeisa?geisa/iasi/aerosol/prog/gads.f">here</a>.</li>
216</ol>
217<a NAME="prog_online"></a><i>GADS programs online.</i>
218<p>&nbsp;&nbsp;&nbsp; GADS programs are online accessible from this page:
219<ul>
220<li>
221Global distribution of aerosol microphysical properties => Click
222here <b> (NOT AVAILABLE NOW) </b></li>
223
224<li>
225Global distribution of aerosol optical properties => Click
226here <b>(NOT AVAILABLE NOW)</b></li>
227</ul>
228
229</body>
230</html>
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