详细信息
id
5
标题
meteor-3飞船臭氧及反射率逐日观测数据集(1991-1994)
描述

meteor-3飞船臭氧及反射率逐日观测数据集(1991-1994)
资料集名称: meteor-3飞船臭氧及反射率逐日观测数据集
责任者: 资料中心
资料集编号: DS049
索取号: C6065
索引名: meteor
记录年代: 1991年—1994年
区域:
要素: 臭氧、反射率
编排: 统计报告
统计特征: 观测数据
详介:
观测次数、时间:
站数/层数、层次:
载体说明: CD-ROM光盘
数量: 1张
资料来源: NASA Langley Research Center
参考文献:
Meteor-3 TOMS Version 7 August 21, 1996
Gridded Ozone and Reflectivity Data
1991-1994
INTRODUCTION

This CD-ROM contains the latest version (version 7) of ozone

and reflectivity data from the TOMS (Total Ozone Mapping

Spectrometer) instrument onboard the Russian Meteor-3

spacecraft. Data covering the entire Meteor-3 TOMS

lifetime, August 22, 1991 through December 27, 1994, are

given as daily files of gridded data, as zonal means, and as

overpass data. Software is included to image the data.

Note: because Meteor 3 was in a precessing orbit,

there are periods when the spacecraft was flying near

the terminator. The ozone data taken during these

periods have been edited out because of their decreased

accuracy.

 

HARDWARE REQUIREMENTS

For PC: The data on this CD-ROM are ASCII format and can be

accessed by most systems. The image display software

requires Microsoft Windows and a VGA or better graphics card

that can support at least 256 colors. For best performance,

a 486 or faster machine with a math co-processor is

recommended.

For Mac: Because the software is designed for a

multi-platform environment, it has been written to the ISO

9660 Standard. All filenames are given in the 8.3 format.

For best performance, a 68030 or faster machine with a

floating point unit (FPU) is recommended. Graphic support

for at least 256 colors is also recommended.

OVERVIEW OF THIS CD-ROM

This CD-ROM, designated OPT_006, contains daily gridded

ozone data for the period August 1991 through December 1994.

Daily zonal means and overpass data and daily GIF images are

included for the ozone product. For the reflectivity data

only the daily grid files are included. The data are

described in more detail in the DATA FILES section. The

CD-ROM also contains a SOFTWARE subdirectory with PC and MAC

subdirectories containing platform-specific software to

image or view the data.

 

ORBIT CONSIDERATIONS

The Meteor 3 spacecraft was in a slowly precessing polar

orbit. Ozone measurements were taken for the entire world

every 24 hours. Unlike Nimbus 7, which was in a very stable

near-noon orbit, the Meteor 3 orbit precesses such that it

goes from near noon ascending (south to north) to near

terminator in about 53 days, to near noon descending (north

to south) in about 106 days. A complete cycle is 212 days.

This orbit drift is seen as a variation of the local equator

crossing time (LECT in first line of each daily file). Data

taken for an LECT outside the range 8:00 AM to 4:00 PM have

not been included on this CD-ROM because of the greatly

increased uncertainty in ozone measurements taken at very

high solar zenith angles. Data for 1991 have been

restricted to the range 9:00 AM to 3:00 PM because high

levels of volcanic dust from the Pinatubo eruption increased

the solar zenith angle dependent errors.

Dates for which Meteor 3 TOMS data are available:

Aug 22, 1991 Apr 1, 1993

Sep 2, 1991 Jun 10, 1993

Oct 26, 1991 Jul 17, 1993

Dec 17, 1991 Sep 25, 1993

Feb 9, 1992 Oct 31, 1993

Apr 2, 1992 Jan 9, 1994

May 26, 1992 Feb 14, 1994

Jul 17, 1992 Apr 25, 1994

Aug 31, 1992 Jun 1, 1994

Nov 9, 1992 Aug 10, 1994

Dec 16, 1992 Sep 15, 1994

Feb 24, 1993 Nov 24, 1994

 

THE OZONE MEASUREMENT

TOMS directly measures the ultraviolet sunlight scattered by

the Earth's atmosphere. Total column ozone is inferred from

the differential absorption of scattered sunlight in the

ultraviolet range. Ozone is calculated by taking the ratio

of two wavelengths (312 nm and 331 nm, for example), where

one wavelength is strongly absorbed by ozone while the other

is absorbed only weakly. The instrument has a 60 kilometer

square field of view at the sub-satellite point. TOMS

collects 35 measurements every 8 seconds as it scans right

to left producing approximately 200,000 ozone measurements

daily. These individual measurements vary typically between

100 and 650 Dobson Units (DU) and average about 300 DU.

This is equivalent to a 3 mm (about a 10th of an inch) thick

layer of pure ozone gas at NTP conditions.

In order to derive ozone, the scene reflectivity must first

be derived using channels not absorbed by ozone: 360 nm and

380 nm. Note that this is "effective" reflectivity - the

reflectivity of a Lambertian reflective surface that would

explain the observed backscattered radiance. It can be less

than 0% when volcanic aerosols are present and greater than

100% in areas of sun-glint. The reflectivity values on this

CD are given as percent reflectivity.

 

THE DATA FILES

Gridded Daily: The individual TOMS measurements have been

averaged into grid cells covering 1 degree of latitude by

1.25 degrees of longitude. The 180x288 ASCII data array

contains data from 90S to 90N, from 180W to 180E. Each

ozone value is a 3 digit integer (see sample). LECT is the

local equator crossing time.

example: .M3T

example: .M3R

sample ozone data:

Day: 281 Oct 8, 1994 Production V70 METEOR-3/TOMS OZONE Asc LECT: 1:22 AM

Longitudes: 288 bins centered on 179.375 W to 179.375 E (1.25 degree steps)

Latitudes : 180 bins centered on 89.5 S to 89.5 N (1.00 degree steps)

136136136136136136136136136136136136136136136136136136136136136136136136129

129129129129129129129129129129129129129129129129129129129129129129129129129

129129129129129129129129129129129129129129129129129129129129129129129129129

129129129129129129129129129129129129129129129129129129129129129129129129129

125125125125125125125125125125125125125125125125125125125125125125125125125

125125125125125125125125125125125125125125125125125125125125125125125131131

131131131131131131131131131131131131131131131131131131131131131131131131131

131131131131131131131131131131131131131131131131131131131131131131131131131

131131131131131131131131131131131131129129129129129129129129129129129129129

129129129129129129129129129129129129129129129129129129129129129129129129129

129129129129129129130130130130130130130130130130130130130130130130130130130

130130130130130130130130130129129129129 lat = -89.5

sample reflectivity data:

Day: 281 Oct 8, 1994 Production V70 METEOR-3/TOMS REFLECT. Asc LECT: 1:22 AM

Longitudes: 288 bins centered on 179.375 W to 179.375 E (1.25 degree steps)

Latitudes : 180 bins centered on 89.5 S to 89.5 N (1.00 degree steps)

91 91 91 91 91 91 91 91 91 91 91 91 91 91 91 91 91 91 91 91 92 92 92 92 92

92 92 92 92 92 92 92 92 92 92 92 92 92 92 92 92 92 92 92 92 92 92 92 92 92

92 92 92 92 92 92 92 92 92 92 91 91 91 91 91 91 91 91 91 91 91 91 91 91 91

91 91 91 91 91 91 91 91 91 91 91 91 91 91 91 91 91 91 91 91 91 91 91 91 91

92 92 92 92 92 92 92 92 92 92 92 92 92 92 92 92 92 92 92 92 92 92 92 92 92

92 92 92 92 92 92 92 92 92 92 92 92 92 92 92 92 92 92 92 92 92 92 92 92 92

92 92 92 92 92 92 92 92 92 92 92 92 92 92 92 92 92 92 90 90 90 90 90 90 90

90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90

90 90 90 90 90 90 90 90 89 89 89 89 89 89 89 89 89 89 89 89 89 89 89 89 89

89 89 89 89 89 89 89 89 89 89 89 89 89 89 89 89 89 89 89 89 89 89 89 89 89

89 89 89 89 89 89 89 89 89 89 89 89 89 89 89 89 89 89 89 89 89 89 89 89 89

89 89 89 89 89 89 89 89 89 89 89 89 89 lat = -89.5

 

GIF Image: Each day of data has a corresponding GIF image.

Each image is 640x480 pixels (full screen in standard VGA)

at 256 colors. North polar, south polar, and Aitoff

projections are shown.

Ozone data only example: .gif

Overpass Data: These files contain "overpass" data, the

best match single TOMS observation each day, for 371 ground

locations worldwide. (Dobson and other science sites, along

with major cities) See README file in for list of

sites.

Ozone and reflectivity example: .m3t

Zonal Means: Daily averaged data in 5 degree latitude

zones. At least 75% of possible data must be present in a

zone for the mean to be given.

Ozone data only example: _94.m3t

 

PROBLEMS WITH THE DATA

Polar Night: Because TOMS measures ozone using scattered

sunlight, it is not possible to measure ozone when there is

no sun (in the polar regions in winter). Consequently, maps

of the Antarctic ozone hole for August and September, for

example, will always have areas of missing data due to polar

night.

Missing Data: Because of increased uncertainty at high

solar zenith angles, data are not given for those periods

when Meteor 3 was flying near the terminator. On many days,

data were lost due to missing orbits or other problems.

Edge Effects: At the transition between good and flagged

or missing data, an "edge effect" will appear, consisting of

a few pixels of apparently low ozone values. These are

artifacts generated when the original data were interpolated

to produce the stored image data. A second type of edge

effect will be noticed in the polar plots consisting of

apparent discontinuities in the ozone field. Since TOMS

takes 24 hours to map the entire Earth, near the dateline

the ozone measurements have been taken almost 24 hours

apart. If the ozone is changing with time, this will

produce the observed discontinuity.

High Terrain: The ozone reported is total column ozone to

the ground. Over high mountains (the Himalayas, the Andes)

low ozone will be noticed relative to surrounding low

terrain. This is not an error.

Volcanic Aerosols: After the eruption of Mt. Pinatubo in

June of 1991, there were large amounts of sulfate aerosol

present in the lower stratosphere. This introduces a scan

angle dependent error into TOMS ozone that is negative near

nadir but positive in the outer scan positions. The average

error is small, and by 1992 the aerosol loading dropped

enough for these errors to be small. (See "Properties of

Mt. Pinatubo aerosols as derived from Nimbus 7 total ozone

mapping spectrometer measurements," by Torres, Herman,

Bhartia, and Ahmad, J. Geophys. Res., 100, 14043-14055,

1995.)

 

SOFTWARE DESCRIPTION

1. LVIEW and JPEGVIEW

Lview 3.1 is a freeware imaging program for Windows which

can easily view GIF and JPG images.

JpegView is a commonly used image viewer for the Macintosh.

It can read JPG, GIF and other image formats.

2. THE VISUANALYZE LITE PROGRAM

VisuAnalyze Lite is designed to provide the user with a

means of viewing the daily ozone data. Once loaded, the

program will display a window consisting of a pull down menu

and three boxes: one each for the image, the data table and

the site information selected by the cursor.

The menu allows you to control the viewing process and has a

number of controls over the screen image. North

Orthographic, South Orthographic, and Hammer-Aitoff

projections are supported. An overlay provides grid and

continental maps for easy reference. Palette permits the

user to select between different color patterns to aid in

image analysis. There are minor differences between the MAC

and PC versions. The included version limited to viewing TOMS

ozone data. Contact:

Bharat Thacker

Research and Professional Services (RPS)

5711 Sarvis Avenue, Suite 510

Riverdale, Maryland 20737 USA

(301) 699-7771 or (313) 278-7719

 

DIRECTORY STRUCTURE

OPT_006

root

(Meteor-3 TOMS User's Guide)

 

 

(Daily .GIF images)

(Daily ozone grid files)

(Daily values at specific locations)

(Daily zonal means)

 

(Daily reflectivity data)

(Source Code Templates)

 

(MAC Acrobat reader)

(MAC .GIF viewer)

(MAC imaging software)

 

(PC Acrobat reader)

(PC .GIF viewer)

(PC imaging software)

 

DOCUMENTATION

There are README files on the CD-ROM for all of the software

under the appropriate directory. A complete copy of the

Meteor-3 TOMS User's Guide is on the CD-ROM in PDF format in

the DOCUMENT directory: USRGIDM3.PDF

Adobe Acrobat readers are included in the subdirectories:

and .

Free Adobe Acrobat readers for other platforms can be found

on the Adobe homepage at: http://www.adobe.com

 

INTERNET SERVICES

NASA/Goddard Space Flight Center's Laboratory for

Atmospheres has a Web Site devoted to Atmospheric Science.

This site contains ozone related information including

aircraft missions, spacecraft, tropospheric data,

atmospheric modeling, and more. The URL address of this

site is: http://hyperion.gsfc.nasa.gov

 

News about the TOMS data, the Earth Probe and ADEOS TOMS

missions, and any software updates will appear on the TOMS

homepage. For Internet access to the TOMS Home Page use the

URL address: http://jwocky.gsfc.nasa.gov

Direct data access is available via an anonymous FTP

account:

ftp jwocky.gsfc.nasa.gov.

logon: anonymous

password: your e-mail address

cd pub/meteor3

 

 

CONTACTS

Dr. Jay Herman (science)

NASA Goddard Space Flight Center, Code 916

Greenbelt, Maryland 20771 USA

herman@tparty.gsfc.nasa.gov

(301) 286-7821 (301) 286-1754 (fax)

 

Eric Beach (general)

Hughes STX

7701 Greenbelt Road, M/S 301H

Greenbelt, Maryland 20771 USA

beach@qhearts.gsfc.nasa.gov

(301) 286-4526 (301) 286-1754 (fax)l meteor-3飞船臭氧及反射率逐日观测数据集(1991-1994)

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