Quikscat / Seawinds.

介绍

The Quick Scatterometer (a SeaWinds instrument placed in orbit quickly) was launched in June 1999 and operated until November 2009. We refer to this instrument as QuikScat (or QSCAT) to distinguish it from the nearly identical SeaWinds scatterometer on the same satellite platform Midori-2 (known to US scientists as ADEOS-II), which operated briefly from December, 2002 to October 2003. The primary mission of these SeaWinds scatterometers was to measure winds near the ocean surface. They are also useful for some land and sea ice applications. The SeaWinds instruments are the third in a series of NASA scatterometers that operate at Ku-band (i.e., a frequency near 14 GHz). The first Ku-Band scatterometer was flown on SeaSat in 1978. Eighteen years later, NSCAT was launched on Japan's Midori-1 (ADEOS-I) spacecraft in August 1996. The Europeans also fly satellite scatterometers, which operate at C-band (approx. 5 GHz). Two of these, named ASCAT, are currently operating.

Seawinds散射仪基本上是雷达,将微波脉冲传递到地球表面,然后测量返回仪器的电源。这种“反向散射”功率与表面粗糙度有关。对于水面,表面粗糙度与近表面风速和方向高度相关。因此,从散射仪的反向散射电力的测量中检索海面上10米高的风速和方向。乐动体育官方2.0乐动苹果手机

Over many years, we developed and improved a Ku-band Geophysical Model Function (GMF). The current version is called Ku-2011. We use it to derive Wind Speed and Direction at 10-meter height over ice-free oceans from backscattered scatterometer signals. Our latest version of QuikScat data, V4, was released on April 28th, 2011 after a complete reprocessing using this new GMF. The goal of this activity was to improve wind speed retrievals, with special attention devoted to high winds.

对海洋的高风的准确观察对于分析来自当地(风暴,旋风)到全球鳞片(海洋交易器,海洋循环)的现象的分析很重要。然而,由于两个原因,高风的卫星检索是挑战。首先,它们通常被雨的存在污染,并且很难将风和雨量分离在检索中。其次,大于20米/秒的风的验证数据是稀缺的,因此限制了我们对卫星检索的高风的准确性的理解。

Data Processing

仪器停止运作后,Quikscat数据在仪器停止后进行了最终的再处理。我们使用我们改进的Ku-2011 GMF来生产版本-4(V4)数据产品。GMF用于从反向散射散射计信号的无冰海洋上获得100米高的风速和方向。我们的目标是提供用于气候研究的高质量散射仪风速检索。

当在遥感系统(GVERZ和SMITH,JGR 2001)开发了Quikscat风速检索的方法时,含有高风的验证数据非常有限。乐动体育下载用于大于20米/秒的风的外推和假设。自Quikscat推出以来的10多年,更多的验证数据可用,评估我们的KU-2011高风的质量更容易。

The newly developed Ku-2011 GMF (Ricciardulli and Wentz, manuscript in preparation) was developed using WindSat data as a calibration target. RSS has recently made advancements in polarimetric wind vector retrievals. Meissner and Wentz (IEEE TGARS, 2009) developed a new algorithm for WindSat winds which is valid even in rain and was trained in storm conditions using the NOAA Hurricane Research Division (HRD) dataset. The new QuikScat model function, Ku-2011, uses 7 years of observed radar backscatter ratios (sigma_0) collocated with rain-free WindSat wind retrievals. The WindSat retrievals are believed to be accurate for winds up to at least 30 m/s. Additionally, WindSat is able to accurately detect rain, and is used to discard QuikScat sigma_0 in the proximity of rain when developing the scatterometer GMF.

请注意,Quikscat Ku-2011(V4)风速已被校准到无雨中的Windsat数据。雨会影响散射仪检索,平均导致低风速下的正偏压(由于雨滴下降信号反向散射)和高风速的负偏差(由于信号的大气衰减)。雨水的风向较小,除了高雨率(8 mm / hr以上)。在本网站上显示的Quikscat风检索,并在我们的FTP服务器上提供的数据文件中存在于无雨和雨季。尽可能,除了独立的散射计雨旗之外,我们还提供了我们的一个辐射仪的雨率估计。我们建议用户依赖于散射仪雨旗和文件中的辐射计雨量信息,以从数据处理中清除雨量污染的数据。有关如何访问和应用雨标志的更多信息,请参阅提供的读取例程中的注释。

对于QuikScat的情况,我们使用4个卫星微波辐射仪(F13 SSMI,F14 SSMI,F15 SSMI和TMI)来确定雨水是否存在于QuikScat观察的位置。此外,所有可用的SSMIS用于检测海冰。使用SSMI日常观察海冰,可以正确标记散射仪观察,以便可以在边缘冰区旁边立即获得可靠的风向量。对于ADEOS-II的海风的情况,同一平台上的AMSR微波辐射计用于雨水和海冰检测。

Changes one should expect to see in the v4 QuikScat data include:

  1. 减少风速度大于20米/秒的风速
  2. 在非常低(<5米/秒)和高风速(> 15米/米)的情况下改善风向
  3. Better agreement between radiometer and scatterometer winds in typically high wind speed regions

对于Quikscat V4和Seawinds V3a数据,数据文件格式保持不变。数据文件文件夹名称为“BMAPS_V04”,文件版本指定已更改为“V4”。所有读取例程(Fortran,IDL,Matlab和Python)将在Quikscat V4数据以及Seawinds V3A数据上工作。有关KU-2011 GMF和Quikscat再处理的更多详细信息,请在文章中找到Ricciardulli and Wentz (2015)在RSS技术报告中用KU-2011地球物理模型功能进行再加工风矢量Quikscat V04

RSS Scatterometer Data Products

我们在ADEOS-II(版本-3A)数据产品上发布Quikscat(版本-4)和Seawinds。对于这两种仪器,两种类型的产品可用:1)SWATH产品包含由SWATH行垂直于卫星路径或2)网格的二进制数据文件组织的一个SWATH中的数据,以多种方式与RSS辐射计数据提供的方式相似。

Measurement 定义
Surface Wind Speed

风速10米在水面上方,源自表面粗糙度(风应力),大致相当于8-10分钟的平均表面风。

Surface Wind Direction

空气运动角度(海洋公约)。

雨信息

散射仪数据在雨中较低。数据产品包括散射计衍生的雨旗,以及共同定位的辐射计柱状雨率。

网格二进制文件

We produce daily and time averaged (3-day, weekly, monthly) gridded data files by mapping the scatterometer orbital data to a 0.25 deg longitude by 0.25 deg latitude Earth grid.

Gridded QuikScat and SeaWinds data are publicly available via FTP at:ftp://ftp.remss.com/qscat/bmaps_v04.ftp://ftp.remss.com/seawinds/bmaps_v03.

文件夹和文件名遵循以下约定:

Time Directory Path 文件名
Daily [年] / [月] / qscat_yyyymmddv4.gz

3-Day

[年] / [月] / qscat_yyyyymmddv4_3day.gz.
Weekly 周/ qscat_yyyymmddv4.gz
每月 [年] / [月] /

qscat_yyyymmv4.gz

Where [year], [month], "yyyy", "mm", "dd", and "v" stand for:

[year] 年文件夹 y2002, y2003 etc.
[月] month folder M01(Jan),M02(2月)等
yyyy year 2002, 2003 etc.
毫米 month 01 (Jan), 02 (Feb) etc.
dd 01,02,... 31
v version 4

Note that 3-day and weekly files are named for the day they end on (including that 3rd or 7th day).

Data are encoded in single byte values. Each data file contains a sequence of byte maps, or bmaps, each representing the Earth at quarter degree resolution: 1440 x 720 bytes.

每日文件字节数组的大小是1440 x 720 x 4 x 2 (longit吗ude, latitude, parameter, orbit segment (ascending or descending passes)). The 4 parameters are: UTC Time of Observation, Ocean Surface Wind Speed, Ocean Surface Wind Direction, and a Rain Flag / Collocated Radiometer Rain combination value (见下文)。每个参数都存在两种地图:一个升序轨道段(当地晨报)和另一个降序轨道段(当地傍晚通过)之一。

尺寸 Represents 范围
1440. 经度 0到360.
720 latitude -90 to 90
4 范围 UTC time, wind speed, wind direction, rain info
2 轨道部门 ascending passes, descending passes

Thus, daily files contain 8 global maps:
[升序,上升速度,上升方向,上升雨信息,下降时间,下降速度,下降方向,下降雨信息]

Time averaged files (3-day, weekly, monthly)字节阵列大小1440 x 720 x 3(经度,纬度,参数)。3个参数是:海面风速,海面风向,以及雨旗/搭配辐射计雨率组合值(见下文)。

尺寸 Represents 范围
1440. 经度 0到360.
720 latitude -90 to 90
3 范围 风速,风向,雨信息

时间平均文件包含3个全球地图:[风速,风向,雨信息]

对于平均散射仪数据,风速是标量平均,而风向是矢量平均。因此,如果日常观察记录在相反方向上吹风的强风,则标量速度平均值将反映高平均速度,并且矢量方向平均将指出普遍的方向。

如果存在最小值的观察数,则时间复合网格单元将包含数据:

Averaging Time 潜在的#观察 Typical # observations Minimum # observations
3-Day 6 〜4 2
Weekly 14 〜10 5
每月 〜60 〜45 20

日常地图上的数据被覆盖在连续轨道交叉和在当天最后一个轨道的“缝”或区域中的“缝”或区域之间的高纬度。

1440列和720行地图的第一电池的中心处于0.125 e经度和-89.875纬度。第二个电池的中心是0.375 e经度,-89.875纬度。

The data values fall between 0 and 255. Specific values have been reserved:

0 to 250 = valid geophysical data
251 = not used for scatterometers
252 = not used for scatterometers
253 = 存在散射仪观察,但很糟糕
254 = no scatterometer observations
255 = land mass

The data values between 0 and 250 need to be scaled to obtain meaningful geophysical data. To scale the data:

时间: 要么是乘法 6.0 to get UTC的0到1440分钟
or multiply by 0.1 to get UTC的0.0至24.0小时
风速 multiply by 0.2 to get 0.0至50.0 m / sec
风Direction multiply by 1.5 to get 0.0 to 360.0 degrees
Rain Flag 提取第一位 to get 0 =没有下雨; 1 = rain
辐射计雨 提取位3到8 (x / 2)-0.5 to get 0 to 31 km*mm/hr

风化在海洋公约中提供。这表示:

吹北风: 0°(或360°)
风s blowing East: 90°
风s blowing South: 180°
风s blowing West: 270°

The Rain byte contains 3 pieces of information. Use bit extraction to obtain the following:

scatterometer rain flag
(第1位)
0 =没有下雨
1 = rain
搭配辐射计标志
(第2位)
0 =在60分钟内没有辐射计数据
1 =在60分钟内的辐射计数据
radiometer columnar rain rate
(比特3-8)
0 =没有下雨
1 = rain in adjacent cells
2到63 =值/ 2 -0.5雨率以KM * mm / hr)

The files are stored in zipped form. If your programming environment does not read compressed files directly, use any GZIP compatible tool to unzip files before reading.

Read Routines

We provide Fortran, IDL, Matlab and Python read routines via FTP atftp://ftp.remss.com/qscat/scatterometer_bmap_support

QuikScat和Seawinds数据文件格式是相同的。读取程序适用于Quikscat和Seawinds数据集。

缺失数据

这些数据中存在差距。缺少数据通常会影响每日和3天的产品,但也可以在每周和每月平均值中减少观测数量。

浏览图像时,导航可能会跳过没有数据的日期,或者您可能会看到空白地图,说明该时间没有任何数据。

Binary data files for dates with completely missing data are not produced; they will be absent from our FTP server.

Data gaps are generally due to missing data upstream from our processing facility, such as the instrument being turned off. Occasionally, there are delays in obtaining and/or processing recently recorded data; beyond several weeks, it is unlikely that missing data will become available.

有关缺少Quikscat和Seawinds数据的官方信息可以在:
http://podaac.jpl.nasa.gov/OceanWind/QuikSCAT/SeaWinds-QuikSCAT_KnownProblems/L2B_DataGaps

Rain Contamination

雨是影响散射仪的众所周知的问题。它倾向于导致错误的交叉轨道矢量和/或不切实际的高速。

Here is an example:

Quikscat风向量2006/02/14晚上通过夏威夷

注意图像中的雨污染数据。散射计衍生的雨旗用于绘制箭头灰色而不是黑色。数据文件中也提供了搭配辐射计雨率。科学家应该使用雨旗和辐射计雨率,帮助在进行研究时从数据文件中清除雨量影响。乐动帐号注册

区域冰和土地问题

Undetected winter sea ice affects the Sea of Asov (northern Black Sea) and the Northern Caspian Sea. The shrinking Aral Sea is affected year round by land exposure. Note that all of these areas are rain flagged.

Browse Images

Each daily, weekly, or monthly scatterometer image in our browse data section shows the wind speed and direction for a specific geographical region.

每日浏览图像显示升序和下行卫星单独通过。每个通过的近似UTC时间在图像的底部附近标记。显示数据的数据日期是收集数据时的UTC日期(See the Map dates and Times section of the FAQs)。The observation times of ascending and descending pass segments are interleaved throughout the day. When browsing daily pass segments with the Previous and Next buttons, approximately half of the Earth will be browsed in temporal order; the other half will not be browsed in temporal order.

A scale of 10 meter ocean surface wind speeds is located on each image and extends between zero and 45 m/s. Land regions are colored gray. Areas where scatterometer data are not available are black. For the daily maps, the black color includes areas where the satellite did not pass over and no data was collected, areas where data was collected but it was determined to be bad, coastal areas, and regions containing sea ice.

The browse images are produced from the same gridded data files available on our FTP server.

SWATH数据文件

除了网格日常和时间平均文件之外,我们还仅释放仅用于散射计数数据。这些文件包含在地球周围卫星的一个轨道的测量。乐动体育官方2.0乐动苹果手机通过观察电池组织的数据,该观察电池垂直于卫星行进的方向。这使得数据网格与我们其他产品中使用的标准LAT / LON网格成一定的角度。

轨道散射仪数据出版icly available via FTP at:ftp://ftp.remss.com/qscat/qscat_wind_vectors_v04/ftp://ftp.remss.com/seawinds/seawinds_wind_vectors/

这些文件基于轨道号(00000to09999,02000to02999,02000to02999等)存储在目录中。文件名具有表单:

QuikSCAT: winvec_RRRRR_v04.gz
SeaWinds: winvec_rrrr_v03.dat.

其中rrrrr是五位数字轨道号码。

轨道数据文件格式如下所述:ftp://ftp.ssmi.com/qscat/readme_scattereter.txt.txt.

Date and time information for each orbit is located at:

QuikScat:

http://data.remss.com/qscat/qscat_info.txt

SeaWinds:

http://data.remss.com/seawinds/seawinds_info.txt

上述文件的列代表:

Orbit Number 好WVC行数 Equatorial Crossing Date (UTC) Equatorial Crossing Time (UTC) Equatorial Crossing Longitude

Orbit Period

Fortran,IDL和Matlab提供读取例程:ftp://ftp.remss.com/qscat/scatterometer_orbit_support/

The QuikScat and SeaWinds swath file formats are identical. The read routines work for both QuikScat and SeaWinds datasets.

Verification data to help ensure you are reading the data file correctly is at:ftp://ftp.remss.com/qscat/scatterometer_orbit_support/readme.txt.

参考

mears,c.a.,d.k.smith和f.j.wentz,1999,Development of a Rain Flag for QuikScat,技术报告编号121999,遥感系统,圣罗莎,CA,13 pp。乐动体育下载

Ricciardulli, L. and F.J.Wentz, 2011,Reprocessed QuikSCAT (V04) Wind Vectors With Ku-2011 Geophysical Model Function, technical report number 043011, Remote Sensing Systems, Santa Rosa, CA, 8pp.

Ricciardulli, L. and F.J. Wentz, 2015:A Scatterometer Geophysical Model Function for Climate-Quality Winds: QuikSCAT Ku-2011Journal of Atmospheric and Oceanic Technology, 32,1829-1846。

Wentz,F.J.和D.K.史密斯,1999年,A Model Function for the Ocean-Normalized Radar Cross Section at 14 GHz Derived From NSCAT Observations, Journal of Geophysical Research, 104(C5), 11499-11514.

Related Data Sets

KU-2011 GMF被提供给喷气机推进实验室,以便在Quikscat数据上运行。NASA PO.DAAC可用的数据与RSS可用的数据非常相似。应用不同的雨标记和质量标记,并使用不同的网格过程来在JPL创建水平-3的风产品。风值本身应仅包含与RSS数据的微小差异。

有关更多信息和访问Quikscat数据,请参阅jpl po.daac.

承认

QuikScat and SeaWinds data were produced by Remote Sensing Systems with funding from the NASA Ocean Vector Winds Science Team. Thanks to NASA JPL for providing the L2A data files used in creating these products.

如何引用

Production of this data set could not have happened without support from NASA. We need you to be sure to cite these data when used in your publications so that we can demonstrate the value of this data set to the scientific community. Please include the following statement in the acknowledgement section of your paper:

"QuikScat (or SeaWinds) data are produced by Remote Sensing Systems and sponsored by the NASA Ocean Vector Winds Science Team. Data are available atwww.dldq88.com。"

下面给出了用于出版物的官方数据引文。乐动软件下载在括号中插入适当的信息。

For bytemap version of QuikSCAT data: Ricciardulli, L., F.J. Wentz, D.K. Smith, 2011: Remote Sensing Systems QuikSCAT Ku-2011 [indicate whether you used Daily, 3-Day, Weekly, or Monthly] Ocean Vector Winds on 0.25 deg grid, Version 4, [indicate subset if used]. Remote Sensing Systems, Santa Rosa, CA. Available online at乐动体育 。[Accessed dd mmm yyyy].

For orbital QuikSCAT data: Ricciardulli, L., F.J. Wentz, D.K. Smith, 2011: Remote Sensing Systems QuikSCAT Ku-2011 [indicate whether you used Daily, 3-Day, Weekly, or Monthly] Orbital Swath Ocean Vector Winds L2B, Version 4, [indicate subset if used]. Remote Sensing Systems, Santa Rosa, CA. Available online at乐动体育 。[Accessed dd mmm yyyy].

对于Adeos-II上的海风:Wentz,F.J.和D.K.史密斯,2005年:遥感系乐动体育下载统Seawinds [指示您是否每天使用3天,每周或每月]海洋矢量风在0.25°Grid,3A版本中,[表示子集,如果使用]。乐动体育下载遥感系统,圣罗莎,加利福尼亚州。在线提供乐动体育 。[Accessed dd mmm yyyy].