The VIP Data Explorer is your gateway to all our remote sensing data and online data analysis tools. From here you can explore the multi-sensor Vegetation Index and Phenology Earth Science Data Records, other remote sensing datasets, perform visual and time series analysis, order and download data products and much more.
Please share with us your experience, problems, suggestions, or data uses.
For system status, issues, or updates please check our system status first..
NOTE Chrome no longer supports Google Earth plugin. We developed a Cesium or HTML5 based solution that is browser independent. In the meantime FireFox, IE, or Safari still work with GE plugin. NOTE-1 A new V5.0 of the Data Explorer with additional online tools is being developed.
V4 Products will become public in Mid-October 2014.
*The V4 reprocessing addressed all issues in prior versions additional and feedback from our user community. V4 will be an validated stage 3 research and application grade product suite.
V3 Products are now being planned.
*The V3 reprocessing will combine all learned lessons and feedback from our user base. V3 will be an application grade product with known error and uncertainty. Plans is to have V3 ready by Jan/Feb. 2013
V2 Product suite issues [July, 2012].
* We just found out that the shadow bit of our input daily surface reflectance from the MODIS CMG surface reflectance product suite and as such it is not set in the output product. This has a minimal impact on the product suite (no shadow in that area).
All V2 Products are research grade.
* Research grade data is the standard product suite released to the public with great research and application values. Nonetheless, it is expected to have minor bugs and spatial artefacts.
The V2 data set error and uncertainty is well understood but continue to be assessed.
All V1 Products are provisional.
* Provisional data have minimum to no research and application values and is expected to exhibit large error and uncertainty (being assessed).
* We're releasing these ESDRs to the public so our user community become familiar this new data records, assesses their usefulness, and tests their research and application values.
* V2 data, to be released soon, is expected to be the first ESDR record of high quality that could be used for research and application.
* Contact our Lab. with any questions.
VIP Data Explorer (all versions) is an Web- and Google Earth based interface to explorer our 30-year Vegetation Index and Phenology data records (Earth Science Data Records). Within this system you can perform simple visual inspection of any of the daily, multi-day, or multi-year products (Surface reflectance, vegetation index and land surface phenology). You can also explore the time series of any site/location on Earth (with delays), search for data, and order and download it through our ftp server or from within the Data Explorer.
Although, we've tried to make the system as simple and as intuitive as possible, there are still few operations that require more explaining. To learn how to properly use this Data Explorer go through the sections on the left pane.
Frequent Asked Questions
* Why some functions do not seem to work?
Due to many system and resources limitations some of the functions listed under the DataExplorer are not accessible except through on-demand basis. This means that the function is offered when the users ask us directly. We will try our best to fulfill the request. This pertains to things like spatial subsetting and format conversion. If you need these operations let us know and we will arrange via email.
* I need further assistance, where or what I should go or do?
If none of the information provided seems to help, please contact the Lab. and we will try to help you. Please be advised that it may take some time to receive an answer.
* I noticed errors, things that make no sense, or strange values for either the VI or Phenology data. What is going on?
Here are two key answers that you should keep in mind anytime you work with Remote Sensing data, especially global and very long term data records.
1. Our data records are still in development and may still contain some errors (please report them with specific info so we may correct the errors and/or find out what went wrong). As such please view the products in a global context (i.e., meant for large scale, regional to global use and application & research). Over certain areas and sometimes things may be quite bad with these products (winter snow/ice cover, cloudy seasons, low sun angle, etc...).
2. As with all remote sensing data, especially from synoptic satellites, multiple science processing algorithms are applied automatically after testing them over many seasons and globally, however, in some instances all of this testing still fails to catch certain problems associated with these algorithms once applied to the full record. Example issues associated with this behavior are spatial and temporal inconsistencies, bizarre and extreme values, etc.. Please report these problems and we will find out what went wrong and fix it in later reprocessing.
* When inspecting the phenology of a time series, I noticed some strange numbers, especially with the LOS.?
With the rollover of our V2 we noticed a bug with our pixel extraction algorithm (a server end algorithm). This bug should be fixed soon, however, we expect some residual effect may still exist in the algorithm/data. As with all data, your expert judgment and visual inspection are keys to a successful research and effective data use. Please ignore any data that makes no sense.
* Why there are so many product levels, and which one should I use for my work?
Here is the short answer, for all purposes use the last level product, continuity & Gap filled, those are the ESDRs (you can even screen out the gap filled pixels by using the per-pixel rank layer if you wish). The other product levels (Preprocessed, Filtered, Gap filled), are provided for thoroughness and to allow specialized users to see what happened to the data (from input to ESDRs generation). That information could be useful for evaluating the products, to perform accuracy analysis, and to allow for user specific operations (process the data your way starting at any level, literally setting aside what we did to it).
For more info consult our production plan, which details what happens to the data, how it is processed, and what are the different product levels.
* How many files can I order at once? Is there a limit?
Yes, but the only hard limit is actually imposed on the amount of data ordered rather than number of files. We're currently imposing a 50GB/day order size, so the number of files will depend on the individual file size. As our resource improve and as we get more band width we may ease this limit. However, if you feel like you need additional files or special arrangements let us know via email (email@example.com) or through the contact form (home page).
* I may need special attention, what then?
If you need more files, more data, or any other special attention we request that you contact us directly and we'll try to help(firstname.lastname@example.org) or through the contact form (home page).
* Any other means for data order?
Our resources only permit online data transfer for now, however, we'll assess if we can provide data (case by case basis) to people who would like it on DVD, CDs, or other mediums.
* I notice a problem with the data, what then?
As with any Remote Sensing data, we do expect a level of issues with our data, especially with earlier versions. These issues are location and time dependent, and may be related to the input data we use in our algorithms.
1.If you notice a consistent and or a serious problem (like wrong values, missing values over larger areas or long periods of time, etc...) please contact us so we may look into it and correct it.
2.If you notice a problem with only few dates, places, and on occasions then it is most likely an inherent input related issue and there is little we can do about it. We still want to hear from you regarding the issue.
3. Before you do contact us with any problem please check our documentation (ESDR status, that is where we will report problems that we already know about) confirm it first since our resources are rather limited.
* Are the current Dataset (V1.0) ready for Research & Applications?
Yes and now! We're currently distributing Version 1.0 of our products, this version is being provided so our user community can experience this new RS data records, develop a feel for these products, understand their specs, characteristics, etc...while we assess, correct bugs, and improve them. Our advice is that a user needs always to use common sense, if something looks suspicious it more than likely is a data problem. For these reasons we suggest the following:
1. Use V1.0 as a prototype product for your research/application to ready whatever tools, and analysis methods you plan to employ,
2. As always,use the per-pixel QA and the simple Ranking scheme we're providing with the products to filter poor quality data,
3. As with any data set, especially remote sensing based, you're ultimately responsible for the analysis, data interpretation, and conclusions,
4. You should also know that we're about to release the V2.0 ESDR suite, and that should be better, with less problems, and more accurate. With V2.0 we will also provide a global measure of error and uncertainty (these terms are interchangeable) which should help establish a bound on the data usefulness and/or significance of derived results. Stay tunes.
* Why is the Data Explorer slow?
For the most part, you'll experience a significant slowness when you load the explorer for the first time since it will need to download the GE plugin and then cache many of the information from our site. After that the response will improve and will depend on many factors:
1. Your band width
2. Your system speed
3. The images you're exploring. We're now using a tiling scheme to speed things up, but not all images were converted yet.
4. Overall network traffic at our end and your end
These issues mostly impact the Google Earth part of the explorer, all other parts should load faster (database, docs, etc...).
If this becomes a serious problem we suggest you use the single image display and/or animations, they are faster, and chose a degraded resolution (for more info check the Data Explorer help tab).
* Why some images and time series profiles are missing lots of data for certain areas?
Our aim is to provide high quality data only this means eliminating (or discarding) any observation that is compromised with clouds, shadow, cirrus clouds, heavy aerosols (in the case of MODIS), and snow/ice (not in all cases). Retaining only high quality data means that some time of the year (cloud or snow season) certain areas will have no data and this could be over very long periods and year in and year out. Because we also use this filtered data to reconstruct long term averages to be used to gap fill missing data it becomes then obvious that once there is no long term valid observation the gap filling cannot take place and the data will have spatial and temporal holes.
We're trying to design a work around for V2 that will preserve the data quality while gap filling all the missing data.
* How to contact you?
Send us directly an email to
or go to the home page and click on on the top menu.
*. How many ESDR versions are planned?
Officially we're planning 4 reprocessing cycles of the ESDR products with these tentative dates:
V1 : Ready since Spring 2011
V2 : Will released late 2011
V3 : Will released Mid 2012
V4 : Will released late 2012 early 2013
V5 : Last version will be released Late summer 2013
* Where do the False Color Images for AVHRR come from, since there are no green and/or MIR bands from this sensor.?
For consistency with MODIS and to give our users an idea of how the data looks like, we decided to literally create an artificial third band from AVHRR. To do so, we performed a long term analysis of the correlations between Red, NIR and MIR bands using the MODIS sensor. Once this correlation was understood it was simply interpolated to the AVHRR sensor. So to estimate an MIR band we need to know the Red and NIR. It is like saying, if AVHRR were to measure in the middle infrared (MIR) the data will look like this. Once the MIR is estimated we then use the same algorithm to generate the false color images (MIR-NIR-Red) as we did with MODIS. The images are for viewing only and are of now quantitative or scientific value. User can download those images those to their systems.
* What day of the year is considered for the compositing techniques?
The sds layer called Day of Pixel corresponds to the day of the year where the vegetation index values was taken for the CV-MVC technique. In those pixels that were filled the half range of the compositing period is selected. For the other two techniques (All Average and average of 3 maximum values) do not have this information.
* Where does MNR come from on the AVHRR dataset?
MNR images are generated by using mid-infrared, near-infrared and the red surface reflectance bands but the AVHRR dataset does not have the mid-infrared surface reflectance. Using the MODIS dataset, the mid-infrared band data was plotted against both red and near-infrared band data. A simple linear equation was developed and was used to create a "fake" mid-infrared band for AVHRR. An MNR image is then generated.
Acknowledgement and Data Product Citation Policy?
Data Products and/or services
Vegetation Index and Phenology Lab., The University of Arizona (VIP Lab.) 2011. Available online [https://vip.arizona.edu].
Please send us reprints
We request that you please email (email@example.com) us a reprint of your publications that use any of the VIP Lab. Data. This information will help us serve you better and show our sponsors (NASA) who and how these products are being used.
VIP Research Group, BE Dept., The University of Arizona. 1177 E. 4th Street, Tucson, Az 85721