account instrument angle of view or swath width.
NASA GHRC One of NASA’s Distributed Active Archive Centers
  • Find Data
    • Find Data (HyDRO)
      • HyDRO is GHRC's custom dataset search and order tool.

        With HyDRO, you can search, discover, and filter GHRC's dataset holdings.

        HyDRO will also help you find information about browse imagery, access restrictions, and dataset guide documents.
    • Coincidence Search
      • The GHRC Coincidence Search Engine (CSE) may be used to search for times when up to four satellites were over or within the same geographic area simultaneously.

        Searches may be constrained by time, geographic area, and/or distance between the satellites.
    • OPeNDAP
      • This is our current OPeNDAP server.

        You can access, download, and subset our main data catalog using this link through your web browser or stand-alone OPeNDAP client applications.
    • Storm Tracks DB
      • The Tropical Storm Tracks database is derived from the storm data published by the National Hurricane Center (NHC).

        This web page provides a convenient user interface for casually browsing storm information, including location, category, and wind speed.
    • NASA Earthdata Search
      • Earthdata is NASA's next generation metadata and service discovery tool, providing search and access capabilities for dataset holdings at all of the Distributed Active Archive Centers (DAACs) including the GHRC.
  • Measurements
  • Field Campaigns
    • Hurricane Science
      • GHRC has worked with NASA's Hurricane Science Research Program (HSRP) since the 1990's. We are the archive and distribution center for data collected during HSRP field campaigns, as well as the recent Hurricane Science and Severe Storm Sentinel (HS3) Earth Venture mission. Field campaigns provide for intensive observation of specific phenomena using a variety of instruments on aircraft, satellites and surface networks.

        GHRC also hosts a database of Atlantic and Pacific tropical storm tracks derived from the storm data published by the National Hurricane Center (NHC).
    • HS3 (2012-14)
      • Hurricane and Severe Storm Sentinel (HS3) is an Earth Ventures – Suborbital 1 mission aimed at better understanding the physical processes that control hurricane intensity change, addressing questions related to the roles of environmental conditions and internal storm structures to storm intensification.

        A variety of in-situ, satellite observations, airborne data, meteorological analyses, and simulation data were collected with missions over the Atlantic in August and September of three observation years (2012, 2013, 2014). These data are available at GHRC beginning in 2015.
    • GRIP (2010)
      • The Genesis and Rapid Intensification Processes (GRIP) experiment was a NASA Earth science field experiment in 2010 that was conducted to better understand how tropical storms form and develop into major hurricanes.

        The GRIP deployment was 15 August – 30 September 2010 with bases in Ft. Lauderdale, FL for the DC-8, at Houston, TX for the WB-57, and at NASA Dryden Flight Research Facility, CA for the Global Hawk.
    • TC4 (2007)
      • The NASA TC4 (Tropical Composition, Cloud and Climate Coupling) mission investigated the structure and properties of the chemical, dynamic, and physical processes in atmosphere of the tropical Eastern Pacific.

        TC4 was based in San Jose, Costa Rica during July 2007.

        The Real Time Mission Monitor provided simultaneous aircraft status for three aircraft during the TC4 experiment. During TC4, the NASA ER-2, WB-57 and DC-8 aircraft flew missions at various times. The science flights were scheduled between 17 July and 8 August 2007.
    • NAMMA (2006)
      • The NASA African Monsoon Multidisciplinary Analyses (NAMMA) campaign was a field research investigation based in the Cape Verde Islands, 350 miles off the coast of Senegal in west Africa.

        Commenced in August 2006, NASA scientists employed surface observation networks and aircraft to characterize the evolution and structure of African Easterly Waves (AEWs) and Mesoscale Convective Systems over continental western Africa, and their associated impacts on regional water and energy budgets.
    • TCSP (2005)
      • The Tropical Cloud Systems and Processes (TCSP) mission was an Earth science field research investigation focused on the study of the dynamics and thermodynamics of precipitating cloud systems and tropical cyclones. TCSP was conducted during the period July 1-27, 2005 out of the Juan Santamaria Airfield in San Jose, Costa Rica.

        The TCSP field experiment flew 12 NASA ER-2 science flights, including missions to Hurricanes Dennis and Emily, Tropical Storm Gert and an eastern Pacific mesoscale complex that may possibly have further developed into Tropical Storm Eugene.
    • ACES (2002)
      • The Altus Cumulus Electrification Study (ACES) was aimed at better understanding the causes and effects of electrical storms.

        Based at the Naval Air Station Key West in Florida, researchers in August 2002 chased down thunderstorms using an uninhabited aerial vehicle, or "UAV", allowing them to achieve dual goals of gathering weather data safely and testing new aircraft technology. This marked the first time a UAV was used to conduct lightning research.
    • CAMEX-4 (2001)
      • The Convection And Moisture EXperiment (CAMEX) was a series of NASA-sponsored hurricane science field research investigations. The fourth field campaign in the CAMEX series (CAMEX-4) was held in 16 August - 24 September, 2001 and was based out of Jacksonville Naval Air Station, Florida.

        CAMEX-4 was focused on the study of tropical cyclone (hurricane) development, tracking, intensification, and landfalling impacts using NASA-funded aircraft and surface remote sensing instrumentation.
    • CAMEX-3 (1998)
      • The Convection And Moisture EXperiment (CAMEX) is a series of hurricane science field research investigations sponsored by NASA. The third field campaign in the CAMEX series (CAMEX-3) was based at Patrick Air Force Base, Florida from 6 August - 23 September, 1998.

        CAMEX-3 successfully studied Hurricanes Bonnie, Danielle, Earl and Georges, yielding data on hurricane structure, dynamics, and motion. CAMEX-3 collected data for research in tropical cyclone development, tracking, intensification, and landfalling impacts using NASA-funded aircraft and surface remote sensing instrumentation.
    • GPM Ground Validation
      • The NASA Global Precipitation Measurement Mission (GPM) Ground Validation (GV) program includes the following field campaigns:

        a) LPVEx, Gulf of Finland in autumn 2010, to study rainfall in high latitude environments

        b) MC3E, cental Oklahoma spring and early summer 2011, to develop a complete characterization of convective cloud systems, precipitation and the environment

        c) GCPEx, Ontario, Canada winter of 2011-2012, direct and remove sensing observations, and coordinated model simulations of precipitating snow.

        d) IFloodS, Iowa, spring and early summer 2013, to study the relative roles of rainfall quantities and other factors in flood genesis.

        e) IPHEx, N. Carolina Appalachians/Piedmont region May-June 2014, for hydrologic validation over varied topography.

        f) OLYMPEx, Washington's Olympic Peninsula scheduled November 2015-February 2016, for hydrologic validation in extreme coastal and topographic gradients
    • OLYMPEX (2015-2016)
      • Major ground-based and airborne observations for the Olympic Mountain Experiment (OLYMPEX) field campaign took place between November, 2015, and January, 2016, with additional ground sampling continuing through February on the Olympic Peninsula in the Pacific Northwest of the United States.

        This field campaign provides ground-based validation support of the Global Precipitation Measurement (GPM) satellite program that is a joint effort between NASA and JAXA.

        As for all GPM-GV campaigns, the GHRC will provide a collaboration portal to help investigators exchange planning information and to support collection of real-time data as well as mission science, project and instrument status reports during the campaign.
    • IPHEx (2014)
      • The Integrated Precipitation and Hydrology Experiment (IPHEx) was conducted in North Carolina during the months of April-June, 2014.

        IPHEx sought to characterize warm season orographic precipitation regimes, and the relationship between precipitation regimes and hydrologic processes in regions of complex terrain.
    • IFLOODs (2013)
      • The Iowa Flood Studies (IFloodS) experiment was conducted in the central to northeastern part of Iowa in Midwestern United States during the months of April-June, 2013.

        IFloodS' primary goal was to discern the relative roles of rainfall quantities such as rate and accumulation as compared to other factors (e.g. transport of water in the drainage network) in flood genesis.
    • GCPEX (2011-2012)
      • The GPM Cold-season Precipitation Experiment (GCPEx) occurred in Ontario, Canada during the winter season (Jan 15- Feb 26) of 2011-2012.

        GCPEx addressed shortcomings in GPM snowfall retrieval algorithm by collecting microphysical properties, associated remote sensing observations, and coordinated model simulations of precipitating snow. Collectively the GCPEx data set provides a high quality, physically-consistent and coherent data set suited to the development and testing of GPM snowfall retrieval algorithm physics.
    • MC3E (2011)
      • The Mid-latitude Continental Convective Clouds Experiment (MC3E) took place in central Oklahoma during the April–June 2011 period.

        The overarching goal was to provide the most complete characterization of convective cloud systems, precipitation, and the environment that has ever been obtained, providing constraints for model cumulus parameterizations and space-based rainfall retrieval algorithms over land that had never before been available.
    • LPVEx (2010)
      • The Light Precipitation Evaluation Experiment (LPVEx) took place in the Gulf of Finland in September and October, 2010 and collected microphysical properties, associated remote sensing observations, and coordinated model simulations of high latitude precipitation systems to drive the evaluation and development of precipitation algorithms for current and future satellite platforms.

        In doing so, LPVEx sought to address the general lack of dedicated ground-validation datasets from the ongoing development of new or improved algorithms for detecting and quantifying high latitude rainfall
  • Projects
    • HS3 Suborbital Mission
      • Hurricane and Severe Storm Sentinel (HS3) is an Earth Ventures – Suborbital 1 mission aimed at better understanding the physical processes that control hurricane intensity change, addressing questions related to the roles of environmental conditions and internal storm structures to storm intensification.
    • DISCOVER - MEaSUREs
      • DISCOVER was funded by NASA’s MEaSUREs program to provide highly accurate, multi-decadal geophysical products derived from satellite microwave sensors.
    • LIS Mission
      • Lightning observations from the Lightning Imaging Sensors (LIS) aboard the NASA’s TRMM satellite and International Space Station, as well as airborne observations and ground validation data.
    • SANDS
      • The SANDS project addressed Gulf of Mexico Alliance priority issues by generating enhanced imagery from MODIS and Landsat data to identify suspended sediment resulting from tropical cyclones. These tropical cyclones have significantly altered normal coastal processes and characteristics in the Gulf region through sediment disturbance.
    • LANCE AMSR2
      • The Land, Atmosphere Near real-time Capability for EOS (LANCE) system provides access to near real-time data (less than 3 hours from observation) from AIRS, AMSR2, MLS, MODIS, and OMI instruments. LANCE AMSR2 products are generated by the AMSR Science Investigator-led Processing System at the GHRC.
  • Resources
    • Tools & Technologies
      • A collection of tools & technologies developed and/or used by GHRC.
    • Publications
      • View GHRC & ITSC publications on the ITSC website
    • Innovations Lab
      • The GHRC Innovations Lab is a showcase for emerging geoinformatics technologies resulting from NASA-sponsored research at the University of Alabama in Huntsville.
    • Educational Resources
      • A list of resources from NASA, MSFC, and other sources for teachers and students focused on global change, hydrology, and science education.
    • Referencing our data
      • GHRC dataset citation help and examples.
    • Documents
      • Documentation related to GHRC datasets, software, and other offerings.
    • Glossary
      • Terms and their definitions
    • Featured items
      • The latest tools from GHRC.
  • Multimedia
  • About
    • Welcome
      • Local resources, lodging information, and weather to help you plan your visit to GHRC.
    • GHRC Personnel
      • A list to help you keep in touch with our personnel
    • FAQ
      • Frequently Asked Questions about GHRC data and services, and their answers.
    • Data Citations and Acknowledgements
      • GHRC dataset citation help and examples
  • Cite Us
  • Contact Us
feedback
Satellite Coincidence Search Engine

Interface & Database

CSE Home

Web Interface

REST Interface

Two-line Element Sets (TLEs)

 

Other Data Sources

NASA Earthdata Search

Tropical Storm Tracks

HyDRO

 

Wikipedia Article

The Coincidence Search Engine

The Coincidence Search Engine may be used to search for times when one to four satellites were within the same geographic location simultaneously. Searches may be constrained by time, geographic area, and/or distance between the satellite nadirs. Please note that this program does not take into account instrument angle of view or swath width.

The program uses an archived database of element set data to calculate the orbits, using the SGP4 algorithm.

This page describes the web page interface. If you wish to access the CSE using an automated process, see the description of the CSE REST Service Interface which provides plain text or XML output.

Contents

Satellite Selection

The satellite selection area lists which satellites may be selected with a checkbox to the left of each satellite's name. To select a satellite for a search, click the mouse on the checkbox. Up to four satellites can be selected simultaneously. At least one satellite must be selected.

Satellite names listed in bold are still active. The others may be used for historical research.

A coincidence will be recorded when all of the satellites selected satisfy the time and geographic search criteria. Each coincidence is listed as the date and time, satellite name, and longitude and latitude of the satellite.

Time Interval Selection

The time interval selection block is used to bound the time period of the search. It contains boxes for the start date, start time, end date, and end time, as well as a time interval. All times must be in UTC.

  • Enter the start date for the search in the start date box. The default value is yesterday. Use yyyy-mm-dd or yyyy/jjj format.

  • Enter the start time for the search in the start time box. The default value is 00:00:00.

  • Enter the end date for the search in the end date box. The default value is yesterday. Use yyyy-mm-dd or yyyy/jjj format.

  • Enter the end time for the search in the end time box. The default value is 23:59:59.

  • Enter the time increment in the increment box. The default value is 00:00:10 (10 seconds). If the proximity criterion in the area of interest block is used ("Within (km)"), the increment value should be no greater than 0.075 times the proximity value to ensure that an overpass is not missed.

Area of Interest Selection

The four boxes in this block define the area of interest. The default values cover the entire world.

Note that the CSE works by computing the satellite's nadir; that is, the point on the ground directly below the satellite. The instruments on many satellites do not point straight down, but may point forward, backward, or to the side. Furthermore, it also does not take into account the instrument's field-of-view, which may be many kilometers wide for scanning instruments. You may wish to increase the bounds of your area-of-interest and/or your "within" value accordingly.
  • The top and bottom boxes define the north and south boundaries of the area, respectively. Enter a latitude value in degrees, from -90.0 (South pole) to 90.0 (North pole). The northern boundary must be north of the southern boundary and the boundaries must not be equal.

  • The left and right boxes define the west and east boundaries of the area, respectively. Enter a longitude value in degrees, from -180.0 (Dateline) to 180.0 (Dateline). Negative longitude values are west, positive values are east. The area of interest extends from the west longitude eastward to the east longitude. So, for example, if west is -179 and east is 179, the area encompasses all of the world except a two-degree interval along the date line. However, if west is 179 and east is -179, the area only encompasses the two-degree interval along the date line. The west and east values may not be the same, nor may west be 180 while east is -180.

  • You may constrain the search to times when the great-circle distance between the satellite nadirs does not exceed a given value. Enter a positive number of kilometers in the "Within (km)" box. No entry or a value of 0.0 disables the proximity criterion. If the proximity criterion is used, the increment value in the time interval box should be no greater than 0.075 times the proximity value.

Coincidences Shown

You may select to receive "all" coincidences or just the start and end ("begin/end") of the coincidence list. If "all" is selected, a line will be produced for every coincidence for each satellite from the time the coincidence begins until it ends. See the example. If "begin/end" is selected, only the start of the coincidence and the end of the coincidence will be shown. See the example.

Results Format

By default, results are returned in "HTML" format for the web-page interface. A value of "text" or "XML" may also be specified, if desired. For the REST interface, the results are always returned in XML.

Execute

When all of the search criteria are set up, press "Execute" to start the search. The program first checks the search criteria to make sure they are valid.

The elements databases for the selected satellites are opened and advanced to the most recent element set entry that does not exceed the selected starting date. If the database does not contain orbital elements prior to this date, an error message is displayed. If the end date extends past the life span of the satellite, a warning message is displayed, but the search continues. Extrapolations of more than a week become increasingly inaccurate for most satellites.

The search is performed as follows:

  • The positions of the satellites are computed for the "current" time (initially the start time).
  • If any of the satellites are not within the area of interest, the search is not satisfied. Note that the satellites are always within the area of interest if it specifies the entire world.
  • If a proximity value was specified and all of the satellites are within the specified number of kilometers of each other (great-circle distance of their nadirs), then the search is satisfied.
  • If a proximity value was not specified, then the search is satisfied.
  • The "current" time is advanced by the increment and the process is repeated until the "current" time exceeds the end time.

Whenever the search is satisfied, an entry is made in the results area for each of the satellites that satisfied the search. This entry has the format

    yyyy-mm-dd hh:mm:ss yyy.yyy xxxx.xxx zzzzz.zz satellitename

"yyyy-mm-dd hh:mm:ss" is the UT, and "yyy.yyy" and "xxxx.xxx" specify the satellite nadir latitude and longitude, respectively, and "zzzzz.zz" specifies its approximate altitude above sea level in kilometers.

ITSC

UAH

RSS feed GHRC Facebook GHRC Twitter

NASA Official:
Rahul Ramachandran

Website maintained by the
UAH ITSC Web Team

If you have trouble viewing or
navigating this page, please contact
GHRC User Services

NASA Web Privacy Policy and Important Notices


    The GHRC is a member of the ICSU World Data System
GHRC DAAC is supported by NASA and is managed jointly by the Marshall Space Flight Center's Earth Science Office and the University of Alabama in Huntsville's Information Technology & Systems Center.