LIS/OTD 0.5 Degree High Resolution Full Climatology (HRFC)
Table of Contents
LIS/OTD 0.5 Degree High Resolution Full Climatology (HRFC)
v2.2 - Dataset size ~14.4Mb
The product is a 0.5 deg x 0.5 deg gridded composite of total (IC+CG) lightning bulk production, expressed as a flash rate density (fl/km^2/yr). Climatologies from the 5-yr OTD (4/95-3/00) and 8-yr LIS (01/98-12/05) missions are included, as well as a combined OTD+LIS climatology and supporting base data (flash counts and viewing times). Best-available detection efficiency corrections and instrument cross-normalizations, as of the product generation date (1/28/06), have been applied.
The product is distributed in HDF (Hierarchical Data Format). HDF is accessible from C or Fortran using interfaces provided by NCSA, or through various commercial software packages, such as IDL or Noesys (http://www.rsinc.com). All data in this product are stored in HDF Scientific Data Sets (SDS).
Citation and Acknowledgements
In presentations or publications, users are to acknowledge the dataset as follows:
NOTE: Version 2.2 release included new documentation in PDF format, which can be viewed and downloaded here.
Bulk lightning production, expressed in fl/km2/yr, is calculated as a "counting experiment", i.e., all flashes observed by the sensors in a given grid location are summed for the full period considered (OTD, 5 yr; LIS, 8 yr), then divided by the actual instrument viewing time of the grid location. Flashes are weighted during the summation by the best instantaneous estimate of each instrument’s flash detection efficiency (DE); e.g., if the DE estimate is 50%, a value of 2.0 is added to the flash summation grid. Instrument viewing dropouts due to temporary platform or instrument down-time are considered. Partial grazing of a grid location by the instrument FOV is considered in the LIS estimates, but not considered in the OTD estimates. Best available DE corrections are applied as a function of instrument, local hour, and for the OTD, spatial location (see below). The combined flash rate climatology merges the corrected OTD and LIS climatologies to reduce variance in the tropical estimates.
The HDF file contains 12 Scientific Data Set (SDS) grids. These include:
Of these, HRFC_COM_FR is the primary data product; the combined LIS/OTD flash rate (FR) climatology. It may derived as: HRFC_COM_FR = (HRFC_OTD_SF + HRFC_LIS_SF) / (HRFC_OTD_VT + HRFC_LIS_VT) (for nonzero total viewing time grid cells). The supporting base grids (raw flash counts RF, detection efficiency-scaled flash counts _SF, and total viewing _VT) are provided only for reference or rebinning. Users are encouraged to view the viewing grids to understand the nature of the Low Earth Orbit satellite sampling, which is a component of the uncertainty at each grid location. The diurnally-applied detection efficiency corrections are also included (_DE; see below). A grid cell area (_AREA) product is also included, to simplify net production calculations (e.g., global annual production in fl/yr = sum(HRFC_COM_FR * HRFC_AREA)).
The dimension scales accompanying the SDS grids represent the center coordinate of each 0.5 degree grid cell (e.g., -179.75, -179.25 … 179.25, 179.75 deg lon, etc.). For unit conversion, a year is assumed to contain 365.25 days.
Best-available calibrations for instrument detection efficiency (as of 1/28/06) have been applied in the v2.2 product. These consider variations in instrument sensitivity across the angular field of view, variability in the background scene radiance (the instruments are designed to reduce sensitivity as background radiance increases in order to preserve signal-to-noise ratio), actual cross-sensor ground validation, changing sensor thresholds and cross-normalization of climatological results between the two instruments. The procedure, documented in Boccippio et al  and Christian et al  is roughly as follows:
Users wishing to cite this calibration procedure may use or modify the following:
Consistency between modeled and ground-validated detection efficiency suggests that the applied values are known within about +/- 10%. This is thus the minimum uncertainty in the gridded data, arising from possible bias in the correction. Local variance arises from undersampling of a given grid location, and its relative impact increases as the actual local climatological flash rate decreases. This effect is likely dominant in the HRFC, but less important in the LRFC. A final bias component may arise from OTD sampling in the third through fifth years of its mission; problems with its host platform caused orbits viewing local times near local noon and midnight to be preferentially lost. This bias in diurnal viewing may yield a small bias in the bulk flash production estimate.
All three primary error sources (measurement uncertainty, sampling-related variance and sampling-related bias) are currently being quantified.
All OTD and LIS orbits undergo both automated and manual quality assurance. For the preliminary reanalysis, the most stringent orbit rejection criterion was applied: any orbit which was assigned a manual Q/A "warning" flag has been rejected from the reanalysis. In subsequent versions, these rejected orbits may be examined individually and, if acceptable, added into the climatology to improve sampling.
Each OTD flash is further assigned an automated quality index (the ‘Thunderstorm Area Count’, or ‘Density Index’), indicating its likelihood of being lightning rather than optical or radiation noise. For this reanalysis, only flashes with values of the metric >= 140 have been included. This is the same cutoff value used in all validation and science analysis published by the LIS science team to date. This filter removes most radiation noise from the climatology; a slight residual ‘ring’ artefact of very low spurious flash rates remains at the periphery of the South Atlantic Anomaly (southeast Pacific and southeast Atlantic).
There are no restrictions on the use of these data.
The High Resolution gridded dataset is being provided to illustrate "high contrast" lightning production regions. It is 25x less sampled than the LIS/OTD 2.5 Degree Low Resolution Full Climatology (LRFC), and hence quantitative values from individual grid locations should be used with extreme caution. Rebinning of the HRFC to custom lower resolutions (e.g., 1.0 deg, 5.0 deg) should be performed using the included scaled flashes (SF) and viewtimes (VT) grids, rather than the flash rate (RF) grid directly. E.g. to make a 5 deg x 5 degree climatology:
All subsequent versions of this dataset (both minor and major revisions) will maintain the same product definition, resolution and file format. Additional years of data from the LIS mission may be added into the climatology for future minor versions, but will not alter file format. Any actual definitional changes would be reflected by the creation of a new product.
Subsequent major version updates will only occur if/when the dataset is recomputed using new major version OTD or LIS orbit data. E.g:
Status OTD Orbit Version LIS Orbit Version LRAC Version:
Current version is at v2.2, and covers years 1995-2005.
Minor OTD calibration errors during 1995-1996 fixed.
Calibration procedure now peer-reviewed.
Instrument and Calibration/Validation:
Goodman,SJ; Christian,HJ; Rust,WD (1988): A comparison of the optical pulse characteristics of intracloud and cloud-to-ground lightning as observed above clouds. J. Appl. Met. 27, 1369-1381.
Christian,HJ; Blakeslee,RJ; Goodman,SJ (1989): The Detection of Lightning from Geostationary Orbit. J. Geophys. Res. 94, 13329-13337.
Christian,HJ; Blakeslee,RJ; Goodman,SJ (1992): Lightning imaging sensor for the Earth Observing System. (TM-4350.) NASA. 44 pages. Available from Center for Aerospace Information, P.O. Box 8757, Baltimore Washington International Airport, Baltimore, MD 21240.
Christian,HJ; Driscoll,KT; Goodman,SJ; Blakeslee,RJ; Mach,DA; Buechler,DE (1996): The Optical Transient Detector (OTD). Proc. 10th International Conference on Atmospheric Electricity, Osaka, Japan.
Kummerow, C; Barnes, W; Kozu, T; Shiue, J; Simpson, J (1998): The Tropical Rainfall Measuring Mission (TRMM) sensor package. J. Atmos. Oc. Tech. 15, 809-817.
Christian,HJ; Blakeslee,RJ; Goodman,SJ; Mach,DA; Stewart,MF; Buechler,DE; Koshak,WJ; Hall,JM; Boeck,WL; Driscoll,KT; Boccippio,DJ (1999): The Lightning Imaging Sensor. Proc. 11th Intl. Conf. on Atmospheric Electricity (NASA), Guntersville, AL, 7-11 June. 746-749.
Ushio,T; Driscoll,KT; Heckman,S; Boccippio,DJ; Koshak,WJ; Christian,HJ (1999): Initial comparison of the Lightning Imaging Sensor (LIS) with Lightning Detection and Ranging (LDAR). Proc. 11th Intl. Conf. on Atmospheric Electricity (ICAE), Guntersville, AL, 6-11 June. 738-741.
Christian,HJ; Blakeslee,RJ; Goodman,SJ; Mach,DM (eds.) (2000): Algorithm Theoretical Basis Document (ATBD) for the Lightning Imaging Sensor (LIS). Posted: 1 Feb 2000. (NASA / Marshall Space Flight Center, AL 35812)
Koshak,WJ; Bergstrom,JW; Stewart,MF; Christian,HJ; Hall,JM; Solakiewicz,RJ (2000): Laboratory calibration of the Optical Transient Detector and Lightning Imaging Sensor. J. Atmos. Oc. Tech. 17, 905-915.
Boccippio,DJ; Driscoll,KT; Koshak,WJ; Blakeslee,RJ; Boeck,WL; Mach,DA; Buechler,DE; Christian,HJ; Goodman,SJ (2000): The Optical Transient Detector (OTD): Instrument characteristics and cross-sensor validation. J. Atmos. Oc. Tech. 17, 441-458.
Thomas,RJ; Krehbiel,PR; Rison,W; Hamlin,T; Boccippio,DJ; Goodman,SJ; Christian,HJ (2000): Comparison of ground-based 3-dimensional lightning mapping observations with satellite-based LIS observations in Oklahoma. Geophys. Res. Lett. 27, 1703-1706.
Boccippio, DJ; Koshak, WJ; Blakeslee, RJ (2002): Performance assessment of the Optical Transient Detector and Lightning Imaging Sensor: I. Predicted diurnal variability. J. Atmos. Oc. Tech. 19, 1318-1332.
LIS/OTD-Enabled Science & Applications:
Christian, HJ et al (2003): Global frequency and distribution of lightning as observed by the Optical Transient Detector. J. Geophys. Res, 108 4005, doi: 10.1029/2002JD002347.
Boccippio,DJ; Wong,C; Williams,ER; Boldi,R; Christian,HJ; Goodman,SJ (1998): Global validation of single-station Schumann resonance lightning location. J. Atmos. Sp. Terr. Phys. 60, 701-712.
Christian,HJ; Blakeslee,RJ; Boccippio,DJ; Boeck,WL; Buechler,DE; Driscoll,KT; Goodman,SJ; Hall,JM; Koshak,WJ; Mach,DM; Stewart,MF (1999): Global frequency and distribution of lightning as observed by the Optical Transient Detector (OTD). Proc. 11th Intl. Conf. on Atmospheric Electricity (ICAE), Guntersville, AL, 7-11 June. 726-729.
Driscoll,KT (1999): A comparison between lightning activity and passive microwave measurements. 11th International Conf. on Atmospheric Electricity (ICAE), Guntersville, AL, 7-11 June 1999. 523-526.
Cecil, DJ; Zipser, EJ (2000): Relationships between tropical cyclone intensity and satellite-based indicators of inner core convection: 85 GHz ice-scattering signature and lightning. Mon. Wea. Rev., 111, 979-996.
Buechler,DE; Driscoll,KT; Goodman,SJ; Christian,HJ (2000): Lightning activity within a tornadic thunderstorm observed by the Optical Transient Detector (OTD). Geophys. Res. Lett ., 27, 2253-2256.
Goodman,SJ; Buechler,DE; Knupp,K; Driscoll,KT; McCaul,EW (2000): The 1997-98 El Nino event and related wintertime lightning variations in the Southeastern United States. Geophys. Res. Lett. 27, 541-544.
Jeker,DP; Pfister,L; Thompson,AM; Brunner,D; Boccippio,DJ; Pickering,KE; Wernli,H; Kondo,Y; Staehelin,J (2000): Measurements of nitrogen oxides at the tropopause: Attribution to convection and correlation with lightning. J. Geophys. Res., D 105, 3679-3700.
Boccippio,DJ; Goodman,SJ; Heckman,S (2000): Regional differences in tropical lightning distributions. J. Appl. Met. 39, 2231-2248.
Williams,ER; Rothkin,K; Stevenson,D; Boccippio,DJ (2000): Global lightning variations caused by changes in thunderstorm flash rate and by changes in the number of thunderstorms. J. Appl. Met. 39, 2223-2230.
Nesbitt,SW; Zipser,EJ; Cecil,DJ (2000): A census of precipitation features in the tropics using TRMM: Radar, ice scattering and lightning observations. J. Clim. 13, 4087-4106.
Rodgers, E; Olson, W; Halverson, J; Simpson, J; Pierce, H (2000): Environmental forcing of supertyphoon Paka’s (1997) latent heat structure. J. Appl. Met., 39, 1983-2006.
Boccippio,DJ; Cummins,KL; Christian,HJ; Goodman,SJ (2001): Combined satellite and surface-based estimation of the intracloud / cloud-to-ground lightning ratio over the continental United States. Mon. Wea. Rev. 129, 108-122.
Toracinta, ER; Zipser, EJ (2001): Lightning and SSM/I ice-scattering mesoscale convective systems in the global tropics. J. Appl. Met. 40, 983-1002.
Boccippio, DJ; Heckman, S; Goodman, SJ (2001): A diagnostic analysis of the Kennedy Space Center LDAR network. 2: Cross-sensor studies. J. Geophys. Res. 106, 4787-4796.
Chang, DE;Weinman, JA; Morales, CA; Olson, WS (2001): The effect of spaceborne microwave and ground-based continuous lightning measurements on forecasts of the 1998 Groundhog Day storm. Mon. Wea. Rev., 129, 1809-1833.
Ushio,T; Heckman,S; Boccippio,DJ; Christian,HJ (2001): A survey of thunderstorm flash rates compared to cloud top height using TRMM satellite data. J. Geophys. Res., D, 106, 24089-24095.
Boccippio,DJ (2002): Lightning scaling laws revisited. J. Atmos. Sci. 59, 1086-1104.
Bond, DW; Zhang, R; Tie, X.; Brasseur, G.; Huffines, G; Orville, R.E; Boccippio, DJ (2001): NOx production by lightning over the continental United States. J. Geophys. Res, 106, 27701-27710.
Koike, M.; Kondo, Y.; Akutagawa, D.; Kita, K.; Nishi, N.; Liu, S.C.; Blake, D.; Kawakami, S.; Takegawa, N.; Ko, M.; Zhao, Y.; Ogawa, T. (2003) Reactive nitrogen over the tropical Western Pacific: Influence from lightning and biomass burning. J. Geophys. Res, 108, 8403, doi:10.1029/2001JD00823.
A set of Interactive Data Language (IDL) routines to extract and process the LIS/OTD High Resolution Full Climatology (HRFC), Low Resolution Full Climatology (LRFC), Low Resolution Diurnal Climatology (LRDC) and Low Resolution Annual Climatology (LRAC) are distributed with the data. The IDL syntax is roughly similar to C or FORTRAN and, with the exception of animation code, porting of these routines should be fairly straightforward. Full documentation can be found in the program files themselves; a summary is below.
NOTE: These routines are being provided as a courtesy to the user community. The GHRC and LIS Science Team cannot guarantee technical support or compatibility with IDL version updates or platform-specific implementations.
Questions regarding dataset ordering, media issues, file handling or HDF file access (input/output) should be directed to the Global Hydrology Resource Center (firstname.lastname@example.org). Questions regarding the science data processing, including gridding, viewing, calibration and variance should be addressed to Dennis.Boccippio@nasa.gov. Questions regarding the OTD or LIS missions themselves should be addressed to the OTD/LIS Principal Investigator, Hugh.Christian@nasa.gov.