2006 Meeting of the GRP Working Group on Data Management and Analysis
University of Maryland
13-15 November 2006

The WGDMA chairman opened the meeting by outlining meeting objectives: (1) reviewing project and data center status (processing, issues, funding, near-term plans), (2) planning for radiance re-calibrations (proposed completion in 2007), (3) defining criteria for selecting common ancillary datasets (proposed selection in 2007), (4) reviewing results of data product assessments and planning for retrieval algorithm refinements (proposed completion in 2007-2008), and (5) assessing readiness for joint re-processing (proposed commencement in 2008-2009). The last objective includes a discussion at this meeting of how to foster more comprehensive analyses by enhancing data product content and making product formats more compatible. The meeting sessions were organized into Plenary Sessions on the first half-day and during the last 1.5 hr of the third morning with the remainder of the 3.5 day schedule taken up with separate meetings of the GPCP and ISCCP (with GACP and SRB) groups.

The chairman also provided a brief overview of relevant discussions in the previous meetings of GRP, GEWEX and WOAP. There were two key GRP actions to foster progress on global precipitation. The first was the formation of a Working Group on Precipitation Radar Networks, which will have its first meeting in early 2007, to enhance research access and use of wide-area, but high space-time resolution precipitation measurements. The second was to join with the IPWG to form a working group on development/testing of satellite algorithms for snowfall. The SeaFlux activity (with one workshop in spring 2006 and two workshops planned for 2007) to develop capability for determining ocean surface turbulent fluxes of heat and water is progressing to the point that processing of global products may be feasible by early 2008 at which point representatives of the participating data centers would join WGDMA. The similar LandFlux activity, jointly organized with GLASS, is only just getting started with a first workshop planned for late May 2007. Finally, a brief report was presented on the recent re-scoping of the NPOESS weather satellite mission and the effects on climate observations. There was further work on the GEWEX Phase II roadmap at the recent pan-GEWEX meeting: the GRP inputs included a number of specific milestones for the global data projects, notably completion of radiance re-calibrations by 2007, of product assessments and algorithm refinements by 2008 and of the joint re-processing of all products by 2009. Finally, the chairman noted that the concept of re-processing, expanded to a wider set of products, had now been adopted by WOAP for all WCRP data products and by GCOS, CEOS and GEOSS.

A. Kankiewicz provided an overview of the recently launched CloudSat and Calipso satellites, the former carrying a cloud-profiling radar and the latter carrying a lidar and infrared imager. Not only will these two missions provide a new look at the vertical structures of cloud systems, especially when analyzed together (and with other A-train instruments) to separate liquid and ice phases, but also the former will provide key information about lighter rainfall, which cannot be detected by the TRMM radar, and about snowfall, while the latter will provide key information about aerosols. The first raw datasets and products are just now being released from the first few months of operation of these two new missions.

K. Holmlund provided an overview of the new European polar orbiting weather satellite, METOP-A, recently launched into a “morning” orbit and expected to begin operations by November 2006. In addition to “standard” instruments, such as AVHRR, HIRS, AMSU, MHS and SBUV, this satellite carries an enhanced ozone instrument (GOME), a scatterometer (ASCAT) follow-on to the ERS scatterometers, a radio occultation receiver (GRAS) for GPS-based atmospheric soundings and an infrared spectrometer (IASI) for advanced temperature/humidity/ozone soundings. As of the WGDMA meeting, all instruments were functioning with the exception of the infrared instruments which were still outgassing. A full range of “standard” as well as many experimental products are planned. R. Adler presented an overview of the status and plans of GPCP. GPCP produces three basic products reporting surface precipitation rate, a pentad and monthly merged analysis product on a 2.5° grid and a daily merged analysis product on a 1° grid; these products are produced with about a three month lag and are currently all up to date (available for 1979 to August 2006). There are seven data centers performing different parts of the analysis; all centers are currently funded for GPCP through at least 2009. During the past year, the transition of the polar infrared algorithm from HIRS to AIRS was completed and an adjustment was made to the monthly, multi-satellite product to remove a spurious shift that occurred in 1986 (this does not affect the merged product, however). Four problems with the current products are under investigation: gauge bias errors in mountainous regions, replacing the monthly ocean microwave algorithm with a more modern algorithm that can provide higher time resolution results, reducing the 1986 “data boundary” where geostationary satellite and microwave data are introduced and incorporating or using data from TRMM, AMSU and AMSR. Near-term plans include address the orography problem and replacing the originally-used gauge product (the GPCC Monitoring product) with the newer, 50-yr gauge climatology. Also being developed is a “quick-look” product for more rapid monitoring of the time record. Work also has started on a number of improvements to be incorporated into the re-processed version (Version 3), described in more detail below: unify algorithms and input datasets across different products, introduce daily gauge data, further reduce “data boundary” effects, introduce new passive microwave algorithms calibrated by TRMM radar, implement rain/snow discrimination and/or new snow algorithms, develop a higher space-time resolution product (possibly 25 km, 3 hr) from 1998 at least.

P. Stackhouse presented an overview of the status and plans of SRB. During the past year, new versions (#2.5) of the shortwave (SW) and longwave (LW) flux products were released that not only made some improvements (including switching to the GEOS-4 atmospheric dataset) and corrections (including fixing filling procedures for low solar zenith angles) but extended the data record from July 1983 through June 2005. A newer version of the SW fluxes (#2.7) that has additional improvements in the treatment of the incident solar flux is due to be completed by the end of 2006. Substantial revisions of the SRB website were also completed in the past year. Extensive evaluation activities have been under way (some as part of the Radiation Assessment, see below) exploiting the detailed datasets coming from the Baseline Surface Radiation Network (BSRN). These comparisons show a dramatic reduction in rms differences going from instantaneous to monthly comparisons; average biases are about -8 and -2 Wm² for SW and LW, respectively. Comparisons of SW fluxes have also been performed using the GEBA database but this data collection has not yet been updated to overlap the BSRN time period, which would allow for a direct check on decadal variations being found. The SRB processing center has funding for the early part of 2007; a proposal has been submitted for extended funding through 2009 but a decision has not yet been announced. A near-term goal is to make comparisons with similar products being produced as part of the CERES project, now that a time overlap of a four years is available. Investigations are underway to improve the relative accuracy over interannual time scales of a number of input quantities, particularly atmospheric and surface temperatures, aerosols and land surface albedos. These activities, together with improvements suggested by the assessment results, will set the stage for re-processing the whole product in 2008 or 2009.

W. Rossow presented an overview of the status and plans of ISCCP. All data products (B1/B3 radiances, DX/D1/D2 cloud products) have been processed and delivered from July 1983 through June 2005. One interesting statistic is the fraction of possible data successfully processed in terms of global coverage every 3 hr for 22 yrs: the average for ISCCP is 92% with a minimum of 70% in late summer of 1984 and a maximum of 98% since mid-2002. Processing is currently on hold to transfer and re-establish the calibration for the new “afternoon” polar orbiter, NOAA-18 for which only a little more than 1 yr of data have been accumulated. Nevertheless, processing of B3 is underway with deliveries beyond June 2005 expected in early 2007. Two new data products were completed in the past year. The Convective Tracking Product was actually released previously as part of a software tool that allows one to find the nearest convective cloud system to a particular location at a particular time; the product will be augmented by the complete analysis, which includes convective systems too small to track. The second product is the a complete survey of cloud particle sizes, both liquid and ice, that will be released in early 2007. All data centers for ISCCP appear to have funding through 2010 except for the global processing center, funding for which expires in 2007. The current project plans are to complete on-going evaluations (some as part of the Cloud Assessment, see below) and revisions of radiance calibration by mid-2007 and re-process all data products based on the B3 radiances (30 km sampling) by the end of 2007. Remaining issues are some problems with calibration of the newer AVHRRs (NOAA-15 thru 18) and finding a global atmospheric temperature and humidity dataset that does not have spurious interannual variations. Proposals have or will be submitted to change these plans. Two proposals have already been submitted to complete refurbishing the B1 radiance dataset (10 km sampling) and to perform more extensive calibration studies, particularly to take advantage of a wider range of newer instruments and to tie the ISCCP radiance calibration into a systematic set of calibrations of all solar-infrared imagers. Another proposal will be submitted to re-engineer the analysis code not only to switch over to the B1 radiances but also to make it possible to turn over the global processing center task to an operational organization. If these proposals are accepted, then re-processing of the ISCCP products would be delayed until 2008.

Summary of GPCP Sessions

R. Adler opened the GPCP sessions with a review of the project status and the main topics/issues that needed to be discussed where to consider modifications of the analysis to mitigate known problems/issues: (1) correcting the gauge underestimate in mountainous regions, (2) changing the gauge dataset to remove sampling artifacts in the record, (3) replacing the ocean-microwave algorithm with modern, TRMM-based methods, (4) adding rain/snow discrimination, (5) adding a specific snowfall algorithm, (6) considering whether and how to merge TRMM, AMSU and AMSR data into the product and (7) changing data sources to allow for higher time resolution over a longer portion of the GPCP record. Some of these changes (1, 2 and 4) can probably be implemented in the next year or so, whereas the others will likely take a couple of years to develop.

All of the participating data centers reported on their status and activities. R. Ferraro (Microwave-Land Center) reported that processing of two microwave-based precipitation products over land (as well as ocean) is up to date. Two issues have come up, one related to a change in the F15 spacecraft operations that causes interference in the SSM/I water vapor channel and the other related to problems with the new SSMIS calibration, including accounting for spectral differences with SSM/I. Research continues on AMSU-based precipitation algorithms, including determinations of snowfall (an added complication is the change of channels between the AMSU-B and MHS instruments), and new treatments of coastal areas. L. Chiu (Microwave-Ocean Center) reported that processing of the microwave-based precipitation product over oceans is up to date. A slightly revised version of the processing, Version 5, was recently introduced; the primary effect of which was to increase rainrates by about 10%. He also provided an update on changes to TRMM products produced by the orbit altitude change. J. Janowiak (Geosynchronous Center) reported that processing of the infrared-based precipitation product is up to date, noting recent changes in the constellation. Beginning in 2000, full IR imagery has been collected in addition to the standard brightness temperature histograms. Missing geostationary data are filled by polar orbiter infrared measurements. The possibility of replacing this variety of infrared data with the more uniform ISCCP B1 (10 km sampling) product was described. G. Huffman (Merge Center) reported on resumption of routine processing after switching from HIRS to AIRS for the high latitude precipitation: the same analysis algorithm is used but there were a number of technical differences that had to be accommodated. Other recently discovered inconsistencies in parts of the satellite analysis were removed by re-processing. Some results of work towards an improved analysis approach based on use of TRMM radar data to refine the passive microwave analysis approach were presented. In particular, prospects for producing higher time resolution products appear very good: comparisons with surface evaluation datasets show reasonably good results but also show systematic differences in performance between ocean and land.

A. Gruber reviewed the conclusions of the formal Assessment of the GPCP and other extensive precipitation products; a draft report was recently completed and is now being reviewed by the GEWEX Radiation Panel. The review involved over 40 scientists and two workshops. The review focused on the GPCP products but also included examinations of other state-of-the-art satellite products, of various analyses of long-term gauge collections and of satellite precipitation retrieval techniques. The Assessment results show that the GPCP product reliably quantifies the geographic distribution of precipitation and its seasonal and interannual variations, particular ENSO-related changes. Over the short time record (27 yr), there does not appear to be a significant trend in the global mean precipitation; however, there are significant regional trends in a few locations, mostly at lower latitudes. If variations associated with ENSO events and volcanic eruptions are removed from the record in the tropics, there appears to have been a small, but significant increase of about 3% in precipitation over this period.

The next presentations reported on some new developments in precipitation retrieval methods. W. Olson reported on the TRMM passive microwave retrieval method, called GPROF. A point was made that, although many products have been produced using a single retrieval method, the available collections of microwave radiances are not homogeneous and produce different results even in the same analysis. A new version of GPROF has been produced by replacing the a priori database derived from cloud resolving model runs with one created from the combination of TMI and TRMM PR. This change substantially improves performance where TRMM data are available but still leaves higher latitudes and land areas to be improved. A new bias correction to account for water vapor effects on the passive microwave has also been developed. R. Ferraro provided an update on snow retrieval methods and products from passive microwave. The snow detection uses higher frequency measurements by instruments like AMSU. Currently this approach is only used to identify falling snow, but methods to determine snowfall rate are being explored by employing a dense network of radars and surface gauges in the central US. The snow rate is sensitive to assumptions about particle size in the form of empirical relationships between rate and measured water path, but some of these relations give good results at least for the US. G. Huffman reported on the tests of the algorithm used on HIRS data to determine precipitation when applied to AIRS data; BALTEX datasets were used in the evaluation. The correspondence of daily values to the surface-based measurements over a two-month period was found to be good.

The next set of presentations considered alternative merging techniques to obtain higher time resolution information (3 hr or less). R. Joyce described the method called CMORPH. This method, using either an external source of wind information or deriving motion vectors from the infrared images, advects features seen in microwave results to intervening times to obtain higher time resolution precipitation results. To account for more complicated situations and missing data, a combination of techniques is applied, including one that merges satellite with surface gauge information, and the best selected for each case. K. Hsu described the merging method used in the PERSIANN system to obtain higher space-time resolution. The infrared radiances are analyzed with a neural network to estimate precipitation; this result is then combined with microwave-based products for determination of the bias (employing algorithms developed by others) and surface gauge data. Another system is being investigated that uses a hydrological model to combine various estimates of precipitation. G. Huffman outlined the TRMM Multi-satellite Precipitation Analysis (merging) technique being developed to combine observations from many satellites, anchored by the TRMM radar/radiometer results, to obtain higher time resolution precipitation. Since about 2000, there have been 6-8 microwave radiometers in orbit (including AMSU), so that more of the earth can be covered by direct microwave retrievals with higher time resolution (3 hr). The method calibrates IR data to the microwave and uses the former to fill the remaining gaps. There is also a bias correction using the monthly satellite-gauge combination. In future the TRMM radar will be used to calibrate the passive microwave. Error studies illustrate the expected increase in noise as the space-time scales of the products become finer. T. Smith described a merging method being developed to minimize time-of-day errors. The data from various satellites (microwave only) are composited into 6-hr intervals and then an optimal interpolation is used to obtain hourly values. The largest differences with the GPCP analysis appear over oceans at high latitudes where GPCP is relying almost exclusively on IR-based estimates.

M. Sapiano described the Project to Evaluate High Resolution Precipitation Products; there were five different methods compared to each other and to rain gauge and radar products. Comparisons are planned to be made on global and regional scale, as well as using field experiment products for case-study comparisons. A specific effort will be made to compare with special high time resolution evaluation datasets. So far, all of the high resolution products look pretty good, meaning that their detail is useful for studies needing both higher space and time resolution.

The remainder of the GPCP session was occupied by a discussion of what improvements and changes should be implemented for a GPCP Version 3. P. Xie opened the discussion with some overall considerations of the available datasets and the analysis methodologies that could be applied to these data, including various possible merge techniques now developed, that might lead to improvements in the precipitation product over land, particularly in rough topography regions. He proposed implementing a simplified version of the PRISM algorithm to correct the gauge data for orographic effects and then combined these corrected data with satellite products by optimal interpolation. The goals for GPCP Version 3 are to obtain the highest time resolution compatible with maintaining consistency over the whole time record; there is also a compromise to be made between high spatial resolution and good error characteristics. The input microwave radiances also need a more homogeneous calibration for the whole record over all instruments. Given the number of microwave instruments available after 1998, it appears possible to obtain 3-hr resolution after that; however, the possibility of employing one of the newer techniques to produce 3-hr data before that will be investigated. The fallback position will be to produce only daily time resolution in the older period. A strategy of producing several different versions of the products is being explored. Alternative, more complete gauge products are now available that might be used; these already have improved corrections for wind effects and might be improved to reduce orographic effects. The new products will also discriminate precipitation types, at least by air temperature; but snow algorithms will continue to be studied.

Summary of ISCCP, GACP, SRB Sessions

P. Stackhouse presented a more detailed description of the current data products, research activities and plans of the SRB data center. One of the main foci for the coming year is completion of comparisons and investigations as part of the Radiation Assessment (see below). A key concern in preparing for a re-processing in late 2008 is to find the causes of artifacts in the long-term flux anomaly record: some of the shorter-term variations appear to be real but some abrupt changes are associated with changes in input datasets. Using the more detailed BSRN products, which include information on meteorological conditions, shows that the comparison of SRB and BSRN values for surface downwelling SW fluxes remains similar in character in different ranges of cloud amount: there is more scatter as expected for overcast than for clear sky conditions. Using the longer SW flux record from the GEBA collection shows that the SRB results show the same 20-yr trend as the GEBA record when co-located values are used (and that this trend is not necessarily the global mean trend in the SRB dataset). Additional comparisons are also being made using the newer products (both top-of-atmosphere and surface fluxes) from the CERES project. Improvements being worked on include: (1) testing alternative climatological aerosol products, (2) exploiting new CERES angular distribution models, particularly for ice and snow surfaces, (3) including explicit spectral dependence in surface albedo and (4) allowing for a temperature discontinuity between near-surface air and the skin. Other longer-term investigations involve (1) alternative datasets for ozone and other trace gases (to include their variation), (2) including variations of solar irradiance and (3) adding a treatment of cloud microphysics variations. Some other improvements will come from on-going developments in the CERES project. New products being considered are UV, PAR and “window” fluxes.

P. Stackhouse then presented a summary of the Radiation Assessment activity. The second workshop set the space-time scales that would be the focus of the comparisons and investigations, including instantaneous-FOV, daily-mesoscale, monthly-mesoscale and monthly-global. A central website has been established, into which most of the products have now been posted (nine products to date), that will provide all participants access to all the products. Four papers have already been submitted or published from early comparison work and several more are in preparation. A notable early result is that, although there are absolute differences in mean fluxes among the observational products, the seasonal to interannual variations agree well quantitatively. The agreement of the main reanalysis products is not as good. A third workshop to review assessment results is being planned for spring 2007.

The presentations were followed by a short discussion of possible improvements to the SRB products and actions needed to prepare for the re-processing. The main points raised concerned efforts to re-evaluate the radiance calibrations used by ISCCP, which provides the cloud property inputs to SRB, and to find a common global atmospheric product (temperature, humidity) that covers the whole time period and has little or no changes of character (ie, spurious interannual variations): the availability of such a product is not known.

W. Rossow began the review of ISCCP by summarizing the project status and listing some issues to be considered. The main data products have been completed through June 2005 but, having now transferred the calibration standard to NOAA-18 (the newest afternoon polar orbiter), processing preparations had resumed: the next data released should extend the record through at least June 2006 if not slightly beyond. New products soon to be released included a complete 18-yr survey of cloud particle sizes (both liquid and ice) and composite cloud properties for midlatitude cyclones. Four issues were raised: calibration artifacts still in the record, problems with the new AVHRRs, finding a global atmospheric dataset that covers the whole ISCCP record with no spurious changes and what to do with all the new satellites now becoming available. China and Brazil have expressed interest in participating in ISCCP (the status of the former is described below, the latter would use GOES-10) but this means that there would be three geostationary satellites covering a relatively narrow range of longitudes (< 80°). Although it is mechanically easy to include these data in the ISCCP products, it raises some questions about the format and which data should be processed: it was proposed that all satellite data offered be accepted and processed to DX level but further investigation is needed to see how to handle this situation for the gridded products. Moreover, with the successful launch of METOP-A, there are now two morning polar orbiters; however the situation in this case is not clear as to what will be done operationally.

All of the participating data centers reported on their status and activities. K. Knapp reported on the NOAA Satellite Processing Center for the polar orbiters: there are currently six NOAA polar orbiters operating (and METOP-A), two as primary (NOAA-17 morning and NOAA-18 afternoon) and four as backup. NOAA-N’ is currently scheduled for launch at the end of 2009 and METOP-B is scheduled for launch in mid-2010. NPP is scheduled for launch in 2009 to bridge between NOAA-18 and NPOESS-C1. Two more GOES satellites are planned for launch in 2008. Processing of B2 data for ISCCP is fully automated and has been routine. A. Okuyama reported on the JMA Satellite Processing Center. The transition from GMS-5, through GOES-9 as a temporary replacement, to MTSAT-1R was completed in fall 2005 with very little loss of data; MTSAT-1R is operating well and routinely now. MTSAT-2 was successfully launched in February 2006 and is now the backup for MTSAT-1R. The follow-on satellite to these two will have a “SEVERI-like” imager. JMA has now established a web site to monitor MTSAT data collection and quality. JMA has also been developing a capability to cross-normalize geostationary satellite image radiances to the NOAA AVHRR; early but good results have been obtained for GMS-5. K. Holmlund reported on the EUMETSAT Satellite Processing Center: METEOSAT-5, 7 and 8 are all healthy with METEOSAT-6 and 9 as backups. METEOSAT-7 was moved to Indian Ocean and resumed normal operations in October 2006 and will replace METEOSAT-5 in February 2007. METEOSAT-8 (MSG-1) replaced METEOSAT-7 at zero longitude in July 2006 and is doing well, except for mysterious short outage, during which time METEOSAT-9 took over. There are still some anomalies in particular spectral bands of the SEVERI instrument on METEOSAT-9. A. Kankiewicz reported on the Colorado State University Satellite Processing Center for GOES-WEST. GOES-11 replaced GOES-10 at the west position in late June 2006; a few days of overlapping data were obtained from both satellites. At the time of the switch-over, the agreed to change from 1 byte to 2 byte radiance counts was done for the B1 dataset. It was discovered that an incorrect visible radiance calibration was supplied to the Satellite Calibration Center since 1996; however, the ISCCP normalization procedures removed the effect of this error as they were designed to do. W. Rossow presented a report on behalf of Y. Liu, who was unable to complete visa arrangements in time for the meeting, concerning the CMA Satellite Processing Center. Data collection and processing from FY-2C for ISCCP commenced in July 2005 since which time more than 99% of the data have been collected. Arrangements for ftp delivery of B1 and B2 radiance data were implemented in September 2006 (service was disrupted shortly after the meeting by an earthquake in China and was only restored in early 2007). Once the ftp deliveries resume, the backlog of data deliveries will be accomplished by mailing DVDs. FY-2D was planned for launch in December 2006 (it was successful). K. Knapp reported on the status of the ISCCP Central Archives at NOAA NCDC. All B1 radiance data since the last meeting have been received and archived, except for METEOSAT-8 which is now being delivered. The ICA is also working to bring all the GEWEX global data products online on an active server (using the UNIDATA THREDDS system). The ICA effort to refurbish the B1 dataset so that it can be more easily accessed and processed with common software continued with a preliminary check of the overall homogeneity of the infrared calibration. An anomaly was found that was triggered by mis-communication of the infrared calibration for NOAA-16 during the first few years of its operation. This investigation also showed that the spectral response of the “water vapor” channel on the new HIRS instruments was too different from previous ones to used to normalize the calibration of the geostationary channels, so this activity by the Satellite Calibration Center was terminated in late 2006. A search has begun (with some early success) to look for geostationary radiance data from before the start of ISCCP (the polar orbiter imaging data are available and usable back to 1979 for TIROS-N): the discovery of earlier data from the Japanese satellite, as well as the availability of data METEOSAT-1 and earlier GOES satellites, may make it possible to extend the ISCCP B1 data record back to 1981 with reasonable coverage. This effort is also filling a lot of missing GOES data that were either dropped in the earlier years or were poorly navigated and not included in the cloud products. W. Rossow reported on the status of the Global Processing Center. Investigations are underway to understand several anomalies in the infrared radiance calibration and behavior from the new AVHRRs (starting with NOAA-15 and 16). An evaluation of polar cloudiness by comparison of ISCCP with results from the surface lidar/radar operated during the SHEBA experiment shows that, although the total cloud amount is not too bad, this result is composed of offsetting false and missed detections. During sunlight seasons, the missed clouds exceed the false detections somewhat, causing an overall underestimate by about 10%; the missed clouds are almost all very low altitude and optically thin according to the SHEBA results. During unlit seasons, the false detections exceed the missed clouds, causing an overall overestimate by about 20%; the false clouds occur almost exclusively with strong temperature inversions and the ISCCP analysis has overestimated the surface temperature. A investigation of the effects of calibration errors on the ISCCP total cloud amount showed that, by design, the cloud detection procedure is very insensitive to such errors: estimated calibration uncertainty translates into a cloud amount uncertainty < 0.5%. Investigations of other effects discovered by other ISCCP participants continue to be refined. Work continues towards a complete reprocessing of the ISCCP products by the end of 2007.

C. Bishop presented a summary of activities at the Satellite Calibration Center on behalf of Y. Desormeaux, who could not attend. New satellites added to the processing system included MTSAT-1R, replacing GOES-9 over the western Pacific, FY-2C beginning operations over eastern Asia and METEOSAT-8 (MSG-1) replacing METEOSAT-7 over Europe-Africa. The transition from NOAA-16 to NOAA-18 as the reference polar orbiter was made at the beginning of 2006 as planned. However, due to the continuing bad quality of the “water vapor” channel (6.7 µm) on NOAA-18 HIRS, all normalization of this channel was discontinued in July 2006. It was noted that one or two more geostationary satellites could be accommodated as long as the AC data formats remain simple and stable. C. Bishop continued with an overview of calibration activities at the Global Processing Center. A major confounding factor in monitoring the calibration of the polar orbiting satellites is the significant drift of the overflight time of day over the lifetime of the satellite; this causes apparent changes in the radiance statistics associated with real diurnal and angle-dependent factors and with changes in the geographic coverage for the visible channel. Although the record of lifetime average radiances shows good homogeneity, there are changes in the detailed variability in the monitoring statistics that are not understood: the newer AVHRRs show much “noisier” (2-3 times larger amplitude seasonal variations) infrared statistics than the older ones. Two specific conclusions are that on-board calibrations of radiometers are not yet sufficiently accurate, showing variations of at least 1K, sometimes more, and that a new reference standard for the record is needed since the last time an adequate aircraft absolute calibration was performed for AVHRR was in the late 1980's.

W. Rossow presented a report of the on-going Cloud Product Assessment activity on behalf of C. Stubenrauch and Bryan Baum, who could not attend the meeting. One of the results being investigated is the reliability of the longer-term variations found in the ISCCP and other cloud products: ISCCP shows a ±2% variation of global monthly mean cloud amount over a little more than a decade, whereas two analyses of the HIRS observations suggest a 1% linear increase over this time period and the surface weather observations analysis shows little change (maybe a slight increase). However, all of these datasets show excellent quantitative agreement about the geographic distributions and shorter-term, larger amplitude variations such as the seasonal and diurnal cycles, including good agreement in the variations of clouds at different altitudes. Work is on-going to investigate various factors that can cause spurious long-term variability and to exploit newer data products to understand the accuracy of the older (longer) data records.

The remainder of this breakout session was occupied discussing what can be done to improve the ISCCP data products and correct for deficiencies and problems that have been discovered as well as plan for a complete re-processing to start in the next couple of years. Investigations have revealed a number of more subtle issues that need to be checked before reprocessing, including angle-dependence in the calibration results, a determination of whether cloud properties are changing to create an apparent disagreement on cloud amount changes among datasets with different detection sensitivities and checks for more subtle effects of sampling changes. Other actions that are already underway are to tighten quality checking and upgrade the retrieval model to include better treatments of aerosol and surface effects. The main opportunity that has been created by the refurbishment of the B1 dataset is to switch the ISCCP analysis from the 30km-sampled to 10km-sampled data: this would make the ISCCP products much more useful for cloud process studies, especially in combination with the daily-to-3hr GPCP products and newer satellite missions such as TRMM, CloudSat and Calipso, and would reduce the sampling noise in the SRB products.

Final Plenary Session

R. Adler summarized the GPCP breakout session: although the focus of GPCP continues to be on improving the long-term global record of precipitation, more effort will now be directed to increasing the time resolution, at least for part of the period covered while maintaining consistency with the longer- record, and increasing the information content (primarily phase of precipitation) of the products. Work will also focus specifically on improving mountainous and high-latitude (snow) results. In the next version of the products (Version 3), in addition to the longer-term (1979 to current) heritage product (possibly changed to 1° grid), a 1° product with 3hr or daily time steps will be produced from the early 1980's exploiting the ISCCP B1 radiance dataset and a 0.25°, 3hr product anchored on TRMM from 1998. However, available techniques that combine microwave with higher space-time resolution infrared radiances to produce 0.25°, 3hr results will be explored to see if using B1 can extend this resolution back to at least 1983. The gauge analysis that is used will also be upgraded to a version that has better and more homogeneous sampling; corrections for orographic effects will also be developed. The precise map grid selected for Version 3 will be coordinated with the other projects. It is appears feasible to begin testing all of these changes by the end of 2007 and begin re-processing of the whole data record sometime in 2008.

W. Rossow summarized the SRB, GACP, ISCCP breakout session: the most important points were that significant progress has been made to improve radiance calibrations, even extending the record back in time a little further, and in preparing to switch processing from the 30km to 10km sampled dataset. The assessment activities are also helping to identify analysis refinements. Re-processing could begin as early as the later half of 2007 but if the switch to B1 is approved (funding issue), then it would be delayed until the end of 2008. Specifically, SRB continues to improve the treatment of the clouds, aerosols and surfaces in its products and to develop new products (mainly fluxes in particular spectral intervals) while ISCCP works to improve its treatment of polar clouds and cirrus and to reduce the satellite viewing angle dependence of the retrievals. In the coming year, while preparing for re-processing, ISCCP will also take actions to accommodate more satellites than originally planned, including METOP-A and GOES-10 operated by Brazil. The main open issues are whether funding support will be obtained to switch processing to the B1 radiances, whether a completely global GACP product will be ready in time for ISCCP and SRB re-processing and whether a better (more homogeneous) atmospheric temperature-humidity dataset can be found (GPCP would use this same dataset for phase discrimination). Except for funding uncertainty (the ISCCP Global Processing Center and the SRB center are both awaiting funding renewal), progress towards re-processing to produce significantly improved products with higher (consistent) space-time resolutions are well underway: if all goes as planned, these new products would all be available by the end of 2009.

Since the next GRP meeting will be held in Brazil, the next WGDMA meeting may be held in the U.S. again, possibly New York.

2006 Meeting of GRP Working Group on Data Management and Analysis
Agenda

13 November 2006
	0830-0850:	Welcome, Meeting Objectives and Organization (Rossow)
	0850-0910:	Report on GRP/GEWEX/WOAP/WCRP (Rossow)
	0910-0935:	Report on CloudSat/Calipso (Kankiewicz)
	0935-1000:	Report on METOP-A (Holmlund)
	1000-1030:	Break
	1030-1100:	Project Overview – GPCP (Adler)
	1100-1130:	Project Overview – GACP (Rossow)
	1130-1200:	Project Overview – SRB (Stackhouse)
	1200-1230:	Project Overview – ISCCP (Rossow)
	1230-1345:	Lunch
	1345-1515:	Project Sessions #1
	1515-1545:	Break
	1545-1745:	Project Sessions #2
	1745:		Adjourn
	1800:		Reception

14 November 2006
	0830-1000:	Project Sessions #3
	1000-1030:	Break
	1030-1200:	Project Sessions #4
	1200-1330:	Lunch
	1330-1500:	Project Sessions #5
	1500-1530:	Break
	1530-1730:	Project Sessions #6
	1730:		Adjourn

15 November 2006
	0830-1000:	Project Sessions #7
	1000-1030:	Break
	1030-1230:	Plenary Session: Summaries, Action Items, Wrap-up
	1230:		Adjourn
 
	Project Sessions for GPCP

13 November 2006	Session #1 for GPCP
	1345-1425:	Project Status and Issues/Goals for the Meeting (Adler)
	1425-1445:	Project Data Center Report (Microwave-Land Center -Ferraro)
	1445-1515:	Project Data Center Report (Microwave-Ocean - Chiu)
	1515-1545:	Break
			Session #2 for GPCP
	1545-1605:	Project Data Center Report (Geosynchronous Center - Janowiak)
	1605-1625:	Project Data Center Report (Gauge Center - Schneider)
	1625-1645:	Project Data Center Report (Merge Center-Huffman)
	1645-1745:	Discussion
	1745:		Adjourn
	1800:		Reception

14 November 2006	Session #3 for GPCP
	0830-0900:	Data Product Assessment Report: Precipitation (Gruber)
	0900-0930:	GPROF Status and Plans (Kummerow)
	0930-0945:	Status of High latitude/Snow Algorithms/Products (Ferraro)
	0945-1000:	High latitude precipitation with AIRS/ATOVS (Huffman)
	1000-1030:	Break
			Session #4 for GPCP
	1030-1050:	Merge techniques-CMORPH (Janowiak)
	1050-1110:	Merge techniques-PERSIANN (Hsu)
	1110-1130:	Merge techniques-TMPA (Huffman)
	1130-1150:	Merge techniques-NESDIS (T. Smith)
	1150-1200:	Discussion
	1200-1330:	Lunch
			Session #5 for GPCP
	1330-1400:	PEHRPP (Sapiano)
	1400-1420:	Next Generation Gauge Analysis (Schneider)
	1420-1500:	Discussion of Version 3 attributes, methods, choices
	1500-1530:	Break
			Session #6 for GPCP	
	1530-1630:	Additional presentations on Version 3 topics 
	1630-1730:	Additional discussion
	1730:		Adjourn

15 November 2006	Session #7 for GPCP	
	0830-0900:	Draft synthesis (from discussion) of Version 3 approach (Adler)
	0900-1000:	Final discussion with choices/directions, schedule for Version 3
	1000-1030:	Break
 
	Project Sessions for ISCCP, GACP and SRB

13 November 2006	Session #1 for ISCCP, GACP and SRB
	1345-1430:	Project Data Center Report (SRB - Stackhouse)
	1430-1515:	Data Product Assessment Report: Radiation (Stackhouse)
	1515-1545:	Break
			Session #2 for ISCCP, GACP and SRB
	1630-1715:	Discussion of Product Improvements and Re-processing
	1715:		Adjourn
	1800:		Reception

14 November 2006	Session #3 for ISCCP, GACP and SRB
	0830-0900:	ISCCP Status and Issues (Rossow)
	0900-0930:	Project Data Center Report (ISCCP SPC-NOA - Knapp)
	0930-1000:	Project Data Center Report (ISCCP SPC-JMA - Okuyama)
	1000-1030:	Break
			Session #4 for ISCCP, GACP and SRB
	1030-1100:	Project Data Center Report (ISCCP SPC-EUM - Holmlund)
	1100-1130:	Project Data Center Report (ISCCP SPC-CSU - Kankiewicz)
	1130-1200:	Project Data Center Report (ISCCP SPC-CMA - Rossow)
	1200-1345:	Lunch
			Session #5 for ISCCP, GACP and SRB
	1345-1415:	Project Data Center Report (ISCCP ICA - Knapp)
	1415-1445:	Project Data Center Report (ISCCP GPC - Rossow)
	1445-1530:	Break
			Session #6 for ISCCP, GACP and SRB
	1530-1600:	Radiance Calibration (also SCC Report) (Bishop)
	1600-1630:	Radiance Dataset Refurbishment (Knapp)
	1630-1700:	Data Product Assessment Report: Clouds (Rossow)
	1700-1730:	Discussion of Product Improvements and Re-processing
	1730:		Adjourn

15 November 2006	Session #7 for ISCCP, GACP and SRB
	0830-0915:	Wrap-up Discussion of Product Improvements	
	0915-1000:	Discussion of Coordinated Re-Processing Plans
	1000-1030:	Break

ATTENDANCE LIST
Global Precipitation Climatology Project

>Robert Adler (NASA Goddard Space Flight Center)
> Long Chiu (NASA Goddard Space Flight Center)
> Ralph Ferraro (NOAA NESDIS)
> Arnold Gruber (U. Maryland)
> George Huffman (NASA Goddard Space Flight Center)
> Kuo-lin Hsu (UCI)
> John Janowiak (NOAA CPC)
> Robert Joyce (NOAA CPC)
> Matt Sapiano (U Maryland)
> Tom Smith (NOAA NCDC)
> Pingping Xie (NOAA CPC)

International Satellite Cloud Climatology Project

> William Rossow (NASA Goddard Institute for Space Studies)
> Chris Bishop (Columbia U at NASA GISS)
> Violeta Golea (SSP at NASA GISS)
> Ken Holmlund (EUMETSAT)
> Adam Kankiewicz (CSU)
> Ken Knapp (NOAA NCDC)
> Arata Okuyama (JMA)

Surface Radiation Budget project

> Paul Stackhouse (NASA Langley Research Center)
> Steve Cox (NASA Langley Research Center)