During 2023 analysis showed that with the current solar activity an increasingnumber of altitude raising boosts would be needed to keep the Global Precipitation Mission (GPM) core satellite within the required altitude box. Estimates indicate that this would have meant that the station keeping portionof the mission would likely end in 2027 with an additional 3 years of a driftdown period. This drift down period would have impact on the science data. Less impact for the radiometer data but a significant impact on the radar data.The decision was made to raise the nominal altitude from 405 km to 435 km. Analysis showed this would lead to the station keeping part of the mission to be extended to 2030 with an additional 3 years of a drift down period. Afterthe drift down, the satellite would have a controlled reentry. This presentation will provide the details of the boost that occurred on 7 and 8November 2023. This will include a discussion of the impact on the data products and its influence on further reprocessings. After the boost and totally unrelated to the boost two anomalies occurred. The first was a spacecraft anomaly and the second was a GMI anomaly. Thispresentation will provide information about these anomalies and their impact on processing.
Periodic reprocessing of the complete GPM data suite is an integral part of thescience processing strategy for the GPM mission. The first publicly available data was identified by the data product version V04 in 2014. In 2017 product version V05 for the radiometer products and in 2018 V06 for the radar products were completed.This reprocessing cycle extended the radar data back to the TRMM era (1997) and radiometer data back to 1987. It also officially integrated a considerable amount of earlier data into the GPM data suite. Reprocessing cycle V07 began at the end of 2021 with the radar based data and completed in May 2022 with all the radiometer data. The V07 version had significant changes in radar data because of a change in the Ka radar scanning strategy in May 2018 that allowed the Ka radar to cover the entire swath of the Ku radar. This allowed dual frequency retrieval across the entire Ku swath rather than just in the interior. The GPROF precipitation retrieval for the radiometers reverted back to a probablistic output. This presentation will summarize these major changes as well as other algorithm changes that improved the precipitation retrieval. It will also present other data that the mission makes available to users.
This poster provides the design, content and purpose of the Global Precipitation Measurement (GPM) gridded text products. Gridded text products at the same time and space resolution are available from the start of the TRMM period in January 1998 through the current GPM data collection period. The poster provides an example of the use of this data product by examining the structure of the Indian monsoon as well as examining the monsoon during El Nino and La Nina periods. It will also look at diurnal precipitation during the Indian monsoon season. As part of the examination of the Indian monsoon using the gridded text product, the poster demonstrates the ease of integration with other data. In this case, Sea Surface Temperature (SST) data that is relevant to the Indian monsoon is examined side-by-side with the precipitation data. It further demonstrates the ease of aggregating the daily gridded data across many years while still retaining the hourly structure that enables diurnal studies. The GPM gridded text product is currently the only level 3 GPM product which can be aggregated in this way. The representation of data in ASCII format allows potential users to concentrate on the scientific analysis rather than the physical format of the data. In summary, the poster provides an overview that uses examples to demonstrate the efficacy of this unique GPM data product.
The GPROF algorithm is used to retrieve precipitation values from all the GPM mission partner radiometers (i.e. GMI, MHS, ATMS, SSMIS, AMSR2). GPM produces two precipitation retrieval products (processing at level 2) using the GPROF algorithm. One has the type designation 2A and the other the designation 2A-CLIM. As a result understanding the difference between the two products is important for using and understanding them. Both of these GPROF products use exactly the same algorithm and a-priori databases. The only difference between the two types is the ancillary products used in the initial processing step. In the case of the 2A-CLIM products, ECMWF ERA-I is used as ancillary data. In the case of the 2A products, JMA's GANAL product is used as ancillary data. This presentation will provide a comparison between the two products using zonal mean comparisons. It will provide comparisons separately for land and ocean retrievals. It will compare the GMI differences over the entire current GPM mission life. As the only difference between the two products is the ancillary information used to create them, the comparison provides an elementary sensitivity study of the variables used from the reanalysis products and their impact on the GPROF retrieval. The purpose of the presentation is to provide users with an insight into the two GPROF products and provide them key information useful when using either of the products in scientific studies. Lastly, the presentation also discusses the reasons why only the 2A-CLIM product can be produced for the 17+ years of TRMM era data products.
The National Aeronautics and Space Administration (NASA) has always included data reprocessing as a major component of every science mission. A final reprocessing is typically a part of mission closeout (known as phase F). The Tropical Rainfall Measuring Mission (TRMM) is currently in phase F, and NASA is preparing for the last reprocessing of all the TRMM precipitation data as part of the closeout. This reprocessing includes improvements in calibration of both the TRMM Microwave Imager (TMI) and the TRMM Precipitation Radar (PR). An initial step in the version 8 reprocessing is the improvement of geolocation. The PR calibration is being updated by the Japan Aerospace Exploration Agency (JAXA) using data collected as part of the calibration of the Dual-Frequency Precipitation Radar (DPR) on the Global Precipitation Measurement (GPM) Core Observatory. JAXA undertook a major effort to ensure TRMM PR and GPM Ku-band calibration is consistent.A major component of the TRMM version 8 reprocessing is to create consistent retrievals with the GPM version 05 (V05) retrievals. To this end, the TRMM version 8 reprocessing uses retrieval algorithms based on the GPM V05 algorithms. This approach ensures consistent retrievals from December 1997 (the beginning of TRMM) through the current ongoing GPM retrievals. An outcome of this reprocessing is the incorporation of TRMM data products into the GPM data suite. Incorporation also means that GPM file naming conventions and reprocessed TRMM data carry the V05 data product version. This paper describes the TRMM version 8 reprocessing, focusing on the improvements in TMI level 1 products.
Radio Frequency Interference (RFI) continues to be an annoyance to passive microwave remote sensing as spectrum demands escalate. For microwave imagers such as GMI and WindSat, the X-band and Ku allocated passive bands exhibit RFI from terrestrial based sources and from space-based geostationary satellites reflecting from the ocean, lakes, frozen ground, and other reflective surfaces. The GMI bands were designed to maintain the 3-dB bandpasses within the ITU allocated Earth Exploration-Passive bands, while WindSat, due to its sensitivity requirements, has much wider bandpasses. Both sensors have very similar viewing geometries, creating an ideal situation to address the question "Is it worth compromising radiometric sensitivity with lower bandwidths to stay within the allocated bands." We find that the only benefit for these sensors of remaining within the allocated band is the elimination of reflected RFI from geosynchronous satellites around Europe at 10 GHz. Other than that, remaining within the protected bands appears to not provide much benefit.
This presentation will summarize the changes in the products for the GPM V05 reprocessing cycle. It will concentrate on discussing the gridded text product from the core satellite retrievals. However, all aspects of the GPROF GMI changes in this product are equally appropriate to the other two gridded text products. The GPM mission reprocessed its products in May of 2017 as part of a continuing improvement of precipitation retrievals. This lead to important improvement in the retrievals and therefore also necessitated reprocessing the gridded test products. The V05 GPROF changes not only improved the retrievals but substantially alerted the format and this compelled changes to the gridded text products. Especially important in this regard is the GPROF2017 (used in V05) change from reporting the fraction of the total precipitation rate that occurring as convection or in liquid phase. Instead, GPROF2017, and therefore V05 gridded text products, report the rate of convective precipitation in mm/hr. The GPROF2017 algorithm now reports the frozen precipitation rate in mm/hr rather than the fraction of total precipitation that is liquid. Because of the aim of the gridded text product is to remain simple the radar and combined results will also change in V05 to reflect this change in the GMI retrieval. The presentation provides an analysis of these changes as well as presenting a comparison with the swath products from which the hourly text grids were derived.
In June 2015 the TRMM satellite came to its end. The 17+ year of mission data that it provided has proven a valuable asset to a variety of science communities. This 17+ year data set does not, however, stagnate with the end of the mission itself. NASA/JAXA intend to integrate the TRMM data set into the data suite of the GPM mission. This will ensure the creation of a consistent, intercalibrated, accurate dataset within GPM that extends back to November of 1998. This paper describes the plans for incorporating the TRMM 17+ year data into the GPM data suite. These plans call for using GPM algorithms for both radiometer and radar to reprocess TRMM data as well as intercalibrating partner radiometers using GPM intercalibration techniques. This reprocessing will mean changes in content, logical format and physical format as well as improved geolocation, sensor corrections and retrieval techniques.
In February 2015, the Global Precipitation Measurement (GPM) mission core satellite will complete its first year in space. The core satellite carries a conically scanning microwave imager called the GPM Microwave Imager (GMI), which also has 166 GHz and 183 GHz frequency channels. The GPM core satellite also carries a dual frequency radar (DPR) which operates at Ku frequency, similar to the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar, and a new Ka frequency. The precipitation processing system (PPS) is producing swath-based instantaneous precipitation retrievals from GMI, both radars including a dual-frequency product, and a combined GMIDPR precipitation retrieval. These level 2 products are written in the HDF5 format and have many additional parameters beyond surface precipitation that are organized into appropriate groups. While these retrieval algorithms were developed prior to launch and are not optimal, these algorithms are producing very creditable retrievals. It is appropriate for a wide group of users to have access to the GPM retrievals. However, for researchers requiring only surface precipitation, these L2 swath products can appear to be very intimidating and they certainly do contain many more variables than the average researcher needs. Some researchers desire only surface retrievals stored in a simple easily accessible format. In response, PPS has begun to produce gridded text based products that contain just the most widely used variables for each instrument (surface rainfall rate, fraction liquid, fraction convective) in a single line for each grid box that contains one or more observations.This paper will describe the gridded data products that are being produced and provide an overview of their content. Currently two types of gridded products are being produced: (1) surface precipitation retrievals from the core satellite instruments GMI, DPR, and combined GMIDPR (2) surface precipitation retrievals for the partner constellation satellites. Both of these gridded products are generated for a.25 degree x.25 degree hourly grid, which are packaged into daily ASCII (American Standard Code for Information Interchange) files that can downloaded from the PPS FTP (File Transfer Protocol) site. To reduce the download size, the files are compressed using the gzip utility.This paper will focus on presenting high-level details about the gridded text product being generated from the instruments on the GPM core satellite. But summary information will also be presented about the partner radiometer gridded product. All retrievals for the partner radiometer are done using the GPROF2014 algorithmusing as input the PPS generated inter-calibrated 1C product for the radiometer.
The Tropical Rainfall Measurement Mission (TRMM) is a joint U.S. and Japan mission to observe tropical rainfall, which was launched by H-II No. 6 from Tanegashima in Japan at 6:27 JST on November 28, 1997. After the two-month commissioning of TRMM satellite and instruments, the original nominal mission lifetime was three years. In fact, the operations has continued for approximately 17.5 years. This paper provides a summary of the long term operations of TRMM.
The Global Precipitation Measurement (GPM) mission quarter-degree gridded-text product has a similar file format and a similar purpose as the Tropical Rainfall Measuring Mission (TRMM) 3G68 quarter-degree product. The GPM text-grid format is an hourly summary of surface precipitation retrievals from various GPM instruments and combinations of GPM instruments. The GMI Goddard Profiling (GPROF) retrieval provides the widest swath (800 km) and does the retrieval using the GPM Microwave Imager (GMI). The Ku radar provides the widest radar swath (250 km swath) and also provides continuity with the TRMM Ku Precipitation Radar. GPM's Ku+Ka band matched swath (125 km swath) provides a dual-frequency precipitation retrieval. The combined retrieval (125 km swath) provides a multi-instrument precipitation retrieval based on the GMI, the DPR Ku radar, and the DPR Ka radar. While the data are reported in hourly grids, all hours for a day are packaged into a single text file that is g-zipped to reduce file size and to speed up downloading. The data are reported on a 0.25deg x 0.25 deg grid.