Global Energy and Water Exchanges
Permanent URI for this community
The Global Energy and Water Cycle Exchanges (GEWEX) a core project of the World Climate Research Programme, is dedicated to understanding Earth’s water cycle and energy fluxes at and below the surface and in the atmosphere. We are a network of scientists gathering information on the global water and energy cycles through research, observations, and science activities, which will help to predict changes in the world’s climate.
The International GEWEX Project Office (IGPO) supports these activities by planning meetings, implementing research goals, and producing a quarterly newsletter to keep the GEWEX community informed.
GEWEX coordinates science activities to facilitate research into the global water cycle and interactions between the land and the atmosphere. One of the primary influences on humans and the environments they live in, the global water cycle encompasses the continuous journey of water as it moves between the Earth’s surface, the atmosphere, and beneath the Earth’s surface. Clouds, precipitation, water vapor, surface radiation, aerosols, and other phenomena each play a role in the cycle. Many GEWEX scientists conduct research on those and other elements to help fine-tune our understanding of them and their impact on the climate. GEWEX also points out important gaps in knowledge and implements ways to fix those gaps, whether through new studies, reviews of datasets, gatherings of experts, or other opportunities.
The International GEWEX Project Office (IGPO) supports these activities by planning meetings, implementing research goals, and producing a quarterly newsletter to keep the GEWEX community informed.
GEWEX coordinates science activities to facilitate research into the global water cycle and interactions between the land and the atmosphere. One of the primary influences on humans and the environments they live in, the global water cycle encompasses the continuous journey of water as it moves between the Earth’s surface, the atmosphere, and beneath the Earth’s surface. Clouds, precipitation, water vapor, surface radiation, aerosols, and other phenomena each play a role in the cycle. Many GEWEX scientists conduct research on those and other elements to help fine-tune our understanding of them and their impact on the climate. GEWEX also points out important gaps in knowledge and implements ways to fix those gaps, whether through new studies, reviews of datasets, gatherings of experts, or other opportunities.
Browse
Browsing Global Energy and Water Exchanges by Issue Date
Now showing 1 - 20 of 24
Results Per Page
Sort Options
Item List of Acronyms(World Climate Research Programme, 2021)This list contains the acronyms used in The Joint IPWG/GEWEX Precipitation Analysis along with their definitions.Item The Joint IPWG/GEWEX Precipitation Assessment(World Climate Research Programme, 2021) Roca, Rémy; Haddad, Ziad S.; Akimoto, Fumie F.; Alexander, Lisa; Behrangi, Ali; Huffman, George; Kato, Seiji; Kidd, Chris; Kirstetter, Pierre-Emmanuel; Kubota, Takuji; Kummerow, Chris; L’Ecuyer, Tristan; Levizzani, Vincenzo; Maggioni, Viviana; Massari, Christian; Masunaga, Hirohiko; Schröder, Marc; Tapiador, Francisco J.; Turk, Francis J.; Utsumi, NobuyukiThis report reviews the current state of precipitation products, and includes assessments of sub-daily global satellite precipitation products, discussions of various climate applications of precipitation products, and deliberations on emerging directions and the future of precipitation products.Item Intrinsic uncertainty in the sub-daily satellite products at their native resolutions(World Climate Research Programme, 2021) Haddad, Ziad S.; Turk, Francis J.; Utsumi, Nobuyuki; Kirstetter, Pierre-EmmanuelLevel-3 “sub-daily global merged satellite precipitation products” are typically reported on a fixed rectangular latitude-longitude grid at high spatial and temporal resolution (respectively 0.1º and ~0.5 hour). This section is specifically concerned with the uncertainties in these products at their reported resolution. The discussion reviews the uncertainties that are inherent in the retrieval and processing steps that are used to produce the Level-3 estimates. These include the detection error, the passive microwave (MW) and infrared (IR) estimation errors, and the error incurred when using frequent IR information to fill long revisit gaps between passive MW estimates. Advantages and disadvantages of Level-3 products are also summarized.Item Validating the intrinsic uncertainty: Implications for hydrologic applications(World Climate Research Programme, 2021) Kirstetter, Pierre-EmmanuelThe critical importance of accurate water flux estimates for science and applications explains the large body of verification analyses focusing on precipitation estimates. Very few are implemented at the relevant scales to address the intrinsic uncertainty of precipitation products. This endeavor requires the expert use of other precipitation sensors such as radar-gauge combinations. The intrinsic uncertainty structure of satellite-based quantitative precipitation estimates is still largely unknown at the spatiotemporal scales near the sensor measurement scale. Without relevant information on key uncertainty features, applications making use of satellite Level-3 precipitation products are impacted both in terms of outcomes and physical realism. Ultimately, it requires more than just one deterministic “best estimate” to adequately cope with the intermittent, highly-skewed distribution that characterizes precipitation. Advancing the use of uncertainty as an integral part of the relationship between sensor measurements and precipitation estimates has the potential to provide a framework for diagnosing intrinsic uncertainty.Item Monitoring of satellite precipitation estimates through the IPWG validation studies(World Climate Research Programme, 2021) Kidd, Chris; Maggioni, VivianaA major activity of the International Precipitation Working Group (IPWG) is the verification, validation and intercomparison of precipitation products to enable product developers and users to continually monitor and assess the performance of the available products. This activity has developed an ongoing validation program, comparing surface reference datasets and satellite precipitation products to better inform product developers and the user community. This section gives an overview of the IPWG validation program. IPWG validation aims to improve satellite precipitation products, focusing upon statistical analysis over regions with existing reference data at moderate temporal/spatial resolutions.Item Climate model validation(World Climate Research Programme, 2021) Tapiador, Francisco; Levizzani, VincenzoThis chapter reviews the use of satellite-derived precipitation datasets to validate climate models, with an emphasis in quality control and normalization. Two checklists are provided: one with the facts regarding the major issues that must be considered in the use of precipitation for validation, and another with recommendations for a proper use of precipitation datasets in model validation, on the line of the ISO normalization rules and quality-assurance of the whole process of validation. Validation of latent heat release, microphysics of precipitation and extremes are considered, and some examples of extensive validations of simulations vs. observations are provided.Item Extreme and intense precipitation(World Climate Research Programme, 2021) Roca, Rémy; Masunaga, Hirohiko; Alexander, LisaThe availability of numerous gridded precipitation products and the importance of the question of extreme precipitation have led to a number of new findings. Over land, this intercomparison generally emphasizes that global space-based precipitation products show the potential for climate-scale analyses of extremes to serve as a complementary source to in situ gridded data, while reanalysis should be used with caution. Over the ocean, the spread among the products of extreme intensity is larger than over land. The global characteristics of the representation of precipitation extremes are found at the regional scale as well. Yet, the magnitude and the behavior among the products show significant regional disparities that are more and more carefully documented in the literature. With these caveats, the new generation of satellite products are successfully used for process-oriented studies and climate models evaluation.Item Toward the new generation of products(World Climate Research Programme, 2021) Huffman, George; Kirstetter, Pierre-EmmanuelModern precipitation products provide fine resolution precipitation estimates by combining estimates from many individual high-quality satellite sensors and by using approximations to fill numerous gaps in the mosaics of short-interval segments from the various sensors. Challenges include (1) the need for consistent estimates within the mosaics and across generations of sensors with differing capabilities, and (2) increasing the information content to better resolve uncertainty and extremes at full resolution, spanning from retrievals to merged estimates. These challenges are accentuated by the diversity of current and new sources of satellite and surface observations. The future directions of global observationally-based precipitation products involve improvements in the individual retrievals, improvements and operationalization of additional sensor estimates, and innovations in assembling the merged products, including the intercalibration and homogenization of the data record. Seamless integration of ground networks, numerical models, new observations, and improved conditioning with precipitation processes are keys for future precipitation products.Item Energy and water closure(World Climate Research Programme, 2021) Roca, Rémy; Kato, Seiji; L’Ecuyer, TristanEnergy and water budget closure has recently been extensively used to assess the consistency of precipitation products with various other terms of the water and energy budget. Most efforts are focused on water closure and explore regional scales. These studies reveal the difficulty of closing the regional water budget with the current generation of satellite and/or reanalysis products. The addition of energy constraints on the water budget allows us to enforce the closure and shows more consistent results of optimized observations. At the global scale, fewer studies have been conducted. They tend to show that only a handful of precipitation products are consistent with the radiation budget at this scale. The major recommendation of this chapter is to elaborate on the characterization of uncertainty of the precipitation product to better serve the energy and water closure study.Item Emerging techniques for precipitation assessment and consistency studies(World Climate Research Programme, 2021) Behrangi, AliBesides traditional sensors used to estimate precipitation amount and distribution, several other Earth-observing sensors can provide valuable insights about precipitation quantity. Here, we show how observation of mass change from GRACE and GRACE-FO satellites can help quantify snowfall accumulation over Antarctica and frozen surfaces in the Northern Hemisphere, two regions that precipitation estimation from typical precipitation measuring sensors are the most uncertain. Similarly, we discuss how snow depth observation from the Operation IceBridge (OIB) can help assess snow accumulation over sea ice, where almost no other reliable in situ data exists. These independent observations can also give us insights into the consistency of variables used in the water budget equation. Furthermore, we discuss how complementary observations from radars can help refine our estimate of precipitation over the ocean and serve as a reference to assess other precipitation products.Item Intercomparison of products for climate applications(World Climate Research Programme, 2021) Masunaga, Hirohiko; Akimoto, Fumie F.; Kubota, Takuji; Kummerow, Chris; Schröder, MarcObservational datasets of global precipitation are widely used for a range of climate applications. The precipitation products, however, are not strictly a “true” representation of nature, but have their own uncertainties related to issues such as sampling errors and algorithmic assumptions. We present here an intercomparison of 11 global precipitation datasets. Major conclusions are: - While the overall geographical pattern of precipitation is coherent among products, the magnitude varies from one dataset to the other. The agreement is poor particularly at high latitudes, since light and/or solid precipitation typical of high latitudes is difficult to estimate accurately from satellite microwave radiometry. - A systematic bias is present between gridded gauge products, which is presumably partially responsible for the spread in merged multi-satellite datasets adjusted to the gauge products. - The bias characteristics in the annual/monthly mean precipitation are a poor predictor of those in extreme precipitation.Item Climate variability and trends(World Climate Research Programme, 2021) Tapiador, Francisco J.This chapter describes the role of satellite precipitation datasets in the analysis of climate variability and trends. Two major applications are explored, namely the validation of the variability in the statistical moments of the climatology (mean, variance, kurtosis, etc.), and the analysis of the model-derived modes of variability (PDO, AMO, IOD, MJO and ENSO). It is shown that precipitation may be seen as the privileged field to reveal, diagnose and quantify the nonlinear relationship between the variability in the climate system and changes in mean state. The fingerprints of climate variability and trends in precipitation are highly revealing of model performances, and thus arises the need for continually improving precipitation datasets based on satellite retrievals.Item Directions in error modeling(World Climate Research Programme, 2021) Maggioni, Viviana; Massari, ChristianAlthough in the recent past numerous attempts have been made to develop error models of satellite precipitation products, several issues limit their use in applications. First off, the majority of these approaches is based on assumptions regarding the distribution of precipitation and/or associated errors. Second, simple error models may be preferable for some applications, but more complex solutions may be more appropriate for others. For instance, hydrological models used to simulate floods should be particularly sensitive to extreme precipitation events and the ability of detecting such events. Thus, an error model that account for missed precipitation cases and false alarms would be preferable. Third, precipitation errors and uncertainties depend on seasonality, rain rate, geophysical features, and the product’s temporal and spatial resolutions. Thus, the same error model would unlikely perform similarly everywhere in the world, at any time, for any precipitation event type, and for any application.Item Requirements for a constellation of precipitation sensors(World Climate Research Programme, 2021) Kidd, ChrisSatellites within the current precipitation constellation are old, with many missions beyond their designed operational lifetime. It is therefore crucial that there is a concerted program of new satellites and sensors to ensure continuity in satellite-based precipitation measurements. Planning the future constellation of precipitation sensors should include a long-term strategy for sensors that meet scientific and user requirements, support for current missions beyond their normal lifetime, new technology such as cubesats, and, fundamentally, a commitment to and support for current and planned precipitation-capable missions. Issues and considerations in designing this next generation of precipitation sensors are discussed in this subchapter, which also includes a concise inventory of missions planned for launch over the next decade.Item GEWEX Quarterly, Vol. 31, No. 1(2021-02) Stephens, Graeme; van Oevelen, Peter; Gupta, Hoshin; Maddock, Thomas III; Zeng, Xubin; Redelsperger, Jean-Luc; Couvreux, Fleur; Bouniol, Dominique; Hourdin, Frederic; Galarneau, Thomas J. Jr.; Su, Zhongbo; Zeng, Yijian; Zhao, Hong; Lv, Shaoning; Wen, Jun; Scipal, Klaus; Roca, Rémy; L’Ecuyer, Tristan; Nazemi, Ali; Dominguez, Francina; Cuxart, Joan; Takayabu, Izuru; Rasmussen, Roy; Nakakita, Eiichi; Prein, Andreas; Kawase, Hiroaki; Watanabe, Shun-Ichi; Adachi, Sachiho A.; Takemi, Tetsuya; Yamaguchi, Kosei; Osakada, Yukari; Wu, Ying-HsinItem GEWEX Quarterly, Vol. 31, No. 2(International GEWEX Project Office, 2021-05) Polcher, Jan; Gulizia, Carla; Bahar, Faten Attig; Rabanal, Valentina; YESS Executive Committee; Guimond, Julia; Zeng, Yijian; Verhoef, Anne; Or, Dani; Cuntz, Matthias; Gudmundsson, Lukas; Weihermueller, Lutz; Kollet, Stefan; Vanderborght, Jan; Vereecken, Harry; Polcher, Jan; International GEWEX Project Office; Hartogensis, Oscar; Cuxart, Joan; Ek, Michael; Findell, Kirsten; Verhoef, AnneItem GEWEX Quarterly, Vol. 31, No. 3(International GEWEX Project Office, 2021-08) Xubin, Zeng; Polcher, Jan; Guimond, Julia; Rabanal, Valentina; Gulizia, Carla; Attig Bahar, Faten; YESS Executive Committee; Stammer, Detlef; Cleugh, Helen; van der Wel, Narelle; Fowler, Hayley J.; Ohmura, Atsumu; Huffman, George J.; Unninayar, Sushel; Lawford, Richard; Gutierrez, Angelica; Wang, Minghuai; Rosenfeld, Daniel; Christensen, Matthew; Gettelman, Andrew; Jensen, Michael P.; Fan, Jiwen; Collis, Scott; Stier, Philip; Andreae, Meinrat O.; Feingold, Graham; van den Heever, Sue; Kahn, Ralph; Quaas, Johannes; Suzuki, Kentaroh; White, Bethan; Wood, Rob; Pomeroy, John; Schuster-Wallace, Corinne; Bigas, Harriet; DeBeer, ChrisItem GEWEX Quarterly, Vol. 31, No. 4(International GEWEX Project Office, 2021-11) van Oevelen, Peter; Guimond, Julia; International GEWEX Project Office; Attig Bahar, Faten; Gulizia, Carla; Rabanal, Valentina; YESS Executive Committee; Lettenmaier, Dennis; Sheffield, Justin; Pan, Ming; Ferguson, Craig; Kaye, Jack; Braun, Scott; Cauffman, Sandra; Huffman, George; Kirschbaum, Dalie; Piña, Aaron; Jakob, Christian; Bauer, Peter; Bony, Sandrine; Klocke, Daniel; Findell, Kirsten; Verhoef, Anne; Dominguez, Francina; Wan, Hui; Woodward, Carol S.; Samadi, Vidya; Prein, Andreas; Roundy, Joshua K.; Dominguez, Francina; Ward, Helen C.; Rotach, Mathias W.; TEAMx Coordination and Implementation Group; Purcell, Amanda; Melvin, April; Delle Monache, Luca; Ralph, F.M.; Boone, Aaron; Bellvert, Joaquim; Best, Martin; Brooke, Jennifer; Canut-Rocafort, Guylaine; Cuxart, Joan; Hartogensis, Oscar; Le Moigne, Patrick; Ramon Miró, Josep; Price, Jeremy; Quintana Seguí, Pere; Wooster, Martin; Sorooshian, Armin; Zeng, Xubin; Kleb, Mary; Ferrare, Richard; Hair, Johnathan; Vervoort, FernandeItem History of the International Satellite Cloud Climatology Project(2022) Rossow, William B.The International Satellite Cloud Climatology Project (ISCCP) was formally established as the first project of the World Climate Research Programme (WCRP) in August 1982 to collect and analyze global satellite observations of Earth’s clouds for climate research. This 40-year history emphasizes the evolution of ideas about the purposes of the project and how that evolution shaped the characteristics of the data products. The history first covers a period before ISCCP, the planning workshops, the project initiation and the development in the first project phase, followed by a discussion of the evolution of the project concept to articulate more specifically the tasks required to quantify cloud effects on radiation exchanges in climate. The history continues with the production of the first version of the cloud data products in the late 1980s and early 1990s. Significant achievements at this stage were: (1) establishment and release of the first absolute radiance calibrations for the global constellation of weather satellite imaging instruments, (2) development and testing of a cloud detection procedure from quantitative evaluations of available ideas, (3) production of usefully accurate determinations of cloud radiative effects by employing radiative transfer models both for retrieval and flux calculations with consistent cloud microphysics and (4) provision of globally uniform depictions of diurnal, synoptic, and seasonal cloud variations. The interruption of satellite radiance calibration monitoring by the aerosols injected into the stratosphere by the Mt. Pinatubo volcano led to a period of evaluation based on an international set of supporting field experiments. Also, the reorganization of ISCCP within the Global Energy and Water Cycle Experiment (GEWEX) under WCRP shifted the project focus to include clouds and precipitation along with clouds and radiation. These events led to a second version of the data products produced from the 1990s into the early 2010s. This new version included improved polar cloud and cirrus detection, identification and treatment of ice clouds and release of higher resolution products for cloud process studies. The subsequent use of the new products led to better understanding of cloud types and their vertical structures, which allowed determination of radiation flux profiles. Analysis of patterns in mesoscale cloud property distributions helped advance understanding of cloud processes, including precipitation, in different meteorological situations. The advent of more advanced satellite cloud measurements in the late 1990s and 2000s supported a second revision that enhanced the usefulness of the ISCCP products for cloud process studies. In the 2010s, a growing emphasis on extending the length of record for climate studies led to the decision to transition the project to a fully operational organization to provide long-term context for field and other satellite measurements. The evolution of the project concept finally encompassed elucidating the complete role of clouds in weather and climate variations. On-going studies using ISCCP products include diagnosis of exchanges of radiative and latent energy by clouds, evolution of cloud properties over the lifecycle of tropical and extratropical storms, and estimates of cloud feedbacks on weather systems. The final sections summarize the accomplishments of ISCCP, discuss the status of knowledge about clouds and cloud processes as of 2022, and briefly outline of the next measurements and analyses.Item GEWEX Quarterly, Vol. 32, No. 1(International GEWEX Project Office, 2022-02) Arias, Paola A.; Espinoza, Jhan-Carlo; Polcher, Jan; Kanavas, Zoe; Myers, Dan; Byrnes, Danyka; Bahar, Faten Attig; Abid, Muhammad Adnan; YESS Executive Committee; ; Sherwood, Steven; ; Friedlingstein, Pierre; ; Harris, Neil; Holland, Beth; Kim, Hyungyun; Nobre, Paulo; Otto-Bliesner, Bette; Reed, Kevin; Renwick, Jim; Xie, Shaocheng; Tang, Shuaiqi; Alves, Lincoln M.; Ometto, Jean P.H.B.; Lemos, Cássia M.G.; Andrade, Pedro R.; Bezerra, Karine R.A.; Santos, Diogo V.; Arcoverde, Gustavo F.B.; Toledo, Peter M.; Salazar, Juan F.; Berrouet, Lina; ; Martínez, J. Alejandro; QuinteroVallejo, Estela; Vieira, Sara C.; Villegas, Clara I.; Villegas, Juan Camilo; Zuluaga, Jorge I.; Vera, Carolina; ; Sierra, Juan-Pablo; Segura, Hans; Junquas, Clémentine; Condom, Thomas; ; Agudelo, Jhoana; Andrade, Marcos; Apaestegui, James; Autin, Philémon; Basantes, Rubén; ; Biron, Romain; ; Caceres, Bolivar; Caro, Alexis; Ceballos, Jorge Luis; Champollion, Nicolas; Duwig, Céline; Espinoza, Raul; Fita, Lluís; Garcia, Ayón; Garreaud, René; Gascoin, Simon; Gomez, Jesus; Junquas, Clémentine; Lavado, Waldo; Lengtchenko, Anatoli; MacDonell, Shelley; Maisincho, Luis; Martinez, Alejandro; Masiokas, Mariano; Molina-Carpio, Jorge; ; Poveda, German; Sicart, Jean-Emmanuel; ; Racoviteanu, Adina; Ruelland, Denis; Reveillet, Marion; RuizHernandez, Jean Carlo; Saavedra, Miguel; Satgé, Frédéric; Segura, Hans; Sicart, Jean-Emmanuel; Sierra, Juan Pablo; Suarez, Wilson; Soruco, Alvaro; Takahashi, Ken; Tavernier, Adrien; Villacis, Marcos; Fita, Lluís; Alves, Lincoln Muniz; Boisier, Juan P.; Parra, Lenin Vladimir Campozano; Espinoza, Jhan Carlo; Junquas, Clémentine; Llopart, Marta; Martínez, J. Alejandro; Sörensson, Anna; South America Affinity Group (SAAG)This special issue of GEWEX Quarterly contains the articles on the following: South America as a focus for hydroclimatological studies; active bystander training from H3S; a Learning Group on machine learning methods and more from YESS; the WCRP Safe Landing Climates Lighthouse Activity; understanding the diurnal cycle of precipitation in weather and climate models using long-term SCM simulations; Prof. Dani Or, GEWEX SoilWat Initiative member, is elected to the National Academy of Engineering; AdaptaBrasil MCTI, an innovative platform for analyzing climate change impacts in Brazil; the SOS-Cuenca project and Magdalena-Cauca river basin sustainability; the CLIMAX project and producing climate services through knowledge coproduction; the AMANECER project and impacts of climate-vegetation changes on the water cycle of the Amazon-Andes transition region; the GREAT ICE and ANDES-C2H programs, which share a focus on the ANDES as a nexus of the atmosphere, cryosphere, and hydrosphere; cpAmSur, climate simulations at very high resolution and complexity in South America; learning from convection-permitting simulations with the South America Affinity Group; and advertising for the 2022 3rd Pan-GASS Meeting in Monterey, California.