Status report on the key climate variables technical supplement to the
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- Contributing baseline (GCOS) observations
Oxygen is a key variable needed for understanding photosynthesis and respiration, and can be used to place constraints on the quantity and rate of primary production, and to differentiate between biological processes and physical processes such as mixing and air-sea gas exchange that affect upper ocean chemistry and biology.Concentrations of nutrients (including nitrogen, phosphorus, silicate, and trace elements such as iron) drive the production of organic matter (including carbon complexes) of marine ecosystems, and establish the general trophic structure of the ocean (extremes are oligotrophy and hypertrophy). Because of the complex interplay between biology, chemistry, and upper ocean physics, a suite of biogeochemical variables is required to understand and quantify these processes.Contributing baseline GCOS observationsNone Other contributing observations Temporal variability of biogeochemical variables is generally relatively slow for the deep ocean (years to decades), but quite rapid (minutes to weeks) in the upper ocean. Thus, deep-sea data collected during expeditions as repeat sections several years apart bear useful information. However, high temporal resolution data are needed for the upper ocean through the upper permanent thermocline. The latter types of data sets are rare with process-oriented experiments being typically limited to a single year. Time series data collected at the Hawaii Ocean Time-series (HOT) and Bermuda Atlantic Time Series (BATS) sites provide some of the few records appropriate for studies of biogeochemical variability ranging from weeks to the interannual. Biogeochemical measurements made from ships of opportunity can provide invaluable information on both spatial and low frequency temporal variability in the upper ocean. A large number of individual programmes are currently operating and there is an international effort underway to create a co-ordinated network of data from these programmes. Significant data management issues Although databases for carbon are relatively well developed, there is need to begin integration and data set compilation of a more comprehensive suite of biogeochemical variables (collected from all available ocean sampling platforms) in order to characterize, model, and understand the carbon system and the requisite biogeochemical data suite on time and space scales spanning a broad range of variabilities associated with diverse processes. Analysis products Many atlases have been produced for the biogeochemical variables described above. The World Ocean Atlas 2001 database produced by the World Data Center for Oceanography provides a compilation of global, archived data for standard hydrographic variables and oxygen. The World Data Center for Marine Environmental Sciences contains data sets for environmental oceanography and marine biology. The NASA Global Change Master Directory provides information and links to data sets from national and international research programmes. Current capability New biogeochemical sensors and systems are being developed to sample nearly continuously and several recent assessments of technology development in this area have been made (http://ioc.unesco.org/iocweb/co2panel/). Oxygen sensors, fluorometers, sensors for the principle nutrients, pCO2 sensors, and plankton recorders are either already commercially available or in advanced stages of sea-truthing. Platforms that have been utilized to improve spatial and temporal resolution include ships (underway sampling), moorings, and drifters, and biogeochemical sensors are being developed for use on profiling floats. Additional development and testing is needed to approach the accuracy and resolution of measurements made directly on water samples. Testing needs to include intercomparison exercises with known methods and sampling from ships as sea-truthing. Issues and priorities
Variable: Snow cover Main climate applications Snowfall and other solid precipitation as a fraction of total precipitation is important in hydroclimatic models and as an element in monitoring climate change. About one third of the Earth’s land surface may be covered seasonally by snow. Up to 50% of the Northern Hemisphere land surface has snow cover during the Northern Hemisphere winter. It has major effects on surface albedo and energy balance and modifies the overlying atmospheric thickness and surface temperatures. Characteristics of snow such as thickness, seasonal and interannual variability or snow-cover duration affect permafrost thermal state, the depth and timing of seasonal freeze/thaw of the ground as well as ablation on glaciers, ice sheets and sea ice. Snow melt plays a major role in seasonal energy exchanges between the atmosphere and ground, it impacts soil moisture and runoff, thereby affecting water resources. As a consequence, snow cover is a key component of land surface process sub-models for higher latitudes and altitudes. Contributing baseline (GCOS) observationsNone Other contributing observationsSeveral elements must be considered under the heading “snow cover”: snow extent, snow depth, snow water equivalent, snow all and solid precipitation. The observations commonly involve several different agencies in each country. Snow depth is measured once daily at weather stations, but is not usually reported over the Global Telecommunications System (GTS). There are about 7,000 land stations in the GTS reports. Global snow depth data are available from the WMO-GTS Synoptic Reports for stations that do report that code group in real time (see: ftp://ftp.ncdc.noaa.gov/pub/data/globalsod). Snowfall is not differentiated in 6-hourly/daily precipitation measurements at weather stations although type of precipitation is reported in the synoptic weather code. Snow cover is mapped routinely by satellites. NOAA-NESDIS provides operational hemispheric products; NASA develops hemispheric research products. See details below. Snow water equivalent is determined at snow courses (North America) or along snow transects (Russia) at about 15-30 day or 10-day intervals, respectively. The data are in agency archives and many are not digitized, European data are especially difficult to access (cost and other restrictions). Snow water equivalent is one of the hydrological variables relevant to climate change that is part of the new GCOS/WMO-sponsored GTN-H (Global Terrestrial Network for Hydrology) which was implemented in 2001 to improve accessibility of already existing data. Snow melt onset on sea and land ice can be determined from passive microwave remote sensing. Research products have been developed for Greenland and the Arctic. The data for Greenland are available from W. Abdalati at NASA HQ: ftp://icesat2.gsfc.nasa.gov/pub/waleed/ssmi_melt. A snow-melt data set for Arctic sea ice from 1979-1998 prepared by S. Drobot and M. Anderson is available from NSIDC: http://nsidc.org/data/nsidc-0105.html. Directory: pages -> prog prog -> Regional Association IV (North America, Central America and the Caribbean) Hurricane Operational Plan prog -> Review of the ra IV hurricane operational plan prog -> Cyclone programme prog -> World meteorological organization prog -> World meteorological organization technical document prog -> Regional Association IV (North America, Central America and the Caribbean) Hurricane Operational Plan prog -> World meteorological organization ra IV hurricane committee thirty-fourth session prog -> World meteorological organization ra IV hurricane committee thirty-third session prog -> Review of the past hurricane season prog -> Ra IV hurricane committee thirty-fourth session ponte vedra beach, fl, usa Download 0.61 Mb. Share with your friends:
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