Global Terrestrial Ecosystem Carbon Flux Inferred from TanSat XCO2 Retrievals

TanSat is China’s first greenhouse gases observing satellite. In recent years, substantial progresses have been achieved on retrieving column-averaged CO2 dry air mole fraction (XCO2). However, relatively few attempts have been made to estimate terrestrial net ecosystem exchange (NEE) using TanSat XCO2 retrievals. In this study, based on the GEOS-Chem 4D-Var data assimilation system, we infer the global NEE from April 2017 to March 2018 using TanSat XCO2. The inversion estimates global NEE at −3.46 PgC yr-1, evidently higher than prior estimate and giving rise to an improved estimate of global atmospheric CO2 growth rate. Regionally, our inversion greatly increases the carbon uptakes in northern mid-to-high latitudes and significantly enhances the carbon releases in tropical and southern lands, especially in Africa and India peninsula. The increase of posterior sinks in northern lands is mainly attributed to the decreased carbon release during the nongrowing season, and the decrease of carbon uptakes in tropical and southern lands basically occurs throughout the year. Evaluations against independent CO2 observations and comparison with previous estimates indicate that although the land sinks in the northern middle latitudes and southern temperate regions are improved to a certain extent, they are obviously overestimated in northern high latitudes and underestimated in tropical lands (mainly northern Africa), respectively. These results suggest that TanSat XCO2 retrievals may have systematic negative biases in northern high latitudes and large positive biases over northern Africa, and further efforts are required to remove bias in these regions for better estimates of global and regional NEE.

Past monsoons : A review of proxy data and modelling

Recent modelling studies have given insight into the role of internal feedback processes among components of the climate system on the evolution of monsoon strength since the Last Glacial Maximum (21,000 years ago). Here we present an overview of these modelling studies related to the summer monsoon over India and northern Africa. These studies indicate that the seasonal insolation changes alone do not explain the observed extent of hydrological changes during the early and middle Holocene over northern Africa. To simulate the extent of observed changes during this period incorporation of vegetation as an active component in climate models appears to be necessary. Over the Indian region, model results show that precipitation-soil moisture feedbacks play an important role in determining the response of the monsoon to changes in insolation and glacial-age surface boundary conditions. Indian monsoon strength from proxy records during the early and middle. Holocene have also been used in conjunction with coupled ocean atmosphere general circulation model experiments to refute the suggestion that semi-permanent warm surface conditions prevailed over equatorial Pacific ocean from 11 to 5ka.

Linkages between GRACE water storage, hydrologic extremes, and climate teleconnections in major African aquifers

Water resources management is a critical issue in Africa where many regions are subjected to sequential droughts and floods. The objective of our work was to assess spatiotemporal variability in water storage and related controls (climate, human intervention) in major African aquifers and consider approaches toward more sustainable development. Different approaches were used to track water storage, including GRACE/GRACE Follow On satellites for Total Water Storage (TWS); satellite altimetry for reservoir storage, MODIS satellites for vegetation indices, and limited ground-based monitoring. Results show that declining trends in TWS (60–73 km3 over the 18 yr GRACE record) were restricted to aquifers in northern Africa, controlled primarily by irrigation water use in the Nubian and NW Saharan aquifers. Rising TWS trends were found in aquifers in western Africa (23–49 km3), attributed to increased recharge from land use change and cropland expansion. Interannual variability dominated TWS variability in eastern and southern Africa, controlled primarily by climate extremes. Climate teleconnections, particularly El Nino Southern Oscillation and Indian Ocean Dipole, strongly controlled droughts and floods in eastern and southern Africa. Huge aquifer storage in northern Africa suggests that the recent decadal storage declines should not impact the regional aquifers but may affect local conditions. Increasing groundwater levels in western Africa will need to be managed because of locally rising groundwater flooding. More climate-resilient water management can be accomplished in eastern and southern Africa by storing water from wet to dry climate cycles. Accessing the natural water storage provided by aquifers in Africa is the obvious way to manage the variability between droughts and floods.

A new species Lappula botschantzevii (Boraginaceae) from the Northern Africa

A new species, Lappula botschantzevii, is described from the desert zone of North-Western Africa. The new species belongs to the section Lappula and is close to the species L. patula, from which it differs in a smaller corolla, a scorpioid inflorescence (bilateral flowers) with loosely spaced flowers, a heteromorphic coenobium with two types of eremocarps: A) winged with glochids and a large number of spines along the edges of the disc of eremocarps and B) with a second short row of spines. The species is described based on samples from collections housed in three herbaria: Herbarium of the Komarov Botanical Institute RAS, Sankt-Peterburg (LE, Russia) and Muséum National d ‘Histoire Naturelle, Paris (P, France), Université de Montpellier (MPU). It is named after the Russian botanist Viktor Petrovich Botschantzev, who spent many years studying the flora of Africa and who collected samples of the new species. The absence of holotypes required the typification of the names of the studied species Lappula patula, L. capensis and L. eckloniana.

Illustrated key to the genera and catalogue of Mymaridae (Hymenoptera) in the Afrotropical region

Separate identification keys for females, and for males where known, of the 40 genera of Mymaridae (Hymenoptera: Chalcidoidea) in the Afrotropical region are given. The subgenera of four genera are also included in the key to females. The genera are illustrated with over 300 photographs. The 122 named, valid species reported from the region are catalogued. Reliable host records are reported for 6 genera and 11 species from rearings undertaken in the region. An appendix lists the 27 species from northern Africa and offshore islands (Canary Islands, Madeira) but not recorded in the Afrotropical region as defined in this publication. Camptoptera (Zemicamptoptera) Ogloblin & Annecke, syn. n. is synonymized with Camptoptera (Camptoptera) Foerster. Eofoersteria Mathot, syn. n. is synonymized with Camptoptera Foerster and is treated as subgenus C. (Eofoersteria) Mathot, stat. n.; its type species Eofoersteria camptopteroides Mathot is transferred to Camptoptera as C. (Eofoersteria) camptopteroides (Mathot), comb. n. Polynema megacephala (Risbec) is transferred to Lymaenon as L. megacephala (Risbec), comb. n. Limacis opuntiae Risbec is transferred to Encarsia Foerster (Hymenoptera: Aphelinidae) as E. opuntiae (Risbec), comb. n. A few corrections to Huber et al. (2020) are given.