Interannual variability patterns of the world’s total column water content: Amazon River basin

Bordi, Isabella; Bonis, R. De; Fraedrich, Klaus; Sutera, Alfonso

doi:10.1007/s00704-014-1304-y

Cited by 10 publications

(11 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is those basin‐wide numbers which are the basis of our assertion of an intensification of the Amazon hydrological cycle, while the spatial patterns (Figure ) serve to show where the increases happened. We also find a positive trend of water vapor content above the basin (Figure d) which has most recently been reported also by Bordi et al [], as well as over the northern tropical Atlantic (not shown, region examined: latitude range: 1.5°N, …, 31.5°N and longitude range: 298.5°E, …, 328.5°E). This latter trend is also seen in stand‐alone remote sensing data [ Santer et al , ] and is consistent with expectations given recent tropical Atlantic surface warming (Figure d).…”

Section: Recent Amazon Climate Patternssupporting

confidence: 91%

Recent Amazon climate as background for possible ongoing and future changes of Amazon humid forests

Gloor

Barichivich

Ziv

et al. 2015

Global Biogeochemical Cycles

133

View full text Add to dashboard Cite

Recent analyses of Amazon runoff and gridded precipitation data suggest an intensification of the hydrological cycle over the past few decades in the following sense: wet season precipitation and peak river runoff (since ∼1980) as well as annual mean precipitation (since ∼1990) have increased, while dry season precipitation and minimum runoff have slightly decreased. There has also been an increase in the frequency of anomalously severe floods and droughts. To provide context for the special issue on Amazonia and its forests in a warming climate we expand here on these analyses. The contrasting recent changes in wet and dry season precipitation have continued and are generally consistent with changes in catchment-level peak and minimum river runoff as well as a positive trend of water vapor inflow into the basin. Consistent with the river records, the increased vapor inflow is concentrated to the wet season. Temperature has been rising by 0.7 ∘ C since 1980 with more pronounced warming during dry months. Suggestions for the cause of the observed changes of the hydrological cycle come from patterns in tropical sea surface temperatures (SSTs). Tropical and North Atlantic SSTs have increased rapidly and steadily since 1990, while Pacific SSTs have shifted during the 1990s from a positive Pacific Decadal Oscillation (PDO) phase with warm eastern Pacific temperatures to a negative phase with cold eastern Pacific temperatures. These SST conditions have been shown to be associated with an increase in precipitation over most of the Amazon except the south and southwest. If ongoing changes continue, we expect forests to continue to thrive in those regions where there is an increase in precipitation with the exception of floodplain forests. An increase in flood pulse height and duration could lead to increased mortality at higher levels of the floodplain and, over the long term, to a lateral shift of the zonally stratified floodplain forest communities. Negative effects on forests are mainly expected in the southwest and south, which have become slightly drier and hotter, consistent with tree mortality trends observed at the RAINFOR Amazon forest plot network established in the early 1980s consisting of approximately 150 regularly censused 1ha plots in intact forests located across the whole basin.

show abstract

Section: Recent Amazon Climate Patternssupporting

confidence: 91%

Recent Amazon climate as background for possible ongoing and future changes of Amazon humid forests

Gloor

Barichivich

Ziv

et al. 2015

Global Biogeochemical Cycles

133

View full text Add to dashboard Cite

show abstract

“…(2014); Bordi et al (2014) and Bianchi et al (2016a). Moreover, this effect can also affect other variables.…”

Section: Discussionmentioning

confidence: 99%

“…In this work, the authors also highlight that the models overestimate IWV for sites near the sea. Bordi et al (2014) studied global trend patterns of a yearly mean of IWV from ERA-20CM and ERA-Interim. The authors highlight a regional dipole pattern of inter-annual climate variability over South America from ERA-Interim data.…”

mentioning

confidence: 99%

Comparison of GNSS integrated water vapor and NWM reanalysis data over Central and South America

Fernández

Meza

Natali

et al. 2019

Preprint

View full text Add to dashboard Cite

We compared and analyzed data of vertically Integrated Water Vapor (IWV) from two different re-analysis models (The comparison was performed taking into account the geopotential height differences between each GNSS station and 5 the correspondent values assigned by the models. Thus, the set of GNSS stations was divided into 3 groups: Small, Large and Critical height difference stations. Moreover, the performance of the re-analysis models was also analyzed by using an additional classification of three levels according to the mean IWV (IW V ) value expected at the station: IW V > 30 kg m −2 , 12 kg m −2 IW V 30 kg m −2 and IW V < 12 kg m −2 .Both models (IW V ERA−Interim and IW V M ERRA−2 ) offered a very good representation of the IWV from GNSS values 10 (IW V GN SS ) for stations with a Small height difference (smaller than 100 meters). That is to say, the differences between the mean values of IWV from GNSS (IW V GN SS ) with respect to the IWV averages from both re-analysis models are always below 7 % of the IW V GN SS in the worse case.In general, the discrepancies between the re-analysis models with respect to IW V GN SS raise as the geopotential height difference between the GNSS station and the static geopotential height interpolated from the models grows. Effectively, the 15 difference between IW V GN SS and IWV from the re-analysis models can be as large as 10 kg m −2 for stations with a critical height difference (larger than 500 meters). For this reason, we proposed a numerical correction that compensates the effect of the geopotential height difference and the results were tested with values from ERA-Interim.The suggested correction was successful and reduces the differences |IW V GN SS − IW V ERA−Interim | to less than a 7 % of the mean IW V GN SS values. This strategy is especially recommended for stations that were classified as Critical, most of 20 them located in mountainous areas of South America. In the case of Large height difference stations, the correction procedure is not advisable either for a coastal station and/or stations in islands. Generally in those cases, two or more grid point are on the water. Thus, the interpolated IWV value for the re-analysis model will be overestimated. At one hand, if the geopotential height of the model is smaller than the geopotential height of the GNSS station, the subtracting numerical correction would compensate this overestimation of IWV near the water and thus the strategy will represent an improvement. On the other 25 Water vapor is an abundant natural greenhouse gas of the atmosphere. The knowledge of its variability in time and space is very important to understand the global climate system (Dessler et al., 2008). Most of the regional comparisons of IWV from GNSS are aimed at validating the technique by comparing with radiosonde and radiometers where available. A complete example of this is the work of Van Malderen et al. (2014) who compared IWV GPS (Global Positioning System) with IWV derived from ground-based sun photometers, radiosondes and satel...

show abstract

“…The values of columnar integrated content of water vapor (IWV) as reanalysis products from ERA-Interim (Dee et al, 2011) and MERRA-2 (GMAO, 2015;Bosilovich et al, 2015;Gelaro et al, 2017) were evaluated in this study. The horizontal resolutions are 0.25 • × 0.25 • for ERA-Interim and 0.625 • × 0.50 • for MERRA-2.…”

Section: Iwv From Nwmmentioning

confidence: 99%

“…Additionally, MERRA-2 assimilates observations not available to MERRA and reduces bias and imbalances in the water cycle (Gelaro et al, 2017). Moreover, the longitudinal resolution of MERRA-2 data is changed from 0.667 • in MERRA to 0.625 • , whereas the latitudinal resolution remains unchanged (0.5 • ) (Bosilovich et al, 2015).…”

Section: Iwv From Nwmmentioning

confidence: 99%

A numerical method to improve the spatial interpolation of water vapor from numerical weather models: a case study in South and Central America

et al. 2019

View full text Add to dashboard Cite

Abstract. Commonly, numerical weather model (NWM) users can get the vertically integrated water vapor (IWV) value at a given location from the values at nearby grid points. In this study we used a validated and freely available global navigation satellite system (GNSS) IWV data set to analyze the very well-known effect of height differences. To this end, we studied the behavior of 67 GNSS stations in Central and South America with the prerequisite that they have a minimum of 5 years of data during the period from 2007 to 2013. The values of IWV from GNSS were compared with the respective values from ERA-Interim and MERRA-2 from the same period. Firstly, the total set of stations was compared in order to detect cases in which the geopotential difference between GNSS and NWM required correction. An additive integral correction to the IWV values from ERA-Interim was then proposed. For the calculation of this correction, the multilevel values of specific humidity and temperature given at 37 pressure levels by ERA-Interim were used. The performance of the numerical integration method was tested by accurately reproducing the IWV values at every individual grid point surrounding each of the GNSS sites under study. Finally, considering the IWVGNSS values as a reference, the improvement introduced to the IWVERA-Interim values after correction was analyzed. In general, the corrections were always recommended, but they are not advisable in marine coastal areas or on islands as at least two grid points of the model are usually in the water. In such cases, the additive correction could overestimate the IWV.

show abstract

Interannual variability patterns of the world’s total column water content: Amazon River basin

Cited by 10 publications

References 39 publications

Recent Amazon climate as background for possible ongoing and future changes of Amazon humid forests

Recent Amazon climate as background for possible ongoing and future changes of Amazon humid forests

Comparison of GNSS integrated water vapor and NWM reanalysis data over Central and South America

A numerical method to improve the spatial interpolation of water vapor from numerical weather models: a case study in South and Central America

Contact Info

Product

Resources

About